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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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What is a Sailboat Rudder?

Last Updated by

Daniel Wade

June 15, 2022

A sailboat rudder steers the boat. A rudder is a hinged fin or blade mounted on the stern of the vessel that turns side to side, and it's controlled by a tiller or a helm.

A rudder is one of the primary controls of a sailboat. When the boat moves forward through the water, the rudder causes friction on one side and changes the direction of the boat. Rudders are controlled by moving a tiller side to side or by a helm and a complex linkage system. Rudders are delicate and sometimes flush with and protected by the keel.

Table of contents

Identifying the Rudder

Rudders are connected to the sailboat using a hinge or a shaft. The rudder is always located in the water behind the boat, but some rudders have part of their structure exposed above the waterline. Rudders that aren't visible above the waterline are usually underneath the stern and controlled by a vertical shaft that descends through the bottom of the boat.

Rudder Design

Rudder design varies widely between boats. Some vessels have large, ornate rudders that are exposed above the waterline. Large rudders are common on catboats, canoe yawls, and other traditional designs.

Many modern boats use small, blade-like rudders that are hidden from view. The size of a rudder doesn't necessarily correlate with its effectiveness, but an improperly sized rudder can cause significant issues.

How Does a Sailboat Rudder Work?

Sailboat rudders are simple devices. Rudders are essentially deflectors, as they deflect water to port or starboard as the boat moves along. When the rudder is amidships or in the middle and aligned with the keel, the boat goes straight. Rudders also help keep the boat on a straight track as they increase the area of water moving down the length of the boat.

Rudders only work when the boat is moving. If there's no moving water to deflect, the rudder can do little to direct the vessel. Rudders also don't work when the boat is blown sideways. Maneuvering is only possible when the boat is moving forward.

Can a Sailboat Rudder Steer in Reverse?

But what about moving in reverse? Rudders can be used to steer the boat in reverse, but they're significantly less effective when pushed backward through the water. The distance required to make a turn in reverse is usually much higher than when moving forward, and steering input is less precise. In some cases, sailboat rudders can break off when moving too quickly in reverse.

Sailboat Steering Characteristics

Sailboats steer much differently than cars, and there aren't any brakes to slow down with. Sailboats tend to steer from the middle; picture a fan blade spinning slowly on a motor, and you'll get the picture. As a result, steering too aggressively in tight quarters can cause your bow or stern to hit something that's beside you.

Speed is generally helpful for steering, especially when you want to make precise movements quickly. However, speed is a double-edged sword, as slight rudder movement at speed can dramatically and rapidly alter the course of the boat. But remember, you can't steer without moving forward.

Tiller Steering

Sailboat rudders are often controlled by a tiller. Tillers are a long rod connected to the rudder. Sailors move the rod side to side from the cockpit to turn the rudder directly. Tillers are the simplest form or rudder control, and they're highly reliable. Tillers point in the opposite direction that the boat will travel.

Tiller steering is found most often on small boats. This is because the forces involved in steering boats of greater size can be too difficult to manage with a tiller. That said, there are some relatively large boats with cockpit configurations that allow for the use of a tiller. Sailboats with tillers range in size between 10 feet and 30 feet.

Benefits of a Tiller

Tillers have numerous benefits. Tillers offer precise control of the boat because they connect the rudder directly to the person steering the boat. Additionally, tillers are extremely simple and robust. Many blue water sailors prefer tiller steering, as it's difficult to break and easy to repair.

Over the years, sailors have developed many creative ways to make tillers more useful. Many boats feature tiller extensions that allow the sailor to steer from further away. Tillers also respond much faster than helms, which is great for racing and pushing the limits of the boat.

Tiller Self-Steering

Bluewater sailors developed an extremely useful way to multitask onboard a tiller-equipped sailboat. Self-steering is possible on vessels with a tiller, and no electronics or complex machines are necessary. Self-steering involves connecting the jib sheet to a series of pulleys and opposing bungee cord (or surgical tubing).

As the tension on the jib increases, it'll tighten the jib sheet and pull the tiller and change the course of the boat. The opposite is also true. This keeps the boat at the right angle to the wind and is useful for solo travel. GPS-guided self-steering equipment is also available for tiller-equipped sailboats, and it's relatively easy to install.

Helm Steering

A helm is essentially a large nautical steering wheel. Steering a boat with a helm is somewhat similar to driving a car, as the boat moves in the direction that you steer (unlike a tiller, which moves in the opposite direction). Sailboats equipped with tillers are usually larger. Some larger sailboats have two helms placed side-by-side in the cockpit.

