adding water ballast to sailboat

Yachting World

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Pip Hare’s sailing masterclass: How to make the most of a water ballast system

• May 21, 2020

Water ballast is no longer the preserve of ocean racing yachts, it can now be found on performance cruisers and smaller racing boats. Pip Hare shares her top tips for using it

The JPK 1030 features transfer pipe and inspection hatches. Photo: Jean-Marie Lio

No two water ballast systems seem to be the same, but the principles for use and troubleshooting remain the same. Here are some guidelines for success.

Filling ballast

The ballast is filled via a scoop in the bottom of the boat, which is like a ‘reverse snorkel’. The snorkel is pushed down with the hole forward to fill the ballast, when the hole is facing aft the tanks can empty. To seal the system the scoop is retracted into the hull, leaving a flush finish.

A single scoop will be situated on the centreline, while twin scoops are placed outboard, so the leeward scoop must always be used for filling. When the scoop is pushed down, providing water is moving over the hull it will start to fire water into the boat. Filling can be achieved through continued forwards motion although this can take a lot of time so a pump is often used to accelerate the process.

Before pushing down the scoop, ensure all valves are in the correct position – this takes concentration if you’re not familiar with the system. Check:

• Valve to leeward scoop is open.
• Valves to leeward tanks are shut.
• Valves to water pump is open.
• Valves out of water pump are either directing towards windward tanks, or open on windward and closed on the leeward side.
• Correct windward tanks are selected – you can fill multiple tanks at the same time.

Once the valves are in the correct position push the scoop down then turn on the ballast pump. Once water is overflowing from the breathers on deck, first close the tank valves, then shut off the pump and retract the scoop.

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If you’ve been running the ballast pump but the tanks are not filling then look for air in the system. Airlocks are a common problem with a pump and can be tricky to remove. Start by identifying where the lock is; transparent pipes are helpful. Then your objective is to flood that part of the pipe.

Every system will be different but things that can work include turning off the pump, rotating the scoop aft to empty for a few seconds, then face it forward and turn on the pump again. Or try changing the angle of heel to flatten the boat momentarily.

If all else fails, changing tack but leaving whatever ballast you have on the same side might shift the air. Tack, then tack back and try the whole process again.

Transferring ballast

Any manoeuvre involving transferring ballast is going to take time and it’s important to factor this into your planning and make sure you have enough ‘runway’ to complete your manoeuvre. For example, if you know it takes 140 seconds to drop the ballast and you’re sailing upwind at eight knots you’ll need one third of a mile to complete the tack from the moment you open the valves.

Use the time it takes for the ballast to transfer to get set up on deck for tacking and to move the stack to leeward (if allowed). Remember the trim of the boat will change while the ballast drops, so ease the mainsheet or traveller to control excess heel and feather the boat into gusts.

The process for transferring ballast is simple:

• Check scoops are retracted and valves closed.
• Open leeward tank valves, open transfer valves, open windward tank valves.
• Once all water has transferred, close all valves.

The most common mistake is to close the valves and tack before all the water has run down. Sight glasses can help but they often don’t go to the bottom of the tank. Try putting your ear close to the windward transfer pipe, you should be able to hear water running through; if there’s no sound then the tank is empty. Water will rush out of the deck breathers on the leeward side but this may happen before the windward side is empty.

Always check the leeward side after a manoeuvre and empty out any water that’s left. Expect to top up the windward side over time.

Deck-mounted control rods can open or close the ballast transfer valves. Photo: Jean-Marie Liot

Dropping the ballast

There are no tricks to emptying the ballast, other than adding a little extra heel towards the end of the process. The routine is:

• Push the leeward scoop down and turn it to face aft.
• Double check leeward tank valves are closed.
• Select the tank you wish to empty and open all valves between that tank and the scoop.
• When finished close the valves and retract the scoop.

Management and maintenance tips

• Put luminous tape on the scoops so you can easily see which way they’re facing in the dark.
• Check inspection hatches and seals regularly. These hatches are a constant pain and expect them to leak. If going on a longer voyage, then take plenty of spare hatch seals and a couple of spare hatches.
• Try very hard not to step on ballast pipes or valves.
• Check both tank levels regularly. It’s not uncommon to lose water from the windward tank or for the leeward tank to start to fill over time.
• Check all valves, particularly gate valves, are closing fully and also check the leeward deck breathers are not letting water into the tanks – which can happen if sailing with the rail constantly underwater or if the breathers are damaged.

First published in the May 2020 edition of Yachting World.

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Ballast 101: Basics of Adding Ballast to Your Boat

WakeMAKERS How-To: Adding Boat Ballast, Where To Put It, And More

This isn't some top secret info. The key ingredient to creating a better wake is additional weight in your boat.

At WakeMAKERS, we think about a quality wake requires two things: size and shape. Each is equally important.

Size: A bigger wake means more energy. This means more explosive pop wakeboarding and more push wakesurfing.

Shape: Just as important as the size, the shape of the wake is often a second thought or completely ignored.

You are reading this because you want to build a better wake behind your boat. This guide will cover the basics of boat ballast , where to place ballast, and more. After reading this guide you will be ready to build a better wake. Enjoy!

Wake Size + Wake Shape = Wake Quality

Adding additional weight to your boat, whether it’s in the form of ballast, people, or even gas in the fuel tank makes the boat sit lower in the water. This means the hull is displacing more water, which will result in a larger wake as the boat drives though the water. Your requirements for wake size will depend on several factors:

• Desired wake size: just how big do you want the wake to be?
• Space requirements: how much room are you willing to give up in the boat for ballast?
• Comfort level: how much ballast are you willing to run in the boat?
• Activity: are you primarily wakeboarding, surfing, or both?

The bigger you want your wake, the more hull displacement, and therefore additional ballast you need for your boat . Anywhere you place additional weight in the boat will cause an increase in the displacement of the hull in the water. To increase the wake's size, the location of the ballast is completely trivial. Place it anywhere you want.

The shape of the wake is equally important and often ignored. Whereas ballast location in the boat plays no role in determining the size of the wake, wake shape is completely dependent upon where the weight is placed throughout your boat. The next section will cover how to place ballast in your boat for wakeboarding and wakesurfing.

Ballast Placement | Wakeboarding vs. Wakesurfing

Wakeboarding.

Weight in the rear of the boat will result in a more vertical wake, with a shorter and steeper face. Too much weight in the rear can cause the wake to “roll” or “crumble” over on itself. Moving more weight towards the bow of the boat will make a more mellow wake, with a longer transition from the trough at the bottom to the lip of the wake.

Unless you are currently not happy with the shape of your wake (too steep or too rampy), stick to a 50/50 front-to-rear weight distribution for any additional ballast you add. For example, if you add 400 lbs. to the rear of your boat then you should add 400 lbs. to the front as well. For wakeboarding we recommend not trying to alter the shape of the wake. The wake's shape is one of the reasons we spend more money on boats specifically designed for wakeboarding. If you want a better wake for wakeboarding, just make it bigger. That means evenly weighting the entire hull of the boat, which means the wetted surface of the boat will be the same, it will just displace more water.

An evenly weighted boat has numerous advantages besides creating a clean wake. Keeping your boat evenly weighted maintains the efficiency of the drive train by reducing the prop shaft angle . This results in quicker acceleration and better fuel economy, as well as a smoother ride.

If you want a steeper wake with a more pop, move more weight towards the rear of the boat. On the other hand, if you want to tame some of the wake's steepness, or if you’re having trouble with the wake crumbling, shift weight forward in the boat.

Wakesurfing

You MUST start with additional ballast in the rear of the boat to create a wake with enough “push” or energy to allow a rider to surf without a rope. Adding weight in the rear of the boat results in a tall wake that has a lot of energy, but doesn’t extend very far back behind the boat. Additional weight in the front of the boat will lengthen the wake, but will also remove some of the "push" or energy. It is a fine balance of push vs. length of your surf wake.

The goal is to have the longest wake possible, while having enough "push" to allow a rider to surf without the rope.

Start with adding weight in the rear corner of the boat on the side you will be surfing on (port side of the boat for regular riders, starboard side of the boat for goofy riders). Weighting the boat to one side is required to make a clean,rideable surf wake. Starting in the rear will provide enough “push” to support a rider without the rope, which is the whole goal. From there, begin adding more weight to the front of the boat, on the same side of the rider. Add as much bow weight as you can to lengthen the wake without removing too much "push".

The heavier the rider or the smaller the board, the more rear weight you’ll need to create "push". Lighter riders, or those riding a very fast surfboard will allow you to run more weight in the front of the boat for a longer wake.

Weighting Boat w/ Wakesurf System

Malibu Boats changed the game in 2012 when they introduced their SurfGate system. Now every major wakeboard boat manufacturer has an OEM surf system and there are several aftermarket systems available on the market. These surf systems completely change how you need to weight your boat for wakesurfing. A wakesurf system allows you to evenly weight your boat, removing the need to list your boat to one side. Gone are the days of weighting all the ballast on one side of your boat. If you are using a surf system, fill up all the ballast on your boat for a bigger, better wake. The surf systems are a must-have for anyone serious about building a better surf wake.

How-To: Fill and Drain Additional Ballast In Your Boat

Now that we know why and where to add ballast, the next step is to figure out how to actually fill and drain that additional weight. At WakeMAKERS we classify three different methods for filling and draining weight.

Portable System

The basic solution for filling and draining ballast. A portable pump efforts great speed and minimal investment, but requires more effort to fill and drain your system.

Pros: highest speed, inexpensive, zero installation, works with any boat

Cons: manual process (boat must be stopped to fill and drain)

Factory Integration

Exclusive to WakeMAKERS, this option allows you to control additional ballast capacity using the same system that came built into your boat. Great value, and very convenient, this is a great option for fully automated ballast without spending a lot.

Pros: extremely convenient, moderate speed, inexpensive, easy installation, completely automated

Complete Ballast System

The Porsche of the ballast industry, this option gives you the most speed, convenience, performance and flexibility, but does not come cheap, and requires installation.

Pros: extremely convenient, high speed, works with any boat, completely automated

When looking to add weight to your boat, the best option varies from person to person. Our suggested setup for you will depend on your specific needs as far as speed, convenience, and price. You can always start out with a minimal investment into a portable system and then upgrade to a fully integrated solution in the future.

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MODERN SAILBOAT DESIGN: Ballast Stability

At the end of our last discussion on stability we mentioned the old mono v. multihull worst-case-scenario debate re sinking to the bottom (monohull) versus capsizing on the surface (multihull). This time we’ll focus on that which drags the poor monohull to the bottom, which is, of course, its ballast. Ballast, ironically, is added to a boat to help it stay upright. As with form stability, the principle is obvious: an object is harder to up-end if a heavy weight is placed at the bottom of it. Witness the iconic inflatable punching clown. With the majority of its weight concentrated at floor level, the clown pops back upright every time you knock it down. This, of course, is exactly what you want your sailboat to do.

