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Why Rudder Craft?

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

Why Hydrofoil?

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

Why Use a Kick-up Rudder?

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We build rudders with passion and precision since 1963.

Ships anywhere, cost effective, satisfaction guaranteed.

In the early sixties, an innovative man named Chuck Foss developed several polyurethane foam systems useful for a variety of purposes, including the production of surfboards. His new firm, The Foss Company, soon became one of the top U.S. suppliers of foam surfboard blanks, which he sold under the name of “Foss Foam.”

Later in the sixties, one of his Foss Foam systems used to make surfboard skags was found to be an excellent material for making sailboat rudders. It was not long before The Foss Company supplied rudders to most of the boat builders in Southern California through the seventies and eighties. 

The Foss Company’s former headquarters. During the eighties and nineties, the company specialized in fiberglass and foam composites. High performance sailboards and paddleboards were some of the products produced. With an extensive inventory of rudder molds, the company now specializes in supplying sailboat owners and boat repair yards with replacement rudders.

In recent years, The Foss Company has formed a strategic partnership with FinCo Fabrication, a major fiberglass manufacturing firm based in Santa Ana, California.  This partnership will assure that The Foss Company’s long tradition of quality products and service will continue for years to come.

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Start your rudder with us now (714) 973-2878 or (949)646-0244

Great old boats - cal 40's new rudder, click to open video, our manufacturing process..

Working together with you the owner we select an exciting mold or sketch out a new design for a  custom rudder. All based off years of experience and time tested best practices.

Prepping mold

Experienced Finco craftsmen begin the manufacturing process by sanding, polishing and waxing the rudder mold.

Gelcoat & first layer

After applying Gelcoat to the mold, they apply a layer of unidirectional fiberglass saturated with Vinylester™ resin.

Rudder Shaft Turned​

A new rudder shaft is turned from the same material as the original (or stronger.) After it is cut to length and tapered, the tangs are welded into place.

Shaft set & foam+

Once the fiberglass has cured, the tapered stainless steel shaft is set into the mold. After the shaft is aligned, the halves are mated, clamped and sealed, and liquid foam is poured into the mold.

Sand to Smooth

When the foam has cured, the rudder is removed and the seams sanded smooth. Most OEM rudder fabrication stops here; we go farther .

Taped and cured

Fiberglass tape is laminated to the seams. After the tape has cured and has been sanded smooth, the rudder gets a final coat of gelcoat.

Faired & prepped

In the last step, the entire rudder is faired and sanded in preparation for you to apply a coat of bottom paint.

Packed in custom box

The finished rudder is packed in a purpose-built crate suitable for shipping to you anywhere in the world.

Why Select Us?

We have many of the original molds and tooling for production boats made over the mast 60+ years in our inventory and can replace damaged rudders with the exact factory replacement. If you would like a custom rudder, we can modify or design from scratch a rudder that meets your exact needs. 

The original rudders originally were manufactured by “clam-shell” method and our exact replacements use the same tooling. Plus over the years there have been advances in glass cloth and in laminating resins making them stronger and more reliable. The closed cell foam core of the rudder remains the same, but the selective addition of unidirectional fibers has increased the strength of our rudders, and the use of Vinylester™ resins has eliminated blisters and the need for expensive barrier coats.

Newer designs to improve handling and directional control. This is most important when sailing very fast and can help prevent broaching and spin-outs. Most boats can use upgraded rudders without incurring a rating penalty. Some local PHRF boards will hit some designs with a 3 seconds-per-mile penalty so you should check with your local board before making your change.​

Get in Touch

Here for you.

Phone: (714) 973-2878 (949) 646-0244 Email: [email protected]

Foss Rudders fondued in 1963 has partnered with FinCo Fabrication, a major fiberglass manufacturing firm in Santa Ana, California. We make precision rudders for you.

Where to find us

2520 South Broadway, Santa Ana CA 92707

4 Rudder Types for Sailboats

Last Updated by

Daniel Wade

June 15, 2022

A rudder is an ancient piece of technology that people still use to steer sailboats today. Modern sailboats use many different types of rudders.

If you turn the rudder to the left, the stern will turn right, and vice versa. You can use either a steering wheel or a tiller to move the rudder. Not every type of boat has the same kind of rudder, nor should every boat - different boats need significantly different rudders.

There are several different types of rudders in common use. Sailboats use full keel rudders, spade rudders, outboard rudders, and skeg-mounted rudders, plus variations on each type. What type of rudder is best depends on the shape of the hull and the boat's size.

Table of contents

Different rudder types and their advantages

Full keel rudders.

Many sailboats have a full keel rather than a fin keel, which requires a particular type of rudder. A full keel is the standard type of keel, or flat blade at the bottom of a sailboat. A full keel is designed for stability, not speed - it can keep you safe in rough water.

A generation or two ago, nearly all cruising boats had full keels. However, this is no longer true. Many customers today prefer fin keels, which are designed with speed rather than stability in mind.

A fin keel is smaller than a full keel and shaped differently. Fin keels are more popular today because many sailors today never go far from the coast. If you are near the coast, fin keels are relatively safe.

With a full keel sailboat , the rudder appears to be part of the keel. It is attached with a hinge and looks like a continuation of the keel. There may be a hole between the keel and the rudder, where the propeller is, although not all boats use this design.

What is the advantage of a full keel rudder?

A full keel rudder is strong and protects the boat from harm. A full keel rudder helps a boat survive a storm. Any debris floating by will not snag on a full keel rudder as it will snag on some other rudders.

Do full keel rudders have any disadvantages?

It is harder to move a full rudder than to move other types of rudders. Water flowing by the boat puts a great deal of pressure on a full keel rudder and makes the rudder hard to move. It takes a lot of force to push the rudder against the water moving past the boat.

Spade rudders

Spade rudders are for fin keel boats rather than full keel boats. A spade rudder sticks straight down into the water. A spade rudder can rotate left or right with a rudder post that extends into the hull.

Advantages and disadvantages of spade rudders

The most obvious advantage of the spade rudder is that it can be part of a fin keel boat. A full keel rudder requires a full keel - you could not attach a rudder of this type to another type of boat.

It is also not nearly as difficult to turn a spade rudder as it is to turn a full keel rudder. The water does not put all of its force on one side of the rudder, so it does not take as much force to turn it.

One disadvantage is that debris floating in the water can get caught on a spade rudder. Spade rudders are more delicate than full keel rudders in many ways. Debris can damage a spade rudder.

A spade rudder can also be damaged by rough water. Large waves may exert enough pressure on a spade rudder that it will break. A large wave can bend the rudder post, and after that happens, your rudder becomes useless.

Outboard rudders

An outboard rudder is not part of the boat's hull and is mounted outside of it, at the back of the boat. Usually, an outboard rudder is not hooked up to a steering wheel.

Instead, it is hooked up to a tiller, which is a steering lever. A tiller can take a bit of getting used to if you are used to a steering wheel, but a tiller is not hard to use. Many sailors prefer a tiller, especially for smaller boats.

Advantages and disadvantages of outboard rudders

If an outboard rudder is damaged, it is not likely to damage the rest of the boat. Since there is no rudder post running through the hull, damage to the rudder usually won't mean damage to anything else as well.

You may also be able to remove and fix a damaged outboard rudder while you are still out at sea. There is no way to remove a rudder that is part of the hull and beneath the boat, but a rudder attached to the boat with hinges may be possible to fix at sea.

Outboard rudders are not necessarily weaker than and can be stronger than other types of rudders. The hinges that hold an outboard rudder in place may be stronger than a rudder post.