The helm consists of a steering wheel and a pedestal which is mounted to the deck. Helm pedestals often feature a marine compass to make navigation possible from one location. Engine controls are often located nearby as well. Sailboat helms are often large in diameter, sometimes 30 inches or more. Large wheels make steering easy and precise.

Helm-equipped sailboats are generally 30-feet long and larger. Tillers are excellent for large boats, as they enable precise movement and require little effort to use. This is especially important at speed when the force of water rushing by a large rudder can be too difficult to overcome with a tiller.

The helm is connected to the rudder mechanically or hydraulically. Some high-end sailboats incorporate power steering, but this is unusual on most consumer vessels. Mechanical helm linkage typically utilizes a cable (or multiple cables and pulleys) that stretches from the helm to the rudder.

Hydraulic Rudder Control

Most sailboat helms are hydraulic. These helms use pressurized hydraulic fluid and small diameter lines to replicate the wheel movements at the rudder. Hydraulic systems often include a fluid reservoir and a pressure cylinder, along with mechanical parts to transfer the force at the wheel and the rudder.

Rudder Maintenance

Rudder maintenance is fairly simple and should be performed regularly. As with the hull, rudders are an ideal habitat for all kinds of unwelcome marine life. Within a year or less, your rudder can be completely encapsulated in barnacles, plants, and other organisms. Marine growth will negatively impact your speed and steering, so it must be scraped off regularly.

Maintaining the steering system is also essential. Tillers are relatively easy to maintain, as they use very few moving parts. Look for grease fittings, and make sure your tiller and rudder are fastened tightly. Helms are more complex, and the hydraulic system should be inspected, repaired, and topped off if necessary.

What to Do if the Rudder is Damaged

Rudder damage is a sailor's worst nightmare, and it's akin to a hole in the hull or losing a mast. So what should you do if your rudder gets damaged or breaks off? First, call for help! But if help isn't available, there are a few makeshift ways to steer the boat without the rudder.

If you have an outboard motor, use it to steer. If not, then a run-of-the-mill rowboat oar makes an excellent rudder substitute. Simply lash the oar to the back of the boat with the end in the water, and use it like a tiller. It's not ideal, but it worked for the Romans, and it should work for you. Some sailors have fashioned makeshift rudders from interior cabinet doors, hatches, scrap metal, and whatever else is on hand.

Losing a rudder is a worst-case-scenario, and it doesn't often happen when sailors keep up with maintenance and stay away from dangerous water. Preventative maintenance and proper navigation are the best ways to keep your rudder in good shape.

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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We build rudders with passion and precision since 1963.

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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

The Types of Sailboat Rudders

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Full Keel Rudder

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

Rudder on Full-Keel Sailboat

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

Advantages of Full Keel Rudder

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

Disadvantage of Full Keel Rudder

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

Spade Rudder

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

Advantages of Spade Rudder

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

Disadvantage of Spade Rudder

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

Balanced Spade Rudder

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

Skeg-Mounted Rudder

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

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

Outboard Rudder

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

Advantages of Outboard Rudder

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

Disadvantages of Outboard Rudder

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

A rudder is often related to keel shape .

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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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Diy trailerable sailboat restoration and improvement without throwing your budget overboard.

How To Repair a Rudder

Rudders damage easily. Although they work similar to a keel, they aren’t nearly as tough. If you dry sail, the edges can accumulate nicks and dings in the fiberglass from loading and unloading. The rudders of some sailboats can hit the outboard motor’s propeller if you’re not careful. Add in accidental groundings, storage damage, and stress cracks and it doesn’t take much time in water to make the wooden core swell and damage the rudder even more. Without repairs, a weakened rudder can even break into pieces under stress. It pays to protect your rudder.

Before I continue, a bit of legal housekeeping. This post contains affiliate links. That means I receive a small commission if you make a purchase using those links. Those commissions help to pay the costs associated with running this site so that it stays free for everyone to enjoy. For a complete explanation of why I’m telling you this and how you can support this blog without paying more, please read my full disclosure .

Example of a damaged upper trailing edge

If your rudder is showing any bare wood, has deep nicks in the edges, or has swelled and cracked the fiberglass at the edges, you should repair it while you still can. All of these kinds of damage are easily repairable by the do-it-yourselfer for a small fraction of the cost of a new rudder.

It’s just like doing auto body work

If you’ve ever done any auto body work, you know the goal is to build up and restore a smooth shape to damaged surfaces. It’s the same with your rudder but the finish quality doesn’t have to be as perfect.