 Besides helping boats sink, ballast is counterproductive in another way: it makes a boat heavier and increases displacement , thus increasing resistance and decreasing speed. But this sad fact can be mitigated. The amount of ballast needed to counteract the capsizing forces of wind and wave decreases dramatically the lower it is placed in the boat. Unlike the clown, which must always have its feet on the ground, the bottom of a sailboat can reach as far down as there is water for it to float in. This is one reason why racing sailors always prefer very deep keels and why gunkholing cruisers must agonize over the question of draft. On a stock 40-foot boat, for example, the weight differential between a shoal-draft cruising keel and a deep racing keel installed on otherwise identical hulls can amount to 20% or more of the boat’s total displacement. For many, this will seem a heavy price to pay (pun intended) for shoal-draft capability.

Just as weight down low increases stability, weight up high–generally speaking, just about any weight added at or above deck level–decreases it. It is important, therefore, not to think of ballast as a discrete feature. Think instead of a boat’s total weight and how it is distributed. For example, adding one pound of weight at the masthead of a 35- to 40-foot cruising boat effectively subtracts 7 to 10 pounds of ballast from its keel. Conversely, subtracting that pound adds 7 to 10 pounds of ballast. The effects are less dramatic but are still significant when weight is redistributed closer to the boat’s center of gravity.

Aboard most cruising boats, the center of gravity is more or less about 6 inches above the waterline. Any weight subtracted above or added below this point increases the boat’s effective ballast and lowers its center of gravity. Such increases are multiplied according to the weight’s vertical distance from the center of gravity. For example, subtracting 1 pound of weight 35 feet above the center of gravity is equivalent to subtracting 35 pounds 1 foot above it. Adding 1 pound 7 feet below the center gravity is equivalent to adding 7 pounds 1 foot below it.

The bottom line (another intended pun) is that you should always strive to keep weight as low as possible, whether or not it is officially designated “ballast.” This is why racing sailors always embrace technology that dramatically reduces weight aloft, such as carbon-fiber spars and fiber rigging. It is also why cruising sailors should be more circumspect when adding weight to their rigs. Roller-furling headsails, in-mast furling mainsails, extra-heavy wire rigging, mast-mounted radomes, mast steps, and other such gear may improve a boat’s “cruise-ability,” but their cumulative weight also significantly decreases its stability.

Cruisers often store too much gear on deck, which raises a boat’s center of gravity and can make it considerably less stable

Boats that rely primarily on ballast for stability tend to be narrow and deep. In the past they also often had a great deal of deadrise in their hulls, though this is less true now. Narrow, heavily ballasted boats, particularly those with lots of deadrise, usually are tender and quickly heel to significant angles when pressed by even a moderate breeze. But this does not make them “unstable.” When pressed to extremes, they are usually more stable than stiffer boats that rely more on form stability to stay upright. Unlike form stability, which increases a boat’s initial stability, ballast stability increases what is known as ultimate or reserve stability, which is what helps a boat recover and roll upright again–just like the punching clown–after it has been knocked flat or even capsized.

Tender boats, like stiff boats, can be both comfortable and uncomfortable. Their tendency to heel easily often makes inexperienced crew feel nervous and uncomfortable, and even for experienced sailors, working at severe angles for extended periods of time can be taxing. But when the sea gets rough a tender boat normally has a smoother motion than a stiff one. It rolls to greater angles, but does so more slowly, without the vicious snapping and jerking that characterizes the motion of a stiff boat. Sailing to weather in a strong breeze a tender boat’s lee rail will be buried much of the time, and the crew on deck will get wet, but the boat will not pound as violently as a stiff boat.

For cruising sailors, the question of which sort of stability to favor when selecting a boat is a serious one. Many designs available today, of course, are relatively moderate and compromise between extremes. As a general rule, however, popular modern designs tend to be relatively light and wide with shallow bilges, and thus are more stiff than tender. Older designs from the CCA era are usually heavier, narrower, and more tender. As a general rule, coastal cruisers who expect to sail primarily in moderate conditions can, if they like, favor faster, more modern, stiffer designs. Bluewater cruisers who are more likely to encounter extreme conditions should consider whether they’d be better off in slower, more tender design with more ultimate stability.

Shifting Ballast

The most effective way to increase initial stability aboard a boat that may or may not have good form stability is to shift significant amounts of ballast to windward while sailing. This creates a lever arm that operates at a right angle to the sail plan, which increases the ballast’s effectiveness and allows a boat to carry significantly more sail.

Crews on modern planing skiffs like this 49er have to stay well outboard to keep their boats upright

This principle is seen at work on any unballasted sailing dinghy that depends primarily on crew weight to stay upright. To prevent the boat from toppling over to leeward, the crew hikes out on the windward rail. The further to windward they can get, the more sail the boat can carry, as the crew’s effective weight is increased by the longer lever arm. On modern dinghies you often see devices such as trapezes and/or hiking rails that allow crew to get as far outboard as possible. On traditional boats like Bahamian sloops and Chesapeake log canoes the crew sits out over the water on long planks that protrude from the windward rail. When the boat is tacked, the planks are moved from one side to the other, and there is a mad scramble as the crew repositions itself.

A traditional Chesapeake log canoe in action

These days ballast on larger boats can be shifted in more sophisticated ways. In one method known as water ballasting, large quantities of seawater are moved from one side of the boat to the other as it tacks. The water is shifted between dedicated tanks on the outboard edges of the hull’s interior either with a pump or by letting the water run downhill from the windward tank to the leeward tank before tacking. Water ballast augments a conventional ballast keel and is released overboard when it is not needed.

Another way to shift ballast is with a canting keel. These are struts with heavy ballast bulbs that can swing from a vertical position under a boat’s hull out to angles of up to 55 degrees. Large canting-keel monohulls 70 feet and longer have hit top speeds in excess of 30 knots, which is comparable to speeds routinely achieved by large racing catamarans. Several canting-keel boats have sailed 600 miles or more in open water in a single 24-hour period, maintaining average speeds of over 20 knots. What makes canting keels so powerful is that they shift all of a boat’s ballast to windward while keeping it well below the hull, thus greatly increasing its effectiveness. A keel capable of canting 55 degrees requires 25 to more than 60 percent less ballast than a fixed keel to support the same hull and sail plan. The result is a much lighter boat with a much higher SA/D ratio and a much lower D/L ratio.

A modern raceboat with its ballast keel canted to windward. The daggerboards rather than the keel create hydrodynamic lift

Canting keels do have their complications. When canted well to windward a keel ceases to function as a hydrodynamic foil and other foils must therefore take its place. These can be significantly smaller than the keel itself, due to the high speeds at which the boat travels. Often these auxiliary foils are daggerboards in the boat’s midsection, one on each side, with only the leeward board deployed at any given time. Or there may be a second rudder forward of the keel, often called a canard, that works in conjunction with the primary rudder to both resist leeway and steer the boat. This configuration, referred to as the Canting Ballast Twin Foil (CBTF) system , is a patented technology seen on large maxi yachts such as Roy Disney’s last Pyewacket . Centerboards and centerline daggerboards have also been used.

Another major complication is the mechanism that swings the keel back and forth. This mechanism is somewhat simpler on smaller boats, as the top of the keel, which protrudes several feet into the boat’s interior, can be pulled to either side with nothing more than a hefty tackle. On larger boats, however, the weight that must be shifted can be enormous and mechanical assistance is required. This is normally provided by large hydraulic rams and pumps powered by the boat’s main engine or a donkey engine, which must be running when the keel is moving. In all cases the pivoting keel joint in the bottom of the hull must be properly sealed and protected against flooding. Not surprisingly, dramatic failures are fairly routine.

Canting keels have also been installed on a few high-end custom performance cruisers. Examples include the Baltic 78, certain luxury performance cruisers built by Wally Yachts, and a sleek 65-foot one-off boat, Spirit of Adventure , designed by Owen Clarke Design of New Zealand for a private client. The canting keel on Spirit is also a lifting keel, as is the canting keel on the 100-foot super-maxi Maximus , a no-holds-barred racer launched back in 2005. It is unlikely however that canting keels, lifting or otherwise, will trickle down any further into the cruising-boat market. The systems are just too complex, too expensive, and potentially unreliable.

The keel on this custom cruiser, Spirit of Adventure , designed by Owen Clarke Design, both cants side-to-side and shifts up and down (Photo by Paul Todd)

Water-ballast systems, on the other hand, have proven more popular. Indeed, several small trailerable cruising boats use static water ballast as their primary ballast. On these boats the ballast tanks are low in the bilge on the boat’s centerline and are filled after the boat is launched to increase its displacement and stability. When the boat is hauled from the water, the ballast tank is emptied to reduce trailering weight. Since the ballast is never shifted, these are more appropriately termed static variable-ballast systems. Dynamic shifting-ballast systems are less common but have appeared on several performance cruising designs. These include at least one production boat, Hunter Marine’s old HC-50, which was designed to be sailed by a couple. On some other production performance cruisers it is also possible to shift water stored in the freshwater tanks from one side of the boat to the other.

Like canting keels, water-ballast systems make a boat much more complex. The ballast tanks take up interior space that could otherwise be devoted to accommodations, and they require a great deal of extra plumbing for picking up and discharging raw water and for moving it from tank to tank. Because water is not particularly dense, because ballast tanks must be located inside rather than below the main hull, and because the water ballast represents only a portion of the boat’s total ballast, water-ballast systems also do not have nearly as dramatic an effect upon performance as do canting keels.

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DEAD GUY: Ted Brewer

These are useful advice. Thanks! For quality and affordable boat ballast check out http://www.waterskiersworld.com/category-list/accessories/boat-ballast-fat-sacs-pumps.html

Found this looking for research on a short high-school presentation on how boats work. Made my head hurt with funky words. 10/10

Very helpful in analyzing where to put 500 pounds of batteries for a conversion from diesel to electronic propulsion.

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What Is a Water Ballast Sailboat?

Sailboats have many components that provide stability, including a water ballast. They need these components, otherwise the boat would risk tipping over (also known as capsizing) if the winds got too rough. Does your sailboat have a water ballast? How does it work? We did lots of research to provide you the answer. 

What is a water ballast sailboat? A water ballast sailboat is one with a water ballast built in. This ballast pushes the water towards the boat’s hull, using the natural forces of gravity to boost your boat’s stability. The water ballasts are part of a bigger system that includes pumps and tanks. 

If you’re thinking of getting a sailboat with a water ballast system, then you’re not going to want to miss this informative article. In it, we’ll explain more about how these systems work and how to fill your own ballast tanks. We’ll even go over the pros and cons of water ballast sailboats. Keep reading! 

