sailboat folding propeller

The GORI folding propeller has amassed a record and reputation unmatched throughout the world of propellers for cruising and racing.

Geared blades.

Geared blade design ensures that the blades open and close together giving less vibration ahead and astern.

Gain a Full Knot of Speed

GORI folding propellers reduce total drag by up to 35%. This results in one full knot of improvement in speed under sail.

Full Power Astern

A GORI propeller gives you the optimum thrust in reverse by virtue of it’s propeller blade shape and profile. It does not rely solely on centrifugal force to open the blades as do many other folding propeller types.

Reduce Drag up to 35%

Increased efficiency +11%, benefits of gori propellers.

• No rotation under sail. No strain or loading to the transmission.
• Blades have both camber & curve (aerofoil) to their shape.
• Increases efficiency (thrust) under power and over a greater Rpm range.
• Lower propeller noise from blade wash due to curve of blade.
• Dramatic reduction in prop-walk (almost non-existent).
• Overdrive function allows for a pitch increase over normal of approx. 2″-3″.
• Simple installation. No gear & blade assembly or pitch settings to make at time of install.

GORI 2-Blade

For shaft and saildrive, with engines up to around 50HP

GORI 3-Blade

For shaft and saildrive, with engines from 10HP to 300+HP

GORI 4-Blade

For shaft and saildrive, with engines over 150HP

For shaft and saildrive, with engines up to 110HP

New from GORI

GORI 3-Blade Single Pitch

No Overdrive For shaft and saildrive, engines from 10HP to 300+HP

Quality Construction

All propellers sold by AB Marine are manufactured from NIBRAL, a metal alloy made of nickel, aluminum and bronze. NIBRAL is far stronger in all specification areas than manganese bronze (commonly used by other prop manufacturers).

Tensile Strength

Impact strength, fatigue strength, 0.2% proof strength, cavitation erosion resistance, corrosion resistance, testimonials.

For the last five years my boat, a Catalina 270, has struggled to get through the water under power, especially against a tide or current. After talking with Geoff at AB-Marine, he suggested a GORI folding propeller. I installed it in the spring and it has made an amazing difference. The speed has increased with less rpm’s, the boat is much more maneuverable and responsive in forward and reverse and I have no trouble making my way through an oncoming current. The new prop has been the best upgrade I have made yet.

– Steve Taylor | Catalina 270

Since it came from the factory six years ago our 46 foot sailboat had a fixed three bladed (speed brake). In a quest for more efficient sailing speeds we recently purchased and installed a GORI 3-blade Folding prop. To our delight our new GORI prop has increased our sailing performance one to two knots and we have also gained over a knot while under power. Soon we will leave San Francisco Bay and begin our cruise to the south and on through the Panama Canal to the Caribbean. With our new GORI prop we will arrive at the fun anchorages even sooner.

– Anna & Steve Sabree | Hunter 46

The Gori 3-Blade propeller has proven invaluable. Our boat’s prop-walk-to-port drove us into neighboring boats until we changed to your 3-blade folding propeller. Now we can easily and safely power in reverse to starboard. Another pleasant surprise was the forward power that a combination of our little 18hp engine and the Gori 3-blade over-drive function provides as they lift our 32ft sailboat’s bow to surge across the bay.

– D. Holden | Beneteau 323

Just want you to know that the 3-blade GORI prop is fantastic! I consistently get at least a 1/2 knot improved performance over my old 2-blade folding prop and the boat doesn’t bog down in head winds & seas. Thanks for steering me to this product, it is worth every cent. Sorry I haven’t had a chance to run flat water RPM sea-trials for you, been too busy racing and doing deliveries to regattas.

– Steven | C&C 115 – Primal Scream

Hi Geoff, I am writing you on route from Newport to Martha’s Vineyard. The GORI 3 blade 15” x 12 x 3 RH propeller has performed beautifully for my Catalina 350 with Universal M35, rated at 35hp, 3000rpm, with the 1.88:1 ratio, RH rotation, 1.00” dia. shaft.  I just want to thank you for your assistance, after what we think was a tressle strike a few days prior to the parade when we discovered that the blade had come off our old Autoprop. Thanks again.

– David Olio | Catalina 350

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PROPELLERS FOR YOUR SAILBOAT

GORI Propeller design and manufacture some of the world’s most efficient and manoeuvrable folding propellers for yachts.

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GORI Propeller supplies a full range of folding propellers and custom-made propellers for leisure projects all over the world. Superior stopping power, second to none due to the unique design of the propeller. Our folding propeller range offers the following products:

2-blade folding propellers.

The 2-blade GORI Folding Propeller is designed for sailing yachts fitted with engines up to approximately 60 HP (44 KW). Tests show it’s highly efficient in comparison to many alternative two and three blade feathering and folding propellers available. Looking for efficiency and less vibrations, then look no further.

2-blade Racing propellers

With GORI Racing Propeller, everything is geared towards speed. From the intricately designed aquadynamic shape and the ingenious folding mechanism to the precision engineering.  When looking to reduce drag the Gori Racing Propeller is the choice for the majority of One Design racing yachts. .

3-blade Folding propellers

The 3-blade GORI Folding Propeller is the only folding propeller operating the same pitch in forward and in reverse. This is a techno­logical and functional leap forward in the development of sailboat propellers. Gain the folding propeller’s speed advantages under sail, and the fixed propeller’s thrust capability when motoring.

3-blade Overdrive propellers

The 3-blade GORI Overdrive Folding Propeller give the helm the ability to choose the pitch and profile of the blades without the use of hydraulics or complicated mechanical devices. One propeller. Two settings. When in Overdrive there is less engine noise, less vibration, and better fuel economy. It really is that simple.

4-blade propellers

The 4-blade GORI Propeller has the lowest drag all four blade propellers. It has the same features and operates the same way as the 3-blade GORI Propeller, with the blades pivoting 180 degrees between forward and reverse, providing the same thrust in both directions.

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Yachting Monthly

• Digital edition

Folding and feathering propeller test

• Emrhys Barrell
• March 24, 2015

Which is the best folding or feathering propeller for your boat? Emrhys Barrell compares 15 props in a test of speed, thrust, drag, stopping speed and propwalk

in 2009, Yachting Monthly tester Emrhys Barrell put 15 folding and feathering props through the most comprehensive test ever Credit: Graham Snook/YM

What’s the difference between a bucket and a fixed, three-bladed propeller? Not much, if you want to slow your boat down by at least half a knot when you are sailing. That’s the conclusion of our fixed, folding and feathering propeller test – the most detailed ever conducted as far as we are aware. A fixed three-bladed prop, locked in gear, exerts as much drag as hanging a bucket over the stern.

So what is the solution if you don’t want to sacrifice precious speed? The answer is, fit one of the many folding or feathering props on the market. But which one, and what are the drawbacks?

We measured the force generated by each propeller across the engine’s rev range

We tested all the props we could get our hands on (except the Volvo, Radice and J-Prop, which turned up too late for the test), measuring top speed under power, thrust (bollard pull) ahead and astern, stopping distance, and – for the first time anywhere – we measured the side-force (propwalk) generated when you put the engine into reverse.

We also measured propwalk while running astern. It’s a lot stronger than you think

It is this vital, unwanted component that sends you swinging off to one side when you try to stop suddenly, or back-up in the marina. We then towed three typical props behind a test boat to measure their drag, and how it compares to the overall drag of a yacht under sail.