Follow these steps to make your rudder smooth and watertight again:

1. Start with a 4″ handheld grinder or similar power tool to remove all of the rough and damaged fiberglass down to solid material. Also remove all damaged wood core material. This might seem overly aggressive but the repair won’t last unless it’s built on a solid foundation and a grinder will get you there fast. By removing the rudder’s skin, it will dry out faster.

2. Let the wooden core dry out as much as possible. You don’t want to trap moisture in the core where it will dry rot. If you lay up your sailboat for the off-season, that’s a good time to dry out your rudder. Finish the repair before the start of the next sailing season.

3. After the core has dried thoroughly, use a random orbital or similar power sander to feather the ground edges back a couple of inches all around and to remove any paint so that an epoxy patch will stick properly to the original fiberglass.

4. Mix some thickened West System or an equivalent epoxy and build up the ground and sanded areas to their original shape. Colloidal silica is a good thickener for this application.

5. With a power sander or sanding block, carefully smooth the patched areas to match the surrounding surfaces and edges.

7. Apply a barrier coat of one-part polyurethane or two-part (preferred) epoxy paint over the repaired areas.

Repaired edges with new barrier coat paint

6. Fill small cracks above the water line with Capt. Tolley’s Creeping Crack Cure .

7. Last, re-apply ablative paint or a polyurethane topcoat to match the rest of the rudder or hull. If you keep your sailboat in the water, ablative paint can minimize algae growth. If you dry sail or remove your rudder when you’re not sailing, ablative paint gives no benefit and will just transfer to everywhere you don’t want it. I reapplied ablative paint to this rudder but I sanded it off a year later and applied a gloss white polyurethane when Summer Dance got a different color bottom paint job .

8. Now is a good time to remove, clean, polish, and rebed all of the rudder hardware with butyl tape . If the tiller bushings are worn, read How to Replace Worn Tiller Bushings .

Now that you have a restored and sealed rudder, take good care of it and it will take good care of you!

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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.

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My Cruiser Life Magazine

All About the Rudder on a Sailboat

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

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

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

What Is a Boat Rudder?

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

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

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

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

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

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

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

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

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

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

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

Operating the Rudder on a Sailboat

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

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

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

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

Various Sail Boat Rudder Designs

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Transom-Hung or Outboard Rudders

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

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

Twin Sailing Rudder Designs

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

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

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

Unbalanced vs. Balanced Rudders

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

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

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

Sail Rudder Failures

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

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

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

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

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

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

What is the rudder on a sailboat?

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

What is the difference between a rudder and a keel?

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

What is a rudder used for on a boat?

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

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

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Jordan Yacht Brokerage

We Never Underestimate Your Dreams

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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Professional BoatBuilder Magazine

The rudimentaries of rudders.

By Steve D'Antonio , Jul 12, 2018

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

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

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

Rudderstocks

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Stuffing Box

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

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

Rudder Bearings

Well-engineered rudder bearings support and lubricate the rudderstock.

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

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

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

Propeller Removal

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

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

Rudder Stops

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

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

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Systems & Propulsion

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).

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Sailboat Rudder

Making a Sailboat Rudder for s/y Alacazam

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

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

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

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

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

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

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

twin transom-hung rudders on a racing sailboat

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

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

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

A Transom-Hung Rudder

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

Spade Rudder

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

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

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

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

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

Skeg-Hung Rudder

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

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

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

Semi-Balanced Rudder

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

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

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

Making Alacazam's Rudder

A foam-cored clamshell rudder for a production sailboat

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

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

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

But first, the rudder stock.

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

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

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

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

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

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

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

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

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

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

Fitting the Sailboat Rudder

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

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

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

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

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Foss Foam Products of Florida, Inc. manufactures sailboat rudders and centerboards. Our products are produced with a gel-coat finish and rugged fiberglass shell. Each rudder is filled with foam under pressure. Foss Foam is high density (20 PSI), closed cell, polyurethane foam. This foam core is chemically bonded to the fiberglass shell. The formula for Foss Foam was formulated by Chuck Foss in the 1960’s and still remains a trade secret to this day. Foss Foam is light weight, extremely strong and durable, and is impervious to gasoline and diesel.

Available Rudders We have the ability to modify these rudders to fit many other boats or we can make a mold from your old rudder. Please don’t hesitate to call!

