small sailboat rudder design

Boat Plans, Patterns and Supplies For the Amateur Boat Builder!

• Boat Plans Catalog – 300 Boats You Can Build!
• Boatbuilding Supplies & Epoxy
• Inboard Hardware
• Electrical Design Plans
• Books, DVD’s & Audio
• Boat Trailer Plans
• Raptor® Fastenings & Tools
• Glen-L RV Plans
• Gift Certificates
• Boatbuilder Blogs
• Boatbuilder Galleries
• Newsletter Archives
• Customer Photos Archives
• Where Do I Start…
• About Our Plans & Kits
• Boatbuilder Forum
• Boatbuilder Gatherings
• Boatbuilding Methods
• Featured Design on TV’s NCIS
• Our Boats in Action

Small boat kick-up rudder

Rigging small sailboats.

….. deck fittings

Some comments on winches have been made previously. The variety and type of winches available to the sailor is enormous, but for the small boat sailor, winches usually are restricted to the smaller sizes used to control the jib and Genoa sheets. Winches can be used for the halyards, boom vang, and mainsheets, if desired. On small boats the cost is usually prohibitive, and the extra power gained is not required, as these lines can be handled by the crew or by other means, such as tackles, equally well.

RUDDER FITTINGS

Small sailboats usually have rudders which are called “outboard” rudders because they hang onto the aft end of the boat in full view. Boats which have rudders under the hull and the rudder stock passing through the hull bottom are said to have “inboard” rudders, but these are usually associated with large boats. The ordinary small boat rudder is attached to the boat with fittings that also allow the rudder to pivot or turn. These fittings are called GUDGEONS and PINTLES. These are arranged in pairs, with the gudgeons usually being attached to the boat, and the pintles fastened to the rudder. The pintles are strap-like fittings with the rudder fitting between the straps, and with a pin at the forward edge which fits into the “eye” of the gudgeons (see Fig. 6-10). As with most fittings, many sizes and types are available. Often gudgeons and pintles come in pairs which have a long pintle and a shorter one. These types make it easier to put the rudder on the boat, as the long pintle will be in position first, thereby acting as a guide for the short one. If both pintles are the same length, both must fit into the gudgeons at the same moment, which is frustrating at times, especially when trying to place the rudder in position when afloat. Because many small boat rudders are made of wood, the tendency is for these to float up and out of the gudgeons, of course, making for an immediate loss of steering and much embarrassment. A device called a RUDDER STOP can be used to prevent this from occuring. These are standard marine hardware items very simple in nature.

For small sailboats which land on the beach, it is desirable to have the rudder “kick up” when approaching shallow waters. Special “kick-up” rudder fittings such as shown in Fig. 6-11 are available, which also have the gudgeons and pintles attached as an integral unit, and perform this function. With a little effort, you can make your own “kick-up” rudder similar to the detail shown in Fig. 6-12.

FIG. 6-12 – One method of making a kick-up rudder using wood. When the pin is removed, the rudder will automatically come up when hitting the beach.

FIG. 6-13 – This tiller extension was made by merely cutting the tiller in half at the forward end and fastening it with a bolt. A more convenient type uses a swivel connection in lieu of the bolt for universal action. The line shown is a rope traveler which can be adjusted in length and is secured to the jam cleat on the deck.

The rudder is controlled by a handle called the TILLER. Sometimes the tiller passes through a hole in the transom (back of the boat), but usually it is located above the aft deck area and pivots up and down so the crew can move about easily. The length of the tiller is best determined in actual use, so it should be made longer than necessary. It’s much easier to cut off a long tiller than to add length to a short one. A device recommended for easier control, especially when tacking or sailing to windward, is a TILLER EXTENSION or “hiking stick,” an example of which is shown in Fig. 6-13. When sailing to windward in a small boat, the boat usually heels considerably and the crew must lean out to windward (or “hike out”) to counteract this. In order to hang onto the tiller in this position, an extension is required, fixed to the forward end of the tiller and preferably fitted with a universal-type joint. Naturally, the length of such a unit is best determined in actual use, so it is best to get a long one which can be cut, instead of getting one too short which can’t be added to.

The next WebLetter will start Part II …how to install the rigging.

Comments are closed.

Connect with us:

Customer builds.

Useful Information

• Cost & Time To Build
• Links & Suppliers
• Online Glossary
• Support Knowledge Base
• Teleseminars
• Wood & Plywood

Building Links

• How Fast Does It Go?
• Install A Jet Ski Motor
• Modifying The Motorwell
• Sailboat Hardware Notes

Glen L Marine Design

• About Glen L
• How To Place an Order
• Privacy Policy

Copyright Info.

Copyright 2006-2022 by Glen L Marine Designs. All rights reserved.

Mailing Address: 826 East Park Ave. Port Townsend, WA 98368

[email protected]

Web design by Big Guns Marketing , LLC.

Small Craft Advisor

Build Your Own Kick Up Rudder

William mantis offers up plans for a creative and effective diy rudder.

by Bill Mantis

I built a rudder for my 8.5’ x 4.5’ sailboat—named City Slicker 2. 0—the same time I built the boat itself, two years ago . Since I was in a hurry to get it done, I didn’t bother designing a kick-up rudder, figuring I could make the modification at a later date. But then I lost it. I lost my rudder. How does one lose a rudder? I can’t explain how it happened. I only know I had it when I came ashore one day, and didn’t have it the next time I tried to launch. Fortunately, I’d been designing a kick up rudder before suffering the loss, and I had the necessary epoxy and lumber on hand. Only the material for the rudder blade and new pintles had to be ordered. As a result, I lost only one week of the sailing season.

Keep reading with a 7-day free trial

Subscribe to Small Craft Advisor to keep reading this post and get 7 days of free access to the full post archives.

• New Sailboats
• Sailboats 21-30ft
• Sailboats 31-35ft
• Sailboats 36-40ft
• Sailboats Over 40ft
• Sailboats Under 21feet
• used_sailboats
• Apps and Computer Programs
• Communications
• Fishfinders
• Handheld Electronics
• Plotters MFDS Rradar
• Wind, Speed & Depth Instruments
• Anchoring Mooring
• Running Rigging
• Sails Canvas
• Standing Rigging
• Diesel Engines
• Off Grid Energy
• Cleaning Waxing
• DIY Projects
• Repair, Tools & Materials
• Spare Parts
• Tools & Gadgets
• Cabin Comfort
• Ventilation
• Footwear Apparel
• Foul Weather Gear
• Mailport & PS Advisor
• Inside Practical Sailor Blog
• Activate My Web Access
• Reset Password
• Pay My Bill
• Customer Service

• Free Newsletter
• Give a Gift

How to Sell Your Boat

Cal 2-46: A Venerable Lapworth Design Brought Up to Date

Rhumb Lines: Show Highlights from Annapolis

Open Transom Pros and Cons

Leaping Into Lithium

The Importance of Sea State in Weather Planning

Do-it-yourself Electrical System Survey and Inspection

Install a Standalone Sounder Without Drilling

When Should We Retire Dyneema Stays and Running Rigging?

Rethinking MOB Prevention

Top-notch Wind Indicators

The Everlasting Multihull Trampoline

How Dangerous is Your Shore Power?

DIY survey of boat solar and wind turbine systems

What’s Involved in Setting Up a Lithium Battery System?

The Scraper-only Approach to Bottom Paint Removal

Can You Recoat Dyneema?

Gonytia Hot Knife Proves its Mettle

Where Winches Dare to Go

The Day Sailor’s First-Aid Kit

Choosing and Securing Seat Cushions

Cockpit Drains on Race Boats

Rhumb Lines: Livin’ the Wharf Rat Life

Re-sealing the Seams on Waterproof Fabrics

Safer Sailing: Add Leg Loops to Your Harness

Waxing and Polishing Your Boat

Reducing Engine Room Noise

Tricks and Tips to Forming Do-it-yourself Rigging Terminals

Marine Toilet Maintenance Tips

Learning to Live with Plastic Boat Bits

• Boat Maintenance

Building a Faster Rudder

Boost performance with a bit of fairing and better balanced helm..

We’re cruisers not racers. We like sailing efficiently, but we’re more concerned with safety and good handling than squeezing out the last fraction of a knot. Heck, we’ve got a dinghy on davits, placemats under our dishes, and a print library on the shelf. So why worry about perfection below the waterline?

The reason is handling. A boat with poorly trimmed sails and a crudely finished rudder will miss tacks and roll like a drunkard downwind when the waves are up. On the other hand, a rudder that is properly tuned will agilely swing the boat through tacks even in rough weather, and provide secure steering that helps prevents broaching when things get rolly. The difference in maximum available turning force between a smooth, properly fitted rudder and the same rudder with a rough finish and poor fit can be as much as 50% in some circumstances, and those are circumstances when you need it the most. It’s not about speed, it’s about control.

It Must Be Smooth

Smooth is fast. That’s obvious. But it makes an even bigger difference with steering. Like sails, only half of rudder force comes from water deflected by the front side of the blade. The rest results from water being pulled around the backside as attached flow. How well that flow stays attached is related to the shape of the blade, which we can’t easily change, and to the surface finish of the blade, which we can.

Remember the school experiment, where you place a spoon in a stream of water and watched how the water would cling to the backside of the spoon? Now, try the experiment again as a grown-up, but with a different set of materials.

Try this with a piece of wood that is smooth and one that is very rough; the water will cling to the smooth surface at a greater angle than the rough surface. Try piece of smooth fiberglass or gelcoat; the water will cling even better because the surface is smoother. Try a silicone rubber spatula from the kitchen. Strangely, even though the surface is quite smooth, the water doesn’t cling well at all. We’ll come back to that.

Investigators have explored this in a practical way, dragging rudders through the water in long test tanks (US Navy) and behind powerboats.

If we are trying to climb to windward, it’s nice to get as much lift out of the rudder as practical, before drag becomes too great or before it begins to stall with normal steering adjustments. If the boat has an efficient keel and the leeway angle is only a few degrees, the rudder can beneficially operate at a 4-6 degree angle. The total angle of attack for the rudder will be less than 10 degrees, drag will be low, and pointing will benefit from the added lift. If the boat is a higher leeway design—shoal draft keels and cruising catamarans come to mind—then the rudder angle must stay relatively low to avoid the total angle (leeway + rudder angle) of the rudder from exceeding 10 degrees. That said, boats with truly inefficient keels but large rudders (catamarans have two—they both count if it is not a hull-flying design) can sometimes benefit from total angles slightly greater than 10 degrees—they need lift anywhere they can get it.

How can you monitor the rudder angle? If the boat is tiller steered, the tiller will be about 0.6 inches off center for every degree or rudder angle, for every 3 feet of tiller length. In other words, the 36-inch tiller should not be more than about 2 inches off the center line. If the boat is wheel steered, next time the boat is out of the water, measure the rudder angle with the wheel hard over. Count the number of turns of the wheel it takes to move the rudder from centered to rudder hard over, and measure the wheel diameter. Mark the top of the rim of the wheel when the boat is traveling straight, preferably coasting without current and no sails or engine to create leeway.

The rim of the wheel will move (diameter x 3.146 x number of turns)/(degrees rudder angle at hard over) for each degree of rudder angle. Keep this in the range of 2-6 degrees when hard on the wind, as appropriate to your boat. It will typically be on the order of 4-10 inches at the steering wheel rim. A ring of tape at 6 degrees can help.

How do we minimize rudder angle while maintaining a straight course? Trimming the jib in little tighter or letting the mainsheet or traveler out a little will reduce pressure on the rudder and reduce the angle. Some boats actually sail to weather faster and higher, and with better rudder angles, by lowering the  traveler a few inches below the center line.

On the other hand, tightening the mainsheet and bringing the traveler up, even slightly above the center line on some boats, will increase the pressure and lift.

Much depends on the course, the sails set, the rig, the position of the keel, the wind, and the sea state. Ultimately, some combination of small adjustments should bring the rudder angle into the appropriate range. Too much rudder angle and you are just fighting yourself.

• Turn this rudder just 10 degrees and the end plate is lost, reducing the amount of lift generated.

• This rudder might as well be transom hung, the way that the end cap just disappears.

• Stern-hung rudders, and spade rudders with large gaps between the hull and the top of the rudder will lose their lift at the “tip” of the blade near the surface.

Surface roughness affects the lift from the rudder in two ways. A rougher surface has slightly lower lift through the entire range of angles, the result of a turbulent boundary layer instead of smooth flow over the entire surface. More dramatically, rougher blades stall at lower angles and stall more completely. The difference between a faired rudder with a polished finish and a rudder carrying a 10-year accumulation of rolled-on antifouling paint can be as much is 35 percent (see “Rudder Savvy to Boost Boat Performance,” above).

What can we do? If your rudder is a lift up type, don’t use bottom paint. Fair the blade within an inch of its life and lay on a gloss topside paint as smoothly as possible, sanding between coats. If you use a brush, stroke the brush parallel to the waterline, not along the length of the blade.

Which is faster, a gloss finish or one that has been dulled with 1000 grit sandpaper? Opinions go both ways, and we believe it may depend on the exact nature of the paint, which leads to the question, “Should we wax the blade?” The answer is a resounding, no.

Wax is a hydrophobic (readily beads water), like the silicone rubber spatula you tested, and as a result, water doesn’t always cling as well. Thus, whether the paint should be deglossed or not depends on the chemistry of the paint, but in all cases the final sanding should be 1000 grit or finer.

If the rudder stays in the water, antifouling paint is required. Sand the prior coat perfectly smooth. There should be no evidence of chips, runners, or any irregularity at all. Using a mohair roller, lay the paint on thin, and apply multiple coats to withstand the scrubbing you will give your rudder from time to time.

Even if you use soft paint on the rest of the boat, consider hard paint for the rudder. Sure, it will build up and you will have to sand it off periodically, but the rudder is small and no part of your boat is more critical to good handling. Take the time to maintain it as a perfect airfoil.

Close the Gap

Ever notice the little winglets on the tips of certain airplanes? As we know, those are intended to reduce losses off the tip of the wing. The alternatives are slightly longer wings or slightly lower efficiency. At the fuselage end of the wing, of course, there is no such loss because the fuselage serves as an end plate. The same is true with your rudder.

There’s not much you can do about losses from the tip; making the rudder longer will increase the chance of grounding and increase stress on the rudder, rudder shaft, and bearings. Designers have experimented with winglets, but they the catch weeds and the up-and-down motion of the transom makes them inefficient. However, we can improve the end plate effect of the hull by minimizing the gap between the hull and the rudder.

In principle it should be a close fit, but in practice the gap is most often wide enough to catch a rope. Just how much efficiency is lost by gap of a few inches? The answer is quite a lot. A gap of just an inch can reduce lift by as much as 10-20 percent, depending on the size and shape of the rudder and the speed. A gap of 1-2 mm is quite efficient, but normal flexing of the rudder shaft may lead to rubbing.

If the gap is tight, the slightest bend from impact with a submerged log can cause jamming and loss of steering, though in my experience once the impact is sufficient to bend the shaft, a small difference in clearance is unlikely to make much difference; the shaft will bend until the rudder strikes the hull. Just how tight is practical depends on the type of construction, fitting accuracy, and how conservative the designer was in their engineering.

Carbon shafts, tubular shafts, and rudders with skegs flex less, while solid shafts generally flex more, all things being equal. Normally a clearance of about 1/4-inch per foot of rudder cord is practical, and performance-oriented boats often aim for much less. If you can reach your fingers through, that’s way too much. Hopefully the hull is relatively flat above the rudder so that the gap does not increase too much with rudder angle.

Practical Sailor’s technical editor Drew Frye is the author of the books Keeping a Cruising Book for Peanuts and Rigging Modern Anchors. He blogs at his website, sail delmarva.blogspot.com .

RELATED ARTICLES MORE FROM AUTHOR

21 comments.

How happy to see good technical information about the science of boat speed and control. This information is valuable to everyone, but the “mainly just cruising” cohort usually doesn’t get enough in an easily understandable form. I always suggest some club level racing as the best way to learning how to sail, but many prospective racers have been put off from the sport or haven’t had good opportunities to join the fleets. Technical seminars are generally either too advanced for beginners to understand properly, and the beginner classes are frequently too basic to inspre those who would benefit from a deeper knowledge base in the science of sailing. Good on you, Practical Sailor, for your technical stories hitting the “sweet spot,” getting this information to those we’ll benefit most.

Great article. How about considering modifying a rudder to make it a hydrodynamically balanced rudder. I did it to my boat and the difference is outstanding. If I remember correctly 7% of the rudder area is forward of pivot center. It is a skeg hung rudder that now turns like it’s a spade rudder.

I’m “skeg hung” also. Would you be so kind as to posting a link or providing info as to you accomplished this feat. Thanks!

A very clear explanation of some quite complicated hydrodynamics – thank you! I am surprised by the US Navy results showing benefit of sanding further than 400 grit. Most other experimental data suggest there is negligible advantage in going beyond about 360 grit. Is the original reference publicly available? On Michael Cotton’s comment, a couple of points: Firstly, the amount of balance (i.e how far back you put the stock in the blade) has no impact on the hydrodynamic performance of a spade rudder. What it does do is change the feel of the rudder; a well balanced rudder will be easier to use, thereby probably allowing the steerer to sail the boat better. For a skeg rudder, the hydrodynamic impact of changing the balance depends very much on how the skeg/blade combination is configured. Secondly, 7% of rudder area forward of the stock is not enough for most rudders. The position of the centre of pressure is dependent on a lot of factors (aspect ratio, rudder angle etc.), but it is usually at least 15% back from the leading edge on a spade rudder, more often 20%. A balance somewhere between 10% and 15% is likely to give just enough feel without too much weight. However, rudder balance is still a bit of a black art, it really does depend on the rudder geometry.

the statement that one doesn’t want a silicone/silane coated ( super-smooth, hydrophobic: silicone-silane is just the example I am choosing, since it is now in use as a massively-speeding hull-coating, ttbomk ), as it *induces* flow-separation…

looks to me like conflating cavitation with flow-separation.

People have no problem teflon/ptfe-coating aviation-wings, as a means of *preventing* flow-separation.

the super-slick shape of a Cirrus’s composite wing, if made super-smooth/polished & super-slippery, “air-phobic”, as it were, *improves* its performance, not detracts from it….

Flow is always 1. laminar, then 2. turbulent, then 3. flow-separation.

unless the angle-of-attack ( AoA ) is small-enough to prevent separation.

The Gentry Tufts System, for *seeing* when a separation-bubble begins, on a sail, is brilliant ( Arvel Gentry was a fluid dynamicist, & realized that once one has a *series* of tufts, from luff on back, about 1/4 up the luff, one can *see* the beginning of a flow-separation-bubble, & tune the sail to keep it *just*-beginning, because *that* is MAX lift. Wayback Machine has his site archived, btw )

The aircraft designer Jan Roskam wrote of a DC-10 crashing because pebbled-ice as thick as the grit on 40-grit sandpaper had formed on the upper wings…

obviously, engineered to require laminar, there, but having turbulent, cost all those lives.

iirc, it was Arvel Gentry, or “Principles of Yacht Design”, that stated it takes a ridge of about 0.1mm, only, to trip the flow around a mast from laminar to turbulent…

Given how barnacles & such are generally 100x or more as thick as that, when removed from a hull, I think laminar-flow is something that exists only for the 1st day or so after launching!