Prop drag has been an issue for sailing vessels since the propeller was invented. Early trials were carried out on English warships, using jointed shafts that could be lifted into a trunk in the hull when sailing. In the 1890s, Danish pilot boats used similar lifting shafts.

For many years, long keels reduced the drag of two-bladed props on yachts, but the advent of the fin keel and exposed shafts brought the problem back again, with the added factor of more powerful engines making three-bladed props a necessity. The need to manoeuvre precisely in tightly packed marinas and overcrowded harbours has convinced even the owners of many long-keeled yachts to fit three-bladed props.

1970s: the first folding props

Most cruising skippers simply ignored the unwanted drag and loss of speed, but in racing circles it became increasingly significant. This led to the development in the 1960s and 70s of propellers whose blades folded backwards when sailing, reducing the drag markedly. The blades flew out under centrifugal force when the engine was put into ahead or astern. The earliest folding props had blades that moved independently, but this could lead to the lower blade dropping down when sailing, so the roots of the blades were linked with geared teeth, ensuring that they opened and closed together.

At the same time, an alternative approach was developed: the feathering propeller. Here, the blades were set at right-angles to the boss, as in a conventional prop, but on swivelling hubs. When motoring, the blades swing to the ahead or astern angled position, but under sail they ‘feather’, turning parallel to the boss.

One great advantage of feathering props is that they’re suitable for the many fin-and-skeg and long-keel yachts that have a small prop aperture in the rudder, where a folding prop won’t fit.

In the earliest feathering props, the blades remain in the same orientation to the boss in ahead or astern, as with a conventional fixed blade prop. In astern the aerofoil is working backwards, giving less thrust than in ahead. Some new feathering props have blades that swing right round, so the same leading edge is presented to the water in ahead or astern.

Cut prop drag by 90-95%

Under sail, the drag of folding and feathering props is tiny compared to a standard fixed-blade unit. Feathering props create about 5-10% of a fixed prop’s drag, sometimes less, while folding props have almost zero drag. This gives a significant gain in sailing speed, between half a knot and one knot, with the greatest percentage saving at low speeds.

Inevitably, there are drawbacks. The first is expense: a folding or feathering prop costs between two and six times more than a fixed equivalent. The second issue is complication – the gearing and folding mechanisms are prone to wear and corrosion in the salty and sandy environment, leading to reduced performance, and even loss of blades in extreme circumstances.

The third problem was performance under power. The early folding and feathering props produced less thrust than an equivalent fixed prop, particularly in astern, with dire consequences if the blades fail to deploy when you need to make a crash stop.

Now, the manufacturers claim to have addressed all the issues except cost. They claim the latest generation of their products give as good a performance or better under power, and major gains in speed under sail. We put their claims to the test on two chilly days in February. To our folding and feathering props we added a fixed three-blade prop as a benchmark, and the Axiom prop, a radical new development in fixed propellers, just to see how it compared.

Pitch, diameter, number of blades and handedness all determine a propeller’s performance

To help you understand our test, we will take a quick look at propeller theory and numbers. The four main figures you will see used to describe any prop are diameter, pitch, number of blades, and rotation.

Diameter is twice the distance from the centre of the boss to the tip of the blade. As a rule of thumb, the more powerful your engine, the bigger the diameter you will need.

Pitch is the measure of how far the propeller will advance in one revolution and thus how fast it will push your boat through the water for a given engine rpm (revolutions per minute). To understand pitch, imagine screwing a screw into a block of wood. The angle of the spiral thread governs how far it goes in for each turn. Similarly, the blades of a prop are set at an angle to the boss. The greater the angle, the greater the pitch. However, this is only the theoretical pitch. In practice, as water is not solid, the prop will slip to a degree and not advance so far. The amount of slip is around 30% for the props and speeds we are looking at.

Diameter and pitch are still measured in inches throughout the world – a quirk of history that would delight Henry VIII, and have Napoleon turning in his grave. But pitch can also be measured in degrees, especially relevant with feathering props whose blade angle can be varied.

The number of blades will vary between two, three or four, or even five in some high-speed craft. In practice, more blades will take greater power for a given diameter. For many years sailing boats used two-bladed props as they gave least drag in a boat with a full-length keel and an aperture for the prop, provided it could be locked in the vertical position. Today, most fixed props have three blades. Folding or feathering props have either two for cheapness, or three for higher power.

The hand of the propeller is the direction of rotation in ahead, when you are looking from astern. A right hand prop is one that turns clockwise in ahead.

Blade Area Ratio (BAR), sometimes called Disc Area Ratio, (DAR) is the area of the blades as a percentage of the area of a circle the same diameter as the prop. A prop with a greater BAR will take more power, but have more drag. Figures for sailing boat props are around 60%.

Incidentally, the explanation that a propeller advances just because its blades are angled forward is a convenient way to imagine what is happening, but not strictly correct. The blades of a standard prop are in fact aerofoil in section, like the wing of a plane, and move the boat forwards because as they spin round they develop lift. This lift is caused by a reduction in pressure on the back of the blade (‘back’ being confusingly the blade’s forward face). The faster they go, the greater the reduction in pressure. Once a certain point is reached, the reduction in pressure causes the water next to the blade to vapourise, and form bubbles. This is called cavitation, and limits the amount of power that a given area of blade can cope with. Also, as the bubbles collapse, they erode the metal of the prop, resulting in surface pitting on the back of the blade.

Our test boat was a Beneteau Oceanis 323 with a shaft-mounted fixed three-blade prop

We used a Bénéteau Oceanis 323, kindly leant to us by Sailtime in Lymington. She has a typical fin keel form, but atypically she has a built-in skeg carrying the shaft, rather than the P-bracket or saildrive of most other modern yachts. The skeg protects the shaft and prop from underwater damage, but a downside is increased vibration as the blades of the prop pass through the disturbed waterflow behind the skeg. This is resolved in normal use by fitting a three-bladed prop as standard rather than two, but otherwise did not alter the propulsive element of our test for either two- or three-bladed units.

The engine was a Yanmar YM20, giving 21hp at a maximum 3600rpm. The gearbox ratio is 2.6:1 in ahead, but somewhat confusingly a higher ratio of 3:1 in reverse. This is a very common engine/gearbox combination, so not an unreasonable test. Yanmar says it gives better thrust in astern, but in practice it meant the folding props were forced to use a compromise pitch. Some of the feathering props were able to set a different astern pitch.

We measured the force generated by the engine when running astern

We measured thrust, or ‘bollard pull’, in ahead and astern, throughout the rev range, using a load-cell borrowed from Diverse Yachts, with a remote read-out.

We then measured the side-thrust at full power in astern. This enabled us to predict the prop-walk created when you go into astern. To put this figure into context, the thrust produced by the worst prop in our test is the same as a 3hp outboard mounted on the transom, driving at right-angles at full throttle. No wonder so many yachts veer off to one side!

On the water, we measured speed through the rev range to maximum. We then carried out a crash stop from 6 knots. We recorded the time it took to bring the boat to rest at full throttle from the moment we engaged reverse gear.

To put these times into context, the distance the boat would travel before stopping would be 12m (39ft) with the best prop tested, but 17.4m (57ft) with the worst.

To measure the drag of all 18 propellers precisely enough to compare them with one another, making allowances for different yacht hull forms, we would have had to build a sophisticated testing rig, hire a team of scientists and spend several days in a research laboratory with a very large towing tank. Our objective was just to demonstrate the difference in drag caused by different types of propeller.