Beneteau 325, 331s, 370, 381, 13.5,361, 393, 405, 456, 473, 477, 51 Cabo Rico – 38 Cal – Fun, 22, 24,25, 27, 9.2, 28, 31, 33, 35, 39 New & 39 Old Cape Dory – 30 Captiva – 25, 25 Centerboard Catalina – 25, 30 Columbia – 29 Com-Pac – Order through manufacturer Creative Marine Rudder, Centerboard CSY – 44 Endeavour – 32, 33, 35, 37, 38, 40, 42, 43, 52 Endeavour Cat – E-Cat44, Victory 35, Victory 36, Manta 40, Manta 42, E-Cat 30,34,36 Hunter Marine – All Sizes All years Islander – 40 Irwin – 28, 32, 33, 34, 37, 38, 43, 52, 54, 65

Leopard – 40, 42, 43, 44 Marine Innovator – 17 Morgan – 23 Centerboard, Large centerboard, Rudders – 30 and 30/2, 34, 383 & 384, 41,44, 45 (Cruising/racing), Antigua 51 – 53 Nimble – All Models – All Years O’Day – 19.2, 22.2, 23, 24, 25, 26, 27, 28, 28, 30, 31, 32.2, 34, 35, 39, 40 Pearson – 26, 27, 40 Thru Chip Lawson

Seidelman – 34 Spindrift/Chrysler/OME/Starwind – Swing Keel, 19, 23, 27 Soverign – 17, 21/23

S2 – 9.2, 11.0 Tanzer – 22 and 26 TMI – 27, 30 Watkins – 23 Centerboard – Rudders – 27, 29, 33, 36

Rudder Order Guidelines

Foss Foam ships sailboat rudders all over the world. It is important to verify the dimensions of the rudder and shaft before we begin production. In many cases we have drawings/sketches. If we do not have drawings, it is the responsibility of the customer to provide the drawings. These drawings do not need to be professional quality. Sketches are acceptable, and we will be happy to provide you with examples. If you do not have the ability to make a drawing, please enlist the help of someone who does. Pictures of the rudder with a tape measure laying on it are not accepted. We do not usually drill holes in pipe shaft rudder as this is more accurately done upon installation.

Information required to order a standard rudder:

Verify the rudder outside dimensions of the drawing you are providing.
Verify the shaft od and id, exposed shaft length and any machining and the orientation of the machining.

Information required for nonstandard rudders.

The outside dimensions of the rudder including shaft to the top of the rudder (hull angle). If we do not supply you with a drawing. You will need to make one.
Shaft detail. The od, id, exposed shaft length, along with any machining. The orientation of the machining.

Thanks, Bob “Al” Walker

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Rudder Types for Sailboats

A rudder is a one-of-a-kind technological achievement for sailboats. There are a handful of rudder types for sailboats to allow sailors to steer.

March 16, 2023

This article may contain affiliate links where we earn a commission from qualifying purchases.

Today’s sailboats use various rudders that serve unique purposes in steering or performance. You are probably wondering which rudder type you have on your boat and which one is best.

There are four types of rudders, which are skeg, spade, outboard, and full. Depending on the size of the boat and the hull will determine which rudder it will need. In addition, each rudder type will have a slight variation that will meet certain expectations of performance on the boat.

Sailors need to rely on a rudder in order to steer their boat efficiently. Each boat will not have the same rudder, as different styles of sailing require different rudders.

According to experienced sailors, each rudder has its pros and cons. However, the best rudder needs to match your expectations in sailing.

Table of Contents

‍ Rudder Types

With the four rudder types mentioned, each one will have its pros and cons. As you begin your travels on bluewater or are interested in learning more, then it would not hurt to check out what each rudder is designed to do.

Full Keel Rudder

If you were to picture a sailboat with a rudder, it would likely be a full keel rudder. The most common rudder type is the full since a lot of sailboats use a full keel.

The reason a full keel is the most common keel on a sailboat is that it is the best one to provide stability. In that case, you need a rudder that can accommodate that type of boat.

On a full keel sailboat , the rudder looks like it is part of the keel itself. It is actually attached on a hinge, giving it the appearance that it is fully connected to the keel.

Advantages of a Full Keel Rudder

A full keel rudder is quite strong and actually helps tremendously with the protection of the boat. During a strong storm or harsh waves, it can be easier to navigate with this type of rudder. In addition, debris is significantly less likely to snag on anything like other rudders.

Disadvantages of a Full Keel Rudder

While a full keel rudder might be the best one to handle in strong storms, it is still the most difficult rudder to handle. Since the flow of the water is providing pressure on the full keel, it makes it harder to move the rudder. You would need to put a lot of effort into steering, especially in harsher conditions.

Skeg Rudders

Skeg rudders might give a full keel rudder a run for its money due to its durability. These are often referred to as skeg mounted rudders.