I now want to see experiment showing polar curves for rudders coated normally, uncoated, & ailicone-silane coated, to see if it is the coating that induces separation-bubbles, or if it is AoA exceeding functional angle, for that surface & foil,, while the boundary-layer is in specifically turbulent flow, as opposed to the ideal laminar, as aviation’s results indicate…

just an amateur student of naval-architecture & aircraft-design ( Daniel P. Raymer’s “Conceptual Aircraft Design” is *brilliant*, btw ), who happens to study this stuff autistically, as that is the only way to make my designs become absolutely-competent, is all…

I got a pearson and the rudder broke. Can I just replace with a outboard rudder mount it off set for room for outboard need info.

You could but it will not work very well. How badly it would perform is difficult to say. It might be just poor or disastrous. Things really need to be balanced on sail boats.

Polished rudders stall at low angles of attack and ask any hobie cat racer.

Pi is NOT 3.146

3.1416 maybe

Yup, 3.1416. Typo.

Before 2005 , when I fully retired and went cruising 10 months per year, I changed auto pilots, the hydraulics of which reduced the maximum rudder angle. “Someday” had always been difficult to steer in marinas, so I added 30% more rudder area to the Gulfstar 41′ by deepening and following the existing angles. (the pivot was unchanged, as all added area was aft of that.) It increased rudder effort noticeably, but not excessively, improved motor maneauvering and allowed being able to hold a close line better. Noticeably, it caused a lot more stalling of the rudder whenever it was turned very much. A recent tangle with a Guatemala fish net damaged the extension, which I had intended to be sacrificial. I cleaned up the separation somewhat, but have not replaced the extension. The boat again now requires more steering correction when heading at all upwind, but the rudder does not stall as easily.

This is not a scientific study, just my personal non-scientific observations. The added rudder area was quite low, and the fairing quality was…well! modest.

I’ve seen data suggesting ~ 400 grit is best, and I’ve seen data suggesting polished is best. They were both smart, respected guys that I would not second guess. My conclusion is that other factors, such as the specific foil profile and the type of coating, are involved. Let’s just agree that many layers of rolled bottom paint with a few lumps and chips is sub-optimal! We’re talking about cruising boats.

Thanks for great article. I’m convinced enough to go sand my bottom paint off the lifting rudder of my Dragonfly Tri.

Absolutely! No lifting rudder should have bottom paint. My Farrier rudder was sanded fair and painted with gloss white.

Dagger boards and center boards that retract still need antifouling, since they do not lift clear of the water, but because they are in a confined space with little oxygen or water flow, fouling is very limited. Because the space is tight and paint build-up can cause jamming, sand well and limit the number of coats. For my center board I go with two coats on the leading edge (exposed even when lifted) and one coat on the rest.

I do remember a comment directed to cruisers a few years back suggesting that a faster cruiser would be more likely to get out of the way of dirty weather, especially with modern forecasting. I reckoned that this concept would gain traction, but I haven’t seen it. Can anyone weigh in on this opinion?

As interesting as the article reads, I wonder how it helps a prospective buyer of a used boat. Pictures will not do, and neither will taking several boats out of the water to examine them; it’s too expensive. It would be more helpful to indicate which boat manufacturers have the type of rudder the author recommends. After all, the buyer usually cannot be expected to change a rudder prior to buying it; it is also expensive. By the way, these types of very sophisticated articles are seen when it comes to hulls, keels, or rigging but without identifying the boats that carry the wrong equipment. If a specific rudder or keel configuration is not the proper one for efficient sailing, the author ought to state which boats carry the proper ones so that the buyer will concentrate on the whole (the boat) rather than the part.

I was describing the opportunity to improve the existing rudder. As I think back, I have modified the rudder of every boat I have owned in order to improve efficiency. The first two got small changes in balance and improved trailing edge sharpness. On the third I tightened the the hull clearance and changed the section. On my current boat I adding an anti-ventilation fence to improve high speed handling. https://4.bp.blogspot.com/-2ZGPzKdj_tE/WyF9G2mHtLI/AAAAAAAAOwE/r6zgQEr4vkcDB4ciMLcgboFdazDAseDBgCLcBGAs/s1600/ian%2Brudder%2Bfence.jpg None of these tasks was overly difficult, and none was undertaken until I had sailed the boat for a season and learned what balance she liked and noted her habits.

For me, I buy a boat based on reputation, a test sail, and in most cases, a survey. As you imply, it is the whole boat you are buying. Does it have good bones? Do you feel happy at the helm? Then comes the fine tuning. I’ve been told that I sell a boat when I run out of things to tweak.

wow, so now case reports/medical reports/evidence don’t count as “evidence”, but certain remedies, even if they are cited in medical journals but do not work in the real world, count as evidence to you?? Maybe we need to redefine evidence based on your philosophies.Anyway, i’ve wasted enough time here. goodbye.

Weight 2.5 tonnes

Do you have any articles on the ideal cross section shape for an outboard rudder mounted 50mm from the transom vertically The yacht is a 26 ft trailer sailer weight 2.5 tonnes

The most common choice would be NACA 0012. http://airfoiltools.com/airfoil/details?airfoil=n0012-il

There are many ways to build a rudder, including laminated solid rot-resistant wood and fiber glass covered foam with a metal armature core. For the DIY, laminated wood is probably the most practical.

LEAVE A REPLY Cancel reply

Log in to leave a comment

Latest Videos

Island Packet 370: What You Should Know | Boat Review

How To Make Starlink Better On Your Boat | Interview

Catalina 380: What You Should Know | Boat Review

• Privacy Policy
• Do Not Sell My Personal Information
• Online Account Activation
• Privacy Manager

• Paddle Board

What Is a Sailboat Rudder? An Overview of Its Function and Design

Sailboats have been used for thousands of years to traverse water. They have undergone many changes and improvements over the years, and one of the essential components of a sailboat is the rudder.

Quick Facts

Understanding the sailboat rudder.

The rudder is a vital component of a sailboat that plays a crucial role in steering and maneuvering the vessel. The rudder works by changing the direction of the water flow around it, which moves the boat in the opposite direction. Without a rudder, it would be impossible to navigate a sailboat effectively, especially in different water and wind conditions.

Components of a Sailboat Rudder

A sailboat rudder comprises several components, each with a unique function that contributes to the rudder’s overall effectiveness. The stock is the main vertical shaft that connects the rudder blade to the boat’s helm. It is usually made of stainless steel or aluminum alloy and is designed to withstand the forces exerted on the rudder during navigation.

The blade is the flat portion of the rudder that faces the water current and directs the water flow in the opposite direction to steer the boat. The blade is typically made of fiberglass-reinforced plastic or aluminum alloy and is designed to be lightweight and durable. Pintles and gudgeons are the two connections between the rudder and stern that allow for easy installation and removal of the rudder. Pintles are the vertical metal pins that fit into the gudgeons, which are the horizontal metal brackets attached to the boat’s stern.

Different Types of Rudders

There are several types of rudders used in sailboats, each with its advantages and disadvantages. Transom-mounted rudders are the most common type of rudder, and they are mounted on the stern of the boat. Skeg-mounted rudders are attached to a fixed fin called a skeg, which provides additional stability to the rudder.

Keel-mounted rudders are attached to the boat’s keel, which is the central structural element that runs along the bottom of the hull. Spade rudders are free-standing rudders that are not attached to any part of the boat and are commonly used in racing sailboats. The type of rudder used depends on the boat’s size, design, and intended use.

Materials Used in Rudder Construction

Rudders can be made from various materials, each with its advantages and disadvantages. Wooden rudders are the traditional choice and are still used in some sailboats today. However, they are relatively heavy and require regular maintenance to prevent rot and decay.

Aluminum alloy rudders are lightweight and durable, making them an excellent choice for racing sailboats. Stainless steel rudders are also durable but are heavier than aluminum alloy rudders. Fiberglass-reinforced plastic rudders are the most common type of rudder used today, as they are lightweight, durable, and require minimal maintenance.

The sailboat rudder is an essential component that plays a crucial role in steering and maneuvering a sailboat. Understanding the different types of rudders, their components, and the materials used in their construction can help sailors choose the right rudder for their boat and navigate more effectively in different water and wind conditions.

The Function of a Sailboat Rudder

Steering and maneuvering.

The primary function of a sailboat rudder is to steer and maneuver the boat. The rudder’s blade directing the flow of water in a specific direction allows for the steering of the boat as the blade changes direction. Sailors can use the rudder to turn the boat in any direction they choose, allowing them to navigate through narrow channels or around obstacles in the water. It is essential to note that the rudder works in conjunction with the sails to control the boat’s direction and speed.

Balancing the Sailboat

The balance of the sailboat is critical to ensure safe maneuvering, and the rudder plays a crucial role in achieving this. A balanced rudder helps in keeping the boat steady, reducing drag, and preventing unwanted turning. Sailors can adjust the rudder’s angle to keep the boat balanced and on course, especially in rough water conditions. A well-balanced rudder also helps to reduce the risk of capsizing or losing control of the boat .

Rudder Effectiveness in Different Conditions

Rudder effectiveness varies depending on the boat’s size, weight, and water and wind conditions. A larger boat may require a bigger rudder for proper maneuvering, while a smaller boat can work with a smaller rudder. Sailors must also consider the water and wind conditions when choosing the right rudder for their boat. In calm waters, a smaller rudder may be sufficient, but in rough water, a larger rudder may be necessary to maintain control of the boat. Additionally, the rudder’s effectiveness can be affected by the boat’s speed, with higher speeds requiring more significant rudders to maintain control.

It is also important to note that the rudder’s effectiveness can be impacted by external factors such as weeds or debris in the water. These factors can reduce the rudder’s ability to steer the boat and require sailors to make adjustments to maintain control. Additionally, the rudder’s effectiveness can be impacted by the sailor’s skill level, with more experienced sailors able to make more precise adjustments to the rudder to control the boat’s direction and speed.

Design Considerations for Sailboat Rudders

Sailboat rudders are an essential component of a boat’s steering and maneuvering system. A well-designed rudder can make all the difference in a boat’s performance , especially in challenging weather conditions. In this article, we will explore some of the key design considerations for sailboat rudders.

Rudder Size and Shape

The size and shape of a rudder play a crucial role in determining its effectiveness in steering and maneuvering a boat. A larger rudder provides more leverage and maneuverability, allowing the boat to turn more sharply. However, a larger rudder may also produce more drag, which can slow down the boat’s speed.

The shape of the rudder is also important. A well-designed rudder should be streamlined to reduce drag and turbulence. The thickness of the rudder should be carefully considered to ensure that it is strong enough to withstand the forces exerted on it while remaining lightweight.

Rudder Placement and Configuration

The placement of the rudder on the boat can significantly affect its performance. A rudder that is too far forward can cause the boat to become unstable, while a rudder that is too far aft can make it difficult to steer. The location of the rudder must also take into account factors such as the propeller’s placement and the boat’s shape.

The configuration of the rudder can also determine its effectiveness and balance. A single rudder is the most common configuration, but some boats have twin rudders to provide more steering control. The angle of the rudder blade can also be adjusted to optimize its performance.

Hydrodynamic and Aerodynamic Factors

The design of a rudder must take into consideration the hydrodynamic and aerodynamic factors affecting the boat’s performance. Hydrodynamic factors include water flow, pressure, and turbulence, which can significantly affect the rudder’s performance. The shape and placement of the rudder must be carefully designed to minimize these effects.

Aerodynamic factors consider the wind and air resistance’s impact on the boat’s performance. The rudder’s size and shape must be designed to minimize the wind’s effect on the boat while providing sufficient steering control.

The design of a sailboat rudder is a complex process that requires careful consideration of many factors. The size and shape of the rudder, its placement on the boat, and its configuration must be optimized to provide effective steering and maneuverability. By taking into account the hydrodynamic and aerodynamic factors affecting the boat’s performance, a well-designed rudder can significantly improve a sailboat’s overall performance.

Rudder Maintenance and Repair

The rudder is a crucial component of any sailboat, providing steering and control. As such, it’s essential to keep it in good working order through regular maintenance and inspections.

Inspecting Your Rudder

Regular inspection of the rudder is essential to ensure its continued performance and longevity. A thorough inspection includes checking for cracks, wear and tear, and loose components such as hinges, pins, and screws. It’s also important to check the rudder’s alignment and ensure it moves smoothly and without any obstructions.

During your inspection, be sure to check for signs of corrosion, particularly on metal components. Corrosion can weaken the rudder and cause it to fail, so regular cleaning and maintenance are essential to prevent this.

If you notice any issues during your inspection, it’s important to address them promptly. Small cracks or damage can often be repaired, but if the damage is extensive, it may be necessary to replace the rudder entirely.

Common Rudder Issues and Solutions

One common issue with rudders is corrosion, particularly on metal components. Regular cleaning and maintenance help prevent corrosion and ensure the rudder’s longevity. If you do notice signs of corrosion, it’s important to address it promptly to prevent further damage.

Another common issue is damage to the blade or stock. This can be caused by impact with debris or other boats, or simply wear and tear over time. If the damage is minor, it may be possible to repair the rudder. However, if the damage is extensive or compromises the rudder’s structural integrity, it may be necessary to replace it entirely.

Loose components such as hinges, pins, and screws can also cause issues with the rudder. These should be checked regularly and tightened or replaced as needed.

When to Replace or Upgrade Your Rudder

Sailboat rudders can last for many years, but at some point, replacement or upgrade may be necessary. This includes upgrading to a newer design or larger rudder to improve the boat’s performance or replacing a damaged or worn-out rudder that is beyond repair.

If you’re considering upgrading your rudder, it’s important to consult with a professional to ensure that the new rudder is compatible with your boat and will provide the desired performance improvements.

Regular maintenance and inspections are essential to ensure the continued performance and longevity of your sailboat’s rudder. By staying on top of any issues and addressing them promptly, you can ensure that your rudder will continue to provide reliable steering and control for many years to come.

A sailboat’s rudder is a crucial component that helps steer and maneuver the boat safely. The size, shape, placement, and construction materials must all be taken into consideration when designing or replacing a rudder. Regular maintenance and inspection help ensure its continued performance and longevity.

Rudder FAQS

How does a sailboat rudder work.

A sailboat rudder works by changing the direction of the water flow past the boat’s hull, which in turn changes the direction of the boat. The rudder is attached to the stern of the boat and can be turned left or right. When the rudder is turned, it creates a force that pushes the stern in the opposite direction and turns the bow towards the direction the rudder is turned. This is how a rudder steers a boat.

What is a rudder and its purpose?

A rudder is a flat piece, usually made of metal or wood, attached to the stern of a vessel such as a boat or ship. The main purpose of the rudder is to control the direction of the vessel. It does this by deflecting water flow, creating a force that turns the vessel. Without a rudder, steering a vessel would be significantly more challenging.

Can you steer a sailboat without a rudder?

Steering a sailboat without a rudder is challenging but not impossible. Sailors can use the sails and the keel to influence the direction of the boat. By trimming the sails and shifting weight, it’s possible to cause the boat to turn. However, this is a difficult technique that requires a deep understanding of sailing dynamics and is usually considered a last resort if the rudder fails.

What controls the rudder on a sailboat?

The rudder on a sailboat is typically controlled by a steering mechanism, like a tiller or a wheel. The tiller is a lever that is directly connected to the top of the rudder post. Pushing the tiller to one side causes the rudder to turn to the opposite side. On larger boats, a wheel is often used. The wheel is connected to the rudder through a series of cables, pulleys, or hydraulic systems, which turn the rudder as the wheel is turned.

How do you steer a sailboat with a rudder?

To steer a sailboat with a rudder, you use the tiller or wheel. If your sailboat has a tiller, you’ll push it in the opposite direction of where you want to go – pushing the tiller to the right will turn the boat to the left and vice versa. If your sailboat has a wheel, it operates like a car steering wheel – turning it to the right steers the boat to the right and turning it to the left steers the boat to the left.

How do you steer a sailboat against the wind?

Steering a sailboat against the wind, also known as tacking, involves a maneuver where the bow of the boat is turned through the wind. Initially, the sails are let out, and then the boat is steered so that the wind comes from the opposite side. As the boat turns, the sails are rapidly pulled in and filled with wind from the new direction. This maneuver allows the boat to zigzag its way upwind, a technique known as “beating.” It requires skill and understanding of sailing dynamics to execute effectively.

John is an experienced journalist and veteran boater. He heads up the content team at BoatingBeast and aims to share his many years experience of the marine world with our readers.

What to Do If Your Boat Engine Won’t Start? Common Problems & How to Fix Them

How to launch a boat by yourself: complete beginner’s guide, how to surf: complete beginner’s guide to get you started.

Comments are closed.

Type above and press Enter to search. Press Esc to cancel.

• Types of Sailboats
• Parts of a Sailboat
• Cruising Boats
• Small Sailboats
• Design Basics
• Sailboats under 30'
• Sailboats 30'-35
• Sailboats 35'-40'
• Sailboats 40'-45'
• Sailboats 45'-50'
• Sailboats 50'-55'
• Sailboats over 55'
• Masts & Spars
• Knots, Bends & Hitches
• The 12v Energy Equation
• Electronics & Instrumentation
• Build Your Own Boat
• Buying a Used Boat
• Choosing Accessories
• Living on a Boat
• Cruising Offshore
• Sailing in the Caribbean
• Anchoring Skills
• Sailing Authors & Their Writings
• Mary's Journal
• Nautical Terms
• Cruising Sailboats for Sale
• List your Boat for Sale Here!
• Used Sailing Equipment for Sale
• Sell Your Unwanted Gear
• Sailing eBooks: Download them here!
• Your Sailboats
• Your Sailing Stories
• Your Fishing Stories
• Advertising
• What's New?
• Chartering a Sailboat
• Sailboat Rudder

Making a Sailboat Rudder for s/y Alacazam

It's not enough just for a sailboat rudder to steer the boat effectively, it should also contribute to the keel's job of providing lift to windward, and for it to do this it must be designed as a hydrodynamic foil.

Of course a rudder doesn't have to provide lift, but it's a wasted opportunity if it doesn't.

As with an aircraft's wing, to develop lift the sailboat rudder must have water flowing over its leading edge at an angle of attack.

Fortunately for us sailors, the pressure of air on the windward side of the sails, pushes the boat bodily off course slightly and it's this leeway that provide the angle of attack - or angle of incidence- that enables our keels and rudders to provide lift.

But What Type of Sailboat Rudder would be Best for Alacazam ?

First, we considered twin transom-mounted rudders. The usual argument for twin rudders is:

• as the boat heels, the leeward rudder is more deeply immersed and provides better control, and
• the boat, resting on the keel and two rudders can dry-out upright.

But in the end we decided against the twin rudder arrangement because:~

• with Alacazam's deep draught (7 feet, or 2.2m) the twin rudders wouldn't be deep enough to achieve the drying-out upright benefit, and
• the mechanical complexity of tiller steered twin rudder system went against one of our key design principles - keep it simple, and
• with no propwash flowing over the rudders, manoeuvring under power in tight situations would be a little too interesting for my tastes.

So the conventional single rudder approach it was to be. But what type of sailboat rudder?

A Transom-Hung Rudder

We liked the simplicity of this arrangement, but it didn't suit Alacazam's hull design at the stern. We wanted a sugar-scoop design with a bathing platform to allow easy access from the dinghy which ruled out a transom hung rudder. Similarly, it meant that mounting the servo-pendulum self-steering gear would be unnecessarily complicated.

Spade Rudder

The spade rudder is the most efficient of all sailboat rudders, which is why you're unlikely to see any other design on racing yachts.

The absence of a skeg means that all of its area is used to apply a turning force to the hull, minimizing wetted area and associated drag.

The area ahead of the stock helps to balance the rudder, making life easier for the helmsman.