We tested the drag of three types of propeller using this test rig

We fitted a fixed prop, then a folding one, then a feathering one, to an outboard motor leg mounted on the transom of a lightweight 14ft skiff. We then towed the skiff at speeds up to 7 knots, and measured the difference in drag. We don’t claim this gave us the last degree of accuracy, but it was sufficient to compare with published drag figures. We then compared this drag to the hull-only drag of the Océanis 323 – a typical 10m cruising yacht.

A question of some gravity, Mr Newton

To keep things simple, we have presented our drag and thrust figures in kilograms (kg). Strictly speaking, thrust is a force and should be measured in Newtons – 1kg is multiplied by the acceleration due to gravity to give a figure of 9.81N. On another planet, with different gravity, our units would be wrong, but until we hear they are holding regattas on the canals of Mars, we will rest our case.

The results

Featherstream three-blade

Made in England at the time of writing (2009), this is a three-blade feathering unit with a bronze boss, and stainless steel blades. The pitch of the blades can be adjusted externally, and can be different for ahead and astern. The blades swivel 180º to present the same leading edge in ahead and astern. As a result, it performed well in astern: second best for bollard pull and third for stopping distance. However, occasionally it would not open in astern, and you had to learn to snap the throttle hard to get it to deploy.

Max Prop three-blade

Designed by Massimiliano Bianchi in 1976, the Max Prop was one of the first of the new generation of props. Boss and blades are bronze, and the pitch can be set as you assemble it, or by the factory if you want a different astern pitch. The blades swivel 180º to present the same leading edge in ahead and astern. It gave the best astern thrust, and was in the middle of the pack for stopping distance. It never missed a beat going into astern.

Max Prop two-blade

A two-blade version of the Max prop. As expected, it gave some vibration on our test boat, but this would not occur on a yacht with a P-bracket or saildrive. Mid-range performance for astern thrust and stopping distance.

Kiwi Prop three-blade

Designed in New Zealand in 2000, this is only available as a three-blade unit. The boss is stainless steel, and the blades are glass-reinforced Zytel plastic. Each blade has two different aerofoil sections, as you move out from the boss. It has no internal gears, so each blade feathers independently according to the waterflow over it. The blades do not swing completely round in reverse, so the trailing edge becomes the leading edge. It was one of the simplest to fit – just slide it on and tighten the nut. Mid-range for astern thrust and stopping distance, but the lowest top speed. It also went easily into astern.

Brunton’s Autoprop

Brunton’s Autoprop marked a completely different approach to feathering props when it was brought out in 1987. The three blades are linked together, going from fully feathered while sailing, or in neutral, to fully twisted under power. The difference is that when you go into gear, the amount they rotate depends on engine speed and loading. Thus the ahead or astern pitch varies according to engine rpm, which, Brunton claims, improves performance and fuel economy, with reduced rpm for a given cruising speed. We can confirm the latter: our tests show the Autoprop achieved 6 knots at 2,100rpm, compared to 2,500rpm for our standard prop and most of the others on test. However, previous drag tests have shown that this is achieved at the expense of slightly more drag than other feathering props, though still 80% less than a fixed prop. Bollard pulls were on the low side, but it still achieved near the maximum top speed, with mid-range stopping distance.

Autostream three-blade

From Australia comes the Autostream, a three-bladed feathering unit that has been in production for 20 years. Construction is all-stainless steel, with the blades swivelling 180º to give the same leading edge in astern as ahead. Separate ahead and astern pitch can be adjusted by the owner without dismantling the prop. It has been designed to stay feathered at speeds up to 25 knots, helped by extra blade area aft, making it suitable for fast multihulls. On test, it gave the fastest stopping time of all the folding or feathering units, plus significantly lower side-thrust than the rest, while still maintaining good ahead speed.

Variprofile three-blade

This is a three-blade feathering prop, made in Germany. The blades swivel 180º to give the same leading edge in astern, and the pitch can be set differently for ahead and astern. Usually, this is set in advance for the customer, but can be altered on site. Blades and boss are bronze, with stainless pins, and an anode aft of the nut. Ahead thrust was low, but stopping distance was good.

Flexofold three-blade

Made in Denmark at the time of writing (2009), the Flexofold is an all-bronze folding unit, with stainless steel pins, and the anode cleverly enclosed by the blades. On test, it gave the equal highest forward thrust of all props, and highest top speed. It also had one of the lowest side-thrusts. Astern performance was the best of the folding props. At a cruising speed of 6 knots, the engine was turning at 2,300rpm, compared to the 2,500rpm of our standard fixed prop and most of the others on test.

Flexofold two-blade

A two-blade version of the Flexofold, its performance was only slightly down on the three-blade, and in fact better for astern thrust. Again, it had some vibration due to the skeg. A racing two-blade version is also available.

Gori three-blade

Another of the earliest folding designs, the Gori has been made in Denmark since 1975, in two and three-blade versions, but the company only recommended the three-blade for this boat. They also make a racing two-blade version, with reduced drag. The blades have a three-way gearing system for opening and closing. Boss and blades are bronze, with stainless steel pins. A speciality is its overdrive feature, which sets the blades in a coarser pitch if you open the throttle gradually while the boat has forward way on, which allows you to cruise or motorsail at lower rpm for more comfort. Performance ahead and astern were towards the bottom of our list, with the longest stopping distance, but the prop-walk was third best.

Slipstream three-blade

From the same Australian company as the Autostream comes the Slipstream folding prop. Again the boss and blades are stainless steel, which gives greater strength, allows thinner section blades, and removes the need for an anode. The bearings are bronze bushes, while the blade gears are bevelled, with two rows each, claimed to better chew up any barnacles that might chose to grow on them. Polyethylene side thrust washers further improve the opening action. On test it performed in the middle of the folding props, though with comfortable low cruising revs of 2,250rpm at 6 knots.

Slipstream two-blade

Similar in design to the three-blade version, though with slightly worse astern figures, but it still made 6 knots at a low cruising rpm of 2,350.

Varifold two-blade

Made in the UK, this is mid-way between a racing and cruising prop, with the blades closing tightly for low drag, but still having enough shape to give good motoring performance. As a result of its close fit, you have to give the engine a burst of throttle to get the blades to open initially. It has a bronze boss and blades, and stainless steel pins. It gave equal highest top speed, but was near the bottom of astern performance.

Axiom three-blade

Axiom fixed three-blade

The Axiom is the joker in our pack. It is not a folding propeller, but it does have a revolutionary blade profile and section, if you will pardon the pun, and has never been tested on a yacht before, so we just had to put it into our trials to see how it compared. As the photograph shows, the blade profile is rectangular, while the blade section is almost S-shaped, and symmetrical in ahead and astern, with no twist. Its designers claim it gives greater thrust and stopping power, together with lower wash. So how did it stand up? Well the charts show the story, with its stopping time nearly a second better than any other model, and its side thrust again the lowest by far. However this was at the expense of lower top speed, which suggests some more tweaking is needed, but it is still one to watch.

Drag curves

Drag v speed

In the graph above, you can see that at 5 knots, a fixed three-blade prop with its shaft locked creates almost half as much drag as the entire hull. The drag can be halved by allowing the prop to spin, but the gearbox may suffer. By contrast, the drag of a feathering prop is negligible, and the drag of a folding prop is too small to plot on a graph of this scale.

The hull resistance curve for the Océanis 323 was calculated for YM by the Wolfson Unit, at the University of Southampton, using data from the Delft University Systematic Series. The propeller drag curves are based on data from SSPA Maritime Consulting, using Volvo S-drives. This data were verified by YM’s on-the-water drag test.