In some ways, an outboard rudder is worse than either a spade rudder or a full keel rudder. Unlike a full keel rudder, things like rope floating in the water can get caught on an outboard rudder. Objects floating by can also hit and damage an outboard rudder more easily than they can damage a more durable full keel rudder.

Compared to a spade rudder, the outboard rudder is harder to turn. The water pressure will always be on one side of the rudder; this is not always the case with spade rudders.

Skeg mounted rudders

Skeg rudders are both durable and possible to use on fin keel rather than full keel boats. Skeg mounted rudders are more durable than the spade rudders you usually find on fin keel boats.

Skeg mounted rudders have the same disadvantage as full keel rudders and outboard rudders, which is that they require more energy to turn. The water will put all of its pressure on one side of the rudder. Only spade rudders avoid this problem.

Is a tiller better than a wheel?

Either for inexperienced or veteran sailors, a tiller can work better. With a tiller, you will get immediate feedback. If you turn a wheel, the boat won't turn right away, which can confuse or annoy a new sailor.

The tiller should be long enough, as it is harder to turn if it is shorter. In strong winds, you need a long lever to turn your boat without it taking a great deal of strength.

It is easier to turn a wheel than to turn a tiller, as there is more leverage with a steering wheel. Therefore, wheels are better for larger boats; as a tiller is harder to turn with a bigger boat.

A tiller's advantage is that it is more responsive than a wheel, even though it is harder to turn. The boat will start to change direction almost immediately if you use a tiller. In racing, it is normal to use a tiller because you can change direction more quickly.

How does a rudder work?

A rudder works through water pressure. If you turn the rudder, the pressure becomes higher on one side of the rudder than the other. The rudder then moves toward the side with the lower pressure, which causes the boat to change direction.

When a sailboat turns, it pivots around a point near the middle of the boat. Both the stern and the bow move simultaneously, with the middle of the boat not moving. You have to take this into account while sailing, or else you might swing the end of your ship into another boat.

What is the purpose of the keel?

The keel keeps the boat stable. Without a keel sticking down from the boat into the water, it would be easy for the wind to push the boat around. Without a keel, the wind could easily push you sideways and make the ship much harder to control.

A keel is also weighted. The keel is full of ballast, which is weight that keeps the boat from flipping over. Without ballast, a boat would be top-heavy and unsafe.

Keels are usually made out of the same material as the rest of the boat - if the boat is aluminum, the keel will be as well. The ballast is usually lead.

While full keels are better in rough weather in most ways, a fin keel does a better job of preventing the wind from blowing your boat around. Wind can create leeway, which is sideways movement of the boat. Leeway is most likely if you are sailing into the wind.

Do rudders often fail at sea?

Yes, a rudder failure is one of the more common hazards you might encounter at sea. Not every sailboat has a good, durable rudder. The rudders on cheap boats, especially cheap fiberglass boats, can fail.

The rudder pole should neither be too weak nor too strong. If the rudder pole is too weak, it will bend easily. If it is too strong, it may damage the hull rather than bend, which is even more dangerous.

A rudder has a metal framework inside of it. If the framework breaks, the rudder will become unusable. With a cheaper boat, the metal framework may not be welded together properly.

Make sure you buy a sailboat that has a reputation for safety. Don't buy the cheapest boat you can find - look into whether or not the boat is safe to take out to sea.

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

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You are here: Home › Marine › Phil’s Foils A-Z › C&C

Several C&C models have had changes through their production run – please confirm all critical measurements when ordering.   You’ll find the 2nd generation boats built by Tartan down near the bottom.

C&c27 mk1 rudder.

The Mk3 shape is also a possible replacement for the Mk1.

Price is for rudder blade only. Replacement post quoted separately.

Click Here for Price          Post Feedback

C&C27 Mk3 Rudder

The Mk3 shape also makes a nice upgrade for the Mk1 and Mk2.

Price is for rudder blade only. Replacement post quoted separately

C&C27 Mk5 Rudder

C&C30 HP

Need a rudder?   We can supply.

C&C30 Redwing Rudder

C&C33 Rudder

C&C34 Plus Rudder

C&C35 MkI Rudder

The “scimitar” shape of the original C&C 35 Mk I rudder was perhaps not their best idea.   We developed a more conventional design for our customer, much in the way that the C&C 27 evolved from the MkI to MkIII.

Click Here for Price    Post Feedback

C&C35 Mk3 Rudder

C&C36 Rudder

C&C37 Rudder

We had one of these come in to the shop that was, honestly, horribly unfair and very waterlogged. Our replacement, while of the same planform, is a much nicer section and considerably lighter.

After a couple of months of sailing with the new rudder I couldn’t be more pleased. The boat is much more balanced and the issues with a very heavy helm that got loaded up with a lot of weather helm are gone. Boat handling is dramatically. I just sailed the boat from Annapolis, MD to Bermuda and back as part of the Bermuda Ocean Race and took second in my class. Everybody is impressed with what a change it’s made.

Regards, – Steve

C&C37R Rudder

We’ve taken a 37R rudder from a rather chunky shoal draft design to one with more ‘normal’ aspect ratio.   If you want one in the original shape, we have those dimensions too.

C&C38 Rudder

C&C38 Landfall Rudder

C&C39 Rudder

The blade was built around his original rudder post. The replacement is higher in aspect ratio (and lighter, due to construction method).

Price is for rudder blade only. Replacement post quoted  separately.

C&C Northeast 39 Rudder

CCI is pleased to offer this replacement rudder for the Northeast 39 designed to match the factory dimensions. Built using E-glass vacuum bagged over a CNC shaped foam core, this rudder can be built with a full carbon fiber post or stainless steel post.

C&C40 Rudder

C&C41 Rudder

C&C44 Rudder

C&C110 Rudder

C&C115 Rudder

Of course CCI can provide a new rudder for your C&C 115.

C&C 115 Bowsprit

For this project we first milled a foam test piece to verify fit to the bow, based on dimensions the customer had provided.  Then we proceeded to build the unit itself.  This sprit allows a headsail to be set an additional 15″ off of the bow.

C&C121 Rudder

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2019 | 2020

The Foss Company can ship replacement sailboat rudders anywhere in the world from our headquarters in Newport Beach, California. Our company has manufactured high density, "closed cell" foam rudders for more than 35 years. Our first "Foss Foam" rudders were created for the famous Cal 40 yacht during the sixties, and most of those vessels--and rudders--are still in service today.

We now make rudders and dagger boards for most sailboats, all in a timely and cost-effective manner. By working with existing molds of a more modern design, we can also supply rudders for older boats that will improve their performance and handling--all for a very reasonable price. Our special manufacturing process assures that our rudders are strong, light and dependable, ready for a lifetime of sailing pleasure.

We have also created rudders from many other sailboats around the world, including those from the following manufacturers:

For more information about our line of Foss Foam replacement rudders, please call (949) 646-0244 or contact us at our office in Newport Beach, California.

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Sailboat Rudders 

The primary purpose of sailboat rudders is of course to give the helmsman the ability to steer the boat, but a well-designed one will also provide hydrodynamic lift to windward, in the same manner as does the keel.

Placing sailboat rudders into distinct categories is fairly straight forward - they're either:

• Outboard or inboard rudders, which can be
• Unbalanced, balanced or semi-balanced, and be
• Keel-hung, skeg-hung, transom-hung or spade rudders.

Take a stroll around any fair-sized boatyard during the lay-up season and you'll see examples of most of them...

Inboard & Outboard Sailboat Rudders

If the rudderstock passes through the underside of a boat's hull, it's an inboard rudder. Conversely, if it doesn't, it's an outboard rudder.

Most outboard rudders are turned by a tiller as there's no rudderstock to which a wheel-steering quadrant can be mounted.

The two rudders shown below are quite different examples of outboard rudders.