But it's not the most robust design, being entirely dependent on the strength of rudder stock to resist impact damage.

Theoretically it's just a matter of engineering, but high performance spade rudders just aren't thick enough to incorporate a rudder stock of sufficient diameter for ultimate security.

Skeg-Hung Rudder

Other than those rudders hung on the following edge of long keels, the skeg hung rudder - supported top and bottom on a full length skeg - is the most robust design.

Without a portion forward of the stock, there's no balancing force to take the load of the helmsman's arms - so loads can be quite heavy in some designs.

Nevertheless, it's a very popular design for offshore cruising boats.

Semi-Balanced Rudder

This design of sailboat rudder is something of a compromise between the spade rudder and the full skeg rudder.

Supported at its mid-point by a half-depth skeg, it benefits by the area forward of the stock, below the skeg.

This applies a balancing force as the rudder is turned making the steering lighter than it would otherwise be. And it was this design we chose for Alacazam's rudder.

Making Alacazam's Rudder

A typical productions boat's rudder is likely to have been fabricated as shown here, with two GRP mouldings 'clamshelled' around a foam core.

Not the most reliable arrangement you might think - and you'd be right.

We wanted something a little more robust for Alacazam's rudder.

But first, the rudder stock.

We fabricated this from a 2" (50mm) diameter stainless steel solid bar and welded on flat stainless tangs that would be embedded within the rudder.

The Admiralty Bronze casting will eventually connect the rudder to the skeg.

With the rudder stock fabricated, we began the construction of the rudder core.

It was made up from half inch (12mm) marine ply sheets, cut to shape and incorporating cut-outs for the tangs, screwed and glued together.

The rudder and skeg was built up as a single unit at this stage.

The rudder design software generated coordinates for various stations along the rudder, and we used these to cut templates so that we could get the shape right.

Shaping the rudder profile was done by hand, initially with a plane to remove the excess, then with a file and diminishingly coarse grades of sandpaper.

Once the rudder profile matched the appropriate template we removed the section that would form the skeg.

Next, the rudder was fitted to the stock with any gaps between the tangs and the ply taken up with high-strength epoxy 'gloop'.

Finally both the rudder and the skeg were sheathed in several layers of epoxy-glass rovings before being filled and faired with epoxy fairing compound.

Fitting the Sailboat Rudder

The skeg was letter-boxed through a slot cut in the hull, securely braced internally and bonded to it with fillets of high-strength epoxy and epoxy glass rovings.

Inside the hull we had constructed a GRP tube to contain the stock, and the skeg was also bonded to the lower end of that.

The rudder was then securely fitted to the stock via the bronze bearing, and located at the top of the rudder by a stainless steel bearing.

That's it, we now have a very robust and efficient rudder securely attached to Alacazam's hull.

Recent Articles

'Natalya', a Jeanneau Sun Odyssey 54DS for Sale

Mar 17, 24 04:07 PM

'Wahoo', a Hunter Passage 42 for Sale

Mar 17, 24 08:13 AM

Used Sailing Equipment For Sale

Feb 28, 24 05:58 AM

Here's where to:

• Find  Used Sailboats for Sale...
• Find Used Sailing Gear for Sale...
• List your Sailboat for Sale...
• List your Used Sailing Gear...

Building Alacazam...

But why go to the bother of building your own boat?

Copyright © 2024  Dick McClary  Sailboat-Cruising.com

My Cruiser Life Magazine

All About the Rudder on a Sailboat

The rudder on a sailboat is one of those important parts that often gets overlooked. It’s hidden underwater most of the time and usually performs as expected when we ask something of it.

But when was the last time you seriously considered your sailboat rudder? Do you have a plan if it fails? Here’s a look at various designs of sail rudder, along with the basics of how it works and why it’s there.

Table of Contents

How are sailboat rudders different than keels, how does the rudder work, wheel steering vs. tiller steering, full keel rudder sailboat, skeg-hung rudders, spade rudder, variations on designs, emergency outboard rudder options, looking to sail into the sunset grab the wheel, steer your sail boat rudder, and get out there, sail boat rudder faqs.

What Is a Boat Rudder?

The rudder is the underwater part of the boat that helps it turn and change direction. It’s mounted on the rear of the boat. When the wheel or tiller in the cockpit is turned, the rudder moves to one side or another. That, in turn, moves the boat’s bow left or right.

When it comes to sailing, rudders also offer a counterbalance to the underwater resistance caused by the keel. This enables the boat to sail in a straight line instead of just spinning around the keel.

Sailboat hull designs vary widely when you view them out of the water. But while the actual shape and sizes change, they all have two underwater features that enable them to sail–a rudder and a keel.

The rudder is mounted at the back of the boat and controls the boat’s heading or direction as indicated by the compass .

The keel is mounted around the center of the boat. Its job is to provide a counterbalance to the sails. In other words, as the wind presses on the sails, the weight of the ballast in the keel and the water pressure on the sides of the keel keeps the boat upright and stable.

When sailing, the keel makes a dynamic force as water moves over it. This force counters the leeway made by air pressure on the sails and enables the boat to sail windward instead of only blowing downwind like a leaf on the surface.

The rudder is a fundamental feature of all boats. Early sailing vessels used a simple steering oar to get the job done. Over the years, this morphed into the rudder we know today.

However, thinking about a rudder in terms of a steering oar is still useful in understanding its operation. All it is is an underwater panel that the helmsperson can control. You can maintain a course by trailing the oar behind the boat while sailing. You can also change the boat’s heading by moving it to one side or the other.

The rudders on modern sailboats are a little slicker than simple oars, of course. They are permanently mounted and designed for maximum effectiveness and efficiency.

But their operating principle is much the same. Rudders work by controlling the way water that flows over them. When they move to one side, the water’s flow rate increases on the side opposite the turn. This faster water makes less pressure and results in a lifting force. That pulls the stern in the direction opposite the turn, moving the bow into the turn.

Nearly all boats have a rudder that works exactly the same. From 1,000-foot-long oil tankers to tiny 8-foot sailing dinghies, a rudder is a rudder. The only boats that don’t need one are powered by oars or have an engine whose thrust serves the same purpose, as is the case with an outboard motor.

Operating the Rudder on a Sailboat

Rudders are operated in one of two ways–with a wheel or a tiller. The position where the rudder is operated is called the helm of a boat .

Ever wonder, “ What is the steering wheel called on a boat ?” Boat wheels come in all shapes and sizes, but they work a lot like the wheel in an automobile. Turn it one way, and the boat turns that way by turning the rudder.

A mechanically simpler method is the tiller. You’ll find tiller steering on small sailboats and dinghies. Some small outboard powerboats also have tiller steering. Instead of a wheel, the tiller is a long pole extending forward from the rudder shaft’s top. The helmsperson moves the tiller to the port or starboard, and the bow moves in the opposite direction. It sounds much more complicated on paper than it is in reality.

Even large sailboats will often be equipped with an emergency tiller. It can be attached quickly to the rudder shaft if any of the fancy linkages that make the wheel work should fail.

Various Sail Boat Rudder Designs

Now, let’s look at the various types of rudders you might see if you took a virtual walk around a boatyard. Since rudders are mostly underwater on the boat’s hull, it’s impossible to compare designs when boats are in the water.

Keep in mind that these rudders work the same way and achieve the same results. Designs may have their pluses and minuses, but from the point of view of the helmsperson, the differences are negligible. The overall controllability and stability of the boat are designed from many factors, and the type of rudder it has is only one of those.

You’ll notice that rudder design is closely tied to keel design. These two underwater features work together to give the boat the sailing characteristics the designer intended.

The classic, robust offshore sailboat is designed with a full keel that runs from stem to stern. With this sort of underwater profile, it only makes sense that the rudder would be attached to the trailing edge of that enormous keel. On inboard-powered sailboats, the propeller is usually mounted inside an opening called the aperture between the keel and rudder.

The advantages of this design are simplicity and robustness. The keel is integrated into the hull and protects the rudder’s entire length. Beyond reversing into an obstacle, anything the boat might strike would hit the keel first and would be highly unlikely to damage the rudder. Not only does the keel protect it, but it also provides a very strong connection point for it to be attached to.

Full keel boats are known for being slow, although there are modern derivatives of these designs that have no slow pokes. Their rudders are often large and effective. They may not be the most efficient design, but they are safe and full keels ride more comfortably offshore than fin-keeled boats.

Plenty of stout offshore designs sport full keel rudders. The Westsail 38s, Lord Nelsons, Cape Georges, Bristol/Falmouth Cutters, or Tayana 37s feature a full keel design.

A modified full keel, like one with a cutaway forefoot, also has a full keel-style rudder. These are more common on newer designs, like the Albergs, Bristols, Cape Dorys, Cabo Ricos, Island Packets, or the older Hallberg-Rassys.

A design progression was made from full keel boats to long-fin keelboats, and the rudder design changed with it. Designers used a skeg as the rudder became more isolated from the keel. The skeg is a fixed structure from which you can mount the rudder. This enables the rudder to look and function like a full keel rudder but is separated from the keel for better performance.

The skeg-hung rudder has a few of the same benefits as a full keel rudder. It is protected well and designed robustly. But, the cutaways in the keel provide a reduced wetted surface area and less drag underwater, resulting in improved sailing performance overall.

Larger boats featuring skeg-mounted rudders include the Valiant 40, Pacific Seacraft 34, 37, and 40, newer Hallberg-Rassys, Amels, or the Passport 40.

It’s worth noting that not all skegs protect the entire rudder. A partial skeg extends approximately half the rudder’s length, allowing designers to make a balanced rudder.

With higher-performance designs, keels have become smaller and thinner. Fin keel boats use more hydrodynamic forces instead of underwater area to counter the sail’s pressure. With the increased performance, skegs have gone the way of the dinosaurs. Nowadays, rudders are sleek, high aspect ratio spade designs that make very little drag. They can be combined with a number of different keel types, including fin, wing keels , swing keels, or bulb keels.

The common argument made against spade rudders is that they are connected to the boat by only the rudder shaft. As a result, an underwater collision can easily bend the shaft or render the rudder unusable. In addition, these rudders put a high load on the steering components, like the bearings, which are also more prone to failure than skeg or full keel designs. For these reasons, long-distance cruisers have traditionally chosen more robust designs for the best bluewater cruising sailboats .

But, on the other hand, spade rudders are very efficient. They turn the boat quickly and easily while contributing little to drag underwater.

Spade rudders are common now on any boat known for performance. All racing boats have a spade rudder, like most production boats used for club racing. Pick any modern fin keel boat from Beneteau, Jeanneau, Catalina, or Hunter, and you will find a spade rudder. Spade rudders are common on all modern cruising catamarans, from the Geminis to the Lagoons, Leopards, and Fountaine Pajots favored by cruisers and charter companies.

Here are two alternative designs you might see out on the water.

Transom-Hung or Outboard Rudders

An outboard rudder is hung off the boat’s transom and visible while the boat is in the water. Most often, this design is controlled by a tiller. They are common on small sailing dingies, where the rudder and tiller are removable for storage and transport. The rudder is mounted with a set of hardware called the pintle and gudgeon.

Most outboard rudders are found on small daysailers and dinghies. There are a few classic big-boat designs that feature a transom-hung rudder, however. For example, the Westsail 38, Alajuela, Bristol/Falmouth Cutters, Cape George 36, and some smaller Pacific Seacrafts (Dana, Flicka) have outboard rudders.

Twin Sailing Rudder Designs

A modern twist that is becoming more common on spade rudder boats is the twin sailboat rudder. Twin rudders feature two separate spade rudders mounted in a vee-shaped arrangement. So instead of having one rudder pointed down, each rudder is mounted at an angle.

Like many things that trickle down to cruising boats, the twin rudder came from high-performance racing boats. By mounting the rudders at an angle, they are more directly aligned in the water’s flow when the boat is healed over for sailing. Plus, two rudders provide some redundancy should one have a problem. The twin rudder design is favored by designers looking to make wide transom boats.

There are other, less obvious benefits of twin rudders as well. These designs are easier to control when maneuvering in reverse. They are also used on boats that can be “dried out” or left standing on their keel at low tide. These boats typically combine the twin rudders with a swing keel, like Southerly or Sirius Yachts do. Finally, twin rudders provide much better control on fast-sailing hulls when surfing downwind.

Unbalanced vs. Balanced Rudders

Rudders can be designed to be unbalanced or balanced. The difference is all in how they feel at the helm. The rudder on a bigger boat can experience a tremendous amount of force. That makes turning the wheel or tiller a big job and puts a lot of strain on the helmsperson and all of the steering components.

A balanced rudder is designed to minimize these effects and make turning easier. To accomplish this, the rudder post is mounted slightly aft of the rudder’s forward edge. As a result, when it turns, a portion of the leading edge of the rudder protrudes on the opposite side of the centerline. Water pressure on that side then helps move the rudder.

Balanced rudders are most common in spade or semi-skeg rudders.

Sail Rudder Failures

Obviously, the rudder is a pretty important part of a sailboat. Without it, the boat cannot counter the forces put into the sails and cannot steer in a straight line. It also cannot control its direction, even under power.

A rudder failure of any kind is a serious emergency at sea. Should the rudder be lost–post and all–there’s a real possibility of sinking. But assuming the leak can be stopped, coming up with a makeshift rudder is the only way you’ll be able to continue to a safe port.

Rudder preventative maintenance is some of the most important maintenance an owner can do. This includes basic things that can be done regularly, like checking for frayed wires or loose bolts in the steering linkage system. It also requires occasionally hauling the boat out of the water to inspect the rudder bearings and fiberglass structure.

Many serious offshore cruisers install systems that can work as an emergency rudder in extreme circumstances. For example, the Hydrovane wind vane system can be used as an emergency rudder. Many other wind vane systems have similar abilities. This is one reason why these systems are so popular with long-distance cruisers.

There are also many ways to jury rig a rudder. Sea stories abound with makeshift rudders from cabinet doors or chopped-up sails. Sail Magazine featured a few great ideas for rigging emergency rudders .

Understanding your sail rudder and its limitations is important in planning for serious cruising. Every experienced sailor will tell you the trick to having a good passage is anticipating problems you might have before you have them. That way, you can be prepared, take preventative measures, and hopefully never deal with those issues on the water.

What is the rudder on a sailboat?

The rudder is an underwater component that both helps the sailboat steer in a straight line when sailing and turn left or right when needed.

What is the difference between a rudder and a keel?

The rudder and the keel are parts of a sailboat mounted underwater on the hull. The rudder is used to turn the boat left or right, while the keel is fixed in place and counters the effects of the wind on the sails.

What is a rudder used for on a boat?

The rudder is the part of the boat that turns it left or right

Matt has been boating around Florida for over 25 years in everything from small powerboats to large cruising catamarans. He currently lives aboard a 38-foot Cabo Rico sailboat with his wife Lucy and adventure dog Chelsea. Together, they cruise between winters in The Bahamas and summers in the Chesapeake Bay.

Leave a comment

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Professional BoatBuilder Magazine

The rudimentaries of rudders.

By Steve D'Antonio , Jul 12, 2018

Even stoutly constructed rudders are vulnerable to deterioration over time, especially when mild steel or high-carbon-stainless steel is buried in composite foil sections, which inevitably become saturated with seawater.

Like other systems and gear aboard cruising and commercial vessels, rudders have terms to identify their parts and functions. When measuring a rudder, the span and chord are the vertical height and fore-and-aft width, respectively, while the top of portion closest to the hull is referred to as the root , and the bottom is called the tip . Another term frequently used when discussing rudder design, particularly for sailing vessels, is aspect ratio —simply the square of the rudder’s span divided by the rudder’s area. As a rule of thumb, longer, narrower rudders are more efficient than short, wide rudders, and the aspect ratio describes precisely this relationship. Thus, rudders on high-performance sailing vessels are said to have a high-aspect ratio. Walking around a boatyard one day and measuring a few cruising sailboat rudders, I came up with aspect ratios of between 1.7 and 2.1, while one high-performance sailing vessel’s rudder came in at 3.5. The 20-knot semi-displacement lobster yacht’s rudder I measured yielded an even 2.0 aspect ratio, which is considered respectable for this application.

More identifiable rudder components include the stock ; web or armature ; rudderport or log ; stuffing box or compression tube ; bearing ; gudgeon ; and pintle . Not every rudder has all these components.

Rudderstocks

The rudderstock is essentially a shaft or tube that protrudes from the top and sometimes the bottom, depending upon type, of many rudder designs. Because this component provides the primary connection between the rudder’s blade (the flat section that imparts the steering force) and the vessel’s steering system, its design, construction, and material are consequential.

Most stocks are made of stainless steel, bronze, or aluminum, while some are carbon fiber, and they may be solid or hollow. Stainless steel is by far the most common, but it has a penchant for crevice corrosion when exposed to oxygen-depleted water. Insidiously, corrosion nearly always occurs in places where it cannot easily be seen—such as inside many composite (fiberglass and core material) rudder blades and beneath flax-type stuffing-box packing (the problem is exacerbated when the vessel is used infrequently).

This all-stainless rudderstock and webbing is well crafted and ready to be covered with its composite shell.

Of the stainless steel alloys, some resist this corrosion better than others. Stainless-steel rudderstocks should be manufactured with strong, highly corrosion-resistant proprietary shafting alloys such as A22. The next best choice is 316L stainless steel, which also resists crevice corrosion well. Critically important is the L suffix, meaning “low carbon,” a requirement if it is to be welded, as nearly every rudderstock must be, to the support within composite rudders, or to all-metallic plate-steel rudders. Failure to source low-carbon stainless steel for the stock or the web leads to weld decay, sometimes referred to as carbide precipitation, where the region around the weld loses its resistance to corrosion and rusts when exposed to water.

Aluminum rudderstocks are nearly always tubular. Common on aluminum vessels to reduce the likelihood of galvanic corrosion, aluminum stocks are also relatively common on fiber reinforced plastic (FRP) vessels, particularly large ones. Rudder blades, particularly on aluminum vessels, are often fabricated from aluminum. Of the various aluminum alloys, only a few possess the necessary corrosion-resistance and strength necessary for use as rudderstocks. Of these, the 6000 series, and 6082 in particular—an alloy of aluminum, manganese, and silicon—are popular for this application.

Because aluminum, like stainless steel, suffers from corrosion, it should not be used as stock or web material in composite rudders. Referred to as poultice corrosion, it occurs when aluminum is exposed to oxygen-depleted water. Because oxygen is what allows aluminum to form its tough, corrosion-resistant oxide coating, the metal should never be allowed to remain wet and starved of air as it would be inside a composite rudder blade after water makes its way in around the stock and pintle.

Rudderstock material can corrode in way of the oxygen-starved environment around the packing in a stuffing box.

Bronze, a once popular rudderstock material, is no longer common in today’s production vessels. Although strong and exceptionally corrosion resistant (immune to crevice corrosion), bronze is not easily welded to attach to a rudder’s internal structural webbing, and has thus been supplanted by stainless alloys. Bronze rudderstocks, particularly those that have seen many sea miles, are also known for wearing, or hourglassing, within stuffing boxes, where the flax rides against the stock. If a bronze stock rudder is chronically leaky, disassemble the stuffing box and check for excessive wear. The same is true for stainless and aluminum stocks: chronic leakage is often an indication of corrosion at the packing. Finally, because of their galvanic incompatibility, neither bronze nor copper alloys should be used aboard aluminum vessels for rudderstocks or any other rudder or stuffing box components.

Mild-steel webbing welded to a stainless-steel rudderstock is a recipe for eventual corrosion and failure.