All but three of the propellers on test produced less prop walk than the standard fixed prop. The fixed Axiom and feathering Autostream were the best performers, but nearly all the folding props fared better than the rest of the feathering propellers.

Maximum speed

There was more than half a knot of difference between the best-performing props and the worst. Four folding propellers and one feathering prop managed to prove the claim of better performance than a standard fixed prop, but nine of them fell slightly short.

Interestingly, some of the best performers were two-bladed props, which are widely assumed to perform worse than three-blade versions.

Bollard pull ahead

The fastest props are generally also the most powerful in ahead, and most of the slower ones are among the least powerful. However, only one unit – the three-bladed Flexofold – generated a greater bollard pull than the standard fixed prop. The most powerful props produce almost a third more thrust than some of their rivals.

Bollard pull astern

Three propellers produced a more powerful bollard pull than the standard fixed prop in astern: two folding units and the newly designed Axiom. Nearly all the feathering props performed better in astern than the folding ones – some by a very wide margin. There’s a huge difference between the best and worst-performing props – the three-blade Max Prop has almost twice the bollard pull of the two-blade Varifold.

Stopping time

The new-concept Axiom prop excelled in this test, but nearly all the feathering props were better at bringing the boat to a standstill than the standard prop. The folding props were less effective and some of them were less than 100% reliable when called upon to perform an emergency stop. The difference between the best and worst stoppers was about 3½ seconds. It may not sound like much, but in a crunch, it could make all the difference.

If you want to add up to a knot to your boat speed, then fitting a folding or feathering propeller is a must, not just for racing boats. And as our test demonstrates, you can usually still retain the handling and performance under power that you had with a standard fixed-blade prop. In fact, often you’ll get better performance.

Five of the tested props gave more speed than the standard prop, with four of them being folding models, and both Flexofolds coming out top. And even though it was only 0.15 knots better, when you look at the hull resistance curve this is a considerable improvement. On the other hand, with astern performance, in general it was the feathering props that came out best, with better bollard pull than the standard, and better stopping times, and the Autostream coming out top. The folding props were generally not as good as the standard, though in the main only by no more than 10%.

But it was the prop-walk figures that proved the most interesting. Ten of our test units gave less prop-walk, with generally the folders coming out best, but the top units being the Axiom and Autostream, with 30% less side-thrust than the standard fixed three-blade, a considerable advantage when you have to stop suddenly or back-up in a marina.

In terms of resistance, our test shows that letting your fixed-blade prop spin, if the gearbox manufacturer will allow it, halves the drag. But to get the real improvement, fitting a folding prop will give at least 95% less drag than a locked, fixed propeller, while a feathering unit will give at least 92% of the drag – still an enormous saving.

But these benefits do have a price, literally on your wallet. A 16in fixed three-blade propeller will cost around £300 (2009 prices in UK). But the cheapest two-blade folding prop will be at least double this price, with most of them between £600-900. For a three-bladed folding unit expect to pay between £1,200 and £1,600. Feathering props are even more expensive, starting at around £1,200 for a two-blade model, rising to £2,100 for the most expensive three-blade version.

Because of the wide variation in cost, performance and specifications of the all the units tested, we have not felt it appropriate to recommend a best buy. The tables and curves give you the information you need at a glance, allowing you to make your own decisions as to which is best for you and your boat.

Some are easy to fit, others difficult. Professional installation is advised for such an important – and expensive – bit of kit

Some of the props on test are very simple to install, others are very complicated. However, while they all have instructions for DIY fitting, unless you’re very confident in your own skills, a piece of equipment as vital as a propeller ought to be professionally installed, both for safety and peace of mind. For our test, we had every prop fitted by the manufacturer’s representative, so there was no question about the installation, and they also observed all our measurements.

Bronze has been the material of choice for propellers almost since they were invented. Strong, resistant to salt-water corrosion, it is also easy to cast, with a low melting point, as our ancestors found out 4,000 years ago. Stainless steel has been making an appearance recently. Even stronger, it allows thinner and so more efficient blades. It is even more corrosion resistant, and also harder, so less vulnerable to impact damage. However, it has a much higher melting point, so it is more difficult and expensive to cast and machine.

Maintenance

A folding or feathering prop will need more maintenance than a fixed prop

Whatever prop you have, it should be checked every time the boat is lifted, for wear, corrosion and movement. Folding and feathering props do require more maintenance than fixed ones. Some bosses are packed with grease, which should be repacked annually. Some have nylon shims or bearings, which should be checked, especially in silted waters. Most have an anode, which should be checked and replaced if necessary.

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Choosing the Proper Sailboat Prop

• By David Schmidt
• Updated: July 21, 2021

As sailors, it’s romantic to think that our locomotion comes from the wind, but most skippers, when pressed, admit to motoring a fair portion of the time. Like it or not, your boat’s propeller is a key element of the propulsion system, and just as there are myriad considerations involved when ordering sails, decisions abound when selecting the prop that best suits your wallet and sailing plans.

Fixed-Blade Options

As the moniker implies, fixed-blade propellers are typically cast out of an alloy such as manganese bronze or nickel, bronze and aluminum. Individual propeller blades stem from a central hub, which in turn attaches to the sailboat’s prop shaft or saildrive. Depending on the manufacturer, these blades typically are pitched in a way that propels the boat forward or backward when the transmission is engaged. The term “pitch” refers to how far forward or reverse a propeller will theoretically travel through a solid material (picture a screw twisting into a wood block). For example, a prop with a 12-inch pitch will theoretically move through 1 foot of solid material with each full rotation.

Sailors have choices available when buying a fixed-blade propeller, with the biggest variables being the ­diameter, the number of propeller blades, and the pitch. Just as sailboats create “dirty air” that spills off their sails, propeller blades push water against the hull, which then reverberates back (call this “dirty water”). When the transmission is in forward, this dirty water is sent back toward the rudder, which can influence steering. An important rule of thumb for all propeller designs and types is to ensure that the propeller has a tip clearance (the amount of space between a blade’s tip and the hull when the blade is in the 12 o’clock position) that’s at least 10 percent of the length of the prop blade (hub to tip). If you don’t have enough tip clearance, the next step is to spec a smaller-diameter propeller with an extra blade. Fixed props are available with two, three or four blades.

While this can be an easy fix, additional blades create additional drag when the boat is sailing. Because of this, sailors who opt for a fixed-blade prop are typically best served choosing a screw with the fewest number of blades that can properly fit their boat and their engine (see “Choosing Screws,” right). That said, additional blades equate to more power when motoring into a stiff headwind, current or big seas. Additional propeller blades can also accommodate a more powerful engine at a given diameter. These latter points are important if you’re planning on cruising unfamiliar waters and might find yourself negotiating a lee shore under power.

While fixed-blade ­propellers are strong, simple, relatively inexpensive, and ­easier to have repaired in remote locales, they do affect sailing performance. Moreover, they’re more likely to foul a lobster pot or other fishing gear than a folding prop when the boat is sailing. If you care about sailing performance, especially in the light stuff, or if you’re planning a long-distance cruise, purchasing a folding or feathering prop is a wise investment. But if you’re seeking maximum power or punch for your buck, and you sail on breezy waters such as San Francisco Bay, where extra drag isn’t a huge concern, a fixed-blade prop could be the way to go.

Folding Propellers

Folding propellers employ a series of gears (situated around the prop’s central hub and on the inboard end of each prop blade) and centrifugal force to open when the engine’s transmission is engaged. The slipstream action of the passing water acts to fold them closed when sailing, and their gear mechanisms hold the blades in their closed position even in light airs. As with fixed-blade props, sailors can choose between models that feature two, three or four blades. Unlike fixed-blade props, however, folding propellers create far less drag when the boat is sailing.