How Does a Water Ballast System Work for Sailboats?

Before we go deeper into what a water ballast system is and how it works, we need to explain ballasts in general. Found on ships, sailboats, and other vessels, a ballast keeps the hull’s lateral forces in check. Without this, the boat becomes much more likely to lean or heel when in the water and faced with strong winds. Leaning too much to one side could cause the boat to capsize, which occurs when the sailboat falls over.  

While there are both live ballasts and high-density ballasts, the one we’ll focus on for this article is the water ballast. Sailboats and other smaller vessels tend to come outfitted with this ballast type. 

A water ballast gets installed in such a way that its vertical center of gravity makes the boat more stable. This means the hull gets covered in water for the system to be effective. The ballast itself can cut into the waterline with no detriment to the stability of your sailboat. It is called a water ballast, after all. 

Today’s sailboats will typically come with their own water ballast systems, including internal tanks. These sailboats are made for recreational purposes like cruising or racing. The positioning of the internal tanks allows for no risk of decreased performance in downwind or upwind sailing. That said, to maintain this careful balance, it’s important to ensure the ballast tanks are mostly empty if riding downwind but full when sailing upwind.  

How to Fill the Ballast Tanks

Like we just touched on, depending on the direction you’re traveling in your sailboat (upwind or downwind), you’ll have to learn to fill and empty your ballast tanks. Since they’re part of a water ballast system, it makes sense these tanks would be filled with water. 

Where can you find your water ballast tanks? How much should you fill or drain them when boating? Let’s answer those questions now.

So, Where can you find your water ballast tanks?

While it can depend on the model of sailboat you own, you should find your water ballast system near the boat’s hull. Remember, the ballast may sit lower, closer to the waterline. As mentioned, the tanks are often internal, so they shouldn’t take away from the silhouette of your sailboat by adding a clunky profile. That’s not true of every sailboat, though. 

Again, while it varies, some sailboats have switches for maintaining ballast tank fullness. These may include on and off switches as well as an empty switch. When you want to fill the tank, you’d press the on switch. As the water nears the top of the tank, you’d hit the off switch.

How much should you fill or drain the ballast tanks when boating?

Certain sailboats will come with water ballast tank systems that turn off on their own when they fill completely with water. Not all tanks will do this, so it’s important you read through your owner’s manual carefully to see what your water ballast system is capable of. If your tank system doesn’t power itself down, then you can keep going and going and accidentally overfill the tank. Water will begin traveling where you don’t want it. 

How does pressing a switch get the water to the ballast tanks?

Sailboats come equipped with what’s called a ballast pump. This transports the water to the tank so you don’t have to do so manually.

Other sailboat models use ballast bags, and some boats have both tanks and bags. If your boat includes ballast bags, you have to fill these yourself. To do so, you want to lay the bag on a flat surface. Then, take your fill connection and attach it to your fill port. You’ll find this port on the ballast bag, typically towards the top.

When both sides of the tube are tightened, take your ballast pump and let it go into the water. Make sure it’s not floating, as you want it deep. Next, grab the extension cord that comes with your ballast pump, connecting it to your boat’s cigarette adapter. If you don’t have one of these adapters in your boat, you can always fill the ballast bags in your car before hitting the water. 

Double-check you don’t have too much air in the ballast bag, as otherwise a lot of water will come with it. Then, you’re done!

To release all the air from the ballast bags, connect your ballast pump to the included field drain. Then, position your hose so the water will pour out of the boat rather than inside it. 

Here is a handy YouTube video that shows how it’s all done.

The Pros and Cons of a Water Ballast System for Sailboats

By this point, you know a lot about a sailboat’s water ballast system. If you have a different kind of ballast for your boat, you may wonder if there’s a reason to make the switch to a water ballast system. 

Indeed, these systems have a slew of advantages, but downsides exist as well. Let’s go over both more now. 

• Besides stability, a sailboat with a water ballast system may achieve greater speeds than one without. By lessening heel angle, the sails, rudder, and keel of the sailboat maintain their lift and profile, staying horizontal. This means downward sail pressure is reduced, allowing for greater speed. 
• You can also gain better control of the boat by filling your ballast tanks with water. For instance, you’ll notice more handling of the draft, trim, and steering. 
• You can change the weight of your boat on-the-go by managing the water ballast tanks, as explained above. Given that it’s not too difficult to add or drain water to the tanks, you can quickly achieve the perfect weigh onboard your sailboat with a bit of practice. 
• The water ballast system sometimes does detract from the overall look of the sailboat. While it’s true the ballast is very functional, some people might see its components as an eyesore. 
• The tanks can be quite bulky and heavy as well. 
• They’re also space hogs, thus motivating some sailboat manufacturers to use ballast bags instead of ballast tanks. These bags get installed near the hull and are outboard for easy access. 

There are of course environmental concerns to talk about, too. After all, boats can take water for the ballast tanks in one body of water and then move elsewhere to drain the tanks. This may release foreign microorganisms, viruses, small animals, and plants into another body of water in which they don’t belong. In turn, this can harm the ecosystem.

While this is a very real problem, it’s much more common for bigger boasts like bulk cargo carriers, sizable tankers, and cruise ships instead of sailboats. Still, with the U.S. Coast Guard and the Environmental Protection Agency (EPA) managing what gets dumped and where, it’s best you tread carefully about where you fill and dump your ballast tanks. 

Related Questions 

How can valved pipes be used with a water ballast sailboat system.

Many boaters that have water ballasts use a valved pipe to connect the starboard and link port tanks. You would open the valve on the pipe and let water pass through the windward or upward tank. This is positioned higher than the valve, letting water move. An included sheet contains the water so it doesn’t travel too much and cause the sailboat to heel.

As the water moves to the leeward or downward side, the boat sail sheets. This raises your upward tank, transferring the water back. If it doesn’t all move, then use a hand pump for transferring it. 

Why do sailboats need ballasts?

As we said in the article, sailboats with water ballasts tend to have greater stability. Through adjusting the water levels in the ballast tank, it’s also possible to increase the speed of your boat. 

Does a sailboat need a keel?

Yes, absolutely. A keel serves a very important role on your sailboat, maintaining the ballast weight. This works against the wind force that could knock your sailboat over into the water. Keels also create lift thanks to their airfoil wing shape. This allows you to sail nearer the wind than you could with keels of a different shape.  Click here to read more on keels.

I am the owner of sailoradvice. I live in Birmingham, UK and love to sail with my wife and three boys throughout the year.

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Why a Water Ballast System is Worth Thinking About

A water ballast system in a cruising boat? Not a concept the traditionalists are likely to accept unreservedly. But providing the boat isn't dependent on this for stability it can be very beneficial in a seaway.

Such a water ballast system was part of the design philosophy when we built our cruising boat Alacazam , where it just supplements the permanent ballast in the keel bulb providing additional weight to windward when required.

The water is carried in two tanks on each side at the extremity of the waterline beam, each capable of being independently filled and drained by two 12v electric pumps. This is well below the point of maximum beam, but provides substantial benefits.

The Benefits of a Water Ballast System

• the boat's Centre of Gravity is no longer on the centreline, but is transferred outboard;
• as the boat heels, the righting moment increases due to the extended horizontal distance between the centre of buoyancy of the hull, and the centre of gravity of the water ballast;
• the Roll Moment of Inertia is significantly increased in terms of both pitch and roll;
• if caught with the water ballast on the wrong tack, the converse of the above applies such that the heel to leeward is not dramatically affected.

Freshwater or Seawater Water Ballast?

Initially the cruising man in me was reluctant to forego the increased freshwater capacity that the ballast tanks could provide, so they were used to supplement the standard water tanks located close to, and either side of, the centreline.

However, after lugging over 1,000lbs of this additional water all the way across the Atlantic without using any of it, I converted it to a seawater system.

Now I can get rid of it and replace it as required, and think of it as adjustable displacement . Tacking is done by opening a couple of simple valves and switching on the appropriate transfer pump. The boat's then tacked in the normal way, and then when the transfer is complete, the valves are closed and the pump's switched off.

Hard on the wind, with both windward tanks full, Alacazam heels about 6 degrees less for the same sail area and wind strength than she otherwise would, and sails quicker as a consequence. The concentration of outboard weight in the centre section of the boat noticeably improves the fore-and-aft stability, and coupled with less heel, reduces pitch and roll appreciably, the increased displacement making the boat generally more comfortable.

As the wind moves aft, the forward tank is drained and when well off the wind both tanks are drained. Of course in a short-tacking situation, the valve turning and pump switching involved in swapping the water from one side to the other requires a lot more rushing about that I'm accustomed to, so we only use the water ballast system on long offshore tacks.

The downside is that the tanks and the plumbing take up space that could otherwise be used for stowage, but there's no doubt that a moderate degree of water ballast in a light-ish displacement cruising yacht can improve both her performance and crew comfort.

Water Ballast: A Few FAQs...

What is a water ballast system?

A water ballast system is a device that allows a sailboat to fill or empty tanks with seawater to adjust its stability, trim, and performance. The water ballast can be transferred from one side of the boat to the other, or from the bow to the stern, depending on the sailing conditions.

How does a water ballast system work?

A water ballast system works by using scoops, valves, pumps, and tanks to control the flow of water in and out of the boat. The scoops are openings in the hull that can be lowered or raised to capture or release water. The valves are switches that direct the water to the desired tanks. The pumps are devices that speed up the filling or emptying process. The tanks are containers that store the water ballast.

What are the benefits of a water ballast system?

A water ballast system can provide several benefits for a sailboat, such as:

• Increasing stability by lowering the centre of gravity and reducing the angle of heel;
• Improving performance by optimizing the sail area and reducing the wetted surface;
• Enhancing comfort by smoothing the motion and reducing the rolling;
• Saving space and cost by eliminating the need for fixed ballast.

What are the drawbacks of a water ballast system?

A water ballast system can also have some drawbacks for a sailboat, such as:

• Taking up precious room on board that could be used for storage or accommodation;
• Increasing complexity and maintenance costs due to the additional equipment and plumbing;
• Creating potential environmental issues by spreading invasive species or pollutants through the water exchange;
• Losing effectiveness at low speeds or when sailing upwind due to the reduced water pressure on the scoops.

How much water ballast do I need for my sailboat?

The amount of water ballast needed for a sailboat depends on several factors, such as the size, shape, and design of the hull, the weight and distribution of the fixed ballast, the rig and sail plan, and the sailing conditions. There is no simple formula to calculate the optimal water ballast, but some general guidelines are:

• The water ballast should be between 10% and 30% of the total displacement of the boat;
• The water ballast should be placed as low and as far outboard as possible to maximize its righting moment;
• The water ballast should be adjusted according to the wind strength, wave height, and point of sail to achieve the best balance and trim.