Fig 1 shows an example of a keel-hung outboard rudder that is seldom seen on today's cruising boats.

Outboard rudders like the one in Fig 2 can be easily removed for service or repair with the vessel afloat. You might struggle with trying to do that with the 'barn door' of a rudder in Fig 1 though!

Examples of inboard rudders can be seen in Figs 3, 4, 5, 6, 7 & 9.

Unbalanced Rudders

This unbalanced rudder is supported by a full-length skeg.

It is unbalanced because the entirety of the rudder is aft of its axis, the axis being on the centreline of the rudderstock.

When turned, the full force of the water flowing past the skeg acts on one side of the rudder - a fact that will be very much apparent to the helmsman, particularly on a tiller-steered boat.

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Rudder Mods for Low-speed Docking

A ny sailor who has tried to wrestle a full-keel ketch with a barn-door rudder into a tight slip has probably wondered if they could modify the rudder to improve low-speed maneuvering without slowing the boat down under sail. As it turns out, there are several rudder design tweaks designed to improve control on ships, large working boats, and trawlers, but few have been implemented widely in the sailing world.

Most sailors have a general understanding of how a rudder works, because the concepts of lift and drag that apply to sail trim and keels also apply to what happens underwater with respect to rudder trim. The rudder’s angle in relation to the flow of water as the boat moves through the water is its angle of attack. When this angle changes, it creates a low-pressure zone on one side of the rudder that “lifts” the rudder forward toward that zone. On the other side of the rudder is drag, the enemy of lift.

At low speed, or when making sharp turns—two essential features of any docking exercise—the lift is so anemic that drag can cause the rudder to stall, and the skipper must rely on other forces such as prop walk (forces generated by the propeller’s rotation) or prop wash to squeeze the boat into its slip. For responsive steering when docking, you want a rudder profile that has a healthy lift-to-drag ratio at low speed. This is not possible using the most popular rudder designs, which are based on foils developed by the National Advisory Committee for Aeronautics (NACA). The NACA foil shapes, designed to provide optimal lift-drag ratios for aircraft operating at higher speeds when flying a relatively straight line, are not the best suited to making sharp turns at slow speeds (see illustration, page 20).

Our dive into the world of rudder designs for low-speed maneuvering was triggered by questions from a reader who was frustrated with the close quarter maneuvering capabilities of his full-keel sailboat. He was happy with the boat’s performance when sailing, but under power, and particularly at low speed, the boat simply would not turn. He had read that if he attached a 90-degree angle iron on each side of his rudder’s trailing edge, his rudder would be far more effective.

Since a modification that adds drag at the trailing edge seems to go against the conventional wisdom that a knife-like trailing edge is best for sailboats (see “Building a Faster Rudder,”  PS  June 2021), he was baffled to say the least. We were curious, too. Are there unconventional rudder profiles—at least in the world of sailing—that might be a better fit for a boat like his? When docking in close quarters, an auxiliary-powered sailboat effectively behaves as a powerboat, so it is worth looking at what rudder modifications have helped trawlers, fishing boats, or commercial ships tighten their turning radius.

SAILBOAT RUDDERS

Sailboat rudders serve as both a control device for steering and lateral plane to develop lift. When sailing straight, or nearly so, the rudder operates at a relatively steady, low angle of attack. The low angle is nowhere near one that would interrupt the flow of water and cause the rudder to stall.

On a well-designed sailboat in good trim, weather helm is about 2-5 degrees. This is the rudder angle required to steer a straight course while reaching. But that’s just part of the equation. Like the keel, the rudder is impacted by leeway, slipping about 5- to-10 degrees in relation to the course steered. This means the rudder’s actual angle of attack through the water is about 7-to-15 degrees.

An efficient NACA rudder profile will provide a favorable lift-to-drag ratio up to an angle of attack of about 16-to-20 degrees, so you have limited “wiggle-room” before the rudder will begin to stall.

Because a sailboat rudder needs to provide lift at relatively low speeds, it needs a relatively large surface area and a foil shape with a high aspect ratio. Aspect ratio is the ratio between the chord—the straight-line distance between the leading and trailing edges of the foil—and the foil’s span, or length (depth in the case of a sailboat rudder).

These narrow and deep NACA-based rudder shapes are designed for maximum efficiency going to windward. They provide adequate maneuverability under sail but aren’t very efficient under power. Racing designs exacerbate low-speed steering problems by putting the rudder as far from the prop as possible to minimize turbulence at the rudder. This makes it virtually impossible to nudge the stern to port or starboard by redirecting propwash with a sharply turned rudder a common tactic during docking maneuvers.

POWERBOAT RUDDERS

The rudder on an inboard-powered trawler or cabin-cruiser by comparison, operates in the high velocity slipstream of the propeller. It is not asked to resist the steady sideways pressure of the wind, only to provide turning force. Any additional rudder area hanging below the prop’s stream only adds drag (and draft) with very little benefit. The profile must be low drag, and as a result, many powerboat rudders are nothing more than a flat plate welded to a shaft with whatever reinforcement is required. This provides acceptable docking performance so long as the timely bursts of power are applied at the right rudder angle. Larger ships, with a lower power-to-mass ratio, require some additional help.

SHIP RUDDERS

Ocean going ships focus on straight-line efficiency. They are assisted by a harbor tug when docking. They use rudder sections like those of sailboats for slightly improved lift-to-drag ratios, but the rudder remains small. However, some ships, including tugs, coastal freighters, and barges, require greater maneuverability. When navigating in constrained waterways, these ships and work boats spend a great deal of time with the helm turned at high angles.

As a result, naval architects have developed different rudder sections that will operate effectively at much higher angles than traditional NACA sections we see on sailboat rudders. These convex shapes are referred to as “fishtail sections”. Examples of fishtail rudder designs are the Schilling and Thistle rudders (proprietary foil sections named by their designers), which can reduce the turning circle of a boat by as much as 50 percent. Some examples of these low-speed designs are shown alongside conventional sailboat rudder (NACA) profiles in the illustration.

If you have a spade rudder located a few feet away from the prop, you won’t gain anything with a fishtail section. Effective use of prop-wash—along with an experienced hand at the helm—should be enough to get you in and out of a slip. However, if you are the owner of a shoal draft boat with a short rudder, a full-keel cruising boat, or a motorsailer, and have been kept awake by visions of bow thrusters dancing in your head, read on.

LOW SPEED STEERING UNDER SAIL

At low angles of attack, water flows relatively evenly around both sides of the rudder, creating minimum drag. This streamline, also called laminar flow, remains “attached” to the rudder’s surface. Any change in relative speed or direction that interrupts this flow can cause the rudder to stall.

When a rudder stalls, the water on the low-pressure side is no longer deflected effectively, creating a separation bubble that reduces lift on the low-pressure side. At the same time, drag on the high-pressure side of the rudder continues to rise. As result, the low-pressure side of the rudder’s trailing edge becomes less important, because it is within the eddy zone (separation bubble, see adjacent illustration). Since there is very little water flow over this surface, it does not create much drag. Only the flap on the high-pressure side sees flow and generates drag. We’ll come back to the latter point, but it should be apparent that sailboat rudders cannot operate in the stalled region; the drag is too high for windward work, and the lift is too low for high-speed corrections in big waves.

When maneuvering under power at low speed we need more lift, so drag doesn’t really matter. To overcome any drag, we can just use more throttle. Airliners use massive flaps when landing. The drag is horrendous, but since they are descending and trying to reduce speed, they have plenty of reserve power to overcome drag. The tradeoff is worth it. During take-off, when they have less power to spare, they use zero flaps (and sometimes high-lift devices called slats on the wings’ leading edge).