“For the same diameter and number of blades, folding propellers have 85 to 100 percent less drag than a fixed prop, depending on the fixed propeller’s blade area and the folding propeller’s make and model,” says Geoff Prior, owner of AB Marine, the Newport, Rhode Island-based importer and distributor for Gori folding props and AutoProp, Variprofile, and Variprop feathering propellers. “Geared folding propellers stay closed or folded when the boat is sailing, so a blade cannot drop down to be exposed to the water flow, and does not catch lines and weeds like fixed and feathering propellers can.”

Others agree. “Most sailboats will gain 0.5 to even 1 knot of speed by using a low-drag folding propeller,” says Keld Willberg, Flexofold’s general manager. “Many boat owners don’t look just at the speed gains, but also the ability to sail in very light wind.” Also, he says, when tacking, a boat that’s equipped with a low-drag prop won’t lose as much momentum.

This latter point is critical to anyone who sails in places with typically light breeze. “The folding propeller’s drag reduction and increased sailing speeds produce less turbulence over the rudder, enabling you to point higher, steer easier and more precisely, and tack and jibe the boat easier,” Prior says. “The biggest speed difference is in light or medium air and with clean water flow over the rudder—the boat is a lot more responsive, especially when fine sailing on the wind.”

One important consideration when selecting a folding prop is ensuring that your boat can physically accommodate the length of the prop when it’s folded. This is especially important on full-keel boats that have an aperture between the keel and rudder. For anyone who cruises with a saildrive(s), Prior advises that saildrive propellers must be approved for use by the saildrive’s manufacturer to ensure that the prop is electrically isolated from the saildrive’s leg and shaft; also the prop’s hub must incorporate a rubberized bushing to absorb shock and inertia, as well as an easily changed and ­streamlined anode.

As with all props, ­selecting the diameter, number of blades, and pitch of the propeller are all key decisions. “Diameter is the single most critical factor in determining the amount of power that a propeller absorbs and transmits into the water,” Prior says. “It’s the most important single factor in determining the amount of thrust delivered. The larger the diameter, the greater the efficiency. A small increase in diameter dramatically increases thrust and torque load on the engine and shaft.”

Blade count is also critical, but Willberg cautions that it’s overly simplistic to think that additional blades equate to additional power (see “Calling the Pitch,” right). “What ­matters is to get the right combination of blade area and pitch for the engine and gear box,” he says. “On flat water, a two-blade propeller can be just as efficient or even slightly better than a three-blade. However, when motoring against wind and waves, and when maneuvering, you get more power from a ­three-blade prop.”

Blade shape also matters. “Propellers with flat, planar blades are like a paddle,” Prior says. “The flat shape is not ­efficient at producing thrust because a flat blade is overloaded at the tip and underloaded at the blade base, whereas a fully shaped airfoil blade shape has a constant loading over its whole surface.” Much like fixed-blade props, most folding propellers employ an efficient blade shape, while feathering props use flatter and more ­planar-shaped blades.

One drawback of most (but not all) folding props emerges when the transmission is put into reverse. “In reverse, the suction side is on the back or aft side of a blade, and with the typical folding propeller design, the blades are trying to close in reverse, giving low thrust and lots of prop walk,” says Prior, who added that Gori’s three-blade prop presents identical leading-blade edges in both forward and reverse, negating this issue. Willberg advises that folding props require slightly different operation than fixed-blade or feathering props to ensure that they stay open. “For more stopping and reverse power, it’s just a matter of giving more revs on the throttle,” he says.

RELATED: Understanding Your Sailboat Propellers

As with all props, folding propellers must be kept clean of marine growth, and anodes must be regularly changed to ensure cathodic protection. “One millimeter of growth on a blade and your propeller loses approximately 12 percent efficiency,” Prior says, adding that this applies to any make, model or design. And, he notes, “folding propellers are water-lubricated, so they do not need to be greased.”

The final consideration is cost. Folding props are roughly four to six times more expensive than a fixed-blade propeller for a given diameter and blade count. While this is a big difference, the gains are huge, and—for bluewater cruisers—can translate to ­significantly faster passage times (potentially measured in days) and happier crews.

Feathering Propellers

As do folding propellers, feathering props greatly reduce drag when the boat is sailing; however, the way that they achieve this gain is significantly different. Moreover, the physics behind how the prop transitions from its sailing mode to motoring mode is also different.

Feathering props are available with two-, three-, four- and five-blade configurations. A central hub attaches to the prop shaft or a saildrive, and it features a series of internal beveled gears. Geared propeller blades attach to the hub and rotate through 180 degrees, depending on if the transmission is in forward or reverse (more on this later); this articulation is governed by machined stops inside the hub that prevent the blades from overrotating. When the transmission is engaged, the blades present their broad sides to the slipstream, but when the boat is under sail, the blades rotate 90 degrees to align with the flow of the water.

“Feathering props work off torque from the shaft or saildrive,” says Fred Hutchison, at PYI, which distributes Max-Prop feathering propellers. Because feathering props use torque—not centrifugal force—to open, it’s “instantaneous,” says Hutchison, who points to this as the design’s biggest advantage. “It takes a feathering prop only three-quarters of a turn to go from full forward to full reverse. In that time, the blades rotate 180 degrees, and it doesn’t generate much shock load.”

Prior adds, “In the sailing position, the water flow turns the blades to the feathered position when the engine is off for vastly reduced drag.” He estimates that this drag reduction is approximately 85 percent compared with fixed-blade props.

As previously mentioned, feathering-prop blades rotate through 180 degrees, which is a big advantage when operating in reverse compared with most folding props. “A feathering propeller gives reverse thrust with the same efficiency as in forward, as the leading blade edge in forward is turned 180 degrees, and without prop walk,” Prior says.

Another advantage of feathering props for boats with full keels or with tightly spaced skegs or rudders is that they “can fit in a small aperture as they have shorter overall lengths compared to folding propellers, which have a greater length when folded,” Prior says. “If there is a diameter constraint, the feathering prop can easily be designed and built with a higher pitch to make up for the loss of diameter and blade area.”

Most feathering props are machined out of a nickel, bronze and aluminum alloy, which, Hutchison says, makes them easy to repair. Unlike fixed or folding ­propellers, feathering propellers employ flat-shaped blades to reduce drag when the boat is sailing. “Feathering propeller blades are foiled and aren’t as efficient as the helical twist found on most fixed-blade or folding props,” Hutchison says, adding that manufacturers compensate for this less-efficient shape by increasing each blade’s surface area. “Blade surface area and shape make a big difference in how efficient it is,” he says. “No low-drag prop will be as efficient under power as a fixed-blade propeller.”

Lobster pots and fishing nets are common concerns when operating under auxiliary power, and feathering props are not snag-proof. “When motoring, feathering props are the same as fixed-blade and folding propellers,” Hutchison advises. “But when sailing, a folding propeller has less of a chance of catching a pot or fishing net than a fixed-blade or feathering propeller.” This is a consideration for anyone who cruises extensively in, say, Maine or in heavily fished waters off the West Coast.

As with all propellers, feathering props require basic care and maintenance to ensure their efficiency and the engine’s longevity. This starts with a properly spec’d and regularly refreshed anode, and the prop blades must be kept clean.