The above answers were drafted by sailboat-cruising.com using GPT-4 (OpenAI’s large-scale language-generation model) as a research assistant to develop source material; to the best of our knowledge,  we believe them to be accurate.

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The Physics of Water Ballast

Nick Newland recently wrote an informative article on water ballast for Water Craft magazine (Newland 2015).  Following a discussion on the Swallow Yachts Association Forum, this article aims to explain the physics behind the use of water ballast.

Water ballast is… ballast!

So water ballast works like any other ballast – end of story!   But there are differences.  The lead could have been put in a smaller box so it would take up less space in the boat and be positioned lower.  With water, the box will take up more space in the hull and probably will be higher in the boat.

On the other hand, if the wind drops and you don’t need ballast,  with lead you are stuck with it.  With water you can get rid of it and,  if you then change your mind you can refill the box from the river or sea.  And, you don’t have to take all that weight of water home on the trailer!

This ability to sail a water ballasted boat with tanks either empty or full, depending on the conditions,  means it’s worth considering in greater detail the effect ballast has both on boat stability and handling characteristics.

Mass, weight, and buoyancy

A boat like any other object is made up of various bits of material – wood, GRP, etc. which all added together make up the mass of the boat.  The mass of the boat is a physical characteristic which only changes if you add a new gadget, or more ballast, or you break a bit off!

Before putting your boat in the water, if you hang it from a spring balance you would measure its weight .  Weight is the force of gravity pulling the boat down.  It is proportional to the boat’s mass, and it acts through the centre of that mass,  which is called the centre of gravity ( CoG ).  Here on earth, spring balances are calibrated so that the weight is numerically equal to the mass.  On the moon your boat would have the same mass as on earth but would weigh less, because gravity is less.

As you lower your boat into the water it starts to be supported by the force of buoyancy.  The size of this buoyancy force depends on the amount of water displaced by the boat’s hull.  It acts through the centre of buoyancy ( CoB ) which is the centre of volume of the bit of the boat below the water surface. The boat will settle in the water until it is floating at a level where the buoyancy force exactly balances the weight of the boat.  So your spring balance now shows the apparent weight as zero even though the real weight of the boat has not changed, and of course, the boat still has the same mass.

How people think stability works – Deep keeled yachts

Many racing yachts have a very long fin keel with a big bulb of lead at the bottom.  For yachts like that the centre of gravity can be below the centre of buoyancy (figure 1).  Thus when the yacht heels, the force of gravity and the force of buoyancy act to rotate the boat back towards an upright position.

A longer the keel will give a bigger offset between the CoG and the CoB when the yacht heels, and hence a larger the rotational force bringing the yacht upright.  Also a heavier keel will increase both the weight of the yacht and the  balancing buoyancy force, again resulting in a larger righting moment.

This “yotties “ view of the world,  is NOT how most boats and ships work!  However it is how many people tend to think of stability.  When they look at a large cruise ship with many decks above the waterline and wonder how it stays upright, they are unconsciously assuming that the CoG must be below the CoB to create stability.

How stability usually works – Most Boats and ships

Most boats and ships don’t have a deep keel and the ballast or cargo is carried within the main part of the hull.  In this case, the centre of gravity, CoG, is higher than the centre of buoyancy, CoB.

Figure 4a illustrates what happens when the ship or boat heels. Lets assume the view is from astern so the boat heels to starboard.  The effect is to move the CoG to starboard and slightly downwards.  However the CoB is moved further still in a starboard direction.  As a result the weight and the buoyancy form a force couple which tends to rotate the boat back into an upright position.

Figure 4b illustrates the effect of adding a full ballast tank.  When the boat is upright it is lower in the water and the CoG is closer to the waterline. As a result, when the boat heels the CoG does not move as far to starboard as when the boat is empty whereas the CoB moves slightly further.  This increases the stability compared to the unballasted boat.

However the main effect of filling the ballast tank is to increase the boat’s weight.  As discussed above, the boats sinks downwards until the opposing buoyancy force is also increased by the same amount.  The two forces tending to rotate the boat upright  are therefore, not only spaced further apart, but also much larger.  Thus the boat is more stable with a full ballast tank.

That the effect of increased boat weight is important is easy to imagine if you think of trying to tilt a box placed on the ground.  If the box is empty it is relatively easy.  If the box is full of water it will be much harder to tilt.

Note the increased stability does not require the water ballast to be raised above the water surface, as sometimes believed.  As long as the CoB moves out more than the CoG the boat will remain stable, and the heavier the full ballast tank, the more the stability.

The “gz curve” – righting lever values

To indicate the stability of a boat, yachting magazines publish a “gz curve”.  “gz” is  simply the horizontal separation of the forces of gravity and buoyancy – what we have just been discussing.  It should really be called the righting arm or lever.  Figure 6  illustrates how the term “gz” seems to have arisen and shows as an example of a curve (the BC20 with full ballast tanks).  For this example the gz value remains positive until about 132° of heel which indicates that the boat would self-right from a knock down condition.

For most boats there is one, characteristic gz curve.  But for a water ballasted boat that can be sailed with or without ballast,  the large changes in the overall weight and it’s distribution within the boat result in two distinct gz curves.  These are shown in figure 7 for four Swallow Boats using data published in Practical Boat Owner (Harding, 2009, 2010, 2011, 2013).

Figure 7 Righting Lever or “gz” curves for various Swallow Boats as published in Practical Boat Owner reviews.

Unfortunately,  curves for gz for the ballasted and un-ballasted cases (as in Figure 7) don’t fully represent the effect of ballast on stability because they neglect the change in boat weight.  In his article on water ballast,  Nick Newland (2015) states that for a Bay Raider, the water ballast increases gz by about 30% but more than doubles the righting moment. ( In fact, for the BR20 Figure 7 suggests that the difference is much more than that.  However it is possible that the unballasted curve published in PBO is wrong.  It implies that the BR20 is less stable than the BRe which, being more or less a BR20 with a cabin, should be the less stable.)

Comparing the change in stability – the “Righting Moment”

The actual righting force (the “ righting moment ” ) is given by:

(righting moment, rm) = (righting lever, gz) x (weight of boat)

Unfortunately,  righting moment values for different boats are difficult to compare because the boat weights are different.  Therefore Figure 8 demonstrates the increase in stability caused by the weight of the water ballast by plotting an “adjusted righting lever” defined by:

(adjusted gz) = ((righting lever gz) x (weight of boat +ballast + equipment)) (weight of bare boat)

Thus, if the boat has no ballast or equipment, the “adjusted gz” is the same as the gz value plotted in Figure 7.  The equipment weight (“ load ” =  weight of outboard, cooking gear, battery, etc.) has been added so as not to exaggerate the fractional effect of the water ballast weight by comparing to an empty hull.  The nominal values used for each boat are shown in the figure.  One should also add in the weight of crew but, since people move around and may even hike out, the crews effect on stability is hard to define and has not been included.

Figure 8 “Adjusted righting lever” values (see text) showing the relative difference in stability between having empty ballast tanks (red) and full tanks (blue). The grey lines are the unadjusted “gz” values as shown in Figure 7.

For the unballasted case the small increased magnitude of the adjusted value (red line) compared to the original gz value (grey) is due to the nominal “load” value assumed.  When the ballast tanks are filled with water, there is a small increase in stability due to the change in the righting lever length (upper grey line) but the actual change in stability is much larger (blue line) because of the weight of the ballast.

Stability near capsize

Figures 7 and 8 show that for each of the boats the maximum stability occurs at around 40° of heel. With greater heel the stability decreases with the unballasted curves showing zero or even negative stability when the boat is on its side at 90°.  If the position of added equipment such as the outboard were taken into account,  the curves suggest that, unballasted, each of these boats would tend to turn turtle. However beyond 90° the curves become positive and for the BR20, BRe, and BC20, the PBO reviews suggest that this is because of immersion of the hollow masts.  For the BC23, immersion of the coachroof is suggested. Whatever the cause , this positive stability peak might be enough to keep the boat floating on it’s side rather than turning to 180°.

The situation is much better if the boat is sailed with the water ballast tanks full. In that case all the boats show self-righting ability from a 90° knock down, although the Bay Cruisers, with their smaller cockpits have a greater margin of safety.

Figure 9 The yellow shading indicates the amount of the aft section of a Bay Cruiser 20 hull occupied by the buoyancy tanks needed for self-righting.

Nick Newland (2015) notes that with water ballast this self-righting ability comes at the cost of sacrificing part of the hull space near the gunwale to provide the correct buoyancy distribution.  For example the BC20 has large full depth buoyancy tanks at each quarter and across the stern.  The hull space lost to tanks for ballast and for buoyancy would seem to be the main disadvantage of using water as ballast.

Dynamic stability

So far the discussion of stability factors has not taken into account the effects of motion.

An oft quoted stability parameter, the “ metacentric height ” is related to the positions of the centre of gravity and centre of buoyancy, as discussed above. It is of relevance to ships and motor boats since it is related to the period of roll – the time taken to roll one way and back the other, in other words how fast the boats rocking motion is.  It is much less relevant for sailing boats because of the aerodynamic forces of the sails and the inertial effect of the mast.  More important are factors such as momentum and moment of inertia .

Both the momentum (mass  x velocity), and the force needed to accelerate the boat, are proportional to the boat’s mass.  Adding water ballast increases the boats mass by exactly the same amount as a similar weight of any other type of ballast.  If the ballast tank is full, that extra mass is exists whether the boat is on its trailer or in the water.

“ Moment of inertia ” is a measure of how difficult it is to rotate an object around a given axis (Figure 10).  Where the water ballast is contained in tanks fore and aft, as in the Bay Cruiser, filling the tanks makes the boat more similar to the dumbbell shaped object.  The axes for which moment of inertia is increased are those for yaw and pitch.  The roll axis is not significantly affected.

Is the boat faster with ballast tanks full or empty?

Obviously there is no one answer; whether you decide to sail with ballast tanks full of empty will depends on circumstances.  If you are out for a day’s sail in your Bay Raider you might have the tanks empty and enjoy planing past another boat which is carrying the equipment needed for a few days cruising.  But the cruising owner the security of having a self righting boat might well be the decisive factor in keeping the tanks full.

At least with a water ballasted boat you have the choice and, hopefully the above discussion will help in weighing up the factors.  For example, consider beating into a choppy wind sea.  Having full tanks will do more than increase stability and allow the boat to sail more upright.  The extra momentum (from the increased mass) will mean that the boat is slowed down less by oncoming waves.  The increased moment of inertia will make the boat less “twitchy” so it is less deflected from the desired course.  You can use the Tiller Tamer and make a cup of coffee!