In search of new symmetrical shapes with the same high lift characteristics as an asymmetrical airplane wing, ship designers began experimenting. In fact, some ships use rudders with flapped trailing edges, like airplane flaps, but simpler. After much trial and error, simpler, non-articulating sections, referred to as fishtails, were found to have many of the same beneficial characteristics as a jet wing.

As a result of this research, a series of foils were developed in Germany by the Hamburgische Schiffbau Versuchsanstal (Hamburg Model Ship Basin) and the Institute für Schiffbau (Institute for Ship Building). Named after their place of origin, these shapes were designated HSVA shapes and HVS shapes. A variety of proprietary wedges and fishtails grew from there.

When a vessel is steering a straight path and the rudder has a low angle of attack, HSVA and HVS shapes create slightly more drag than NACA profiles of equal lift. However, they delay stall and create more lift at higher angles. Although the wedge or flap slightly increases drag, once the foil stalls, this drag is minimized because it is in the separation bubble.

As shown in the example foils (see Figure 1), the “fishtail” is a wedge-like section at the trailing edge. Generally, the maximum thickness of wedge will be no more than the maximum thickness of the rudder. The ideal thickness of a sailboat rudder is about 20 percent of the chord—the distance between the leading and trailing edge measured parallel to the normal laminar flow (see Figure 2). Ideally, a fishtail rudder will be based on a concave HSVA or HVS section, but simply adding a wedge at the trailing edge of NACA profile or a flat plate has proven to be a cost-effective way to achieve similar performance.

ADDING END PLATES

Another feature of high-lift rudders are endplates. Just as the name implies, these are plates at the top and bottom “ends” of the rudder. Their purpose is to help direct laminar flow over the rudder, by reducing loss of flow at the rudder tips (known as tip loss).

You don’t often see endplates on sailboat rudders or keels because they can create a lot of turbulence and drag. In addition, the deep, narrow (high-aspect) rudder of a sailboat will suffer much less tip loss than a broad shallow (low-aspect) one found on most powerboats. Finally, the narrow gap between the top of the rudder and the flat stern section of a racing sailboat effectively creates an endplate at the top of the rudder, eliminating the need for one there.

Endplates will be more appealing to owners of motorsailers, heavy-displacement sailboats with barn door rudders, or other large auxiliary sailboat designs that can create headaches during docking. On these boats, the additional drag under sail may be worth better maneuverability under power.

These “endplates” on a sailboat rudder don’t have to be at the ends of the rudder as they are on a powerboat; they can be at the top and bottom of the rudder’s prop wash zone to help direct laminar flow and improve rudder lift under power. On a motorsailer, to make full use of the prop thrust, the distance between the end plates should about 120 percent of the prop diameter. The plate width should be about 120 percent of the maximum thickness of the foil, or, in the case of a thin, flat rudder, 20 percent of the chord.

OTHER CONSIDERATIONS

Adding endplates or a fishtail can have some unintended consequences. For example, it will move the rudder’s center of effort aft, making it harder to steer. The change is most pronounced at low speeds with the helm well over, but forces are low, so this is not typically a problem. At higher speeds, the difference will be more noticeable, and this is something to look for during a sea-trial before you commit to a permanent change.

To get the maximum benefit of a fishtail rudder with or without endplates, one could also experiment with moving the end stops, which limit the maximum angle you can turn the rudder to either side—although we’d be very careful with this. Rudder end stops generally limit rudder angle to 35 degrees, the maximum angle at which conventional rudder designs are effective.

A fishtail design will work beyond this limit, up to 45 degrees, potentially reducing turning radius by up to 50 percent at speeds of 2-to-4 knots. However, increasing rudder angle will also increase loads on the rudder stock and rudder bearing when the boat is in reverse or, more seriously, getting tossed backward by a wave in extreme conditions. Although we have few qualms about experimenting with end plates and wedges, we wouldn’t mess with rudder stops on an offshore cruising boat without some professional guidance from an engineer or naval architect.

While this seems like a lot of effort to make docking easier, having control at low speed can be beneficial at sea, as well. You will have better control when powering in adverse weather, slowing down to the minimum speed that allows for control—steerage speed—which can help in heavy weather.

This report is not advocating for rudder redesign on a sailboat that steers adequately at low speeds under power. Nor should it be construed as surefire way to fix steering problems on problem boats, although we’re optimistic that it will help. Based on solid evidence from the world of trawlers, working boats and ships, it is a concept that deserves more study. We have not yet been able to test fishtail rudders on our own sailboats, but many vessels, both commercial and recreational—have added fishtails with positive results. We’d be interested in hearing from sailors who might have experimented with either.

As for endplates, we strongly believe that they are smart idea on trawler rudders; the only downside is that it can snag weed. To prevent this, we would leave the forward portion of the plate flush with the leading edge of the rudder and then rake it in a streamlined form as it extends aft. Shallow-draft motorsailers with trawler-like rudders could also benefit from streamlined endplates. As mentioned, the endplates don’t have to be at the rudder tips, they could be positioned to maximize prop wash.

Adding a fishtail becomes more complicated. What angle works best? How will it impact rudder balance? The HVSA sections are a good starting point when conceptualizing fishtail sections. Although adding a simple 90-degree angle at the trailing edge is common, naval architect Dave Gerr, the author of several books on yacht design and engineering, suggests starting with a metal plate that can be adjusted to alter its angle.

If you want to experiment, you could attach a stainless-steel sheet metal strips to each side of the rudder. The metal would be bent at an angle that mimics the shape of your preferred fishtail. During sea trials, you can adjust the angle until you find one that works. If you are using stainless-steel bolts or screws to fasten the sheet metal, you will want to be extremely careful about not allowing any water into the rudder laminate or foam core. Seal the core with epoxy as you would when fastening deck hardware or fasten the angle using high-strength adhesive.

If the angle doesn’t seem to help, you can take it off, fill the holes, and master the art of using spring lines to squeeze your boat in and out of its slip on windy days. If your improvised fishtail does improve low-speed steering, consider shaping a more permanent section that can be bonded to the original rudder—or building a new rudder to the improved design. If you are also adding endplates, the fishtail sections do not need to be mechanically attached to the endplates, but they should be very close.

Full keel sailboats are never going to turn on a dime; they like to go straight. But there is plenty of evidence that a fishtail section, such as the concave IFS61, located just aft of the prop, could improve low-speed performance. We doubt this fishtail section located directly behind a 3-to-4 blade fixed prop will have any negative effect on sailing—the flow is turbulent behind the prop anyway. As for the potential benefits, based on what we’ve seen in the powerboat world, a low-speed rudder design is worth investigating.

REFERENCES:

SHIPS AND OFFSHORE STRUCTURES Volume 12 (2017),  Issue 4. “Sixty Years of Research on Ship Rudders: Effects of Design Choices on Rudder Performance,” by Jialun Lee and Robert Hekkenberg. www.tandfonline.com

GREAT HARBOUR TRAWLERS  – www.greatharbourtrawlers.com

MARINE TECHNICAL SOCIETY 2012 CONFERENCE. “Station Keeping with High Performance Rudders, ” by Joerg Mehldau www. dynamic-positioning.com .

OCEAN NAVIGATOR  June/July 2005. “High Lift Rudders and Improved Boat Handling, ” by Dave Gerr. www. oceannavigator.com

PROFESSIONAL BOATBUILDER. “Keel and Rudder Design, ” by Eric Sponberg. www.ericwsponberg.com

T he rudder plays a much simpler role on a power boat. It doesn’t have to resist leeway to the same degree that a sailboat does, nor does it have to help provide the significant lift required to make windward progress. However, sailboats maneuvering under power alone behave similarly to trawlers. The increasing popularity of fish tale rudders among trawlers prompted our research into their potential for cruising sailboats that might benefit from the design.