Unlike folding props, which typically use exposed self-­lubricating gears, the internal gears of feathering propellers need to be greased annually. While this adds an item to an owner’s yearly to-do list, Hutchison says that this can be tackled by a diver.

Finally, while feathering props are a great upgrade, they don’t come cheap. “Feathering props are more expensive than folding props,” says Hutchison, who ­advises that a feathering prop is roughly 10 to 15 percent more ­expensive than a folding prop with the same blade count and a ­comparable diameter. “This is primarily because of ­machining costs,” he says.

David Schmidt is CW ’s electronics editor and also writes about topics ranging from sailing gear to environmental issues from his home in Bellingham, Washington.

Choosing Screws

Choosing the right propeller is complex, but the most important variables for selecting the correct prop are your boat’s make, model, LOA and displacement, the engine’s horsepower rating and its maximum rpm, as well as the transmission’s reduction ratio. While most of this information is easily ascertained, determining the reduction ratio can be challenging. But, Prior says, “the best method to get the actual ratio is to use your cellphone camera and take a photo of the plate on the transmission,” adding that this beats hanging upside down and trying to read this information using a mirror and flashlight. For the DIYer, online calculators exist that can help crunch the numbers. “After that, it gets into the art,” Hutchison says. His advice: Ask an expert.

Calling the Pitch

Unlike fixed-blade propellers, feathering and folding propellers are often designed so that the pitch can be adjusted, perchance it doesn’t perfectly match your vessel, engine and transmission right out of the box. Depending on the prop, this adjustment is typically made by changing a screw(s) or swapping out the prop blades. These adjustments can usually be done by a diver while the boat is in the water. Some general rules of thumb as to when to change the pitch involve engine rpm: If the prop doesn’t meet the engine’s ideal rpm, the blade’s angle needs to be reduced; conversely, if the prop is exceeding the engine’s rpm metrics, the blade’s angle of attack needs to be increased. As a cautionary note, overpitching a propeller can cause the engine to overheat, and it can also lead to injector-choking problems and create excessive internal engine pressure, so be sure to stay within the engine ­manufacturer’s lines.

Vendor Information

EWOL: ewoltech.com , 410-317-8104; from $2,120

Flexofold: flexofold.com , 781-797-0809; from $980

GORI: gori-propeller.com , 401-847-7960; from $650

J Prop: betamarinenc.com , 252-249-2473; from $2,500

Kiwiprop: kiwiprops.co.nz , 877-549-4872; from $1,350

Max-Prop: pyiinc.com , 425-355-3669; from $1,900

Michigan Wheel: ­ miwheel.com , 800-369-4335; from $550

Variprofile: spw-gmbh.de , 401-847-7960; from $800

Variprop: spw-gmbh.de , 401-847-7960; from $1,200

Volvo: volvopenta.us , 800-522-1959; call for pricing

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Varifold Folding Sailboat Propeller

Varifold folding propellers have taken the market by storm. Regularly fitted by such notable yacht building names as Baltic, Swan, Leopard Catamarans, Moody and Oyster. The Varifold range of folding sailboat propellers has a model for larger cruiser and racing yachts in 3 blade folding propeller and a 4 blade folding propeller options. Varifold is revolutionary in design and brings a revolution to the yachts they are fitted to. Radical reductions in noise and vibration and excellent performance under engine, both ahead and astern, are the result of the propellers unique design.

Varifolds have proper helical pitch distribution, including pitch reduction towards the blade tip. This pitch reduction ‘unloads’ the blade tips and, combined with the skewed blades, greatly reduces noisy pressure pulses against a yachts hull. While some other folding propellers have a helical pitch shape, few have proper sections or pitch distribution. None, put all these requirements into a complete package, except Varifold .

Why Choose Varifold Folding Sailboat Propellers?

There are many choices when choosing a sailboat propeller. There are three main types to choose from: fixed, folding and feathering. The fixed propeller provides the best propulsive solution but has significant drag when locked-off under sail. The drag can be as much as a knot of lost speed. The feathering propeller is great to use in an aperture and has low drag when not in use, but the flat paddle like blades are significantly less efficient than a fixed pitch propeller and prone to noise and vibration when in use. The folding propeller offers all of the advantages of a fixed pitch propeller with none of the drawbacks. Check out our page on the design of folding sailboat propellers to learn more!

The Varifold model range is extensive. There is a propeller available to fit most yachts with engines rated up to 1000 HP. Versions specifically designed for saildrives are also available. Fore the larger sailboats over 100 ft in length Varifold folding sailboat propellers dominate the market as few manufacturers are able to design and manufacture a folding propeller able to deliver the required thrust efficiently, quietly and without vibration while remaining structurally sound. Details of the Varifold sailboat folding propeller are below and further information can be found in our brochure.

Service & Support

Whether it is for your yearly service or a little maintenance, getting parts for Varifold propellers is easy. King Propulsion carries all of the spare parts in stock at our Virginia Beach office. So if you are replacing buffer pads, pivot pins, zincs or fasteners we have the right Bruntons parts for the job.   Visit our online store where you can order parts 24 hours a day from anywhere in the world.  We ship USPS, FedEx and UPS as standard from Virginia Beach with most parts shipping same day when ordered before 4:00 PM EST.

Find out how Varifold folding sailboat propellers can benefit your sailboat by requesting a hassle free no obligation Varifold Propeller Quote . Simply click on the link below and enter the details of your sailboat such as boat type , engine, gearbox ratio and so on in our online web form and we will conduct a power prediction for your vessel to size the right Varifold propeller for you and give you a competitive quote.

8142 South March Point Rd. Anacortes, Wa 98221 1.866.790.7767 360.299.8266

Sailboat Propellers

AutoProp Feathering Propeller

The Autoprop’s reversing blades swing through 180 degrees and produce the same thrust as in forwards. When sailing the blades feather automatically, reducing drag by up to 85%.

Hung Shen HTP3

The Hung Shen Heavy Thrust Propeller series 3 Blade propeller is especially suited for use on displacement vessels such as sailboats, fishing & work boats.

Volvo Penta Folding Propeller

The Volvo Penta 2-blade folding propeller is an excellent choice for most boats.

Volvo Penta Saildrive Propeller

Volvo Penta S Drive Aluminum Propellers for Volvo Penta and Yanmar Saildrive Engines. Available in 2 or 3 blade configurations.

VariProp Propeller

Variprop is the finest automatically feathering propeller available in the world today.

Slipstream Propeller

Geared design keeps blades synchronized, allowing the blades to fold back properly regardless of the propeller position, even at low speeds – No crawling into the bilge to position the shaft when racing.

Michigan Sailor Propeller

The Michigan Sailer 2 blade fixed pitch propeller is the popular choice for sailboaters seeking to maximize sailing speed.

With the increased popularity of the cruising vessel, Max-Prop introduced its three blade classic model in the early 80’s.

Hung Shen TP Propeller

The Hung Shen SSBP is suitable for Yachts which have wider stern.

Gori Propeller

First off, you will see an increase in sailing speeds over a fixed 3-blade propeller.

Flexofold Propeller

The Flexofold Folding Sailboat Propeller is the most efficient, lowest drag propeller you can buy.

Autostream Propeller

The Autostream self-feathering propeller has evolved through 8 models, over more than thirty years.