If you empty the ballast tanks, the boat will be significantly less stable, heeling more and forcing you to spill wind or feather windward.  With less mass the boat will be slowed more by slamming into waves.  On the other hand, if slowed up by a wave it will then accelerate faster.  The lower moment of inertia along the yaw axis will allow the boat to be quicker in responding to the helm.  Rather than cut through the waves, you may be able to thread a course between them or (with less inertia to pitching) ride over them.  Actively helming the boat dinghy fashion, you might be able to work  up higher to windward.  However you probably won’t have time to make coffee!

Water ballast gives you the choice and can vary that choice during the course of a day’s sailing.

Water ballast and safety

Finally, it is worth considering the safety factors inherent in a water ballasted boats. First, the ballast tanks create a double skinned hull over much of the boats underwater area. Puncturing a ballast tank will not sink the boat!  Second, consider those two crates illustrated in figure 1.  If placed in water the wooden crate full of water would float with it’s lid more or less awash.  Since the crate containing lead is the same size and weight, it would float in a similar fashion.

Figure 11 – The crate containing water doesn’t sink when holed.

Now imagine what will happen if you make a hole in the two crates (figure 11).  It won’t make much difference to the crate contain water; it will continue to float more or less at the surface.  On the other hand, the crate using lead for ballast will fill with water and sink!

Of course, people like me put heavy things like lead-acid batteries in their boats so even a wooden, water ballasted boat could sink if holed.  However it only needs some relatively small sealed buoyancy chambers (as built into Swallow Yachts) to ensure that a water ballasted boat will float even if holed.

(Peter Taylor, February 2015, revised October 2015)

Harding, David (2009) A different sort of dayboat (review of BR20) , Practical Boat Owner 506, February 2009, 44 – 47.

Harding, David  (2010) High-tech tradition (review of BC20) , Practical Boat Owner 526, September 2010, 39 – 42.

Harding, David  (2011) Technology meets tradition: Baycruiser 23 (review of BC23), Practical Boat Owner 539, September 2011, 40 – 43.

Harding, David  (2013) The super-simple trailer-sailer (review of BRe) , Practical Boat Owner 556, January 2013, 76 – 79.

Newland, Nick (2015) What’s the Point of Water Ballast? , Water Craft no. 109, Jan/Feb 2015, 30 – 33

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Water Ballast....Race Boat Applications

Water Ballast….Race Boat Applications

Water ballast, in one form or another, has been around for the past 150 years. It has only been in the last 20 years that racing boats have utilized water ballast as a performance enhancing feature in their design criteria. We have seen this development primarily in the Open Class 30s, 40s, 50s, and 60s as well as the Whitbread 60s (Volvo 60s), and more recently, Class 40s. The use of water ballast has added to the strategy and excitement of these ocean racers and has become a proven, accepted feature as well as being reliable and safe.

Why does water ballast work? Like crew on the rail, water ballast adds weight outboard to increase a boat’s stability, or righting moment, helping it to sail more upright. This is important because a sailboat’s hull drag is usually the least when sailed upright. As the boat heels, hull drag increases and the boat slows down. Also, lift on the appendages decreases with an increase in heel angle, so the yacht’s pointing ability is reduced. It’s a similar principle for the sails as excessive heel will cause a reduction in lift and an increase in sail drag.

So when the seas are running and the breeze is heavy, a water ballasted yacht has a distinct advantage of being able to stabilize herself and become a more powerful offshore design. Sailing close-hauled in breeze is usually the time to carry the additional ballast as the boat will be heeling the most. Off the wind, it’s often more advantageous to sail with the tanks empty or partially full depending upon the conditions. However, if the wind and sea are running fairly high, then water ballast could be carried in both port and starboard tanks for proper weight and trim distribution. The extra weight of the water will keep the boat steady in waves. If the boat hobby-horses (pitch moment) too much, drag increases in both the rig and hull, and the boat’s efficiency through the water decreases dramatically.

If the water ballast tanks are divided into multiple compartments fore and aft, certain sections may be filled to correct for trim. These compartments would then be sub-divided with baffles to combat any free surface effects caused by the water sloshing back and forward. Depending upon the design, trial-and-error is necessary to optimize performance and develop a strategy for the use of the system for any given weather conditions. Even in light air conditions water ballast can be an advantage. By inducing heel the sails can hang full and continue to draw, keeping the boat going. The increased momentum created by the added weight also keeps the boat drifting forward when the puffs pass by.

When racing offshore or sailing shorthanded, classes like the Open 60s (left), Class 40s (above), and Mount Gay 30s have a full range of stability available via their water ballast tanks. This added righting moment gives the boat a marked performance increase in a variety of sea and wind conditions. The Mount Gay 30 Rule allows up to 600 litters of water ballast total. That is 300 litters each side, equivalent to 307.5 kgs per side. At 72.6 kgs per crew member, that’s equal to 4 1\4 crew members for on-the-wind conditions.

The stability characteristics of a Mount Gay 30 are a product of the Rules which define the boats dimensions: length, beam, draft, displacement, keel weight, keel center of gravity, mast weight, and mast center of gravity. The keel moment (keel weight times the distance between its center of gravity and the flotation waterplane) must be at least 1,180 kg-m which is easy to achieve for boats of normal proportions. However, in the unlikely event that the keel moment is less than this limit, then the boat must undergo a stability test. This involves pulling the boat over to 90 degrees heel and weighting the mast with 70 kgs (154.3 lbs) at the top of the jib halyard (IG measurement). The boat must at least balance this way, or preferably return upright, but not turn turtle. With such well-defined parameters, the 600 liter (158.5 gals) capacity of the water ballast tanks was determined as a safe and prudent amount.

The only design restrictions other than maximum capacity are that the tanks, which must be located aft of the chainplates, be integral or permanently secured to the hull, and be symmetrically arranged about the boats center line. The tanks must be plumbed with one system of pumps and valves. The pumps may be manual or powered. If power operated there must be a manual back-up. The inlets may be flush openings or retractable inlet scoops to take advantage of the ram effect at high speeds.

There are definitely strategic advantages to racing with water ballast, particularly on longer offshore competitions where there is little tacking to do. Water ballast can be taken on when you need it, you don’t have to feed it, it doesn’t talk back to you, and you can dump it when its usefulness has expired. The negative side is that, the plumbing requires some occasional maintenance and you don’t have as many warm bodies who can handle lines. Conversely, for round-the-cans racing where the ability to tack quickly is a necessity, dealing with water ballast become impractical. Crew weight, rather than transferring water, is far more efficient on these short, inshore courses as there are people to handle lines and reposition their weight for the best boat trim.

The system on the VG30 is quite simple and can be readily applied to boats of a similar size. Water is pumped on board with an electric pump or the hand pump backup. The 30 gpm electric pump may be brought on line at any time and takes approximately 2-1/2 minutes to fill a tank. The flow controls are located in the cockpit just forward of the traveler, providing quick and convenient access to the trimmer. The plumbing of the tanks is designed to be simple, easy to maintain, yet highly efficient. There are only three flow controls to this system; the 3″ dia. inlet/outlet gate valve, and two port and starboard gate valves for the 3″ dia transfer pipe. Two-way diverter valves are located down below to switch from the tank fill to a bilge pickup. The gate valves are all spring-loaded with shock cord (positive closed) and controlled lanyards leading up into the cockpit which can be held open by cam-cleating the lanyard in place.

Operating the water ballast system couldn’t be easier. To pump water into the port tank, the starboard and overboard gate valves are closed. Begin pumping until the port breather valves, located on the shear, blow water. To dump the water ballast, simply open the port and overboard gate valves, and the water will drain out with gravity. Tacking the VG30 with water ballast is just as easy. Prior to the tack, open both port and starboard gate valves, keeping the overboard gate valve closed, so the water will downflood from one side to the other. The transfer should take approximately 30 to 40 seconds, and once it is complete, close both gate valves and tack. It’s almost like roll tacking the boat! If there is any water loss, the new windward tank can be easily topped up with a few strokes on the hand pump.

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When the ballast was poured into our full keel back in 1978 they didn't get it quite right. She sits about 2 inches higher at the stern than the bow. We're in the process of replacing our engine with one that is around 100 pounds lighter, which might make the problem even more noticable. While the engine is out I'm considering adding some ballast to the very stern end of our bilge. Has anyone done anything like this? Any suggestions on how to figure out the correct amount? I would imagine I would fiberglass in some lead pigs? Any advice appreciated. Thanks.  

Is the boat actually loaded with your gear yet? You may want to hold off a bit before adding ballast, because things like BBQ grills, full fuel tanks, and otherwise loading the boat - if you load center and aft, will definitely bring your stern lower. When I was cruising on my C-27 - the stern dropped a inch or 2 - and it didn't really take that much...If it is really a concern use something you can remove like sand bags or water jugs... The stern really doesn't have to be weighted down too much to get it to squat right..but fiberglassing in lead - you may regret it later... some re-positioning of gear / storage items may make the difference you are looking for...  

Year, make, and model?  

Also, how many crew do you typically sail with? If you usually have 2-3 or more adults in the cockpit, that will often balance it out pretty well on a small-medium size boat. If you are talking about a 40+ footer then crew weight might not be as noticeable. Another question, are you carrying a large inventory of anchor chain in the bow?  

It's a '78 Pacific Seacraft Mariah 31. I'm told it was the very last Mark I, but had the ballast poured the way they did it for the Mark II, which had some slight design changes. I'll certainly see what I can do about packing some gear a little differently. Using something removable is also a great idea, remove the possibility of regrets. We don't have an enormous amount of chain, but we do have 2 anchors right out on the bowsprit (35lbs and 20lbs). We only have the 2 of us as crew. Thanks for the replies.  

Sorry, Dhornsey, I'd forgotten that you have a Mariah. I wouldn't call that an inordinate amount of anchor weight on the rollers (we have a 35 lb and 25 lb anchor on ours.) And if you aren't carrying all chain rodes, then anchor and chain weight wouldn't be contributing much to the bow-down trim. And two average adults in the cockpit probably won't correct it either. Interesting about the ballast change between the Mark 1 and 2 Mariah. Good to know. Do you know whether your boat was factory finished or built out by an owner from a hull/deck kit? Sometime in the past year or so, there was an interesting article in Good Old Boat magazine by Jerry Montgomery, in which he described ballast modifications that he had to make on one of his Montgomery pocket cruisers. He worked with the designer, Lyle Hess, to correct the problem, but the gist was that very small amounts of ballast can make a big difference in trim and righting moment. The advice above about loading the boat first, with heavier gear further aft, is good. If you decide to add ballast, add it gradually. Another variable is tankage -- maybe you could use-up your forward water tank first, or if you only have one consider adding a second water tank somewhere aft so that you get something useful for the extra weight being hauled around?  

The boat was factory finished, with the exception of the mast & rigging. I'll try to track down that good old boat article, thanks for the suggestion.  

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The Ballast to Displacement Ratio Explained (with Formula)

Ballast to displacement ratio explained.