The webbing, or internal metallic support system, in most composite rudders must be strong enough to carry the loads of service and be made of the appropriate material. At one time, many rudders were built using stainless-steel stocks and ordinary, rust-prone mild or carbon-steel webbing. Inadvisably, some still are. The union between a stainless stock and FRP rudder blade is tenuous at best (the two materials expand and contract at different rates) and stainless steel’s slippery surface makes adhesion to the laminate resin a short-lived affair. Once water enters the gap between these two materials, it will reach the webbing and associated welds. Thus, all the materials within this structure must be as corrosion- and water-resistant as possible, and the core material must be closed-cell—often foam—and nonhygroscopic.

This destroyed foam-core and stainless-steel rudder reveals the conventional construction of such appendages.

Additionally, where possible, the stock should consist of a single section of solid or tubular material; i.e., it should not be sleeved, reduced, or otherwise modified or welded unless done so in an exceptionally robust manner. The webbing must be welded to the stock, but the structure of the stock should not rely on a weld that would experience cyclical, torsional loading.

The webbing in the form of a plate or grid should be welded to the stock with ample horizontal gussets (small wedges welded where the stock and webbing interface), which will reinforce welds 90° to the primary web attachment.

Whether the rudder is spade (supported only at the top) or skeg hung (supported at the top and the bottom), the stock must pass through and be supported by the hull. This is usually accomplished by a component known as a rudder log, or port. In its simplest form it’s a tube or pipe through which the stock passes. Nearly all logs incorporate two other components—a bearing and a stuffing box. The bearing may be as simple as a bronze or nonmetallic bushing or tube inside of which the stock turns; or it may be as complex as a self-aligning roller-bearing carrier that absorbs rudder deflection and prevents binding.

This rudder log is leaking, corroded, and poorly supported, with washers compressing into the backing plate and gelcoat cracking off.

The log transfers tremendous loads and must be exceptionally strong and well bonded to the hull. Fiberglass vessels should rely on a well-tabbed-in purpose-made tube (its filaments are wound and crisscrossed and thus quite strong) that is supported with a series of vertical gussets that distribute the load to the hull’s surrounding structure. On some spade rudder installations, particularly where the log is not, or could not, be long enough, an additional bearing is used at the top of the stock, above the quadrant, where it is supported by the vessel’s deck.

On metal boats the design is similar but with a metal tube welded in place, supported by substantial gussets. For vessels with skeg-hung rudders, the strength of the rudder log is still important. However, because the loads are not imparted by a cantilevered structure, logs used in these applications may be less substantially supported.

Stuffing Box

Unless the rudder log’s upper terminus is well above the waterline or on the weather deck, it is typically equipped with a stuffing box similar to those used for propeller shafts. But unlike a shaft stuffing box, the rudder’s stuffing box shouldn’t leak much, if any, seawater. Because the rudder turns slowly, friction and heat are not a problem. Packing (i.e., waxed-flax packing like that in traditional stuffing boxes) can typically be tight enough to stem all leakage, and lubricating it with heavy water-resistant grease will reduce friction and leakage.

Stuffing boxes that are above the waterline while the vessel is at rest, such as those on many sailboats, are often the most chronically leaky, because the packing tends to dry out and contract. To avoid this, liberally apply grease to the packing material itself; this requires partial disassembly of the stuffing box. Alternatively, a galvanically compatible (316 stainless or Monel for bronze stuffing boxes) grease fitting may be installed and periodically pumped with grease to keep the packing lubricated.

Rudder Bearings

Well-engineered rudder bearings support and lubricate the rudderstock.

Rudder bearings range from the basic rudderstock turning inside a bronze log, to the sophisticated aluminum, stainless, or nonmetallic roller bearings installed in a self-aligning carrier. For most cruising vessels, the choice of bearing is not as important as knowing which type of bearing is in use and its strengths, weaknesses, and maintenance needs. The simple shaft that turns inside a bronze log is durable and reliable but more friction-prone than roller bearings. If lubrication access or a grease fitting is available, it should be pumped with grease periodically, although most rudders rely solely on seawater for lubrication, which is perfectly acceptable.

This synthetic upper bearing worked fine in cool temperatures, but when it heated up in the sun, the material expanded and caused binding in system.

Nonmetallic sleeve and roller bearings, often made of ultra high molecular weight polyethylene (UHMWPE), require no maintenance, are extremely slippery, and will not absorb water, an essential attribute for nonmetallic bearings. Delrin and nylon, for instance, will absorb water, expand, and lead to rudder binding. On several high-performance sailing vessels, I’ve had to replace nylon or similar bearings with UHMWPE to restore the steering to its proper specification and effort level.

Propeller Removal

Shaft removal should be possible with the rudder in place. This conventional skeg-hung rudder has a hole to facilitate shaft removal when the rudder is swung hard to port or starboard.

Whether a rudder is a spade or skeg-hung design, it’s important to determine how it will affect the removal of the propeller or the propeller shaft. Is there enough clearance between the shaft’s trailing end and the leading edge of the rudder to allow the propeller to be removed or to use a propeller removal tool? Can the shaft be slid out without removing the rudder? Some rudders are equipped with shaft-removal holes, while others are installed slightly offset from the centerline; or the rudder’s leading edge has an indentation to allow the shaft to be removed. The propeller should be removable without having to unship the rudder. The dimensional rule of thumb calls for clearance of at least the prop’s hub length between the aft end of the shaft and the leading edge of the rudder.

Rudder Stops

The rudder’s movement should be unimpeded as it swings approximately 35° in either direction, making no contact with hull or propeller. Just as important as the rudder travel is how its movement is checked. Other than for the smallest runabouts with jacketed cables, all inboard rudders should rely on hydraulic cylinders to check rudder travel (provided they are designed to do so, and most are) or be equipped with robust stops. Stops must be integral to the hull, supported by substantial tabbing or a welded and through-bolted structure for fiberglass vessels, or by welded angle and shelves for metallic hulls.

About the Author: For many years a full-service yard manager, Steve now works with boatbuilders and owners and others in the industry as Steve D’Antonio Marine Consulting. He is an ABYC-certified Master Technician, and sits on that organization’s Hull and Piping Project Technical Committee. He’s also the technical editor of Professional BoatBuilder .

Read more Repair articles

Quick Custom Molds

Making one-off composite parts in the shop.

Repairing Bent Props with TrueProp Software

With all the advances in automation and electrification of boat propulsion systems, propellers remain critical to the task of converting power into propulsion. Made of bronze, nickel, aluminum, stainless steel,… Read more »

VacPuc Checks Your Vacuum Bags

It’s possible to monitor houses, cars, cats, and boats by smartphone, so why not check vacuum bags during resin infusion? Now composite technicians have this option with VacPuc, a new… Read more »

Recent Posts

• How Australia II Got its Wings Part 2: Finding Truth in the Tank
• How Australia II Got Its Wings Part 1: Prelude to a Controversy
• Learn Electrical Systems from Nigel Calder
• PRO-SET Epoxy Named an Official Supplier for New York Yacht Club American Magic, Challenger for the 37th America’s Cup
• CNC Construction on the Rise
• Companies (82)
• Construction (105)
• Design (156)
• Drawing Board (8)
• Education (24)
• Environment (15)
• Events (20)
• Materials (48)
• Obituary (17)
• People/Profiles (46)
• Products (16)
• Propulsion Systems (30)
• Racing (15)
• Repair (37)
• Rovings (313)
• Short Cuts (3)
• Sponsored Partner News (13)
• Systems (80)
• Task Sheet (1)
• Uncategorized (28)
• Wood to Glass (7)

ProBoat.com Archives

What’s the best rudder design and why are Sirius Yachts so easy to manoeuvre?

If you’ve seen the videos of our deck saloon sailboats manoeuvring effortlessly in the tight space of a marina, you may wonder how we can make it look so easy. The simple answer is that it looks easy because it is easy. Years of practice are absolutely not required as we prove on every test sail; after 10 minutes of simple instruction anyone on board who is more than eight years old can manoeuvre a Sirius with the same confidence. Part of the reason our yachts are so easy to manoeuvre is rudder design, combined with the position of the propeller.

A rudder needs to work well for both sailing and motoring, but many believe a rudder can only be good for sailing or motoring, not both. Most boatbuilders nowadays just focus on producing a rudder that’s efficient for sailing, but it doesn’t have to be one or the other. You can indeed have both. We even have a solution for hard-to-manoeuvre twin-rudder yachts, which have no prop wash to steer with.

The three rudder options we offer

We offer three rudder options. The first is a single, partially balanced spade rudder with a skeg for added protection. This is the standard setup on all our fin-keel yachts and also on the twin-keel versions.

On all our lifting keel yachts we use twin rudders because when the yacht is dried out, the height from the hull to the sea bed won’t allow enough span (rudder height) to give good control under sail. Instead of one deep rudder, we use two shorter rudders, angled outwards at the bottom so that at any heel angle one rudder is always fully immersed and close to vertical for optimum performance. Twin rudders also give the security of a wider support base when the boat is dried out.

The third option is three rudders: the standard twin rudders as above plus a small, central third rudder whose sole purpose is to improve manoeuvrability under power, especially from a standstill and at low speed.

The best rudder design for motoring

Let’s first look at how our rudders are optimised for use under power. If we were making a motorboat, the rudder would have little or no area forward of the rudder stock. It would only need to be the height of the propeller, and the distance between rudder and propeller would just be a quarter to half of the propeller’s diameter. Most motorboats are steered entirely by prop wash (the flow of water from the propeller passing over the rudder). As mentioned above, our twin-rudder boats also have the option of a smaller, central third rudder. Like a powerboat rudder, it steers the boat by efficiently deflecting prop wash and also directing a laminar current onto the two rudders.

Life isn’t so simple for our single rudder designs; they have to be equally efficient under sail and power. To get maximum manoeuvring efficiency from prop wash we locate the propeller at an optimum distance from the rudder, so that the cone-shaped, moving mass of water is the same height as the rudder when it hits it. The positioning has to be precise. The rudder blade needs a large surface area for efficient performance under sail, and if it’s too close to the propeller there will be a lot of pressure on the rudder, making it heavy on the helm with lots of vibration under power. If it’s too far away from the propeller, the energy of the prop wash dissipates into the surrounding water before it hits the rudder. One reason we prefer saildrives, rather than shaft drives, is that they allow us to fit the engine in what would typically be an aft cabin (this is one reason why the aft cabin of the Sirius 40 DS is transverse), which puts the propeller in an optimal position and gives the owner an excellent mid-cabin plus a workshop. We do also fit shaft drives to some of our yachts, but they generate more noise and vibration and this moves the engine a bit further forward. You can have whichever drive you prefer.

When a yacht is motoring, the area of rudder blade forward of the post (or stock) is doing the most work. It’s under the highest pressure from prop wash and helps to deflect more water over the high-pressure side of the rudder. The area forward of the stock also helps to balance the helm. Without it, the rudder would require more effort to turn. But if there is too much surface area forward of the stock, the rudder will become unbalanced and twitchy under sail – the helm will require constant attention, which is clearly a bad thing on a cruising yacht. It’s all about striking the right balance (if you’ll excuse the pun) between a rudder that provides a good steering response and one that is not hard work to turn at high speed.

The water pressure is highest at the point where the prop wash hits the hull, and because our propeller is closer to the rudder than on most other boats, a lot of pressure is exerted on the top (or root) of the rudder. One way to avoid it experiencing too much pressure is to remove the area forward of the stock where the pressure is highest. We do this with the addition of a skeg. Under power, the skeg absorbs the water pressure and directs the flow of water over the rudder. It acts like the wing of an aircraft and the rudder is the control surface on its trailing edge – if the whole wing of an aircraft were to move in flight it would be very unstable, it’s the same principle. The skeg stabilises the flow of water, so by the time the water hits the rudder there is minimal turbulence. This translates into less movement and vibration of the rudder under power. Adding a skeg is an expensive complication in the production process, that’s why it is rarely seen in production yachts. Twin-rudder yachts don’t suffer the same way because the turbulent water from the propeller passes cleanly between the rudders, and in our triple-rudder design the third rudder is small enough and designed not to be affected.

The best rudder design for sailing

Our yachts are not just designed for party tricks in marinas, they are also designed to sail well. So any rudder design we use has to work at least as well, if not better, for sailing as it does for motoring. To achieve this the rudder blade must be deep, so when the yacht heels there is still enough of the rudder in the water to maintain control. Under sail, it’s the trailing edge of the rudder that is doing the work and is under the most pressure.

Why twin rudders have become popular

There is a trend for yachts to carry their maximum beam a long way aft to enlarge the aft cabins. Sirius yachts don’t need the aft cabins to be the master cabins because the accommodation is on two levels, and we prefer to keep our cockpits low down for greater comfort in rough seas. For single-rudder boats, the problem with a broad, overly buoyant stern (apart from excessive heeling and being vulnerable when docking) is that as the boat heels, the root (top) of the rudder is lifted out of the water. If the top 30cm (1ft) of a 1.3m (4ft 3in) rudder blade comes out of the water, more than a quarter of the blade’s effectiveness is lost. The top quarter of the blade becomes useless and the rest of the blade is operating in less dense water. The angle the blade is working at also makes it less effective and when under pressure it will ventilate: a vortex of air swirls down one side of the rudder, which loses its grip in the water, causing a sudden loss of control as the boat rounds up into the wind. To stop that happening, the crew needs to play the mainsheet constantly in gusty winds, which is exhausting if you’re sailing long distances, and the yacht will need to be reefed (and unreefed) more often.

To avoid this effect, many yachts have twin rudders that are angled outboard on each side of the stern. As the yacht heels, the leeward rudder is pushed into deeper, denser water and becomes vertical, making it more efficient. Twin rudders tend to be narrow-chord with a short span (short and skinny) and they must be set well apart to make them efficient while sailing. The problem is that there’s no prop wash over the rudders when manoeuvring in harbour, so unless the yacht is moving relatively fast through the water you have no steerage. When the yacht is stationary, she cannot be turned by applying helm and giving the engine a burst of power. Only when there is water passing over the blades at a speed faster than is prudent in confines of a marina will the yacht start to turn. One way to overcome this trait is to fit a retractable stern thruster in addition to the bow thruster, but they come at extra expense and need to be operated simultaneously with the rudder and engine and bow thruster, as well as using more power. Also, they take up space inside the hull and they’re something else for debris to catch in.

Sirius yachts don’t have fat aft quarters, they have a more balanced hull form for better all-round performance and comfort and safety at sea, so we don’t need twin rudders or stern thrusters – a single rudder works well. When a Sirius heels, the rudder blade is deep under water and remains fully immersed.

The reason we use twin rudders on some of our yachts

We do, however, use twin rudders for a different reason on our lifting-keel and twin-keel yachts, which are designed to dry out. With a draught up to 75cm (2ft 5in), a single rudder wouldn’t have a long enough span to work properly. Where we fit twin rudders, they have a relatively long chord (wide blade) and because our hulls are only moderately wide at the stern, the rudders are quite close together. A burst of power from the engine can be diverted by the rudders, creating a turning effect – not as much as with a single-rudder boat, but more than most twin-rudder yachts.

We can fit twin rudders on any of our yachts. We offer the option of twin electric drives (for propulsion and power regeneration) and we recommend twin rudders, one behind each drive, to give the very best manoeuvring ability. Not only is the thrust directed over both rudders, the two drives can be powered individually so with one drive in forward and the other in reverse she will pivot on the spot.

Construction of the rudder and skeg

As mentioned above, our single rudders have a half skeg that serves many purposes. As well as absorbing the energy of turbulent prop wash at the top of the rudder it also helps direct the water passing onto the rudder blade while sailing. It boosts the efficiency of the rudder and also protects it from hitting submerged objects. Inside the skeg is a stainless-steel structure that is through-bolted and bonded to the hull. We don’t hang the rudder off the skeg, though; three bearings would create a rudder that is harder to turn when heeling and wear out the bearings faster. Instead, we use two self-aligning bearings. A well-designed, strong rudder design doesn’t need a skeg for support, only for protection.

A rudder to dry out on

We use an alloy stock in our rudder blades that is optimised for seawater and strength. The blade is built in two parts, laminated onto the stock on the inside, and filled with closed-cell foam then laminated along the leading edge. On our yachts that are designed to dry out, the rudder has a wide foil on the tip to give a larger surface area for the rudder to rest on. When our twin-keel yachts dry out on concrete or any other hard surface, the rudder will be about 80mm (3in) off the ground and she will sit happily on her keels – we wanted to see how stable, so we had 12 guys jumping up and down on the stern and they were unable to get her to move.

On softer surfaces, like sand and gravel, the keels sink in by about 2-5cm (1-2in). Our boats’ longitudinal centre of gravity is slightly aft of amidships, so the stern tends to sink in a bit further. The wide foil, or foot, at the tip of the rudder spreads the load and prevents the rudder blade from sinking in. The rudder has a Delrin sheave to transfer the weight onto the hull and it is designed to provide a stable tripod stand for the hull. The rudder is deliberately a little shorter than the keels for added safety – when you run aground while feeling your way into your perfect spot to dry out, the keels will touch the bottom before the rudder does. On our lifting keel models, the twin rudders support the stern of the boat so she will dry out upright.

General Manager – Torsten Schmidt SIRIUS-WERFT GmbH Ascheberger Straße 68 24306 Plön/Holstein

Fax: 0049 – 4522 – 744 61-29

Receive regular updates from Sirius Yachts

Subscribe to our email newsletter

Privacy Overview

How To Make A Rudder For A Sailboat?

• REPAIRS AND MAINTENANCE

Sailboats are propelled through the water by wind power, and a rudder accomplishes steering. It is a flat piece of wood or metal that hangs in the water and is fastened to the back of the boat. A tiller connected to the rudder controls its side-to-side movement.

A crucial skill that releases your sailboat’s full potential is making a rudder. Start by carefully choosing the right materials, such as wood or fiberglass, based on your preferences and financial constraints.

Next, meticulously design the rudder’s shape to ensure optimal hydrodynamics. With precision, cut the materials according to your design, shaping them into the perfect rudder. But that’s not all; we have more valuable steps ahead to enhance your rudder’s performance.

Ready to take control of your sailboat like a seasoned captain? Let’s delve into the detailed process of making your very own rudder, turning your sailing dreams into reality!

Read Related Articles:

• How Often Do Sailboats Get Struck By Lightning?
• How To Hang A Hammock On A Sailboat

What Materials Do You Need to Make a Rudder?

The following supplies are necessary to launch this ship if you’re prepared to learn the technique of building sailboat rudders. Let’s take a step-by-step look at how to create this nautical beauty and then give you the lowdown on what you’ll need.

Perfect Wood

When choosing the right wood for your sailboat rudder, durability and water resistance are key. Two types of wood are excellent choices: marine-grade plywood and hardwoods like oak or mahogany.

Marine-grade plywood boasts superior resistance to water and decay, making it an ideal option for exposed marine environments. On the other hand, hardwoods bring a touch of elegance and strength to your rudder, but they may require additional waterproofing measures.

Plywood Thickness – Striking the Right Balance

The thickness of the plywood used for your rudder is a crucial consideration. While thicker plywood tends to be more durable, it can also add unnecessary weight to your sailboat.

In general, a thickness of ¾-inch plywood strikes the appropriate mix between strength and weight, ensuring that your rudder stays functional and maneuverable.

Your sailboat’s size and weight will determine whether you can use somewhat thinner plywood without compromising strength.

Get yourself a trusty jigsaw, a powerful drill, and a router. Oh, and don’t forget some sturdy clamps because you’re going to need them to hold things together while the magic happens.