1.  This Defever trawler rudder has end plates for better steering at low speeds. There is also a slight “fishtail” flare at the trailing edge.

2.  The flare consists of a triangular strip of 3⁄8 inch steel welded to each side. The endplates are flat stock welded to the end of the rudder.

3.  Directly aft of a big four-blade prop, this fishtail wedge helps the boat achieve a tighter turning radius by improving lift at extreme rudder angles.

4.  The wedge on this high-lift rudder on this 50-foot trawler is much more pronounced than the one on the Defever (images 1 and 2).

RELATED ARTICLES MORE FROM AUTHOR

My boat is a Swallow Craft Swift 33. It had a “barn door” skeg hung rudder. it was a bear to steer and zero directional control in reverse. I’ve forgotten most of the math but basically I lengthened the rudder 11″ and extended the rudder forward of the pivot point. There was a fair amount of math involved (for me anyway). Now I had a hydrodynamic counterbalance forward was like power steering and some control in reverse. Great article, just adding my experience.

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

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

Quick Facts

Understanding the sailboat rudder.

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

Components of a Sailboat Rudder

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

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

Different Types of Rudders

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

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

Materials Used in Rudder Construction

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

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

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

The Function of a Sailboat Rudder

Steering and maneuvering.

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

Balancing the Sailboat

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

Rudder Effectiveness in Different Conditions

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

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

Design Considerations for Sailboat Rudders

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

Rudder Size and Shape

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

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

Rudder Placement and Configuration

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

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

Hydrodynamic and Aerodynamic Factors

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

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

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

Rudder Maintenance and Repair

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

Inspecting Your Rudder

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

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

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

Common Rudder Issues and Solutions

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

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

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

When to Replace or Upgrade Your Rudder

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

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

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

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

Rudder FAQS

How does a sailboat rudder work.

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

What is a rudder and its purpose?

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

Can you steer a sailboat without a rudder?

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

What controls the rudder on a sailboat?

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

How do you steer a sailboat with a rudder?

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

How do you steer a sailboat against the wind?

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

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

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

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

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New Rudders

Replacement Sailboat Rudders and Centerboards

Sailboat Rudder – Replacement or New

How to Build a Sailboat Rudder From Scratch

Introduction: How to Build a Sailboat Rudder From Scratch

This particular rudder is built off of the original rudder for a ~20' Bayliner Buccaneer sailboat.  The original had cracked and rotted pretty badly.  The owner of the sailboat cut the top of the rudder off and made a wooden 'boot' to cap the rudder.  However, it wasn't water sealed with fiberglass, and over time more and more moisture got in until it became so flimsy that it wasn't reliable.   While this instructable is specifically for this Bayliner sailboat with a tiller-style rudder, the instructions should be general enough for you to modify it to work for many sailboats.  With that said, there are many many nuances to fiberglass/composite marine construction, so this type of build will require more research beyond what is covered here.

Step 1: Previous Rudder

In these photos you can see the extent of the damage.   The rudder was foam-core/fiberglass sandwich.  Think of it as a Big Mac; the three buns of the Big Mac were layers of fiberglass, and the meat was the foam (the yellow stuff).  The only difference was that the buns would have all been connected and fully enclose the meat. First, I cut apart the rudder along its perimeter with an oscillating saw, so that I could use the pieces as templates for the build. In the fifth image you are seeing a piece of balsa (I think) at the edge of the rudder where the mounting hardware was located so as to provide compressive stability for the tightened hardware. In the last image, if you look at the top of the image you can see where the previous owner had chopped off the top of the rudder.  There was a rudimentary wooden cap on that, so you can see how easy it would have been for water to get in.  

Step 2: Rebuild

Because of the difficulty of rebuilding the rudder the same way, I chose to use two sheets of 3/4" solid plywood.  While this increased the overall weight of the rudder, it ensured maximum strength and stability.  There is a good reason that I chose to do it in two pieces:  I wanted to be able to sand the exterior faces of the rudder in order to get a tapered surface, and by doing it in two pieces allowed me to have the piece be level on one side. In the first image below, you can see the old pieces of the rudder all stripped of foam next to the new plywood pieces.  In the background you can see the middle fiberglass 'bun' of the whole kit 'n caboodle.  I scraped away all of the foam because I had originally wanted to save the exterior pieces and reuse them, but the Big Mac style construction made it more difficult to reuse them.   Simply place the old pieces on your sheet of plywood, trace, then cut out with a jigsaw.   If for some reason, you only have one template to work with, and you are using two pieces of ply that will later get glued together, be sure to flip the template over before tracing, so you have mirrored pieces.   The customer asked for a little more material at the top of the rudder, as you will see in the last images of the Instructable.  It ended up making it look a little strange, however.

Step 3: Sanding

Unfortunately, I only took one image of the sanding process, shown below. As I mentioned, it is good to sand the two pieces separately, although this picture is of the two already glued together.  A handy trick is to imagine your surface and the lines of ply as the lines on a topography map.  The curved edge of the rudder closest to us in the image is the narrowest edge, from the little notch all the way down the side to the very bottom of the rudder.  This is because it is the edge of the rudder that points forward when it is on the boat.   I started by using a disc sander, but it was too slow, so I switched to a grinder.  The grinder worked well, but it was a bit too fast, so if you decide to use one, be very judicious in your use of it, otherwise you will end up with big divots.  

Step 4: Fiberglass Layup

As I already alluded, there are many many variations to fiberglass construction.  For this project I used chopped strand mat (which you can see in the first image), and a woven fiberglass cloth on top of that, with vinylester resin.  Later on in the project I switched to West Systems Epoxy 105 and 205, because it was on hand.  This type of layup requires you to use both the mat and the cloth in one process.  The general idea is that you cut your mat to about the same size as your rudder, pour your resin on top, spread it and around, then immediately lay on the cloth (that you have also already cut to size), and the resin underneath should be enough to saturate the cloth.  Often, however, it wasn't, and I had to mix more up really quick and pour it on top of the cloth to get it fully saturated.  This is where you will need to conduct more research on mixing ratios of resin, temperature, amount per surface area, etc.  Generally, I was able to get about 30 minutes of working time out of each batch. In the back is a finned roller that you use after you mix and start pouring the resin to remove the air bubbles from under the chopped strand mat and to spread the resin around.  After a while the roller gets all gummed up, and I ended up using just my gloved hand to push out the bubbles, and I found that a simple plastic spreader worked best for spreading. Don't worry about the stuff that hangs over the sides.  Originally I wanted to have it fold over and seal the edges at the same time, but this was near impossible, as we will see soon, and I just let it hang and harden from any of the spilled over resin.  I dealt with it later with a lot of sanding.

Step 5: First Layer and Sanding

The order I used was as follows: Glass one side of the rudder, let cure. Cut off excess edge stuff and rough sand/grind. Glass other side of rudder, let cure. Cut off excess, sand until flush. Glass edges based upon which were generally 'up' when clamped in a mostly horizontal way (images 4 and 5). Glass the remaining edges. Sand the nasty edges until flush. The first image is after the glass on the faces have cured, showing the excess.  The third image was after sanding the excess from the faces.  The following  images were taken doing first layers of the edges, after the faces.  