The ballast to displacement ratio is one of the ratios sailboat enthusiasts use to quickly compare sailboats. It is simply the percentage of ballast against the displacement of a boat.

What is a good ballast ratio?

Sailboats with a ballast ratio of over .40 are generally stiffer, more stable, and have better handling in rougher conditions. Sailboats with a ratio below .40 will typically be less stable, have a higher heel angle, and be more prone to rolling. However, the ballast ratio doesn't account for other important factors, such as righting moment.

Ballast to displacement ratio formula

The formula for this ratio is:

ballast displacement ratio = ballast / displacement

In other words, it tells you what percentage of the sailboat's weight is in the ballast.

The average value is between 0.35 and 0.45 for cruising boats. This means that on average, 35-45% of the weight of a cruising boat will be carried in the keel ballast .

It is a simple indicator that can give you a rough idea of how stiff and stable the boat will be. However, there are limitations to the use of this number, since the ballast weight doesn't tell the whole story. For example, it doesn't tell you how much righting moment the keel design provides, or how much wetted surface there is - while both of these factors greatly affect handling and stability.

To get a more complete picture of the boat's handling, one should also look at the capsize screening ratio (as explained by Ted Brewer) and the comfort ratio .

How Do Sailboat Keels Work?

In short, a sailboat keel's weight is used to increase displacement and lower the center of gravity, while its surface is used to increase wetted surface. This helps to stabilize the boat, but also provides directional stability. For a more detailed explanation on how sailboat keels work , I recommend reading this article.

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How To Make Your Boat More Stable? (The 4 Best Tips)

Are you looking for ways to make your boat more stable and safe? Whether youre an experienced sailor or a first-time boat owner, there are numerous steps you can take to maximize the stability of your vessel.

In this article, well discuss the four best tips for making your boat more stable, including adjusting weight distribution, utilizing outriggers or stabilizers, adding ballast, and choosing the right boat.

Well also discuss reducing speed, tips for smooth sailing, and how to prevent unnecessary risk.

If youre looking for ways to make your boat more secure and reliable, this article is for you.

Table of Contents

Short Answer

To make your boat more stable, you can add ballast to the bottom of the boat to increase its weight.

You can also make sure the center of gravity is as low as possible by keeping heavy items on the bottom and center of the boat.

Additionally, you can add outriggers or sponsons to the sides of the boat to increase its beam and provide more stability.

Finally, adding floatation devices to the sides of the boat can help keep it stable in rough waters.

Adjusting Weight Distribution

When it comes to increasing the stability of your boat, one of the most effective measures you can take is adjusting the weight distribution.

By ensuring that weight is evenly distributed throughout the vessel, it will be less prone to tipping or rocking when out on the water.

This is especially important when navigating rough or choppy waters.

When adjusting the weight distribution, it is important to take into account the size and shape of your boat.

Smaller and more compact vessels, such as kayaks or canoes, will require a more precise weight distribution than larger boats.

Additionally, the type of material your boat is made from can also affect the weight distribution.

One way to ensure a balanced weight distribution is to make sure that weight is evenly distributed across the boat, including the bow, stern, and sides.

This ensures that the vessel is less likely to rock or tip in different directions.

Additionally, it is important to ensure that heavier items such as fuel tanks, tackle boxes, and fishing equipment are placed in the center of the vessel.

This will help to keep the boat balanced and reduce the risk of tipping.

Finally, it is important to consider the placement of passengers when adjusting the weight distribution.

If the boat is overloaded or has passengers sitting in the wrong areas, this can cause an imbalance and reduce the stability of the vessel.

Ensuring that passengers are seated in the appropriate areas and that the weight is evenly distributed throughout the boat will help to increase stability.

Utilizing Outriggers or Stabilizers

One of the most effective ways to make your boat more stable is to utilize outriggers or stabilizers.

Outriggers are a type of stabilizer that extends from the sides of the boat, providing it with greater stability in choppy waters.

Outriggers are most common on smaller boats, as they dont require a lot of space or weight to install.

Stabilizers, on the other hand, are usually installed on larger boats and create a platform that extends below the boat, providing it with additional stability.

Both outriggers and stabilizers are effective at increasing a boats stability, though they can be expensive to install.

Before investing in either of these, be sure to consider the type of waters youll be navigating and the size of your boat.

Additionally, make sure to check with your local marina to ensure the installation of outriggers or stabilizers is allowed.

Adding Ballast

Adding ballast is an important step in making your boat more stable.

Ballast helps to increase the displacement of your boat, which helps to lower its center of gravity and thus its stability.

This is especially important when sailing in choppy or windy waters, as the added weight helps to keep your boat from rocking and swaying too much.

When adding ballast, it’s important to ensure that you are not adding too much weight.

Balance is key here, as too much ballast can cause your boat to become sluggish and difficult to maneuver.

You should also make sure that the ballast is evenly distributed throughout the boat, as this helps to keep the center of gravity low.

Additionally, adding ballast should always be done with the boat in the water; adding it while out of the water can cause it to sink.

There are several options for adding ballast to your boat.

The most common is the use of water ballast tanks.

These are specially designed tanks that can be filled with water to provide an additional weight.

Another option is to add lead ballast, which is available in various shapes and sizes to fit any boat.

Alternatively, you can also add extra passengers, but this is not recommended as it can cause the boat to become overcrowded.

No matter which ballast option you choose, it’s important to ensure that it is properly secured to the boat.

Additionally, be sure to regularly check the ballast and make sure that it is evenly distributed throughout the boat.

With these simple steps, you can make your boat more stable and enjoy a safe and comfortable ride.

Choosing the Right Boat

When it comes to making your boat more stable, choosing the right boat for the type of waters you are navigating is an important step.

Different types of boats are designed for different waters and conditions, so you should always take the time to research the ideal boat for the environment youll be in.

A boat designed for calm lakes or rivers might not be ideal for navigating choppy seas, for example.

In addition, the size of the boat can also affect its stability.

A smaller boat may be less stable than a larger one, so if youre looking to navigate rougher waters, it might be best to look into a larger boat.

You should also take into account the size of your crew and cargo, as a full boat may be more susceptible to rocking and swaying, while an empty boat may be more prone to capsizing.

When it comes to the type of boat, the hull design can play a major role in stability.

A deep-vee or round-bottom hull, for example, will provide more stability than a flat-bottom hull in choppy waters.

Additionally, wider boats are generally more stable than narrow boats, as they have a larger surface area for the waves to push against.

Finally, the type of propulsion system you choose can also affect the stability of your boat.

Inboard engines generally provide more stability than outboard engines, as they sit lower in the water and provide more weight.

Additionally, the bow of a boat with an inboard engine is typically higher than a boat with an outboard engine, which helps to reduce the risk of swamping.

In summary, there are a few key factors to consider when choosing the right boat for maximum stability.

Research the ideal boat for the type of waters you are navigating, take into account the size of your crew and cargo, and consider the hull design and propulsion system of the boat.

By taking these steps, you can ensure that your boat is as stable as possible and that you have a safe and enjoyable boating experience.

Reducing Speed

When it comes to boat stability, one of the most important factors to consider is the speed of your boat.

By reducing the speed of your boat, you can significantly reduce the amount of rocking and swaying that comes with higher speeds.

This is especially important in choppy waters, where the boat can become unstable and dangerous at higher speeds.

Reducing your speed can also help to increase fuel efficiency, allowing you to get the most out of your boat.

When slowing down your boat, make sure to do it gradually as sudden changes in speed can cause the boat to become unstable.

It is also important to be aware of the conditions of the waters you are navigating and adjust your speed accordingly.

For instance, if you are navigating in a busy area or in bad weather, it is best to slow down your boat to reduce the risk of an accident.

Additionally, if you are navigating in shallow waters, reducing your speed can help you avoid running aground.

Overall, reducing the speed of your boat is an important factor in improving its stability.

By being aware of the conditions of the waters you are navigating and slowing down your boat at the right times, you can greatly reduce the risk of accidents and make your boating experience more enjoyable.

Tips for Smooth Sailing

Making your boat more stable is an important factor in ensuring a safe and enjoyable boating experience. As any experienced boater knows, the stability of your boat can mean the difference between a pleasant day on the water and a rough, rock-filled ride. Fortunately, there are some simple steps you can take to increase the stability of your boat, making it easier to navigate and enjoy the waters. Here are four of the best tips to make your boat more stable:

1. Adjust the Weight Distribution – One of the best ways to make your boat more stable is to adjust the weight distribution. The best way to do this is to move heavier items such as engines, fuel tanks, and batteries to the center of the boat, which will help balance out the weight. Additionally, avoiding storing heavy items on the sides of the boat will help keep the boat from tilting when you turn or maneuver.

2. Use Outriggers or Stabilizers – Outriggers or stabilizers are devices that can be attached to the sides of the boat to provide additional stability. These devices are designed to reduce the amount of rocking and rolling that occurs when the boat is in motion. They work by creating a larger surface area for the boat to rest on, which helps to evenly distribute the weight and reduce the amount of rocking and rolling.

3. Add Ballast – Another way to make your boat more stable is to add ballast. Ballast is a weighted material, usually in the form of sand or water, that helps to keep the boat level. Adding ballast to the bottom of the boat will keep it from rocking and rolling, making it easier to navigate.

4. Choose the Right Boat – Finally, choosing the right boat for the type of water you are navigating is key to ensuring a stable ride. Different types of boats are designed for different types of waters, and selecting the right boat for the conditions will help to ensure a smoother ride and greater stability. Additionally, reducing the speed of your boat will help to reduce rocking and rolling, making for a more comfortable ride.

By following these simple tips, you can make your boat more stable and enjoy a safe and comfortable ride.

Whether you are just starting out in the world of boating or are a seasoned veteran, these tips can help you to navigate the waters with greater ease and stability.

With these easy steps, you can make your boat more stable and enjoy a smooth and enjoyable ride.

Preventing Unnecessary Risk

Making your boat more stable is an important factor in maintaining a safe and enjoyable boating experience.

Unstable boats are more prone to tipping over or capsizing, which not only puts the passengers and crew in danger, but can also cause significant damage to the vessel itself.

To make sure that your boat is as stable as possible, there are a few simple steps you can take.

The first step is to adjust the weight distribution of your boat.

If there is too much weight on one side of the boat, it can cause the boat to become unbalanced and unstable.

To prevent this, you should make sure that the weight is evenly distributed throughout the boat.

Additionally, it can be helpful to use outriggers or stabilizers to keep the boat from rocking from side to side.

These devices can help to keep the boat steady, even in choppy waters.

The second step is to add ballast to the boat.

Ballast is a heavy substance that is placed at the bottom of the boat in order to provide additional stability.

This can be beneficial in a variety of situations, including when navigating rough waters or in high winds.