Glue it All Together:

Time to get sticky! You’re going to need some marine-grade epoxy or a heavy-duty adhesive to bond those plywood layers together. Trust me; you want to go heavy on that glue – no room for gaps in this masterpiece!

Gudgeons and Hinges:

Now, we can’t forget the rudder’s backbone – the gudgeons and hinges. Look for some stainless steel gudgeons, my friends. They’re tough, they’re reliable, and they can handle the rough waters like a champ.

Pivot Bolts:

Ah, yes, the pivot bolts. Get yourself some stainless steel bolts because you want them to hold up against the salty sea spray. You don’t want those rusty bolts seizing up when you’re out on the water, do you?

The Sturdy Tiller:

Don’t forget about the tiller! Craft it from solid wood, and ensure it’s long enough to give you proper steering control. You want to feel that connection with your rudder, am I right?

Eye Bolts and Cleats:

We need some eye bolts and cleats to keep things in place. These little guys will make your life much easier when raising and lowering the rudder. Just the way we like it: simple and effective.

How Do You Design and Shape the Rudder Blade?

Now that we have gathered our materials, it’s time to delve into the art of designing and shaping the sailboat rudder blade. A well-crafted rudder not only ensures smooth steering but also enhances the overall performance of your vessel.

The Art of Rudder Blade Design

Designing your rudder blade is akin to crafting a work of art. The key considerations are the blade’s size, shape, and foil design. First, determine the ideal size of the blade based on the dimensions of your sailboat. A larger sailboat will require a proportionately larger rudder blade to ensure effective steering control.

Next, the shape of the rudder blade plays a crucial role in its hydrodynamics. A balanced and streamlined shape will reduce drag and enable smooth maneuvering. Many sailors opt for a symmetrical foil design, similar to an airplane wing, which ensures equal pressure on both sides of the blade for optimal performance.

Shaping the Rudder Blade – From Plywood to Foil

Now, let’s roll up our sleeves and bring our rudder blade design to life! Start by tracing your desired shape onto the plywood using a template or drawing your unique design. Precision is key here, as even small deviations can impact the rudder’s functionality.

With the outline in place, carefully cut the plywood along the traced lines using a sharp saw. For the finest precision, a jigsaw or bandsaw is ideal. As you make each cut, envision the graceful motion of the blade gliding through the water, guided by your craftsmanship.

Perfecting the Foil Shape – Hydrodynamics at Play

Ah, the magic of hydrodynamics! Now that we have the basic shape of the rudder blade let’s fine-tune it to achieve the perfect foil shape. The foil shape, similar to an airplane wing, generates lift and minimizes drag as the water flows past it.

For a symmetrical foil shape, gently taper the front and back edges of the blade to create a graceful curve. Imagine the water caressing these contours, guiding your sailboat effortlessly across the waves.

Remember, precision is paramount in achieving an efficient foil shape. Use a sander to smooth the edges, refining the curves and angles until you achieve hydrodynamic perfection. Remember that even subtle adjustments can significantly affect your sailboat’s performance.

How to Assemble the Rudder Gudgeons and Hinges?

We’ll now get started on the rudder assembly process and learn how to put the hinges and gudgeons—two crucial parts—together. These essential components not only guarantee the correct operation of your sailboat’s rudder, but they also offer the flexibility required for easy navigation.

Understanding the Role of Rudder Gudgeons

• Gudgeons and Pintles : Rudder gudgeons are small metal brackets or plates attached to the transom of your sailboat. They serve as the pivot point for your rudder, allowing it to swing smoothly. Corresponding to the gudgeons are pintles, which are mounted on the rudder’s sides and fit into the gudgeons to form the hinge mechanism.
• Material Matters: Rudder gudgeons are typically made from marine-grade stainless steel or other corrosion-resistant materials. The robustness of these components ensures their longevity in the harsh marine environment.

Assembling the Rudder Gudgeons and Hinges

With a clear understanding of the gudgeons’ role, it’s time to assemble these vital components:

• Preparing the Transom: Begin by positioning the rudder gudgeons on the transom’s surface. Ensure that they are aligned and centered to create a stable hinge point for your rudder.
• Marking and Drilling: Using the gudgeons as guides, mark the spots for the screw holes on the transom. Carefully drill pilot holes to avoid any splitting or damage to the wood.
• Mounting the Gudgeons: With the pilot holes in place, attach the rudder gudgeons firmly to the transom using stainless steel screws. Ensure a snug fit to maintain stability during rudder operation.
• Fitting the Rudder: With the gudgeons securely mounted, position your rudder with pintles in place. Ensure that the pintles fit smoothly into the gudgeons, allowing for easy movement.
• Securing the Rudder: After testing the movement of the rudder, secure it in place with retaining pins or bolts. This prevents the rudder from accidentally dislodging during your sailing adventures.

Fine-Tuning the Hinge Mechanism

To achieve flawless rudder movement, fine-tuning the hinge mechanism is crucial:

• Lubrication: Applying marine-grade lubricant to the gudgeons and pintles enhances the smoothness of the hinge action, reducing friction and ensuring easy steering.
• Eliminating Play: Check for any unwanted play or wobbling in the rudder movement. Adjust the gudgeons or pintles if needed to achieve a snug fit without excess movement.

What’s the Process of Making the Tiller?

Ahoy, shipbuilders! As we continue our voyage into sailboat construction, it’s time to focus on the essential tiller – the steering companion of our rudder. Making the perfect tiller ensures smooth navigation and precise control. So, let’s set our sights on the art of tiller craftsmanship!

Selecting the Perfect Tiller Material

Before we set our hands to work, let’s consider the materials for your tiller:

• Wood: Wooden tillers are a popular choice, offering a classic and traditional look. Hardwoods like oak, teak, or mahogany are excellent options due to their strength and resistance to water damage.
• Composites: For a modern touch, composites like fiberglass or carbon fiber provide a lightweight and durable alternative.
• Length Matters: Choose a tiller length that allows for easy maneuvering while providing enough leverage for precise steering control.

Crafting the Tiller Handle

• Shaping the Handle: Start with a rectangular piece of wood or composite and shape it into a comfortable grip. Rounding the edges and creating ergonomic contours enhances handling and reduces hand fatigue.
• Pivoting Mechanism: If you desire a tiller that pivots for ease of navigation, consider attaching a pivot bolt to the tiller handle’s base. This allows the tiller to lift easily when needed.

Reinforcing the Tiller for Strength

• Multiple Layers: If using wood, glue multiple layers of plywood together to achieve the desired thickness. This ensures your tiller can withstand the forces of steering.
• Bolt or Eye Loops: Strengthen the pivot point by inserting a bolt or eye loop through the tiller handle. This provides a secure connection to the rudder mechanism.
• Tapering the Tiller: Taper the tiller towards the rudder end, reducing its width for a sleek and aesthetically pleasing look.

Finishing Touches

• Varnishing: Apply marine-grade varnish to protect the tiller from water damage and give it a glossy finish.
• Grip Enhancement: Consider adding a non-slip grip surface, such as rubber or leather, to the tiller handle for improved control in wet conditions.
• Customization: Add a personal touch by carving your sailboat’s name or a unique design onto the tiller.

How to Install the Rudder on the Sailboat?

As we approach the final leg of our sailboat construction, it’s time to install the rudder – the heart and soul of our steering mechanism. A well-executed rudder installation ensures smooth sailing and ultimate control.

Choosing the Right Rudder Location

Before we dive into the installation, let’s consider the ideal location for your rudder:

• Transom Position: The transom, or the rear part of the boat, is the most common location for rudder installation. Ensure that the rudder gudgeons are aligned with the pintles on the rudder blade for a secure and stable fit.
• Clear Path: Make sure there is enough clearance around the rudder to allow for smooth movement without any obstructions.
• Balance and Control: Position the rudder in a way that provides optimal balance to your sailboat and allows for effortless control during navigation.

Mounting the Rudder Gudgeons

• Precise Measurements: Use a level and measuring tape to ensure the gudgeons are mounted at the correct height and alignment on the transom.
• Marking and Drilling: Carefully mark the spots for the screw holes and drill pilot holes to prevent any damage to the transom.
• Securing the Gudgeons: Attach the rudder gudgeons firmly to the transom using stainless steel screws. Double-check their alignment to ensure a proper hinge mechanism.

Fitting the Rudder in Place

• Pintle Alignment: Carefully insert the pintles on the rudder blade into the gudgeons on the transom. Ensure a smooth and snug fit to allow for effortless rudder movement.
• Testing the Rudder: Move the rudder back and forth to test its range of motion. Verify that it swings smoothly and without any binding or resistance.
• Securing the Rudder: Once satisfied with the rudder’s movement, secure it in place by inserting retaining pins or bolts through the pintles and gudgeons.

Waterproofing and Final Checks

Before setting sail, let’s take some additional steps to protect your rudder and ensure a safe voyage:

• Waterproofing: Apply marine-grade sealant or epoxy to the areas around the gudgeons and pintles to prevent water from seeping into the transom.
• Quality Checks: Perform a thorough inspection of the rudder installation, checking for any loose fittings or potential points of concern.
• Rudder Lines : If your rudder design includes lines for raising and lowering, make sure they are properly attached and secured to the tiller and rudder.

How Does a Rudder Work on a Sailboat?

A sailboat rudder is a vertical, blade-like appendage mounted either on the transom (the flat surface of the stern) or under the boat. It operates by deflecting water flow: when the helmsman turns the rudder, the water strikes it with increased force on one side and decreased force on the other.

The rudder moves toward lower pressure, causing the boat to turn. During turns, the boat pivots around a point close to its middle, changing direction as the stern and bow move in opposite directions.

A tiller, a wooden or aluminum pole affixed to the top of the rudder on smaller sailboats, is often used to control the rudder. Hydraulic, steam or electrical machinery turns the rudder on larger vessels.

Why Is the Rudder So Important?

The rudder is crucial for steering and changing the direction of a sailboat. It is mounted at the stern and controlled by the helm or tiller. When the helmsman turns the wheel or tiller, the rudder moves to either side, which turns the boat’s bow left or right.

This directional control is essential for navigating the water, avoiding obstacles, and maintaining stability during sailing. A functional rudder ensures safe and efficient maneuvering of the sailboat, making it an indispensable component of any sailing vessel.

What Are the Different Types of Rudders for Sailboats?

There are four types of rudders for sailboats: Full Rudder, outboard Rudder, Spade Rudder, and Skeg-Mounted Rudder.

Full Keel Rudders:

Some sailboats boast a full keel rudder, which extends along the entire length of the boat’s bottom. These rudders offer stability and protection, making them ideal for rough waters. Back in the day, many cruising boats rocked the full keel, but times have changed, and modern sailors tend to favor speedier fin keels.

Spade Rudders:

Spade rudders are like the cool cats of the sailing world, often found on center-console boats. They’re separate from the keel and turn easily, thanks to water flow rushing against both fore and aft edges. Less wet area means they’re fast and perfect for modern sailboat designs.

Skeg-Mounted Rudders:

If safety and performance are your jam, the skeg rudder is your go-to choice. Popular on current production boats, the skeg rudder combines the best of both worlds. It’s modern, stable, and performs like a champ.

Outboard Rudders:

These rudders are the real deal when it comes to simplicity. They can be unbalanced, balanced, or semi-balanced, and their location behind the hull determines whether they’re inboard or outboard.

Frequently Asked Questions

• What Is the Best Material for the Rudder?

A boat’s rudder is a steering device. To withstand the power of the water, it is typically composed of sturdy and rigid material like metal. The best material for a rudder depends on where it will be used. If it is used in salt water, it must resist corrosion. When used in freshwater, it must be resistant to sunlight degradation.

• What Type of Bearing Holds a Rudder?

Two bearings commonly hold a rudder in place: roller and journal. Roller bearings are composed of small cylindrical rollers arranged perpendicular to the axis of the shaft. On the other hand, journal bearings consist of a smooth inner surface on which the shaft rotates.

• Do Motor Boats Have Rudders?

Rudders are a feature of motor boats used to steer the vessel. It is attached to the back of the boat and regulates the direction.

• What Happens If the Rudder Is Too Big?

When the rudder is overly large, the boat may veer off course. The rudder is what steers the boat; thus, if it is excessively large, it could be challenging to manage the boat’s direction. A boat might become slower if its rudder is excessively large and causes drag.

• How Much Is a New Rudder?

The kind, size, and material all affect the price of a new rudder. A sailboat’s rudder can usually range between $200 and $500 for small sailboats and between $800 and $2,000 for bigger vessels. It’s best to consult with a marine supplier or boatyard for precise pricing.

Congratulations, skilled shipwrights! You’ve navigated the intricate waters of sailboat rudder construction with finesse. From selecting the right materials to crafting the perfect foil shape, you’ve honed your craftsmanship like seasoned sailors. With the rudder securely mounted and tested, your sailboat is ready to embrace the vast horizon.

As you set sail on new adventures, may your well-crafted rudder be your faithful companion, steering you toward endless nautical wonders. Embrace the sea’s call and embark on a journey filled with the wind’s whispers and the thrill of the open ocean. Smooth sailing awaits you! Bon voyage!

Jack K. Pride

Jack K. Pride is an accomplished author and a prominent figure in the boating community. With a passion for boats and a deep understanding of the maritime industry, he has been sharing his expertise through his compelling articles on OutedWeb.com.

Known for his insightful and informative writing style, Jack's articles provide valuable insights, tips, and knowledge to boat enthusiasts worldwide. His dedication to the subject matter and commitment to delivering high-quality content makes him a trusted voice in the boating world.

Leave a Reply Cancel Reply

Your email address will not be published. Required fields are marked *

Name  *

Email  *

Add Comment  *

Save my name, email, and website in this browser for the next time I comment.

Post Comment

World Class Rudders, Tillers, and other Gear for Real Life Sailing

Sailboat rudders, sailboat tillers, custom rudders/ tillers, sailboat accessories, rudder repair worksheet, instructional handbook, looking for a product for your sailboat.

Can't Find your Sailboat?

Why Rudder Craft?

At Rudder Craft we build every sailboat rudder with the singular focus of improving your sailboat’s steering performance. In order to accomplish this our sailboat rudders incorporate a hydrofoil design, as a matter of course. Sailboats ranging from the West Wight Potter 15, all the way up to the MacGregor 36 and Catalina 42, will find a more accurate helm once a Rudder Craft hydrofoil sailboat rudder is installed.

Why Hydrofoil?

Operating on principles similar to airplane wings, the foiled sailboat rudder design generates lift as the sailboat makes way. By employing the sailboat rudder to reduce drag, and increasing the force the sailboat rudder is able to exert, any sailboat will find themselves performing better: weather helm is reduced, tacking is crisper, points of sail are easier to keep, and helm effort is greatly reduced in light and moderate air.

Why Use a Kick-up Rudder?

Subscribe to our blog.

Join our mailing list to receive the latest news and updates from our team.

You have Successfully Subscribed!

No results found.

The page you requested could not be found. Try refining your search, or use the navigation above to locate the post.

Blog Coming Soon!

Customer reviews.

Small Boats Annual 2012

The Sea Bird Yawl

Simplicity in a hard-chined cruiser

I n 1901, Thomas Fleming Day, who founded The Rudder a decade earlier, conceived a boat that would bring ocean voyaging to the common man. Simple enough to be built by amateurs, small enough to be singlehanded, and big enough for long passages, the Sea Bird yawl still beckons those with a sense of adventure.

She was originally a centerboarder, but Day soon added a deep keel for ocean passages, including an Atlantic crossing he made in 1911. With The Rudder’s publicity, plans, and instructions, the design soon caught hold. Hundreds have been built. Day’s vision turned out to be unusually lovely for a hard-chined hull, in plans formalized by C.D. Mower and Larry Huntington. Boats of this type have cross-sectional shape consisting of nearly straight lines rather than the svelte curves of racing craft. Sea Bird’s sweeping chine curve rises high forward and aft and just kisses the waterline amidships. The shape is complemented by her gaff-headed yawl rig. In 1981 WoodenBoat, working with Mystic Seaport, had the plans redrawn by Dave Dillion (see WB No. 43), and the seven-sheet set of plans, which includes the deep-keel option, is still available through The WoodenBoat Store.

At 25’ 7 1⁄2” overall, the centerboard version of the Sea Bird can—with effort—take to the water each spring from a launching ramp, with her 1,300 lbs of ballast added later.

I first saw a Sea Bird in a photograph published in a book I’ve long forgotten. Taken from astern in a calm harbor, the picture captured the distinctive transom, which was intriguing to draw and immediately made me imagine building the boat. Some years ago, sailing into Robinhood Cove, Maine, I saw a boat that instantly brought me right back to that photo. She had a rightness about her. This particularly fine Sea Bird, I learned, was built by Alex Hadden in nearby Georgetown.

Hadden launched his centerboarder in 1988. He had come by a marconi rig complete with masts, sails, rigging, and hardware, from a Sea Bird that had been cut up, and he planned to build the boat for sale. The project launched Hadden’s business, but not the way he intended: somebody with an aged Sea Bird hired him for a reconstruction instead. It was his first commission, but he ended up keeping the boat he hoped would be his first sale.

After sailing the boat for years, Hadden has concluded that his 361-sq-ft marconi rig (which is not included in the plans set) would be best suited to the deep-keel version, and the original gaff rig, with its 383 sq ft of area but a lower heeling moment, would be a better fit for the original centerboard version. He compensated for the marconi-centerboard combination by using 1,300 lbs instead of 1,000 lbs of internal lead ballast to keep her on her feet. He has considered changing to gaff rig but loves the simplicity of the triangular sails.

Hadden has devised A-frame sheer legs for stepping his masts before launching.

There’s that word again: simplicity. If Hadden has learned one thing about the Sea Bird in more than two decades, it is to make things ever simpler. During a recent deck replacement, he eliminated both a large bridge-deck hatch and a foredeck hatch. He removed his built-in VHF radio, together with its masthead antenna and wires, in favor of a handheld model. His red and green side lights are fitted into shroud-mounted blinds that take a little time to reinstall every year, but “It’s less obtrusive than pretty much anywhere else I can think to put them. And they work better up there, if you’re actually out sailing at night.

“The whole effort was to make it as simple and easy to paint as possible, because that’s all I do is paint,” Hadden said. He has strived to remove deck fittings. “If it’s not absolutely necessary, I don’t want to even look at it. You’re either sanding or you’re reminded of when you were sanding.”

The Sea Bird seems to scream it like a gull’s cry: Simplify, simplify. It’s a good antidote to life’s increasing complications.

Hadden launches his boat each year from a trailer, which is very unusual for a 25′ 7 1⁄2″ LOA boat that displaces some 6,000 lbs. It takes some effort. For example, he raises the rig while still ashore, and his bread-pan-sized lead ballast castings have to be transferred to the boat by skiff, one at a time, in what has become an annual ritual. But he pays nothing for haulage. He has the vast satisfaction of independence.

Having a deep keel would free up cabin space, true, but at a price: “There goes your hauling out on the trailer. There goes going happily wherever you want without navigating, which I enjoy. I can explore, and you really don’t have to worry, you’re just going to hit the centerboard.” He once poled the boat up a creek too narrow to turn around in, and next morning poled her out stern-first. He tells me this as we sail within what seems an arm’s reach of the cove’s rocky shore. “You wouldn’t be doing this if you converted this to a keel boat.”

With low freeboard, a proportional low-profile cabin trunk has everything to do with the Sea Bird’s appearance and also its function, giving the helmsman a clear view forward.