Step 6: Additional Layers and Difficult Spots

I don't remember exactly how many layers went on total, because after sanding where necessary, sometimes more wood gets exposed, and all that's required is a simple patch.  The first image is after fully sanded face and edge layers.   There are some really difficult spots that you need to pay attention to.  Generally, corners are the spots you need to look out for.  It's like trying to wrap a piece of paper over a 3D form without letting any edges lift.  They will tend to lift up one end of your saturated cloth and allow air to get right in there, which means you'll have to sand that air bubble out and re-do it later.  The very bottom tip of the rudder was one of them.  Although the second picture is after I had drilled the holes for the hardware, it's useful to see the method for tackling those difficult spots.   Visibile at the tip of the rudder is a bit of blue painter's tape.  For that spot and others, which I will mention later, I basically taped the heck out of it, making a small well, and poured in enough resin to cover it.  You can also see in this picture, how it has started to get thick/bulky.  That's normal as layers build, you just need to sand it down flush later.  Sometimes the tape gets sealed in there, so I just left it in.

Step 7: Notes of Caution

If, after a good amount of sanding, your rudder has patches of white at the surface and you can feel a clothy texture when you run your fingers over them, it means the cloth did not get fully saturated and means the surface is not fully sealed.  When this happens, it is sufficient to mix up a new batch of epoxy/resin, and spread it over the surface(s) without the need for another layer of cloth.  The entire surface is sealed when all of it feels smooth/looks glossy and hard, although some spots may still be bumpy. After you think you've sealed the whole rudder and you go to sand it smooth, you may uncover more white patches or air bubbles.  It's extremely frustrating to think you're almost done and find another one of those, but it pays off to patch them properly. If there are some air bubbles or pockets that just don't seem to patch up and keeps reappearing after you sand this product is really helpful: http://www.marinetex.com/marinetexepoxyputty.html.  It's a putty-like marine epoxy, so it serves the same purpose as regular epoxy, but it is much more workable and can be packed into a hole to completely seal it.  The is the best product for repairs of deep scratches or small punctures in a fiberglass surface.   The notch at the top of the first image was one spot that I taped significantly in order seal every spot with epoxy.  This is the point where I switched to epoxy from resin, as I had run out.  The purple is the natural color of the epoxy after it hardens.  

Step 8: Hardware Holes

This step is extremely important and tricky.  If, by chance, you have the previous hardware which mounts the rudder to the transom of the boat, great.  Use them as guides as you don't want to make your rudder thicker than the original and not fit into the hardware.  If you don't have previous hardware and your boat needs a very specific bracket, go buy it early so you can make sure to construct your rudder to fit into those, otherwise, just buy some to suit. Use this tutorial to help you get the holes right:  http://www.boat-project.com/tutorials/drill.htm. Basically, you need to drill your holes bigger (1.5x, I think.  The tutorial with specify this.) than the hardware needs.  You then fill the hole with epoxy and let cure.  Then you drill your holes again with a bit sized for your hardware.  After painting, get some sealant (specified in the tutorial) and coat the bolts, holes and the inside face of the bracket immediately before placing them on the rudder. It's really important to drill your holes square through the rudder.  If you don't, you'll find when putting the bolts through, that they won't meet with the bracket holes.  If you're slightly off (like I was), you can just enlarge the hole at the problem end.  If you're really off, you'll have to sand the paint away, drill the new hole, fill with epoxy again, re drill, then paint.

Step 9: Painting

Painting a boat or any underwater surface is another realm that has a large amount of nuance, specificity, and also varying opinions.  It is still a bit unclear to me, but the most ideal situation is to find a marine paint that actually bonds with your fiberglass/epoxy surface.  Interlux makes really good products and they have tutorials on which paints to buy and how to apply them:  http://www.yachtpaint.com/usa/diy/default.aspx. Before painting, you must 'cut' the surface (a light sanding), so there is surface for the paint to bond to, and you will need to remove any oils or chemicals that are on the surface with acetone or a similar product.   The paint will usually specify a total thickness of paint required to be considered sealed, and will allow you to calculate the number of coats from the average thickness per coat.   Next use a top-side paint (I think we used an auto-body paint) to cover the surfaces above the waterline to make it look nice. Lastly, apply a bottom paint (also called anti-fouling paint) below the waterline of the rudder.  Bottom paints, especially, vary greatly by geographical location, type of water, EPA legal restrictions, etc.  Their purpose is to prevent organisms from attaching to the submerged surfaces, so naturally, they will contain certain chemicals and/or metals.  Copper is a common ingredient in anti-fouling paint, as it slowly leeches from the paint, preventing any organisms from attaching permanently.

Step 10: The End!

Attach the hardware and tiller, and you're ready to put it on the boat!!! (That's my pops holding the rudder.)

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Sailboat rudder types – full, spade, skeg, outboard.

The four rudder types are: full, spade, skeg, and outboard. This article discusses the advantages and disadvantages of each.

Full The full or full keel rudder lies at the aft end of a full length keel. The keel-rudder streches along the entire length of the bottom of the hull. The full rudder is safe and nearly invulnerable to damage. The leading edge of the keel protects the rudder from flotsam. The full rudder is quintessential of offshore cruisers like Wetsails and Cabo Ricos. Even grounding may not cause damage. The boat will sit comfortable on its side until the tide returns and floats the boat back up.

Spade The spade rudder lies at the aft separate from the keel. A spade rudder is easy to turn because the water rushes both against its fore and aft edges – great for using a tiller. A spade rudder is also fast as the wet area less than a full keel. The boat racing along with less resistance. Spade and partial spades are becoming the most popular rudder type. The Hylas 70 has a partial spade rudder as well as early 54’s.

Skeg A skeg rudder is more modern in performance and safety. It is the most popular and common type of rudder on production boats these days. The rudder is fast and looks like a spade keel. Except, the skeg rudder has a fake keel which extends from the hulls aft and protects the fore edge. Most Hylas yachts have skeg rudders.

Outboard Outboard rudders are seen on smaller boats. They simply hang over the stern of the boat. For example, racing prams use outboard rudders. They are easy to fasion as emergency rudders. You can make one out of a handlerail and cabin door.

Conclusion A rudder is either full, spade, skeg, or outboard. Each type has its benefits. The most important part is make sure she is in good condition and have a spare.

4 Replies to “Sailboat Rudder Types – Full, Spade, Skeg, Outboard”

Ahoy Mateys, it’s Fox Axel the Pirate. I’ve got a swashbuckling yarn to tell ye. Me was drifting along way out at sea. Me had lost me steering while pillaging a friendly ship. The knaves canon knocked me rudder off. Me had nought to to turn to. The authorities would hang me, the villainous lot. But, me was getting desperate out of grub and rum, nothing to sage me drunken pirate ways. I had lost me last vestige of sanity.

Finally, me saw in the distance a giant whaler coming. The big ship sailed straight at me. “Ahoy mateys!” me spake. The freighter came near, too near. Shiver me timbers. The goulish crew must be drunk out of thee minds. Me could not steer away. She rammed straight slicing me ship in twain. Down to Davy Jones’ locker we went. Take care with ye rudders mateys – the Pirate of Monkey Isle.

Ok ye swabs ave a told me to finish me story. Ere dis da rest. As the freighter tore away leaving me to perish in the sea. I climbed on a board of driftwood from me sinkin’ ship. I passed out adrift, alone. When I came to, I found meself shipwrecked on a deserted island. I stumbled around and ran into, who of all? Big Red, me pirate enemy! Aye, I’m shipping as mate with his goulish fleet until I can betray and kill him. Aye, hope Big Red ain’t reading dis here blog. Black Fox the Pirate.

I am ye swab. I am too sharp for some ere fool like ye. I ain’t gots no book learning, but me hast carniving ways from many years below the mast. Iffen ye be trying to betray me, I am a gonna get ye.

Thank you for sharing this article.It’s quite easy to understand the difference.

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Orcas have sunk another vessel off the European coast. Why won't they stop ramming boats?