Additionally, ballast can also help to reduce the risk of tipping over in the event of a sudden gust of wind or wave.

The third step is to choose the right boat for the type of waters you are navigating.

Different boats are designed for different types of conditions, so it is important to make sure you are using the right boat for the job.

For example, if you are navigating rough waters, it is important to choose a boat that is designed for those conditions.

This will help to increase the stability of your boat and reduce the risk of an accident.

Finally, you can reduce the speed of your boat to increase stability.

When your boat is moving at high speeds, it can become less stable due to the forces of inertia and momentum.

By reducing the speed of your boat, you can reduce these forces and make your boat more stable.

By following these four steps, you can make your boat more stable and enjoy a safe and comfortable ride.

Adjusting the weight distribution, using outriggers or stabilizers, adding ballast, choosing the right boat for the type of waters you are navigating, and reducing the speed of your boat are all simple and effective ways to increase the stability of your boat and reduce the risk of an accident.

With these easy tips, you can make sure your boat is as stable as possible and enjoy a safe and enjoyable boating experience.

Final Thoughts

Making your boat more stable is an important part of having a safe and enjoyable boating experience.

By following the four best tips outlined in this article, you can adjust the weight distribution, use outriggers or stabilizers, add ballast, and choose the right boat for the type of waters you’re navigating.

Additionally, reducing your boat’s speed and preventing unnecessary risks will help to ensure a smooth and stable ride.

Now that you know how to make your boat more stable, get out there and enjoy a safe and comfortable boating experience!

James Frami

At the age of 15, he and four other friends from his neighborhood constructed their first boat. He has been sailing for almost 30 years and has a wealth of knowledge that he wants to share with others.

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What is Ballast on a Boat? – The Key for Stable Boating

Written by Anthony Roberts / Fact checked by Jonathan Larson

Ordinary folks have many questions about boating terminologies, making the query, “What is ballast on a boat?” no longer surprising. In simple terms, ballast is anything (mostly water) that stabilizes a structure or, in this case, a vessel. It’s a crucial element in ensuring a safe voyage.

Of course, that’s an oversimplification of this all-important vessel component. Join us in exploring what the ballast of a ship means.

Table of Contents

Understanding Ballast

1. solid ballast, 2. water ballast, how does a ballast work, 1. impact of ballast on performance, 2. factors influencing boat stability, 3. how ballast affects stability, advantages of using ballast in sailing, factors to consider for proper ballast distribution, 1. maintenance and safety considerations, 2. best practices for ballast management, frequently asked questions.

Let’s define ballast. Ballast is anything (i.e., water, sandbag, stone, improvised weights, and other objects or materials) vessel operators can use to ensure stability. In the case of boats, ballast adds weight to watercraft when it’s lighter than its safe operating limits.

For example, a container ship can carry tons of cargo. It would not have any issues maintaining stability on the high seas because the weight increases its draft. However, problems can arise once the vessel unloads its cargo. It would be bobbing in the ocean like a cork in the water.

Hence, the purpose of ballast is to ensure the container ship’s stability without its safe load, allowing it to stay afloat.

Now, you might hear some folks talk about a ballast light. That’s a different technology in lighting fixtures, especially high-intensity discharge (HID) bulbs and fluorescent lights. This ballast type allows lighting fixtures to start and operate optimally.

Some might also refer to a track ballast. It’s the bed of aggregate (mainly crushed gravel or rocks) supporting a railroad track and the train’s load while ensuring efficient water drainage.

Given these variances in definitions, we recommend appreciating this boating terminology by understanding the ballast synonym, including equilibrium, counterbalance, stabilizer, brace, and weight.

Different Types of Ballast in Boating

As mentioned, ballast could be anything a skipper or ship crew can use to balance and stabilize the vessel. Hence, we can categorize ballast into two.

Before the late 19th century, skippers and sailors relied on sandbags, rocks, and other “solid” objects to balance the ship’s empty cargo hold. They would secure these items on structures aboard the vessel.

Unfortunately, it’s not unusual for a ballast stone to break free, potentially shifting the ship’s weight to one side and causing it to list and capsize.

The 20th century saw drastic yet worthwhile improvements in boat designs, with pumps and steel hulls dominating the field. The days of the solid ballast material are numbered.

Steel-hulled ships in the 20th century began featuring a specialized compartment we call today a ballast tank. The innovation holds water as the balancing or counterbalancing material for the vessel. Rightfully, sailors call it ballast water.

Revisiting our earlier definition of ballast, we can say that the ballast water definition is a vessel’s use of water to correct stability issues and ensure a safe voyage.

We have two water ballast types: clean and segregated. Vessels with a clean ballast use the same oil cargo hold to fill with water for balancing and stabilizing the watercraft. The crew cleans the compartment before filling it with water and getting underway.

Meanwhile, segregated ballast refers to water in specialized compartments separate from the ship’s oil cargo. These sections can also accommodate other items, except harmful liquids.

Boat ballast works in various mechanisms depending on the ballast material. However, the principle remains the same – to add or reduce vessel weight to maintain balance and floatation stability.

For example, a fully loaded ship doesn’t need ballast because the cargo’s weight pushes the hull deeper into the water. However, a vessel without a cargo load will be light, raising its center of gravity toward the surface.

If the ship uses water as ballast, the crew can pump water from the sea, lake, river, or anywhere the vessel is on. The action increases the watercraft’s weight and improves its stability in the water.

If the vessel is ready to load another cargo, the crew can pump the water from the ballast tanks and discharge it into the sea.

It’s the same principle with solid ballast, albeit the crew will work more to move and secure the sandbags, steel, cement, rocks, or stone in their predetermined positions.

The Role of Ballast in Stability

Marine ballast weights are crucial to a vessel’s stability, especially in rough waters.

Although ballast is crucial to ensuring optimum center of gravity, too much ballast can impact vessel performance.

Increasing the watercraft’s displacement (i.e., adding boat ballast weights) will increase water resistance. There’s more water the ship must push against. Hence, too much ballast can reduce vessel speed.

Increased water resistance creates another issue – increased fuel consumption. The vessel will try to compensate for the reduced speed by increasing engine power, which consumes more fuel.

Vessel stability depends on several factors, including the following.

• Buoyancy – the ship’s ability to stay afloat defined by the water’s upward force.
• Weight location – a vessel’s weight must be near the bottom to improve stability; crowding the deck with a heavy load can upset the ship’s balance and cause it to roll.
• Water conditions – rough weather (i.e., strong winds and high waves) can reduce stability by continuously shifting the center of gravity.

As mentioned, weight location is a crucial factor in ensuring vessel stability. The ballast on a ship plays a vital role in this regard.

If a ballast is high on the deck, there’s a chance of upsetting the balance and causing the watercraft to roll. Moreover, too much ballast can lower the vessel’s freeboard, making the ship more susceptible to swamping.

Sailboats have ballast, providing sailors with two advantages.

The first is increased speed. Water ballast increases a sailboat’s sail, rudder, and keel projected profile, allowing the watercraft to catch more wind and propel it faster than sailing vessels without ballast.

The second is improved comfort. Sailing ballast softens the impact of tossing and rolling due to excessive heeling (the vessel’s tendency to “tip” to one side).

The amount of ballast to use in any vessel is the most crucial consideration for proper ballast distribution. The others are as follows.

• Space requirements – ballast occupies space, requiring boat owners to consider how much ballast their tank or compartment can hold
• Carriage capacity – the goal is to produce an effective counterweight, not overload the boat
• Boat metrics – draft, displacement, freeboard, and deadweight tonnage offer boaters an idea of how to distribute ballast

Ballast Systems and Design Considerations

Shipbuilders and boat manufacturers spend plenty of resources designing the ideal ship ballast system to ensure optimum stability and buoyancy. As a rule, ballast shouldn’t exceed 30% of the vessel’s deadweight tonnage.

One issue with water ballast is its effect on the environment when ships discharge untreated water into open seas and other bodies of water. The effluent could contain microorganisms and other life forms in various stages.

Hence, vessels must institute measures to ensure the safe discharge of water ballast into open bodies of water. It will help curb the proliferation of invasive species in local waters.

Here are some tips for optimizing ballast for stability.

• Research the best possible ballast installation diagram for your boat, preferably a customizable one.
• Understand your needs and choose the correct ballast size.
• Analyze different ballasts and pick the material best suited for your activity.
• Use a ballast calculator to help you determine the amount of ballast commensurate to your vessel’s buoyancy and weight.
• Consider your watercraft’s draft, freeboard, displacement, and deadweight tonnage ratings to determine the optimal ballast for stability.

Do all boats need ballast?

No, not all boats need ballast. Sailboats, particularly those with keels, often use ballast to provide stability and prevent capsizing.

However, many recreational boats or lightweight watercraft, such as kayaks or canoes, do not require ballast. These boats still maintain stability thanks to their design, hull shape, and inherent buoyancy.

Where do you put ballast on a boat?

Boaters must place ballast in their vessel’s lowest part (i.e., bilge). This location lowers the watercraft’s center of gravity to ensure floatation stability.

What are the risks of improper ballast distribution?

Improperly distributed ballast can upset the vessel’s balance, causing it to roll to one side. Swamping can also occur at heavier sections.

Are there any regulations or guidelines for ballast use in boating?

Yes, 82 countries signed the 2004 International Convention for the Control and Management of Ships’ Ballast Water and Sediments. Hence, vessels registered in these nations must comply with the international rules.

“What is ballast on a boat?” is a valid greenhorn sailor’s question. It’s a material that vessels use to ensure the watercraft stays upright even in stormy seas.

Ballast adds weight to the watercraft, increasing its draft and lowering its center of gravity. These effects contribute to better stability amidst rough waters. It’s the perfect element for sailboats, allowing sailors to minimize keeling tendencies.

Although most ships use water as ballast, other materials can be a counterweight, balancer, or equalizer. Knowledge of this boating terminology should make you more confident and secure the next time you sail.

Ten years of enjoying countless trips on boats never made me love them any less! So I am here to put all those experiences into good use for other boaters who want to have a safe and fun trip with their friends and families.

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Jon boat water ballast

Discussion in ' Stability ' started by curttampa , Apr 6, 2020 .

curttampa Junior Member

This may be way out there...but after having read an article about a small 12’ sailboat “Scamp” that uses a chambered water ballast system the usefulness of something similar on my small Jon boat interested me. My goal is to reduce the tippy nature of the Jon boat when standing on the foredeck to cast. The boat is 12’ long with a 42” bottom. It has a flat bottom no V. My crazy(?) idea is to build a box from 2x4” paneled with plywood top and bottom that would sit inside the boat center amidships. Epoxy waterproofed and baffles if needed. Internal bilge pump to drain accessible with a round sealed inspection port. To fill it a second external bait well pump. Depending on the overall dimensions (42x42”) this could add 250-300 pounds of ballast over the lowest point of the boat. The boat is used in mill pond flat waters. The ideal of a fillable/drainable ballast tank makes sense to me but I have zero knowledge boat design and stability. Thoughts, ridicule, improvements and other ideas are all welcome.  