In the light and fluky breeze, she responded well to occasional puffs. She answered the tiller easily, with the feel of a larger boat. She tacks easily. Hadden has made only one change to the rigging: he brought the jibsheets inboard of the cockpit coaming instead of making them off to cleats on their outboard faces. “I brazenly cut holes in the coaming, just so when you are heeled over you can control that from the inside.” She ghosted along, only surrendering when the ebb made it clear that the current, and not the wind, was in control that afternoon. The Yanmar diesel carried us the last few hundred yards to the mooring.

“My favorite times are when it’s kind of dreary out, windy, and you’re going through the chop and the waves are hitting the bottom of the jib and streaming down,” Hadden says. “That’s when I’m saying to myself, ‘Okay, this is like the paintings.’” She handles best in about 15 knots of wind. Her mizzen is fairly large for a yawl, so it gets reefed first. In high winds, Hadden douses the jib and mizzen and sails on a reefed main alone.

Spartan accommodations encourage a simplicity of lifestyle that matches the boat’s overall theme.

The boat doesn’t pound in waves, and Hadden has actually found advantages in the hard chines. “People say, ‘Oh, it’s a hard chine,’ and that’s one of the reasons I think people don’t bother with it. But this particular boat, if you got rid of the chines, you’d lose it. That’s the best thing about it, is the chine line, the shape it makes. If you rounded that, it’d be fine, probably, but you’d lose a lot of the look. But when it gets rough out, t’s throwing the waves and all the water off to leeward. It’s a great thing.”

Hadden used 1″ Atlantic white cedar planking over oak backbone timbers and frames. “Structurally, these sawn frames are great. They’ve got big screws in them, they’re really deep, there’s a lot of them. I can’t imagine anything falling apart.” After it takes up, the hull does not leak. His original deck did, though, because the tongue-and-groove pine moved a lot and cracked the paint of the canvas. He replaced it with plywood sheathed in Dynel set in epoxy to better keep the water out. He couldn’t bear, however, to part with the traditional canvas sheathing over his coach roof, which fared much better because it was planked in fine cedar.

The bridge deck provides comfortable seating and makes the cockpit a sociable size.

Some Sea Bird builders made unfortunate design changes, especially involving the trunk cabin. For Hadden, even his new deck altered the purity of the boat’s profile perceptibly. “This is only a quarter of an inch lower, but I can tell the difference when I sit there in the window and look out at it. It’s not much. I got over it. But people who haven’t done it much, they’re always going, ‘Oh, who’s going to see an inch, inch and a half, two inches.’ So in the Sea Birds, a lot of them, the cabins were inches higher and wider.” Some extended the cabin aft, eliminating the bridge deck and with it the most comfortable place to sit topsides. Some clumsily squared off the cabin and used oversized portlights. Some changes were more drastic: “In the one we rebuilt, the stem was plumb, and had a big knuckle. The boat’s not drawn anything like that.”

The cabin, dominated by the centerboard trunk, provides rudimentary shelter, not comfort. In reality, it isn’t any smaller than those of many other small cruisers, a type that invites clever and inventive tinkering.

Plans for the Sea Bird yawl are available from The WoodenBoat Store , and Hadden Boat Company.

Thomas Fleming Day had ease of construction and limited expense in mind when he conceived the hard-chined Sea Bird yawl, yet the centerboarder proved herself in 1,000 miles of cruising in her first season in 1902. Redrawn by Dave Dillion for WoodenBoat in 1981 to rejuvenate interest in the type, the plans include the original gaff-rigged mainsail and ample detail for amateur construction.

Sea Bird Particulars: LOA 25′ 7 ½”, LWL 20′, Beam 8′ 1 ½”, Draft, board up 4′, Draft, board down 1′ 11″, Sail area (original gaff rig) 383 sq ft, Ballast (internal) 1000+ lbs, Displacement ~6000 lbs

Share this article

Join The Conversation

We welcome your comments about this article. If you’d like to include a photo or a video with your comment, please email the file or link.

Comments (14)

My uncle, Harry Pidgeon, built and sailed the most important Seabird yawl. It was named ISLANDER and he was the first to sail around the world alone twice. He was on his third when he was shipwrecked by a storm in the New Hebrides.

Nice story your uncle shared of his time doing it as well.

Great to hear from you, Bill. I hope you might have seen Eric Vibart’s article in WoodenBoat No. 206 (January/February 2009) about Harry. He must have been a fascinating character!

What a great article about the Sea Bird. Eric Vibart wrote an article about my Sea Bird Yawl L’ESPILL DEL MAR in 2011 for the magazine Voiles et Voiliers .

Harry was a distant relative of mine too; funny to think of all those years sailing down in San Pedro where he built Islander.

Loved your uncle’s book and have sailed by Terminal Island many times, often thinking of the place it was when he built the boat. His attitude and general demeanor proves again that people everywhere respond in kind to the travelers who pass through.

There was a larger Sea Bird yawl in Marblehead, Massachusetts, named SPAR HAWK which had 4 berths, head forward with trunk cabin overhead hatch when open one could stand while peeing. SPAR HAWK was 30′ on deck.

Sweet sailing boat in the ’50s and ’60s.

My step grandfather Jon Brundage had a Sea Bird yawl named SEA BIRD in slip #2 at the St. Francis Yacht Club on San Francisco Bay from the 1930s all the way to his passing in 1982. It is the boat I learned to sail on in the Bay. It was great to read this story and brought back fond memories of summer afternoons and evenings. He single-handed to Catalina and Mexico many times. His estate sold the boat and I was unable to purchase it at the time. I have no idea where it ended up. Glad there is still a following and plans available.

I believe my great grandfather may have owned the Seabird that those Marconi spars came off of, the timeline lines up being cut up right about perfectly 1988 or so and the rigs look identical.

Where was your great grandfather’s Sea Bird? I have a vague idea of how I ended up with those spars. Let me know…

Excellent article about a fine old boat. One would think though that if one were after simplicity and authenticity that the first thing to do would be to jettison the engine. I cannot understand how any boat can be expected to sail dragging a fixed, three-bladed prop around. Without the prop and aperture you likely would have been able to return to her mooring under sail. A further benefit: getting rid of an inboard engine and its associated gear and you have instantly cut maintenance time and cost in half, something that should have particular appeal to owners of traditionally-built wooden boats.

Simple enough for Amateurs? Chapelle writes: If the chine comes up high on the stem spend time in the moaning chair. He also writes in the design book the chine should join the stem near the water line. My boat only took 500 bs lead to float on the designed WL. She is in Wychmere Harbor, Harwich Port, every summer since ’85 and needs a new owner. Michael

Does she still need a new owner?

I grew up in the NYC area. My father purchased a delapadated 30″ Seabird yawl GULL. I spent my high-school years helping refurbish her and sailing between western Long Island Sound and Maine. I am a landlocked Coloradoan now, but those memories of weathering calms, storms, groundings, dismastings, whales, hurricanes, and more are priceless. GULL now calls home Deer Isle Maine, with my brother.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Stay On Course

More From This Issue

From The Editor

Iain Oughtred

Iain Oughtred, the Australian-born boat builder and designer whose boats frequently appeared in Small Boats, passed away on February 21, at the age of 85, in a hospital near his…

Boat Profile

Caledonia Yawl II

The original Caledonia Yawl, a rugged 19′ 6″ double-ended beach boat designed by Iain Oughtred for clinker plywood construction, has four strakes; this second iteration has seven, and was originally…

Chamberlain Gunning Dory

I looked online for an easy-to-build rowboat that we could use for exploring local lakes and rivers, and perhaps, some camp-cruising. I came across Dave Gentry’s Chamberlain Gunning Dory, based…

The Åland Islands

It was August, and under a brilliant blue sky we were off to explore the islands of Åland, the autonomous region at the southernmost tip of Finland where Swedish is…

Fastening Floorboards

Wood screws can hold floorboards in place, but they’re not suited for being removed and reinserted. Wooden turn-buttons are an effective approach in many cases, but in smaller craft, where…

Product Reviews

A Duckbill for a Push Pole

The push poles used in the mudflats and marshes in the East Bay area have lengths ranging from 12′ to 18′. There are many different attachments for the bottom end…

TripTips Retractable Portable Toilet

I’ve become accustomed to the comfort and convenience of portable heads, but they’re too big to carry aboard my canoes and small rowing boats. I’d still like to cruise in…

Reader Built Boats

Sailing DORCAS

Erik imagined putting a sailing rig on DORCAS, and as he developed the idea, he came up with some design parameters: The rig had to fit inside the back of…

More Small Boats Annual 2012

The Shaw & Tenney Whitehall

The Shaw & Tenney Whitehall is a glued-lapstrake-plywood interpretation of a general-purpose workboat dating to the early 19th century. A pure recreational boat, the contemporary version is lightweight and beautiful.

Salty Heaven

The author’s Salty Heaven, JESS, singlehanded in a fresh breeze. Sailed solo, the 17’ cat-yawl is fast and responsive. She will also happily carry passengers or a load of camping…

Peregrine 18

The Peregrine 18, with designer John Brooks at the oars, is a long, lean pulling boat. It’s fast and efficient, yet capable of doubling as a stable conveyance for island…

Colin Galloway built this 19' Thames skiff to an Iain Oughtred design. Oughtred’s plans specify glued lapstrake plywood; Galloway substituted solid wood—“The Real Thing,” says Oughtred. “She really is a…

Subscribe Today!

Become a subscriber today and you’ll recieve a new issue every month plus unlimited access to our full archive of backlogged issues.

Already a subscriber?   Sign In

Subscribe For Full Access

Flipbooks are available to paid subscribers only. Subscribe now or log in for access.

• Rudders & Steering

Custom kick-up rudders

Start here to spec your new rudder.

Leaves warehouse: 30 business days

• Copyright 1998-2024 SB Owners, LLC. All rights reserved.

• Policies | Contact Us

Log in or Sign up

You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser .

DIY rudder build.

Discussion in ' Fiberglass and Composite Boat Building ' started by DennisRB , Sep 28, 2010 .

DennisRB Senior Member

Hey guys. Here is my attempt at making a rudder for my dads 25 foot trailer sailer. My dad snapped it off by reversing up the driveway with it down. The boat is 25 foot long and about 1500kg the keel is 500kg on its own. The original rudder was only 2.5 foot long (water depth) and with some weather helm you would be sailing with it at 30 degrees which cant be good for speed or anything for that matter. So I added an extra foot to the new rudder. Obviously there are heaps of variables to how long the rudder should be but, surely 2.5 foot is way too small for a 25 foot 1500kg boat? Not sure if I am in the right section but being plywood and glass I guess that is more composite than wood right? I realize this is going to make me look pretty clueless but thats OK I have never used fiberglass before, or micro balloons or epoxy and in general just went at it to have a go. So please feel free to tell me all the things I done wrong so next time I can do em better. I sort of figured out a few things I done wrong all on my own anyway. Like glassing the whole rudder in one go! That ended up with a lot of wrinkled glass and way too much resin. I went and got a new orbital sander and that made short work of roughly smoothing it to get rid of the high spots even if I did sand through glass. How much could I have expected a pro to build a rudder replacement for this? My mate Wes and I done this over a few day and many beers. We started by screwing 2 pieces of 15mm marine ply and cutting out the shape of the old rudder and added 1 foot to the length. We then undone the screws and epoxied the 2 pieces together,holding it together with screws again. We removed the screws and power planed it to approximate the foil shape and finished the shaping it with my new electrical orbital sander. The foil shape wont win any races as its just by eye. How important is this? This boat is an old clunker anyhow. Nice work shed. Nice work boots. We then coated the whole lot in glass and epoxy in a very unprofessional manner (many beers had been consumed by this stage). I drilled a larger hole than required for the pivot pin and filled that with micro spheres so that when the whole is re drilled no wood is exposed to keep water out. I then sanded off the high spots and used west system micro spheres to fair it and sanded again. For the last few little imperfections I just used builders bog as I was sick of waiting 24 hours before I could sand the epoxy. Nice work bench Nice glassing job Nothing a sander cant fix.. at least aesthetically. The glass is just for abrasion and water protection anyway not strength. Roughly foil shaped. I did try to make it even in the sanding and planing stage by looking at the layers of ply as I removed material. You can see the size difference. Now its ready to undercoat and paint.  

susho Composite builder

too much resin, use a squeegee, and maybe some peelply to, could save you some sanding. you could use a router to shape it, you can work very symmetrical with it, and very precise. It looks nice though, better than my first one  

Thanks. I think the results so far are actually pretty good despite the somewhat substandard intermediate steps. Fully agree on the too much resin. We were just pouring it on to try and use up what we mixed up. I think because we done the whole lot in one go it became impossible to roll the excess out with the fiberglassing roller tool. I think I will be able to do it right next time by just doing the edges first so I can roll any excess resin out. Peel ply might work then. I don't think it would have helped a lot this time given how bad we laid it up How do you mean a router would help to make it even and shape it? Would I set it to pre determined different depths and scribe grooves at even spacings then plane down to the grooves or something?  

Landlubber Senior Member

...bit late, but have a look at the NACA site for different profiles for different outcomes, it will teach you a few good lessons anyhow..... this one will do.... http://en.wikipedia.org/wiki/NACA_airfoil  

Nice link. I know a little bit about airfoils. I have been into RC planes since I was a kid. But I don't really know how much it matters for a rudder on a boat? Do foil changes really make a big or even noticeable difference for a cruising boat for a rudder? I know on my RC planes the main wing needed a good airfoil but when it came to the rudder and elevator a flat board was good enough. How do people usually get their rudders to match the foil shape? With RC planes its easy as you just print the foil shape out then use a hot wire bow to cut the foam core. I guess this could work with some types of foam for boat rudders too but what about wood?  

..as you can see in the plywood "grain" it is very easy to set parallels and thickness of course because the veneers are the same thickness, therefore you can "see" the shape, that is how I know that you have not done that...have a look at your own pics.  

I did use the veneer lines. I thought the lines were parallel enough that sanding the fairing compound would lead to a pretty straight result. I can see that the lines are not totally straight but pic one shows a (failed?) attempt to get it fairly straight. I took too much material away in some areas and elected to fill those areas later rather than taking more material away to make it even. Given my glassing job I doubt much more accuracy here would have made a differnce anyway The pencil lines were made so I could trace the veneer lines on paper then draw them on the other side to get the same shape on both sides. The thing was I didn't actually have any particular foil shape, just whatever looked OK. But I hear you that my job was pretty shithouse I wont argue there. Maybe I next time I can do what I do for a RC plane wing and draw the airfoil on both ends then shave it to that profile on the ends, and from there I can make parallels down the whole rudder? Given I will actually have a real foil shape then it might pay to put more effort into keeping the lines straight and doing a decent glassing job. Thanks for the tips Does anyone have any input on the new and old rudder sizes?  

PAR Yacht Designer/Builder

On small, light weight boats, a plywood rudder is acceptable, as the loads are fairly light, but once you get over 18', the loads increase enough to make plywood a less desirable rudder material. This is because plywood is about 2/3's as strong as solid wood in this longitudinal flexural role and failure from "rolling shear" is a real possibility. A better wooden approach for a boat of this size is a strip planked blade. The pictures aren't great, but you can see the foil sections are being cut. These pictures where taken as I switched foil templates, which was routed across the blade. You can see the quarter sawn strips (about 1.25" x 1.5") edge glued. What can't be seen is the alternating grain orientation to eliminate internal stresses.  

Attached Files:

hoytedow Carbon Based Life Form

Great reference thread!  

Thanks PAR. I really should have made this thread before I started the build. Do you think my rudder is strong enough realistically? The ply is about 27mm thick at the top where it joins the stock since some material had to be removed so it would fit in. The old rudder didn't snap from normal use. But I assume the extra length will only put more stress on it. I still don't understand how you use a router to accurately cut the foil shape?  

27 mm is a thin blade for your boat, unless you plan on racing and looking to reduce drag as much as possible. The break in the picture looks just like what a break from a rolling shear failure looks like. You may have had some internal fiber failures, but the blade was still whole and the drive way was the straw that broke it's back. In other words it broke at it's weakest point when it hit the driveway. Why did you add length to the blade? Thee are a few methods that I know of for using a router jig to cut foil sections. Naturally each has good and bad points about them. The blade I show was for a light weight, 17' daysailor and finished about 1" thick. Because the blade changed shaped pretty dramatically along it's length I elected to make several templates and adjust the foil type along the length. The top portion of the blade was a surface piercing shape, the middle portions transitioned from 0012 to 0016 and the end of the blade was a 63 series section. This caused me to have to cut in 6" sections at a time, but this isn't unusual. The setup can be tedious for these router jigs, but you end up with precise sectional shapes and more importantly symmetrical foils.  

The bade is over 32mm thick in total for most of the span. Only the section that goes into the stock was shaved to 27mm so the glass could pack it out to 30mm so it would fit in. The stock slot is 30mm. That just happens to be the most stressed part of the rudder too. This boat was used for racing and was apparently one of the fastest trailer boats in Moreton bay 40 years ago. It was owned by the Commodore of the Manly Yacht Club. Now its performance would be regarded as slow with all the cruising "improvements" my dad made to it. Its much slower than my Binks 25. I lengthened the rudder to the same length as my Binks 25 (which is the same length but lighter). It now appears to the same size as most other boats of this length where before it was much smaller than the average. The rudder just seemed too small and always seemed to drive though the water at a overly large angle of attack. I hope it can now sail with the rudder in a more centered position to reduce drag broaching. The way the rudder hit on the driveway would have snapped any rudder. Something had to break with it wedged into the ground and a car reversing up with force. The driveway is steep and the stern lifts high into the air is it comes up from the road. So the rudder would have almost dropped right down before the full weight of the boat would have pushed back down on it while going backwards. Thats not to say it wasn't damaged already though. In fact this was the second rudder he snapped like this. I think a better method of holding it up is required or at least checking its up. If it snaps I now know how to make a stronger version with strip planking But I really don't want it snapping and causing a dangerous situation. Sounds like you really tried to make your rudder as good as possible with all those foil changes. Did it work as you hoped? Was it for a new boat or an upgrade?  

This rudder blade (shown above) was for one of my designs. It was a new build, but the first to have a full foil shape allotment it's full length. Previous versions had flat sided foil sections which are easy to cut by the novice, but not quite as efficient as the "full up" version. Both the centerboard and rudder received this treatment and I had an opportunity to sail it against another of the same design, shortly after launching. The foil section equipped boat, which was identical other wise, right down to the sails. I made both boats (well made one, bare hulled the other) and the sails came from the same supplier. The new foil equipped boat was able to point slightly higher, had less turbulence at the top of the rudder, handled beam sea conditions better, the rudder seemed to stay "in the groove" longer, etc. So, yes the improvements where worth the extra work. The slab sided centerboard would "hum" a touch when up on plane, but the fully shaped centerboard didn't. If you where experiencing a lot of helm deflection with the short rudder, you may have other issues then rudder length. I would have had to access the boat a little before making this change, like what condition are the sails, which is a common cause of excessive helm deflection (weather helm). How about the rig, what is the mast rake and do you know what it's supposed to be? Is the boat sitting on her lines or a little down at the stern? This is also a common problem, usually because the boat has become a storage box and gained a considerable amount of weight, not unusually under the cockpit out of sight and mind until it affects trim.  