The orcas are at it again: for the seventh time in four years, a pod of whales has sunk a boat after ramming it in Moroccan waters off the Strait of Gibraltar. 

The 15 metre-long yacht Alborán Cognac, which carried two people, encountered the highly social apex predators at 9am local time on Sunday, Spain's maritime rescue service said.

The passengers reported feeling sudden blows to the hull and rudder before water started to seep into the sailboat. It is not known how many orcas were involved.

After alerting rescue services, a nearby oil tanker took them onboard and carried them to Gibraltar, a British overseas territory on Spain's southern coast.

Nothing could be done to save the sailboat, which drifted and eventually sank. 

It's the latest incident in what has become a trend of hundreds of interactions between orcas and boats since the "disruptive behaviour" was first reported in the region in May 2020. 

The origin of this new behaviour has baffled scientists, though the leading theory suggests this "social fad" began as a playful manifestation of the whales' curiosity.

Where have orcas interacted with boats?

The latest data from the Atlantic Orca Working Group (GTOA), an organisation that contributes to the animals' conservation and management, shows that there have been at least 673 interactions since 2020. 

GTOA defines interactions as instances when orcas react to the presence of approaching boats with or without physical contact. 

The map below shows the highest numbers of encounters from April to May 2024 took place off Spain's southern coast in the Strait of Gibraltar (red zones), with some lesser activity in surrounding areas (yellow zones). 

A 2022 peer-reviewed study published in the Marine Mammal Science journal found the orcas in these areas preferred interacting with sailboats — both monohulls (72 per cent) and catamarans (14 per cent) — with an average length of 12 metres.

A clear pattern emerged of orcas striking their rudders, while sometimes also scraping the hulls with their teeth. Such attacks often snapped the rudder, leaving the boat unable to navigate.

"The animals bumped, pushed and turned the boats," the authors of the report said. 

Adding this week's encounter, there have been seven reported cases of orcas damaging a boat so badly that it has sunk, though the people onboard were rescued safely each time.

In June 2023, a run-in with the giant mammals in the Strait of Gibraltar forced the crew competing in The Ocean Race to drop its sails and raise a clatter in an attempt to scare the approaching orcas off. 

No-one was injured, but Team JAJO skipper Jelmer van Beek said that it had been a "scary moment".

"Three orcas came straight at us and started hitting the rudders," he said.

"Impressive to see the orcas, beautiful animals, but also a dangerous moment for us as a team ... Luckily, after a few attacks, they went away."

After analysing 179 videos and photos of these types of interactions, which lasted on average 40 minutes, researchers concluded there was no reason to classify the events as intentionally hostile behaviour.

"The behaviour of orcas when interacting with boats is not identified as aggressive," they said.

"One of their main motivations has been identified as competition with boats for speed."

Still, the researchers of the study admitted they were not sure what triggered the novel behaviour in 2020.

"We are not yet certain what the origin of these interactions is, but it is still suspected that it could be a curious and playful behaviour," they wrote.

"[The behaviour] could be self-induced, or on the other hand it could be a behaviour induced by an aversive incident and therefore a precautionary behaviour."

Are the same orcas responsible for these incidents?

Out of around 49 orcas living in the Strait of Gibraltar, GTOA researchers found a total of 15 whales  from at least three different communities participated in the unusual interactions with boats between 2020 and 2022.

Most of those that engaged with greater intensity were juveniles, though it's unclear if others have since joined the group.

These giant mammals, which belong to the dolphin family, can measure up to eight metres and weigh up to six tonnes as adults.

The director of the Orca Behaviour Institute, Monika Wieland Shields, has said there is no evidence to prove the theory these whales were seeking vengeance against humans for a past trauma.

"While I'm sure it feels like an attack for the people on board, for the whales themselves, it really looks more like play behaviour," she said.

"There's something intriguing or entertaining to them about this [boat rudder] mechanism and they're just showing a lot of curiosity about it."

Ms Wieland said it's likely this new behaviour spread through the population as a kind of "social fad".

"Orcas are highly intelligent, very social animals, and with that comes a tendency to be curious about and explore your environment," she said.

"One thing that we see are these kind of fad behaviours that will appear in a certain population.

"One whale discovers something, they find it entertaining or interesting, or fun — it's some type of game. And then they will teach that to other members of their family group."

Are orcas dangerous to humans?

While orcas have earned their fearsome reputation for preying on other marine animals, there is no record of them killing humans in the wild. 

In captivity, orcas have killed four people since the 1990s, though it's unclear whether the deaths were accidental or deliberate attempts to cause harm.  

Ms Shields said she was worried the recent interactions between orcas and boats would skew people's perceptions of these mammals.

"I am concerned that people are going to react with fear, potentially injure or shoot at some of these whales," Ms Shields said.

"We really need to educate boaters about the best things that they can do to make themselves less attractive to the whales and the best case scenario would be the whales lose interest in this and move onto something less destructive."

Spain's Transport Ministry advises that whenever boats observe any changes in the behaviour of orcas — such as in their direction or speed — they should leave the area as soon as possible and avoid further disturbance to the animals.

The ministry also states every interaction between a ship and an orca must be reported to authorities.

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Killer whales attack and sink sailing yacht in the Strait of Gibraltar — again

By Emily Mae Czachor

Updated on: May 14, 2024 / 4:54 PM EDT / CBS News

A sailing yacht sunk in the Strait of Gibraltar on Sunday after an unknown number of orcas  slammed into the vessel with two people on board and caused a water leak, officials said. Both crew members were rescued by a passing oil tanker, said Spain's maritime rescue service, marking the latest killer whale attack on a boat in what has become a pattern in recent years.

The incident happened at around 9 a.m. local time in the narrow strait between Spain and Morocco that has become a notorious site of human interactions with pods of killer whales that, for reasons still not fully understood, ram into boats and at times even sink them . In this case, crew members on board the SV Alboran Cognac yacht put out an emergency call for an evacuation after they encountered orcas roughly 14 miles off the coast of Cape Spartel. 

The crew members reported feeling blows to the hull of the vessel and rudder, which was damaged by the whales, the rescue service said. The agency's coordination center in Tarifa, on the Spanish side of the Strait of Gibraltar, helped arrange for their evacuation via the tanker MT Lascaux. The tanker was able to collect the crew members from the sinking yacht within the hour, and they disembarked in Gibraltar before 10:30 a.m. They abandoned the SV Alboran Cognac, which proceeded to completely disappear into the ocean.

Anyone sailing through waters from the Gulf of Cádiz in southern Spain and the Strait of Gibraltar, either in a larger motorized vessel or a personal sailing boat, is advised to avoid certain areas that the maritime rescue service marks as potentially dangerous spots for orca interactions. The greatest threats exist between May and August, when officials say that pods of killer whales are most commonly seen in those parts of the Atlantic. 

But previously recorded incidents suggest those dangers may be present at any time. Last October, a Polish boat touring company reported that a pod of orcas had managed to sink one of its yachts after repeatedly slamming into the steering fin for 45 minutes, causing it to leak. Last June, two sailing teams competing in an international race around the world reported frightening scenarios in which multiple orcas rammed into or pushed up against their boats or as they sailed west of Gibraltar. 

No one on board any of the vessels was hurt in those encounters, but the documented rise in confrontational behavior has researchers and sailors trying to determine why orcase have attempted to sink or capsize so many boats off the coasts of Spain and Portugal. 

Some sailors have even resorted to blasting thrash metal music in a bid to deter the apex predators.

Reports of orcas interacting with humans have more than tripled in the last two years or so, according to the research group GTOA, which has documented hundreds of such incidents in the region since 2020. But some of the latest data points to possible changes in the orcas' etiquette, with the group reporting only 26 interactions in the Strait of Gibraltar and Bay of Biscay areas between January and May of this year. That number is 65% lower than the number of interactions recorded in the region over the same months last year, and 40% lower than the average number of interactions recorded in the same months between 2021 and 2023, according to GTOA.