Mr Efficiency Senior Member

So when you stand at the bow, and I assume no one else aboard, the bow drops, and the boat also becomes tippy ? I guess if you are standing at a height well above the waterline, you are not a jockey who likes fishing, and you are not always distributing you weight centrally, and especially when casting, it will get a bit tippy. It is after all, a fairly small and narrow boat. I don't think the ballast idea would be worth it, it is a complication in what is otherwise a very simple boat. You might try adding a buoyancy band just above the waterline, that takes up when the boat heels, and especially when you stand right forward, you could experiment with some cheap block polystyrene foam, say 4- 6" thick. Just glue it on temporarily, and if it does the job, you can think of something more permanent.  

Great reply. Thank you. I am still fascinated by the water ballast idea.  

gonzo Senior Member

There are a couple of ways of using water ballast. To fill the tank, make it so the top is not higher than the waterline when the tank is full. To fill it, have a hole on the top with a short pipe coming up. There will be a hole at the transom with an accessible plug. To fill, take of both plugs and the tank will fill. Put on the plugs until you need to empty it. To empty, take the plugs off and motor until the tank is empty. Put on both plugs.  

kapnD Senior Member

You’re asking too much of the design, what you need is a wider boat! You could try Lowering the casting platform to seat level, and stay nearer the center. I see many fishermen actually hanging ten in their zeal to get maximum cast distance, but obviously pushing the stability parameters of their craft. I doubt that sloshing some water about will do much for you, but some bricks across the transom might help keep more of the boat in the water when you’re on the bow.  

That's right a wider boat, but a buoyancy band effectively makes that. The low draught of such a boat makes ballast tankage difficult, and not going to be as effective as extra volume further from centreline.  

jehardiman Senior Member

Remember; water ballast only works when it is above the waterline, otherwise all you did was change the shape of the boat. Lightweight and stable, there is a reason pontoon like hull forms have become ubiquitous for fishing on lakes.  

rwatson Senior Member

jehardiman said: ↑ Remember; water ballast only works when it is above the waterline , otherwise all you did was change the shape of the boat. Lightweight and stable, there is a reason pontoon like hull forms have become ubiquitous for fishing on lakes. Click to expand...

rwatson said: ↑ Huh? THAT idea doesn't "hold water". Water ballast in the keel works, as discussed in this article "Boat A - The stability numbers here again show a clear picture. At 90° of heel, she has more than double the Righting Moment of any of the 3 other boats. " The effects of water-ballast on sailboat stability – Bedard Yacht Design https://www.bedardyachtdesign.com/articles/the-effects-of-water-ballast-on-sailboat-stability/ Click to expand...

jehardiman said: ↑ FWIW, the figure you show is poorly informed at best, deliberately misleading at worst. ....it. Click to expand...

Attached Files:

Stabilwater.png.

rwatson said: ↑ But they do the righting moments IN the example ? Click to expand...

So, tankers that add water ballast below the waterline do not benefit from increased stability ?  

I am surprised that became a matter of contention, presumably all ballast is best placed as low as possible, for the purposes of improved stability, though not necessarily for comfortable motions.  

rwatson said: ↑ So, tankers that add water ballast below the waterline do not benefit from increased stability ? Click to expand...

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curttampa said: ↑ ... My goal is to reduce the tippy nature of the Jon boat when standing on the foredeck to cast. ... Click to expand...

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Adding Ballast to Hunter 240

• Thread starter patbratton
• Start date Apr 2, 2023
• Hunter Owner Forums
• Smaller Boats

I read Sandy Grant's review of his H240 in Brisbane, AU. It is posted in the Hunter 240 section on this site. He added two Plastimo flexible water tanks in the hatch spaces. He put a 100 L bag on each side in order to provide 400 pounds more ballast. He writes,"I have just added 2x 100 litre Plastimo water tanks which I plan to keep full. These are located in the hatch space on either side of the boat. I don't care what anyone else thinks - these boats are tender and I hate having to reef going upwind in 12 knots just when the sailing should be perfect. The difference upwind was amazing and downwind she felt much more stable - no annoying joggle when sailing in choppy seas." I just ordered two from Defender at $104.00 each. They hold about 26 gallons each and can be plumbed into the water system. They are 41 x 27 inches. I will post pictures of the install after the bladders arrive.  

Crazy Dave Condon

For those who are trailering, it depends where those bladders are as to trailering if they are in the back. Generally there is a 10% factor built in for safety on tires and with that, you will need to get rid of the water before putting the boat onto the trailer. where is the article so I can read it? I want to see what he is saying to choppy seas and how much he is heeling. your boat is on a lake, not on the ocean which i sailed everywhere plus being involved with the design. Yes I have reservations but open to see what the article has to say  

Crazy Dave Condon said: This is the link to Sandy Grant's review: Hunter Owner Reviews Hunter Owner Reviews hunter.sailboatowners.com If we have to pull the boat the added 400 pounds would be way to heavy for my trailer. The bladder tanks would have to be drained first. We have been in a slip for two years. It has taken my most of that time to get proficient with the rig. The CDI furler has been the best investment so far. She is just to tender for my wife and I am hoping that the added ballast stiffens her up a little. Elaine has gotten very cautious in her old age and is easily scared, which is odd considering all the time we spent on the Hobie 18. All four children are over 50 and they love the Wet Dog just the way she is. Click to expand

You could also add some ballast by dissolving salts into the ballast tank.  

Pat thank you for that link. It is great that you would drain the bladders before pulling the boat out. I was headed north with a new 260 when another 260 was headed south with tire’s carrying too much weight. Turned around and caught up with the owner headed back to Hunter in Florida with a major warranty issue. The water ballast had not been drained. We were 60 miles from my dealership suggesting to bring his boat there for repairs which Hunter highly suggested he do. Repaired his boat and took it sailing. Two day repairs at no cost plus he stayed at my home I introduced CDI as I met the mfg at the Annapolis boat show. I was one of the first customers and got Catalina and Hunter to offer it as an extra gear which is why I know your system all too well I was involved with the design of the 240. Based on experience I suggest never heel more than 12-14 degree of heel and get ready to reef at 14-17 knots. The mainsail is much bigger than a standard mainsail and it was designed that way for more power. Heel is controlled by sail deployment. The article states moderate winds 16-22 mph, choppy seas without stating how high and shallow waters withouth stating depth. Further, he does not like to reef. The 240 comes with one reef but a second reef can be added. Also I wonder if he sailing into the waves if you do add the tanks, take a look at the water line to make sure it is even with the water. Also you may have to raise the anti fouling paint line as well keep us posted Dave Condon  

rgranger said: You could also add some ballast by dissolving salts into the ballast tank. Click to expand

rgranger said: Okay so I didn't have time to expand on this idea when I first posted. Ammonium nitrate (available at most tractor supply type stores) is soluble in water at 119g per 100 ml. The ballast tank on a Hunter 240 is just a little over 156 gallons... or 590,524 ml .... (multiply by 119g)...and in theory you could dissolve 70.2 million grams of ammonium nitrate into that tank... or 154,764 pounds.... WAY MORE BALLAST THAN YOU NEED. There is an environmental problem with this though... ammonium nitrate is a very potent fertilizer and if you were regularly dumping this into a lake ... you would be causing all kinds of algae blooms etc. BUT If you want to try this out once just to see how it changes how your boat handles... of if you are leaving your boat tied up at a slip and not dumping the tank regularly... the environmental impact would be minimal. I think it would be wise to test it out before you invest in a lot of boat modifications. Try dissolving a few 50lb bags of ammonium nitrate into your ballast tank and see how your boat handles. BTW: Ammonium nitrate is also the active ingredient in those instant cold packs in your first-aid kit. So... if you did this on a hot day, you would get some very refreshing chemical cooling going on... Click to expand

I would not do that as it may well affect the integrity of the water ballast tank  

Johnb said: You may have slipped a cog in the calculation. 100 mL of water weighs 100 gm into which you could dissolve approx 120 gems of the salt resulting in 240% of the weight of the original. In round terms that would be 156x8x2.4 = 3000 pounds. Correct me if I am wrong Click to expand

When the tank is full, it will stop filling up. Simple. Close it up and go drink some grog. I call it moonshine when I use to make it  

Johnb said: Correct me if I am wrong Click to expand

rgranger said: a few hundred pounds of a soluble salt would allow the OP to determine if this fix will get him the performance he is looking for. Click to expand

I added the Starboard flexible tank under the seat. I remembered that Elaine had fallen in the cabin and caught herself on the table. It pulled the top two machine screws out of the fiberglass. Drilled out all six hole and replaced the screws with machine screws with fender washers with nyloc nuts. I did not want the flexible tank to rub against the screw ends, so I did not yet fill the tank all the way. I am looking for a five by seven inch rubber sheet to cover the back of the table mount under the seat. I will post all this information in the modification section of the H240 owners page. I can tell that she is setting lower in the water by the way the gunnels lay up against the fenders on the dock. Time will tell if the tanks hold up.  

I procured a kitchen silicone dish drying pad to place between the flexible water tank and the exposed bolt heads from the table mounting bracket. I doubled it up. I filled the tank with water and now the boat is balanced with about 216 pounds of additional ballast on each side of the cabin. She sits lower in the water as the gunnels are rubbing lower on the fenders attached to the dock. It looks like 9 mph winds and 76 degrees tomorrow on the lake. I will do a shake down if I can find a crew.  

So far the I am pleased the the boat performance. I found that the starboard tank had leaked about three fourths of the water into the bilge. It was no issue for the pump and I now have the cleanest bilge of any boat on the dock. I pulled that tank and checked for leaks. I turned out to be an O ring issue on the bottom connector. I do wish the tanks had come with caps to close the openings. After two tries I got a good seal and put the tank back under the seat. Tuesday, Jessie and I sailed from Aqualand Marina at Lake Lanier to Port Royal across the lake ( about two miles). The trip was uneventful in 12 mph winds. We had a late lunch at Pelican Pete's. Heading back on to the lake we found that the winds had picked up. We did not bother to reef but did pull the end of the boom all the way up with the topping lift so that the main would spill her wind. We were able to maintain a heading close hauled at about 20 degrees heal. Gusts would take her to 30 but pointing into the wind brought her back up. Coming about was a none event; back winding the jib pulled the bow right around. The week before Shawn and I were out in 18 mph winds with the main reefed but without the jib. We could not come about and had to jibe to change course. Mother's day we are going out with six of us but winds will only be about 4 mph. If I went back in time I would do the ballast tanks again. The bow of the boat wants to stay in the water and she has a good heavy feel to her.  

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