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Gori Propellers

Gori Folding propellers are very high quality - thoroughly tested by thousands of sailors all over the world - for cruising as well as racing. Available in sizes from 11" to 20" diameter for shaft as well as saildrive installation. The 3-blade Gori folding propeller "overdrive" function adds a new dimension to sailing under power. The "overdrive" gives the same speed at lower rpms. The result is less engine noise, less vibration and better fuel economy. If you do not see what you are looking for, or are not sure what you need, please call us at 866-790-7767 or email us at [email protected]

Gori 2 Blade Sailboat Propeller 11.5 X 08

11.5 X 08 Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diameters 3/..

Gori 2 Blade Sailboat Propeller 11.5 X 9.5

11.5 RH 9.5 Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diamet..

Gori 2 Blade Sailboat Propeller 12.5 RH 08

12.5 RH 08 Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diamete..

Gori 2 Blade Sailboat Propeller 13" X 09

13" X 09 Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diameters 3/4..

Gori 2 Blade Sailboat Propeller 14" X 9.5

14" X 9.5 Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diameters 3/..

Gori 2 Blade Sailboat Propeller 15"

15" Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diameters 3/4" thr..

Gori 2 Blade Sailboat Propeller 16.5"

16.5" Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diameters thru 1..

Gori 2 Blade Sailboat Propeller 18"

18" Gori 2 Blade folding Propeller fits Volvo & Yanmar Saildrives & Shaft diameters thru 1 3..

Gori 3 Blade Sailboat Propeller 15"

Gori Folding Propeller for Volvo Penta and Yanmar and Shaft drives SAE and Metric.The Gori folding p..

Gori 3 Blade Sailboat Propeller 16.5"

Gori Folding Propeller fits Volvo Penta, Yanmar and Shaft drive SAE or Metric applications.The Gori ..

Gori 3 Blade Sailboat Propeller 18"

Gori Folding Propeller for Volvo Penta, Yanmar and Shaft drive applications SAE or Metric.The 3-blad..

Gori 3 Blade Sailboat Propeller 20"

Gori Folding Propeller for Volvo Penta, Yanmar and Shaft Drive applications - SAE or Metric.The 3-bl..

Gori Propeller 2 Blade Racing 375mm

Gori Folding Sailboat Propeller - 375mm (14.7" diameter) RH 260mm (10.2 pitch) Racing Propeller.Gori..

Gori Propeller 2 Blade Racing 380mm

Gori Folding Sailboat Propeller - 380mm (14.9" diameter) LH 265mm (10.4 pitch) Racing Propeller.Gori..

Gori Propeller 2 Blade Racing 425mm

Gori Folding Propeller 425mm (16.7" diameter) X 300mm (11.8 pitch) Gori Racing Propeller.Gori Prop 2..

Gori Propeller 2 Blade Racing 450mm

Gori Folding Propellers - 450mm (17.7" diameter) X 330mm (12.9 pitch) Gori Racing Propeller.Gori Pro..

Gori Propeller 2 Blade Racing 475mm

Gori Racing Propellers - 475mm (18.7" diameter) X 330mm (12.9 pitch) Gori Folding Propellers.Gori Pr..

Gori Propeller 2 Blade Racing 530mm

Gori Racing Sailboat Propellers - 530mm (20.8" diameter) X 375mm (14.7 pitch) Gori Prop.Gori Prop 2 ..

7 Best Sailboat Propellers

Last Updated by

Daniel Wade

June 15, 2022

If you own a boat, it's very likely that it has a propeller that you can use when you don't want to jib, tack, or hoist the sails. As such, having the right propeller for your sailboat that is extremely efficient under power, while not slowing you down under sail is important. This is why you have to choose the best sailboat propeller for your vessel.

Having the right sailboat propeller that properly fits your boat is one of the most essential things if you want to get the most out of your vessel. When it comes to boat propellers, there's no one-size-fits-all. In most cases, the factory-installed model may not be the best for your boat, so installing an after-market model would be the best way to go, especially if you want to improve your boat's acceleration and top speed.

One of the main duties of a sailboat propeller is to ensure or determine how fast your boat can go. It plays an integral role in enhancing efficiency and improving the boat's handling capabilities. So whether you're planning to set sail or just cruise around, having the best propeller for your boat is of immense importance in enhancing your boating experience.

Whether you're in the market because your boat's current propeller is damaged or you're just looking for a new propeller to improve the performance and efficiency of your boat, you've come to the right place. In this comprehensive guide, we'll help you filter through an ocean of choices and find a perfect propeller that matches the needs of your boat. At the end of this read, it should be quite easy to pick a propeller that makes and keeps your boat running and operating at peak efficiency.

Table of contents

How to Choose the Best Boat Propeller

A propeller is a crucial component of any boat. Without it, you may be forced to only rely on your sails or even row the boat manually. Even though they may all seem the same, these propellers have various features that make them different. So if you're in the market for a boat, here are how to choose the best boat propeller.

Generally, we often use our boats at sea level but there are those occasions when you may have to cruise at higher altitudes. For example, you may want to boat in a mountainous region and this means less oxygen. This means that your boat cannot produce the amount of power as it would in an oxygen-rich environment.

So if you plan to sail at an elevation, you can choose a propeller with a lower pitch as it will deliver more power.

Boat propellers are mainly made from three main materials including aluminum, stainless steel, and plastic. Stainless steel is an ideal choice if you're looking for strength, durability, and performance. In terms of aluminum, you'll get excellent performance, lighter design, and are more affordable. A propeller made from plastic is perfect for small boats but they may not offer the same durability and power as metallic propellers.

A propeller's weight can have significant effects on the performance of your boat. A heavier propeller will require less pitch and your boat's engine might not work at its full capacity. This is why it is of great importance to consider the load or weight of a propeller as well as the load that your boat will be carrying so that you can choose a prop with the right pitch and diameter. You should, therefore, buy two propellers with different pitches so that they can be used interchangeably depending on the circumstance.

Ventilation

Needless to say, a propeller will not function at full capacity without proper ventilation. If a model isn't properly ventilated, the surface air might be pushed into the blades or the propeller, thereby leading to below-par performance. This is why you should ensure that the propeller is properly installed within the lower part of the transom and should be able to work even in very harsh conditions.

When it comes to choosing the right size of a propeller, you'll have to ensure that the diameter of the prop is twice the distance from the hub center to the blade's tip. A propeller with a larger diameter can perfectly accommodate a larger engine. You should also consider the prop's pitch, which is the distance the propeller will travel in one rotation. The pitch is comparable to a car's gear and sometimes you may need low pitches for the boat to move.

Cavitation refers to a situation whereby water vaporizes because there's a lack of pressure on the prop's blades. This low pressure and vaporization can lead to terrible consequences and can lead to erosion of the material. Such issues can be caused by poor polishing, poor design, and other flaws in the blade. This is why you should go for a high-quality propeller to ensure that cavitation doesn't become an issue.

Whether you go for a three-blade or four-blade propeller, they all work great. You, however, have to keep in mind that a three-blade prop offers top performance and speed while a four-blade prop is perfect for difficult conditions, especially when speed isn't a priority. Again a four-blade prop is great in fuel efficiency but may reduce your boat's rpm.

Best Sailboat Propellers

Here are the 7 best propellers currently available in the market.

Mercury Marine Spitfire

If you've held a little interest in boat propellers, you've probably been part of the debate between three-blade and four-blade propellers. While it may be difficult to conclusively choose the best type of propeller based on the number of blades, the Mercury Marine Spitfire puts an end to this debate. This is because it offers the best of both worlds and remains one of the few propellers that are compatible with various motors.

This propeller is designed to be the ultimate prop for a wide range of outboard boats in terms of offering outstanding performance. This aluminum prop is designed with four blades and a long barrel that combine to give it an additional stern lift and lightning-fast holeshot, which is crucial in skinny-water applications. To put it into perspective, this prop can offer 25% faster acceleration and superior holding without necessarily compromising on top speed.