Thanks for the info on your boat design. It seems real foil shapes are well worth the effort. Do you have a pic of the boat? The 25 foot trailer sailer in question has been molested from its original specification. (no pics sorry, I will get some eventually) From day one it had 100mm more freeboard. The swing keel was extended 30cm and with more weight. The keel is pretty much a hollow rectangular steel plate construction with lead filled in the bottom. Only the leading and trailing edges are sharpened so its has a very crude cross section. However in this state it was successful in racing when it was made 40 years ago. From here the boat has had a few mods which detract from performance and aid cruising. It now has a electric anchor winch and carries 50m or chain up high in the bow. It has a heavy copper 80L fuel tank in the stern. The mast snapped from a rigging failure and my dad decided to get a taller mast so that the mainsail and boom could be higher up to fit a canopy under. Despite the extra mast hight the new mainsail that had to be cut is still smaller in area than the original but with a higher center of effort. The new mast was of a significantly heavier section so with the extra length and size it is probably twice the weight. The rigger who set this up was a ***** and the mast has a slight forward rake. It was much worse but we got it to almost vertical. The taller mast would have changed the angle of the forestay but the boat does have adjustable points for the jib sheeting. The hull shape has fairly straight runs aft, which make it good downwind in a strong breeze (planes) but the transom sits about 100mm under water which causes drag in most situations. I'm sure there was a noticeable performance decrease with the new rig. But the boat always had weather helm and this only made it worse.  

• Advertisement:

This is her just coming together. Not all the coming is in place, but most everything else is. The other picture is the only rudder shot and the blade isn't there, just the rudderhead. The blade was also painted, but the tiller was a lovely vertical lamination (instead of the typical horizontal) of mahogany and white fir. Instead of tapering the outside of tiller, I tapered the fir portions of the laminate which made it especially interesting to look at.  

Young-46.jpg

Young-47.jpg.

DIY inspection port?

DIY fairing boards

using DIY boat FG techniques on travel trailer

Is there a definitive book on DIY cabin sole replacement?

DIY Vacuum leak detector for less than $20

DIY Fiberdust collector

DIY hard top for bridge

diy resin trap

Wrong way to open a glass rudder?

Carbon rudder stock: what about torsion?

• No, create an account now.
• Yes, my password is:
• Forgot your password?

Sailboat Keel Types: Illustrated Guide (Bilge, Fin, Full)

The keel type is one of the most important features of your boat. But the different designs can be confusing, so I've set out to create a very clear guide that will help you understand sailboat keels once and for all.

What are the most common sailboat keel types? The most common sailboat keel types are full-length keels, fin keels, bulb keels, wing keels, bilge keels, and lifting keels. Full keels are popular among cruisers, while fin keels are generally used for racing. Bilge keels and lifting keels are typically used in tidal waters, on small fishing boats for example.

In this article, we'll explore the most common keel types together. I'll use diagrams to really hit home the differences of all these keel types, and we'll discuss what keel types are best for liveaboard, ocean cruising, and lake weekend trips. After reading this article, you'll know what to choose - and why.

Sailboat Keels Explained

On this page:, overview of sailboat keel types, keel types: fundamentals, modified full keel, centerboard.

If you just want a quick overview, here's a list with the most common keel types and a short description. More detail will follow below.

The most common keel types

• Full keels run from front to aft and are the most stable keel type, making them the most popular cruising keel.
• Fin keels offer the best performance but are less comfortable. This makes them popular for racing. Fin keels are bolted on to the hull and generally run deep and thin.
• Bulb and wing keels are both variants on the fin keel.
• Bulb keels carry additional ballast in the tip, making them more stable.
• Wing keels have two tips at the end of the keel, which reduces crossflow, improving directional stability.
• Bilge keels are double fin or double full kees, which allows the boat to be beached, making them the most popular keel for tidal waters.
• Lifting keels are moveable keels that can be lowered and raised, allowing the boat to enter shallow waters as well.
• Centerboard keels are a pivoting lifting keel, allowing to sail both coastal and inland waters.
• Leeboards are fins on the sides of flat-bottomed hulls boats, making a keel unnecessary.

Properties of each keel type

What does a keel do?

What does the keel do? A keel is a vertical blade running down from the hull. It is weighted and acts as a ballast, countering the boat's tendency to heel and preventing it from tipping over. The wetted surface under the waterline reduces slippage to leeward by creating a track, which counters the sideway force of the wind on the sails.

The reason sailboats don't tip over is that the weight of the keel counters the buoyancy of the hull, which means it will pull the boat downward. This downward force reduces heel and prevents the boat from rolling.

A canoe doesn't have a keel. Try stepping into that: it will want to roll.

It counters the horizontal force the wind puts on the sails. Whenever the force on the sails increases, the resistance of the water on the keel increases proportionally.

The heavier the keel, the less heel you'll get.

A keel reduces slippage to leeward. Slippage is simply the amount you fall off course because of the direction of the wind and current. Leeward is the side of the boat behind the wind.

So if you don't have a keel, you will fall off course quite a lot because the wind will push you over the water surface.

You will also heel quite a lot since there is nothing beneath the water surface to counter the force of the wind high up in your sails.

A keel fixes both of these issues and makes sailboats one of the most reliable boats in heavy winds and storms.

You can read on about how keels work here.

Keels can be classified by multiple dimensions. You can look at them from the side or the front. You can also classify them based on properties.

Before I dive into each keel type in-depth and show examples, let's make sure we have the same starting point.

There are essentially two sorts of keels:

Fixed keels

Movable keels.

Fixed keels are keels that are integrated into the hull or bolted on. They can't be moved or lifted.

When looking at fixed keels, you can divide them up further based on the side view. There are three main categories:

Bilge keels

Full keels are more comfortable, provide better stability and protection, but are also slower than fin keels.

Fin keels are less comfortable, provide less stability, are more vulnerable, but they're also a lot faster than full keels.

Bilge keels are double keels: one on each side of the hull. This allows them to be beached, which comes in handy in tidal waters. They are generally a lot slower and less maneuverable compared to fin keels.

Movable keels can be lifted from the water, creating a shoal (shallow) draft, allowing the boat to enter both shallow waters and coastal waters. This makes it a very versatile keel type. There are two main designs:

Lifting keels

Lifting keels can be lowered and raised through a slit in the hull. Examples of lifting keels are the daggerboard and centerboard.

Leeboards are wooden swords attached to the side of the hull and prevent slippage to leeward, but they don't stabilize the boat, nor counter heel by adding ballast.

With fin keels, there are different tip designs available. The most common two tip designs are:

These are both variants of the fin keel. Generally, these keel designs are mentioned in one breath with full keels and fin keels, creating confusion on what kind of keel they are. But it's important to understand that they are a sub-category of fin keels.

Rudder design

As with the tip of the fin, there are different rudder designs that may apply to both fin and full keels. The two most common rudder designs are:

Skeg rudder

Spade rudder.

A skeg is a structural part of the keel in front of the rudder that protects the rudder. The keel encompasses the rudder, preventing any rogue ropes, weeds, or rocks from damaging the rudder.

A spade rudder is an unprotected rudder: it doesn't have any structural protection from the keel design. It is simply attached to the hull. This design is very common.

Alright, we understand the big picture. Let's dive into more detail for each keel type and discuss the pros and cons.

Fixed keel Good for cruising and liveaboards Comfortable

What is a full keel? A full keel runs from front to aft for at least 50% of the hull and is fully integrated into the hull. It has the largest wetted surface of any keel type, and it is also the heaviest. This results in directional stability and reduced heeling, providing the most comfortable ride, but also the slowest.

The wetted surface simply means the amount of water contact area. With such a large wetted surface, it decreases slippage to leeward the most of all keel types, while it counters heeling the most as well.

The full keel is the most comfortable and stable keel type available. However, comfort comes at a price. It delivers the worst performance due to this large wetted area. It is the slowest of the keel types, and it has the worst windward performance.

This makes full keels particularly great for longtime cruisers or liveaboards who prefer comfort over speed, but less ideal for daysailers who need to navigate in and out of slips regularly.

Since it runs for at least 50% of the hull, it doesn't need to run as deep as a fin keel, resulting in a more shoal draft.

Heavier keels result in increased displacement, so a full keel boat will need a larger sail area to compensate for its weight.

For a more detailed discussion on full keel advantages, I recommend reading William's excellent article 5 Surprising Advantages of a Full Keel Sailboat here.

Example sailboats with a full keel:

• Nicholson 22
• Island Packet 380
• Beneteau Oceanis 411 Clipper
• Beneteau First 50
• Jeanneau Sun Shine 38
• Dufour 455 Grand Large

There are a lot of great cruising boats with full keel designs , some of them considered classics.

Full Keel with skeg rudder

Full keels with a skeg rudder design have a protected rudder, thanks to putting a structural part of the keel directly in front of the rudder. This helps with fending off any hazards to the rudder, like floating pieces of rope, rocks, or garbage, and protects it in case of running aground. The skeg design ensures the rudder is nearly impossible to break off.

Fixed keel Good for cruising and liveaboards Faster than a regular full keel

What is a modified full keel? A modified full keel is a full keel with a cutout at the front, reducing the wetted surface slightly, which increases performance without sacrificing too much comfort and stability. After the full keel, it has the best directional stability and the least amount of heel.

The modified full keel is popular among (bluewater) cruisers, thanks to its increased handling and performance. Most modified full keels have a skeg rudder, ensuring it is well-protected.

The slightly reduced weight and wetted surface improve windward performance quite a lot, but it is still one of the most stable keel designs out there.

Example sailboats with a modified full keel:

• Hallberg-Rassy HR 40
• Dufour Arpege 30
• Beneteau Oceanis Clipper 281
• Jeanneau Sun Odyssey 37.2

Fixed keel Good for racing Fast

What is a fin keel? A fin keel is a long, weighted blade attached to the bottom of the hull. It is lighter, faster, and more maneuverable than a full keel, but also more vulnerable. The increased distance between ballast and sails provides a lever, reducing the need for a large wetted surface or additional ballast.

Fin keels are generally bolted onto the hull and run deeper and thinner than a full keel. They are also lighter. This helps increasing performance (a lot), making fin keels a lot faster in all situations.

There are some major disadvantages to fin keels, however. Fin keels are a lot less comfortable than full keels and allow for more heel and a less solid track, so less directional stability. Fin keels are also a lot more vulnerable than full keels. They can break off when running aground, or get damaged.

They are very popular among racers and perform better when maneuvering in tight spots, like getting in and out of slips.

Example sailboats with a fin keel:

• Catalina 30
• Jeanneau Sun Odyssey 36.2

Fin keel with skeg rudder

Fin keels with a skeg rudder use a small structural part in front of the rudder to protect it. This design is mostly integrated into the hull, making it less vulnerable, and a great compromise between speed and safety.

Fin keel with spade rudder

Fin keels with a spade rudder have a completely exposed rudder, and typically a fin that is simply bolted on. The keel isn't integrated into the hull, making it more vulnerable and less comfortable.

Fin keel variant Good for cruising Less crossflow

What is a wing keel? A wing keel is a fin keel with a horizontal foil at the tip, which is wing-shaped and generally weighted. Its shape reduces crossflow, improving directional stability, and its ballast decreases heel, resulting in a more comfortable ride. The addition of a wingtip allows for a shorter fin, reducing draft.

Wing keels are good for cruising since this design improves directional stability compared to a regular fin keel or a bulb keel.

We'll discuss the wing keel's advantages and disadvantages in more detail in this article.

Fin keel variant Good for cruising Stability

What is a bulb keel? A bulb keel is a high-aspect-ratio fin keel with additional ballast at the end, which generally has a bulb or teardrop shape. This ballast improves stability and utilizes the distance between force and counterforce as a lever. This design reduces the need for a deep fin, resulting in a shoal draft.

By placing the weight at the largest possible distance from the force on the sails, you need relatively little extra weight for the same reduction in heel, making bulb keels very effective for cruising.

This design reduces the wetted area while increasing the weight of the keel just slightly, which increases sailing comfort big time.

Example sailboats with a bulb keel:

• Bavaria B/One
• Beneteau First 24

Fixed keel Good for racing Can be beached

What is a bilge keel? A bilge keel is a twin keel which uses double fins, allowing the boat to be beached and rest on its keel upright. Bilge keels have double the wetted surface, which increases comfort and directional stability while decreasing heel. Modern bilge keels often provide decent windward performance, thanks to better design.

The bilge keel does sacrifice speed compared to the fin keel but doesn't necessarily offer worse performance overall. Older designs performed considerably worse than other keels and were especially slow.

Bilge keels have some major advantages over full keels and fin keels. The most important is that the boat can be beached, making it a popular design in tidal waters. Bilge keels are especially common along the British coastline, where fishermen keep their boats in tidal harbors.

Another major advantage is that the boat can be stored resting on its keels, making dry storage and maintenance a lot easier.

Of course, there are many more pros and cons to the bilge keel , which we go into here.

Example sailboats with a bilge keel:

• Dufour Dynamique 62
• Hunter Duette
• Patagonia Patago 39
• Macwester 27

Lifting keel Good for daysailers Versatile

What is a centerboard? A centerboard is a type of retractable keel that rests on a hinge and can be lowered through a slot in the hull. It folds out like a pocket knife and allows you to increase or reduce the draft of the boat. Centerboards are mostly used on small fishing boats.

The centerboard is a very versatile keel type, allowing you to have both a very shoal draft for inland waters, as well as steadying the boat and reducing heel for larger bodies of water, or even oceans.

I've sailed a Cornish Crabber with a centerboard for a week, and while we stayed inland, having the option to increase the keel depth really came in handy when crossing the IJsselmeer (a former sea in The Netherlands).

There's more to the center

Olaf Roethele

https://www.theyachtmarket.com/en/new-boats/cornish-crabbers/adventure-17/218/

My name is Olaf and I am the owner of a Cornish Crabber 17 Adventure boat.

I would like to ask you if you can imagine to install on this boat a Torqeedo 2.0 Pod motor? Therefore i guess a modification of the keel/skeg is necessary ?!

Best regards from Uruguay,

You completely missed the hybrid planing/water-ballast keel of the Macgregor range

Thanks a lot for this explanation

Roger Bannon

Very well written article which provides an excellent guide for us small wooden boat builders. Thanks.

Leave a comment

Own your first boat within a year on any budget.

A sailboat doesn't have to be expensive if you know what you're doing. If you want to learn how to make your sailing dream reality within a year, leave your email and I'll send you free updates . I don't like spam - I will only send helpful content.

Ready to Own Your First Boat?

Just tell us the best email address to send your tips to:

The Types of Sailboat Rudders

• Snowboarding
• Scuba Diving & Snorkeling

Full Keel Rudder

On a sailboat , as the rudder is moved to one side by means of the tiller or steering wheel, the force of the water striking one edge of the rudder turns the stern in the other direction to turn the boat. Different types of rudders have different advantages and disadvantages. The type of rudder is often related to the boat’s type of keel.

Rudder on Full-Keel Sailboat

As shown in this photo, the rudder of a full-keel boat is usually hinged to the aft edge of the keel, making a continuous surface. The engine’s propeller is usually positioned in an aperture between the keel and rudder.

Advantages of Full Keel Rudder

The primary benefit of this rudder configuration is the strength and protection provided to the rudder. It is hinged at top and bottom, well distributing the forces on the rudder. Rope (such as lobster pot warps) or debris in the water cannot snag on the rudder.

Disadvantage of Full Keel Rudder

Because the sideways force of the water on the rudder is entirely behind the rudder’s pivoting point at its leading edge, putting all the force on one side of the rudder, it takes more energy to move the rudder. This is one reason why larger boats seldom have tillers—because it can require much force to “push” the rudder out against the water streaming past the keel.

Spade Rudder

Most fin keel boats have a spade rudder, which extends straight down from the aft hull section. The rudder post comes down through the hull into the rudder itself, allowing the entire rudder to rotate to either side, pivoting around the post.

Advantages of Spade Rudder

The spade rudder is self-standing and does not require a full keel or skeg for its mounting. The rudder post inside the rudder can be moved aft from the leading edge (see next page on Balanced Rudder) so that the force of the water is not all on one side when the rudder is turned. This requires less energy to steer than with a keel- or skeg-mounted rudder.

Disadvantage of Spade Rudder

A spade rudder is more vulnerable to debris or objects in the water, which may strike the rudder and exert a force on the rudder post, the only structure supporting the whole rudder. Even the force of water when the boat “falls” off a wave can exert damaging stress on a spade rudder. If the rudder post is bent, the rudder may jam and become useless.

Balanced Spade Rudder

Note the clear air space at the top of the leading edge of this balanced spade rudder. The rudder post is several inches back from the front of the rudder. When the rudder is turned, the leading edge rotates to one side of the boat while the trailing edge rotates to the other side. While the turning action on the boat is the same, the forces on the helm are more nearly balanced, making it very easy to steer.

Skeg-Mounted Rudder

Some fin keel sailboats have a skeg-mounted rudder like the one shown. The skeg offers the same advantages as a keel mounted rudder: the rudder is protected from objects in the water and has more structural strength than a rudder mounted only on the rudder post.

It also has the same disadvantage: because it is not “balanced” as a spade rudder may be, with water forces distributed on both sides, it requires more force to turn the rudder.

Outboard Rudder

An outboard rudder is mounted outside the hull on the boat’s stern, such as shown in this photo, rather than below the hull using a rudder post or hinges to the keel or skeg. Most outboard rudders are turned with a tiller rather than a steering wheel since there is no rudder post to which to gear a wheel.

Advantages of Outboard Rudder

An outboard rudder does not require a hole through the hull for a rudder post and thus is less likely to cause trouble if damaged. The rudder can often be removed or serviced while the boat is still in the water. Hinges at the top and bottom of the rudder section may provide more strength than a single rudder post.

Disadvantages of Outboard Rudder

Like a spade rudder, an outboard rudder is vulnerable to being struck by or caught in objects or rope in the water. Unlike a spade rudder it cannot be balanced in the water flow, so the force of water is always on one side of the pivot point, requiring more energy for turning the rudder.

A rudder is often related to keel shape . 

• Choosing a Centerboard or Fixed Keel Sailboat
• Learn How to Sail a Small Sailboat – 1. The Parts of the Boat
• Control Your Tiller Without a Tiller-Tamer
• Choosing an Inboard or Outboard Engine
• 6 Types of Boat Engines
• How to Tow a Dinghy Behind a Sailboat
• How to Heave To a Sailboat
• The Sunfish: A Perfect Lake or Urban Sailboat
• How to Anchor a Sailboat
• Do It Yourself Boat Trailer Tongue Extension
• Simple Reefing System for Sailors
• How to Rig a Preventer Line
• How Brake Calipers Work
• How to Frog Kick
• RC Airplane Parts and Controls
• From A-Z: A Star Wars Glossary

10 Best Small Sailboats (Under 20 Feet)

Last Updated by

Daniel Wade

December 28, 2023

Compact, easy to trailer, simple to rig, easy to maintain and manage, and affordable, the best small boats all have one thing in common: they offer loads of fun while out there on the water.

So whether you're on a budget or just looking for something that can offer ultimate daytime rides without compromising on safety, aesthetic sensibilities, alternate propulsion, and speed, the best small sailboats under 20 feet should be the only way to go.

Let's be brutally honest here; not everyone needs a 30-foot sailboat to go sailing. They come with lots of features such as electronics, entertainment, refrigeration, bunks, a galley, and even a head. But do you really need all these features to go sailing? We don't think so.

All you need to go sailing is a hull, a mast, rudder, and, of course, a sail. And whether you refer to them as daysailers, trailerable sailboats , a weekender sailboat, or pocket cruisers, there's no better way to enjoy the thrills of coastal sailing than on small sailboats.

There are a wide range of small boats measuring less than 20 feet available in the market. These are hot products in the market given that they offer immense thrills out on the sea without the commitment required to cruise on a 30-footer. A small sailboat will not only give you the feel of every breeze but will also give you the chance to instantly sense every change in trim.