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Emily Mae Czachor is a reporter and news editor at CBSNews.com. She covers breaking news, often focusing on crime and extreme weather. Emily Mae has previously written for outlets including the Los Angeles Times, BuzzFeed and Newsweek.

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Orcas Sink Another Boat Near Iberia, Worrying Sailors Before Summer

Two people were rescued on Sunday after orcas damaged their boat near the Strait of Gibraltar, where the animals have caused havoc in recent years.

By Isabella Kwai

Summer is on the way, meaning that the orcas are out to play near the Strait of Gibraltar — which is bad news for sailors.

Two people were rescued on Sunday after an attack by a group of orcas caused enough damage to sink their boat, according to the Spanish maritime rescue service. It was the fifth such sinking in waters off the Iberian Peninsula and North Africa in recent years.

The Alboran Cognac, a sailing yacht about 50 feet long, was approached by the animals on Sunday morning, some 14 miles off Cape Spartel in Morocco, the rescue service said. Crew members onboard reported that the animals had slammed the hull, damaged the rudder and caused a leak.

A nearby oil tanker quickly maneuvered toward the boat and evacuated the two sailors, who were taken to Gibraltar, the rescue service said. The boat was left adrift, and the Moroccan authorities reported that it eventually sank.

It’s the first boat to sink in those waters this year after an orca-related mishap. A group of orcas that traverse the Strait of Gibraltar and nearby waters has plagued sailors and intrigued marine biologists , who are studying the population. Since 2020, orcas have disrupted dozens of sailing journeys in these high-traffic waters, in some cases slamming vessels hard enough to cause critical damage.

Last November, orcas slammed a yacht’s rudder for 45 minutes, causing its crew to abandon the vessel, which sank near the Tanger Med port.

The group is more likely to appear in the busy lanes around the Gulf of Cadiz and the Strait of Gibraltar between April and August, the Spanish government said in a news release, and sailors have spotted some of the orcas there in recent weeks.

Researchers do not know why the pod is targeting boats, but they have theorized that the behavior is a form of play for the curious apex predators. The interactions have become so frequent that they are now a multinational issue, involving scientists and officials from Spain, Portugal and Morocco. Online, anxious sailors have gathered to share advice on navigating “orca alley,” and biologists are tracking the orcas’ movements and testing methods that could deter them.

In the event of an orca encounter, the government advised in its release, boats should not stop but instead head toward shallower waters near the coast.

But the number of incidents may be declining: Researchers at the Atlantic Orca Working Group said on Monday that the number of orca interactions with boats between January and May had dropped some 40 percent, compared with that of similar periods in the past three years.

Isabella Kwai is a Times reporter based in London, covering breaking news and other trends. More about Isabella Kwai

Orcas sink sailing yacht in Strait of Gibraltar

An unknown number of orcas have sunk a sailing yacht after ramming it in Moroccan waters in the Strait of Gibraltar, Spain’s maritime rescue service said on Monday, a new attack in what has become a trend in the past four years.

The vessel Alboran Cognac, which measured 15 metres (49 feet) in length and carried two people, encountered the highly social apex predators, also known as killer whales, at 9 a.m. local time (0700 GMT) on Sunday, the service said.

The passengers reported feeling sudden blows to the hull and rudder before water started seeping into the ship. After alerting the rescue services, a nearby oil tanker took them onboard and transported them to Gibraltar.

The yacht was left adrift and eventually sank.

The incident is the latest example of  recurring orca rammings  around the Gibraltar Strait that separates Europe from Africa and off the Atlantic coast of Portugal and northwestern Spain.

Experts believe them to involve a subpopulation of about 15 individuals given the designation “Gladis.”

According to the research group GTOA, which tracks populations of the Iberian orca sub-species, there have been nearly 700 interactions since orca attacks on ships in the region were first reported in May 2020.

Researchers are unsure about the causes for the behaviour, with leading theories including it being a playful manifestation of the mammals’ curiosity, a social fad or the intentional targeting of what they perceive as competitors for their favourite prey, the local bluefin tuna.

Although known as killer whales, endangered orcas are part of the dolphin family. They can measure up to eight metres and weigh up to six tonnes as adults.

Orcas again sink yacht near Strait of Gibraltar as high-risk season looms

Two people were rescued after orcas hit the roughly 50-foot Alboran Cognac 14 miles off the coast of Morocco, the 26th orca encounter in the region this year.

The boat-sinking orcas are back.

Around 9 a.m. Sunday near the Strait of Gibraltar, two people on board the roughly 50-foot Alboran Cognac reported blows to the vessel’s hull and saw damage to the rudder as water flowed into the ship, Spain’s maritime rescue agency said.

An unknown number of killer whales had struck again, after hundreds of such encounters in recent years.

Over the radio, responders told the two individuals to put on their life jackets, make sure their GPS locaters were turned on and prepare for emergency evacuation. In the meantime, Spanish and Moroccan rescue agencies began urgently working to save them, locating a nearby oil tanker and electing not to dispatch a helicopter.

After about an hour, that tanker rescued the pair 14 miles off Cape Spartel in northern Morocco, the Spanish Maritime Safety and Rescue Agency (SASEMAR) said in a news release. The boat was left adrift and soon sank.

Spain-based Alboran Charter confirmed its ownership of the sunken vessel and said the individuals were customers. The company declined to say more about what happened or who the clients were.

Iberian orcas sinking a ship is not new. Over the past four years, at least 15 orcas have interacted with hundreds of boats sailing in the waters off Portugal, Spain and Morocco, sinking a handful of vessels in seemingly coordinated ambushes. Some ships have been found with teeth marks; others appear to have been rammed by an orca’s head or body.

On average, there have been 168 interactions each year since 2020, according to Grupo de Trabajo Orca Atlántica, or GTOA, a research group studying the region’s killer whales. GTOA has tracked 26 interactions so far this year, down from 61 through a similar time frame in 2023.

It’s not clear why the orcas have recently bumped, bitten and sank vessels. Some scientists say they are simply being playful, or maybe are curious, or perhaps are coming after boats because of a loss of prey. A handful say the actions could actually be gratifying to the whales.

A leading theory, though, is one of vengeance.

This idea, advanced by a scientist who has studied the encounters, posits that a female orca suffered a traumatic run-in with a boat that led her to start attacking the vessels. And because orcas are intelligent marine mammals that learn behaviors like hunting together, others followed.

But there is disagreement over this theory.

Some scientists argue that the incidents shouldn’t be called “attacks” without knowing the whales’ motives. They fear that label could prompt retaliation by boaters, calling it potentially “harmful” to the critically endangered species with just a few dozen members.

“Science cannot yet explain why the Iberian orcas are doing this, although we repeat that it is more likely related to play/socialising than aggression,” a group of more than 30 scientists wrote in an open letter last summer. “ … When we are at sea, we are in the realm of marine life. We should not punish wildlife for being wild.”

The letter explained that orcas have been observed developing “cultural ‘fads,’” including carrying dead fish on their heads, and the incidents with the boats may be nothing more than a “fashion trend.”

SASEMAR warned that the risk of the encounters is highest between May and August, recommending that boats avoid the area between the Strait of Gibraltar to the Gulf of Cádiz to its west. It added that if a boat comes across orcas, it should not stop moving, and instead should head toward the coast and shallower waters. People should not approach the side of the boat and are barred from using measures that could injure or kill the whales.

“It is possible the behaviour, as previous fads have,” the scientists wrote, “will disappear as suddenly as it appeared.”