This is a unique boat propeller that is magnificently designed to cater to the unique demands of various boats. Whether you're using an outboard boat with 25hp or 125hp, this prop can spin up quite fast and improve your boat's acceleration thanks to its innovative designs.

• ‍ Offers aggressive blade cupping
• It is quiet as it comes with a noise-reducing hub
• Doesn't have blowouts on hard turns
• ‍ Quite expensive

Quicksilver Nemesis 4-Blade Boat Propeller

Featuring arguably the most aggressive geometry of all aluminum props, the Quicksilver Nemesis 4-blade Propeller offers the best cup in terms of acceleration, holding, and tenacity when gripping in turns. The fact that it is designed with a high-rake and reduced diameter makes it incredible if you're looking for a prop that can help your boat maintain top speed.

This is a prop that's helping rewrite the engineering rules as you get top acceleration and tenacious holding without compromising on top speed. This is great for any boat that's powered by stern drives ranging from 25HP to 250HP and will significantly augment the performance of your boat.

If you've been looking for an all-round prop, this is the best option. It will never let you down when it comes to delivering a superb holeshot, fuel efficiency, incredible control and comfort, and top speed. Better still, you don't have to break the bank to acquire one.

• ‍ Offers 3-blade speed with 4-blade performance
• A great and powerful prop for rough waters and water sports
• Offers impeccable quality and performance and a fair price
• Available in a wide range of pitches and diameters to suit different motors and needs
• ‍ Might not be ideal if you want a left-hand rotation

Turning Point Hustler Propeller

If you're in the market for a prop that incorporates in its design some of the newest and most efficient features, then the Turning Point Hustler Propeller can be a superb option. This is a high-performance 4-blade stainless steel propeller that comes with a guarantee that it will be devoid of air bubbles and any other defect that could negatively impact on its performance or that of your boat.

This prop's blade design is structured with one of the best high rake patterns, aggressive cupping, fine-tuned pitch aggression, sharp trailing edges; all to ensure that your boat achieves top speed, maximum acceleration, fuel efficiency, and top-end performance. This prop is designed to be long-lasting thanks to its five-step, powder-coated finish.

The Hustler is designed with a squeeze cast for added strength and a high flow-through barrel exhaust system to increase horsepower while offering top-end speed.

• ‍ Enhanced low consumption and fuel efficiency
• Quite affordable
• Offers improved handling
• One of the most advanced props in terms of technology
• ‍ May interfere with the boat's rpm

Young Marine OEM Grade Aluminum Outboard Boat Propeller

Whether you're on a tight budget or just looking for a quality OEM grade propeller that will offer top performance, the Young Marine OEM Grade propeller can be an ideal option. This propeller is meant for Mercury outboard engines and will cost half the price of other top brands while offering the same if not much better results in terms of quality and performance.

The Young Marine is available in a wide range of pitches and diameters. This not only makes it one of the most versatile props in the game but offers you the flexibility of going for something that perfectly and exactly suits your size and pitch needs. The fact that the diameters and pitches are the same as the original OEM propellers makes installation a lot easier while still offering top performance.

This propeller is made from the highest-quality aluminum, thereby offering an incredible combination of strength and lightness. It's perfectly suited for Mercury outboard engines and works great within a range of 25HP to 75HP.

• ‍ Affordable and offers excellent value for money
• Offers a wide range of diameters and pitches
• The 3-blade design offers improved performance
• ‍ Only works best for an engine with HP ranging from 25 to 75

MotorGuide 3-Blade Machete III Boat Propeller

Designed with 3-blade superiority, MotorGuide Machete 3 is a superb boat propeller that can be of great help if you're planning to sail over skinny water full of seaweed and other aquatic flora. Featuring a prop pint and prop nut, this is an impressive boat prop that's designed to offer efficiency and top speed.

It performs relatively well across various voltages including 12, 24, and 36 voltages. This prop is specifically designed for trolling motors and can easily outperform similar props in this category.

• ‍ Great for trolling motors
• Offers fast and efficient performance
• Works great across a wide range of volts ‍
• ‍ It's affordable
• The tapered hub design is excellent
• ‍ The blades are made of plastic and their durability is questionable

Mercury Max Black Boat Propeller

This is another Mercury propeller model that's widely known in the industry for offering top performance and speed. It's designed with several amazing features such as the combination of a small pitch and a bigger diameter to enhance its efficiency. It is also created using premium aluminum to offer a great balance between strength and lightness.

It comes with the standard 3-blade model to enhance speed and an outstanding hub system that is high-rated by users. This is one of the best-selling 3-blade propellers in the world and will deliver uncompromising performance in virtually every situation. Its geometry may seem conservative but it will never lose even the slightest bite on the water even when your boat is making the modest of turns.

• ‍ Its design is efficient
• Made of premium aluminum material
• Works great in almost any situation
• Can reach top speed in less than 50 mph
• Comes with a flo-torq hub kit
• ‍ Noticeably slower than many stainless steel boat props

Michigan Wheel MICH 3 Blade Boat Propeller

If you have a smaller boat but want a quicker and smoother cruising, the Michigan MICH can be your best bet. Featuring 19 prop pitch and a 14.5 diameter, this 3-blade prop delivers consistently great performance and can be easily customized for various types of boats.

Installing this propeller is quite easy and it will hold up well for many years to come with minimal maintenance. The blades are made of premium aluminum and are coated in black to prevent it from corroding. This can be an excellent option if you're looking for a superb prop for a small boat.

• ‍ It is corrosion-resistant ‍
• ‍ Installing it is easy
• Offers top speed and makes cruising quite smooth
• It can be customized to fit well in a wide range of boats
• ‍ Not perfect for bigger boats

To this end, we hope that you are now more informed when it comes to choosing the best propeller for your boat. Of course, a propeller is of great importance to your boat and will increase your vessel's efficiency. You certainly do not want to spoil your boating experience just because you chose a low-quality propeller and that's exactly why you should go for a prop that perfectly suits your boat.

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Racing sailboat propeller MARK III ELIPTEC folding propeller shaft 2-blade

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When contacting Flexofold you speak directly with us — the manufactures of the propellers. This is why we are able to guarantee you a propeller solution that will perfectly match your boat, engine and sailing habits.

When purchasing a   Flexofold Propeller, you will be joining a rapidly growing number of   sailboat owners   who enjoy the performance and safety benefits that our foldable propellers provide.

But don't just take our word for it, Flexofold has been chosen as the supplier for standard and optional propellers by over   60 producers of quality boats; such as Hanse, Dehler, Dragonfly, Elan, J-Boats, Malö, Najad, Sunreef, Swan, X-Yachts, and many more!

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You can order your brand new Flexofold Propeller at Flexofold. We will confirm your order for you by sending a detailed e-mail which states the price, type and size of the propeller hub and blades, as well as your payment details to make certain that everything is in order.

Flexofold propellers  are delivered all over the world directly from our factory in Vejle, Denmark. No matter where you live or where your boat is located, we ship your new propeller by UPS courier service – directly to your address at very competitive costs. In most cases, we ship your new propeller within 3-5 working days from placing the order / receiving payment. When you receive your new  Flexofold propeller , the box contains the hub, blades and all nuts and screws needed for the installation process. The screws are delivered with pre-applied Loctite® ready for installation in or out of water. A guide with step-by-step instructions and 3D drawings is included for easy installation . You can always find our step-by-step installation guides .

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