In this article, we'll highlight 10 best small sailboats under 20 feet . Most models in this list are time-tested, easy to rig, simple to sail, extremely fun, and perfect either for solo sailing or for sailing with friends and family. So if you've been looking for a list of some of the best small sailboats , you've come to the right place.

So without further ado, let's roll on.

Table of contents

{{boat-info="/boats/hunter-15"}}

The Marlow-Hunter 15 is not only easy to own since it's one of the most affordable small sailboats but also lots of fun to sail. This is a safe and versatile sailboat for everyone. Whether you're sailing with your family or as a greenhorn, you'll love the Hunter 15 thanks to its raised boom, high freeboard, and sturdy FRP construction.

With high sides, a comfortable wide beam, a contoured self-bailing cockpit, and fiberglass construction, the Hunter 15 is certainly designed with the novice sailor in mind. This is why you can do a lot with this boat without falling out, breaking it, or capsizing. Its contoured self-baiting cockpit will enable you to find a fast exit while its wide beam will keep it steady and stable no matter what jibes or weight shifts happen along the way.

This is a small sailboat that can hold up to four people. It's designed to give you a confident feeling and peace of mind even when sailing with kids. It's easy to trailer, easy to rig, and easy to launch. With a price tag of about $10k, the Hunter 15 is a fun, affordable, and versatile boat that is perfect for both seasoned sailors and novices. It's a low-maintenance sailboat that can be great for teaching kids a thing or two about sailing.

Catalina 16.5

{{boat-info="/boats/catalina-16-5"}}

Catalina Yachts are synonymous with bigger boats but they have some great and smaller boats too such as Catalina 16.5. This is one of the best small sailboats that are ideal for family outings given that it has a big and roomy cockpit, as well as a large storage locker. Designed with a hand-laminated fiberglass sloop, the Catalina 16.5 is versatile and is available in two designs: the centerboard model and the keel model.

The centerboard model is designed with a powerful sailplane that remains balanced as a result of the fiberglass centerboard, the stable hull form, and the rudder. It also comes with a tiller extension, adjustable hiking straps, and adjustable overhaul. It's important to note that these are standard equipment in the two models.

As far as the keel model is concerned, this is designed with a high aspect keel as the cast lead and is attached with stainless steel keel bolts, which makes this model perfect for mooring or docking whenever it's not in use. In essence, the centerboard model is perfect if you'll store it in a trailer while the keel model can remain at the dock.

All in all, the Catalina 16.5 is one of the best small sailboats that you can get your hands on for as low as $10,000. This is certainly a great example of exactly what a daysailer should be.

{{boat-info="/boats/hobie-16"}}

There's no list of small, trailerable, and fun sailboats that can be complete without the inclusion of the classic Hobie 16. This is a durable design that has been around and diligently graced various waters across the globe since its debut way back in 1969 in Southern California. In addition to being durable, the Hobie 16 is trailerable, great for speed, weighs only 320 pounds, great for four people, and more importantly, offers absolute fun.

With a remarkable figure of over 100,000 launched since its debut, it's easy to see that the Hobie 16 is highly popular. Part of this popularity comes from its asymmetric fiberglass-and-foam sandwiched hulls that include kick-up rudders. This is a great feature that allows it to sail up to the beach.

For about $12,000, the Hobie 16 will provide you with endless fun throughout the summer. It's equipped with a spinnaker, trailer, and douse kit. This is a high-speed sailboat that has a large trampoline to offer lots of space not just for your feet but also to hand off the double trapezes.

Montgomery 17

{{boat-info="/boats/montgomery-17"}}

Popularly known as the M-17, The Montgomery 17 was designed by Lyle C. Hess in conjunction with Jerry Montgomery in Ontario, California for Montgomery Boats. Designed either with keel or centerboard models, the M-17 is more stable than most boats of her size. This boat is small enough to be trailered but also capable of doing moderate offshore passages.

This small sailboat is designed with a masthead and toe rail that can fit most foresails. It also has enough space for two thanks to its cuddly cabin, which offers a sitting headroom, a portable toilet, a pair of bunks, a DC power, and optional shore, and a proper amount of storage. That's not all; you can easily raise the deck-stepped mast using a four-part tackle.

In terms of performance, the M-17 is one of the giant-killers out there. This is a small sailboat that will excel in the extremes and make its way past larger boats such as the Catalina 22. It glides along beautifully and is a dog in light air, though it won't sail against a 25-knot wind, which can be frustrating. Other than that, the Montgomery 17 is a great small sailboat that can be yours for about $14,000.

Norseboat 17.5

{{boat-info="/boats/norseboat-17-5"}}

As a versatile daysailer, Norseboat 17.5 follows a simple concept of seaworthiness and high-performance. This small sailboat perfectly combines both contemporary construction and traditional aesthetics. Imagine a sailboat that calls itself the "Swiss Army Knife of Boats!" Well, this is a boat that can sail and row equally well.

Whether you're stepping down from a larger cruiser or stepping up from a sea kayak, the unique Norseboat 17.5 is balanced, attractive, and salty. It has curvaceous wishbone gaff, it is saucy, and has a stubby bow-sprit that makes it attractive to the eyes. In addition to her beauty, the Norseboat 17.5 offers an energy-pinching challenge, is self-sufficient, and offers more than what you're used to.

This is a small, lightweight, low-maintenance sailboat that offers a ticket to both sailing and rowing adventures all at the same time. At about 400 pounds, it's very portable and highly convenient. Its mainsails may look small but you'll be surprised at how the boat is responsive to it. With a $12,500 price tag, this is a good small sailboat that offers you the versatility to either row or sail.

{{boat-info="/boats/sage-marine-sage-17"}}

If you've been looking for a pocket cruiser that inspires confidence, especially in shoal water, look no further than the Sage 17. Designed by Jerry Montgomery in 2009, the Sage 17 is stable and should heel to 10 degrees while stiffening up. And because you want to feel secure while sailing, stability is an integral feature of the Sage 17.

This is a sailboat that will remain solid and stable no matter which part of the boat you stand on. Its cabin roof and the balsa-cored carbon-fiber deck are so strong that the mast doesn't require any form of compression post. The self-draining cockpit is long enough and capable of sleeping at 6 feet 6 inches.

The Sage 17 may be expensive at $25k but is a true sea warrior that's worth look at. This is a boat that will not only serve you right but will also turn heads at the marina.    

{{boat-info="/boats/laserperformance-laser-sb3"}}

Having been chosen as the overall boat of the year for 2008 by the Sailing World Magazine, the Laser SB3 is one of the coolest boats you'll ever encounter. When sailing upwind, this boat will lock into the groove while its absolute simplicity is legendary. In terms of downwind sailing, having this boat will be a dream come true while it remains incredibly stable even at extraordinary speed.

Since its debut in 2004, the Laser SB3 has surged in terms of popularity thanks to the fact that it's designed to put all the controls at your fingertips. In addition to a lightweight mast, its T- bulb keel can be hauled and launched painlessly. For about $18,000, the Laser SB3 ushers you into the world of sports sailing and what it feels to own and use a sports boat.

{{boat-info="/boats/fareast-18"}}

As a manufacturer, Fareast is a Chinese boat manufacturer that has been around for less than two decades. But even with that, the Fareast 18 remains a very capable cruiser-racer that will take your sailing to the next level. In addition to its good looks, this boat comes with a retractable keel with ballast bulb, a powerful rig, and an enclosed cabin.

Its narrow design with a closed stern may be rare in sailboats of this size, but that's not a problem for the Fareast 18. This design not only emphasizes speed but also makes it a lot easier to maintain this boat. Perfect for about 6 people, this boat punches above its weight. It's, however, designed to be rigged and launched by one person.

This is a relatively affordable boat. It's agile, safe, well-thought-out, well built, and very sporty.

{{boat-info="/boats/chuck-paine-paine-14"}}

If you're in the market looking for a small sailboat that offers contemporary performance with classic beauty, the Paine 14 should be your ideal option. Named after its famous designer, Chuck Paine, this boat is intentionally designed after the classic Herreshoff 12.5 both in terms of dimensions and features.

This is a lightweight design that brings forth modern fin keel and spade rudder, which makes it agile, stable, and faster. The Paine 14 is built using cold-molded wood or west epoxy. It has varnished gunnels and transoms to give it an old-time charm. To make it somehow modern, this boat is designed with a carbon mast and a modern way to attach sails so that it's ready to sail in minutes.

You can rest easy knowing that the Paine 14 will not only serve you well but will turn heads while out there.

{{boat-info="/boats/wd-schock-lido-14"}}

Many sailors will attest that their first sailing outing was in a Lido 14. This is a classic sailboat that has been around for over four decades and still proves to be a perfect match to modern small boats, especially for those still learning the ropes of sailing.

With seating for six people, the Lido 14 can be perfect for solo sailing , single-handed sailing, or if you're planning for shorthanded sailing. While new Lido 14 boats are no longer available, go for a functional used Lido 14 and you'll never regret this decision. It will serve you well and your kids will probably fall in love with sailing if Lido 14 becomes their main vessel during weekends or long summer holidays.

Bottom Line

There you have it; these are some of the best small sailboats you can go for. While there are endless small sailboats in the market, the above-described sailboat will serve you right and make you enjoy the wind.

Choose the perfect sailboat, invest in it, and go out there and have some good fun!

Related Articles

I've personally had thousands of questions about sailing and sailboats over the years. As I learn and experience sailing, and the community, I share the answers that work and make sense to me, here on Life of Sailing.

by this author

Best Sailboats

Most Recent

What Does "Sailing By The Lee" Mean?

October 3, 2023

The Best Sailing Schools And Programs: Reviews & Ratings

September 26, 2023

Important Legal Info

Lifeofsailing.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon. This site also participates in other affiliate programs and is compensated for referring traffic and business to these companies.

Similar Posts

Affordable Sailboats You Can Build at Home

September 13, 2023

Best Small Sailboats With Standing Headroom

Best Bluewater Sailboats Under $50K

Popular posts.

Best Liveaboard Catamaran Sailboats

Can a Novice Sail Around the World?

Elizabeth O'Malley

June 15, 2022

4 Best Electric Outboard Motors

How Long Did It Take The Vikings To Sail To England?

10 Best Sailboat Brands (And Why)

December 20, 2023

7 Best Places To Liveaboard A Sailboat

Get the best sailing content.

Top Rated Posts

Lifeofsailing.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon. This site also participates in other affiliate programs and is compensated for referring traffic and business to these companies. (866) 342-SAIL

© 2024 Life of Sailing Email: [email protected] Address: 11816 Inwood Rd #3024 Dallas, TX 75244 Disclaimer Privacy Policy

Optimist Sailboat Build

Introduction: Optimist Sailboat Build

Building the Wood/Epoxy Optimist In 1947 a gentleman named Clark Mills designed a small sail boat for kids to learn to build and sail called the Optimist.  This boat was designed to be built from 3 sheets of plywood, with basic woodworking abilities.  As time progressed, builders began to modify the boats to gain speed advantages - as happens with all vehicles. In 1995 the International Optimist Association took the boat back to its roots and a set of dimensions were compiled to retain an exact shape of the boat, so as to remove design advantages from one boat to another.  The Optimist is tightly controlled now with over 60 measurements and tolerances of the hull are generally +/- 5 mm.  The tolerances do not allow the builder to exploit the possible variations of shape of the hull, but do allow a competent builder to construct a legal racing hull.  Half Moon Bay Yacht Club has a summer youth sailing camp.  Through the years we have trained many a young boy or girl to rig and sail the small boats available to us.  Normally in an older Laser or Coronado 15.  In 2011, the sailing program decided that the Optimist had a place in our sailing fleet to allow the younger kids (7-15) to rig, launch, sail and retrieve the boats themselves while under adult supervision.  We set about looking at the building of wood/epoxy Optimist sailing boats.  We quickly focused on making racing legal hulls so as to be competitive with other surrounding sailing clubs.  This is where the accuracy and repeatability of the ShopBot CNC router at TechShop of  Menlo Park www.techshop.ws became an invaluable tool in our fleet building.  I made it at TechShop.  Due to the close tolerances allowed, and the desire to have an almost identical fleet of boats, the ShopBot  fit the bill to the letter.  Once I redrew the plans into CAD drawings and transferred to cut files the different parts of the boats were identical.  Each group of people that wanted to build a boat only had small amounts of fitting, beveling and gluing to accomplish, with very little use of dangerous equipment needed and quick progress to show for their efforts, so kids fit right into the task of building boats.

Attachments

The jig produced on the ShopBot retains the correct shape and supports the boat, while it is being built, to retain the exact design measurements. The plans for the boat can be found from many sources for free on the internet.   Plans are available in many languages, as well.  One such source is http://www.optiworld.org/Woodguide05.pdf Another guide to building an optimist is http://www.burcotboats.co.uk/howToBuild.pdf , as well as half a dozen other well written articles on the internet. But none provide CAD quality drawings or files to work with modern computer controlled machine tooling. Well, here they are:  The jig as well as the major parts of the boat.     The jig sides , mast step, rudder, dagger board , dagger board case ends and doubler pieces are made from 18mm or 3/4" ACX or marine grade plywood; (1219.2mm x 2438.4mm) 48" x 96".

Now to get started, the jig we have designed is the exact dimensions of a finished hull shape. Both ends of the jig have interlocking pieces to allow for inserting and removing as needed during the building of the boat. The cross members are standard 2" x 4" cut to 44" long and with a 3/4" dado 8" to each side of center to fit into the grooves of the forms. These should be cut so as to be flush with the top of the form and screwed into place to prevent movement. The bottom boards provide a stable platform for the jig to sit on. The jig should be placed on a flat surface for the build, as distortion to the jig will transfer to the boat being built. Save the scraps for blocking.

The file for the hull bottom, midship frame, dagger board case sides and corner braces are cut from one 4' x 8' sheet (1219.2mm x 2438.4mm) of 12mm Marine grade plywood  If you save your larger scraps for doubling plates and gunwale rails, you will have very little waste.  The first cuts should be for the 6mm deep dado at both ends of the hull to join the bow and transoms to.   The second cut should be for the dagger board trunk cut out.  The third cut should be the outline of all the pieces.  In order to fit both sides of the dagger board trunk on one sheet, one side will have a joint to be epoxied together to match the other side.

The next setup  should be for 6mm plywood.  Again a 4' x 8' sheet will make both ends, both sides, mast thwart frame and again scraps can be used for doublers and clamping pads. You now have a boat cut and ready for a little fitting.  Bevel the edges of the bottom to the approximate angles of 15 degrees with a block plane and you are ready to start your build.  I would recommend a dry fit of all parts prior to mixing epoxy.  This doesn't take long and may save you a lot of trouble with messy epoxy. 

Center the bottom in the jig, stand on it to bow it and hold it down, and temporarily screw it to the 2" x 4" 's 130mm each side of center line to allow for gluing of the doublers without covering the screws, so they can be removed later.  The holes will be filled in when the boat is removed from the jig with epoxy.  Rip a 4' x 8' sheet of 4mm plywood into 1- 240mm strip and 2-80mm strips with a 45 degree beveled edge.  This can be done on the ShopBot or a table saw.  These are the doublers for the bottom to meet design minimum thickness while saving weight.  Once these are epoxied into place and trimmed you are ready to install the sides, mid ship frame, bow and transom.  The mid ship bulkhead can be used to position the strips in the correct place on the bottom of the hull.  Once these are epoxied in position, placing some weights on top, until cured, works well.  You will be covering the dagger board slot, but that can be easily cut out once the hull is removed from the jig and turned upside down for fitting the dagger board trunk and filling of screw holes.

The plans show two temporary braces.  These can be made from any scrap plywood and are used to hold the proper shape of the sides while doing the assembly and glue up.  Once the gunwale rails are installed these will be removed and discarded.  The bow and transom fit into the dado at the front and rear of the hull bottom panel.  The sides wrap around the outsides.  A couple small blocks of wood screwed onto the jig at the bow and stern help in keeping the sides in position while clamps are applied.   A small slot cut into the two forward jig pieces to allow a small bar clamp of your choice works well to hold the two sides together tightly.  Once you are comfortable with the fit of all the parts your ready to mix epoxy.  Wet out each side with unthickened  epoxy.  Then add a small layer of thickened epoxy and assemble with the temporary braces and mid ship brace installed.  Next is the mast deck and thwart.   Fit and epoxy in place.  Some of the scraps of 18mm can be used for the doubler in these areas.  You can install the bow and transom doubler before or after this step.

Gunwale rails and rub rails are next.  You can use layers of plywood or fancy colorful woods if you plan to use a clear finish to show off your work.   Build up the layers until you get to the final thickness required, per the plans.   Rip 1 for each side of boat starting with a 45mm wide piece stepping down 5mm for each 10mm of thickness.  Cut out pockets for and install the corner blocks next.   Form and shape the rails to the required shape and thickness and you are ready to remove the boat from the Jig.  We used a hand planer for the rough shape and finished with a belt sander.  It will now hold its shape and dimensions.  The jig can be used as a cradle to support the boat as you work on it either upside down or right side up.

Once the boat is removed from the jig, it can be turned over and all joints filled with thickened epoxy.  Install the dagger board trunk through the hull and epoxy in place.  We choose to put our club logo and hull # on the sides of the dagger board trunk.  Once again the ShopBot makes this a blank canvas for your artistry.  Below one of the boys is rounding the edges before the dagger board trunk is installed.  Shape the bottom of the dagger board trunk  to conform to the hull bottom from the outside once it is cured in place.  Install the doubler pieces on the inside to help support the dagger board trunk.  We installed a few wood dowels into the midship frame to add strength as well.   Sand, epoxy and finish the exterior of the hull as desired, with either paint or a clear finish.  On the inside of the hull fillet the joints with thickened epoxy.  Install the flotation attachment pads, and main sheet block pad.  Sand, epoxy and finish the interior of the boat as desired and the hull portion of your sail boat is ready for hardware installation.  We chose white enamel for the insides for a cleaner look.  You will also find the plans from one of the internet sites below.  Download these and print copies to have available as you work. 

To build a race legal hull requires a measurement by a certified Optimist qualified measure person.  Plan on 4 hours or more for this process.  The PDF file is the list of measurements for the hull.  The tolerances are close, but with the use of the CNC controlled cutting you should have a race legal hull that your kids can be fully involved in the building of.  The dagger board piece and rudder that was cut will need to be shaped and profiled.  Again we used a plane for the rough shape, followed by the belt sander.  Hardware kits are available online as well as sails, spars, FRP rudders and dagger boards at very reasonable prices.  One such site is : http://www.mauriprosailing.com/Optiparts-Optimist/Optiparts-Optimist.htm?gclid=CKHtt7O1t64CFQ9-hwodHBRhrA

Sail Plan The sail can be home-made, as well, but with mass production the prices just are hard to beat.  Again the spars can be made from PVC pipe, Wood or Aluminum tubing, but most can be purchased for a cheaper price than your time and investment.   You probably won't need the hottest racing level gear until you see if your kids are in for it.  Then watch out if they catch the bug!  You will be one proud parent to have started them out on such a great and rewarding life of sailing. http://www.mauriprosailing.com/Optiparts-Optimist/Optiparts-Optimist.htm?gclid=CKHtt7O1t64CFQ9-hwodHBRhrA

Finalist in the ShopBot Challenge

Participated in the Make It Real Challenge

Recommendations

Made with AI - Autodesk Design & Make - Student Contest

Make it Resilient

Green Future Student Design Challenge