These are similar to full keel rudders, but can also be used on fin keel boats . This alone gives it a slight edge over full keel rudders, but each boat design will differ.

Advantages of a Skeg Rudder

With similarities to a full keel rudder, you are going to have the stability as well in a skeg rudder. The added bonus is that it works in either a full keel boat and a fin keel.

Disadvantages of a Skeg Rudder

Just like a full keel rudder, all of the pressure of the water hits on one side or the other. This means it will be hard to turn in rough conditions.

Spade Rudders

These rudder types are best fit for a fin keel boat rather than a full keel or to the types of boats. It enters straight down into the water and can rotate left or right using a post that extends within the hull.

Advantages of a Spade Rudder

The best advantage of a spade rudder is that it can be part of the fin keel. You can turn this rudder much easier than a full keel rudder or skeg rudder. The water is not forced one side or the other, allowing a better flow and easier turn.

Disadvantages of a Spade Rudder

If you sail upon a lot of debris in the water, you are likely going to damage the rudder. These are more delicate than skeg or full keel rudders, as they are more exposed.

Debris can get caught in between and potentially wrapped within the space rudder. In addition, rough water can be a nightmare. Tough conditions can cause enough pressure to bend or potentially break the rudder.

Outboard Rudder

Outboard rudders are not attached to the boat’s hull and are mounted outside at the back . Typically, these are not connected to a steering wheel and are connected by a tiller.

A tiller is a steering lever that can take some getting used to if you have solely used steering wheels. On smaller boats, sailors actually like a tiller over a wheel.

Advantages of an Outboard Rudder

If an outboard rudder becomes damaged, it will not typically affect the rest of the boat. This is because there is not a rudder post through the hull.

In the event that you damage it while at sea, you have the opportunity to fix it. Since it is on hinges and not attached to the hull, it might be able to be fixed. This also means the rudder might be stronger than other rudder types.

Disadvantages of an Outboard Rudder

Since the outboard rudder is at the back of the boat, it is vulnerable in some situations. If floating debris or something like a rope is in the water, it can tangle up in the rudder or damage it.

The location of the rudder also makes it harder to turn than a spade rudder. In tough conditions, this might be difficult to turn.

Purpose of a Rudder

A rudder is one of many important components of a boat to operate as efficiently as possible. Some boats are built for speed and others for comfort, so a rudder also has to fit that category.

Water pressure will dictate how the rudder moves in the water. Whichever direction you turn the rudder, then water pressure will push against it and allow you to turn.

While a sailboat is turning, it is pivoting around a middle point of the boat. The stern and bow move at the same time, while the middle point of the boat remains in place. Knowing how to properly operate a rudder to steer can make a huge difference in avoiding a crash.

Variations of Rudders

While some rudders are fairly cut and dry for their intended use, other rudders have slight variations to the design. This allows a little bit of flexibility on some boats, which is great because not all boats are designed the same.

Balanced Rudder

A balanced rudder is a form of a spade rudder with a slight difference in free space at the top. The leading edge allows rotation from one side of the boat while the trailing edge goes opposite.

The post is also a few inches back from the front of the rudder, which is slightly different from a regular spade rudder. Even though the turning action is roughly the same in comparison to a spade rudder, the force on the helm has more balance and makes it easier to steer.

You will usually see this type of rudder in performance boats or yachts. Furthermore, they are always paired with a fin keel to provide the best performance overall.

The only drawbacks to a balanced rudder is that it is susceptible to debris if you were to run anything over in the water. You have to rely on the structural integrity and hope that it is strong enough to take a blow. If it were to fail, it does not revert back to the center and might make it difficult to navigate the boat.

Unbalanced Rudders

Unbalanced rudders have the support from a full length skeg and are attached to the furthermost point of their span. It is unbalanced because the entire rudder is aft of its axis or the centerline where the rudder stock is located.

When you begin turning this rudder type, you get all of the force on one side. Whoever is steering the boat will notice this feeling compared to other rudder types, especially when using a tiller.

As you can gather, these rudder types are not commonly used today. You might find one used in history books or replicas of older boats.

If this were commonly in use today and were to fail at sea, the rudder remains in place and not go back to the centerline. This caused serious issues in the past and arguably why it is not very popular anymore.

Semi-balanced Rudders

If you can picture what a balanced and unbalanced rudder would look like, then a semi-balanced rudder is something in between. The name suggests that it is partially balanced and unbalanced at times.

The top part of the rudder is unbalanced, while the lower part is balanced. With the top part being this way, it helps by providing structural support to the rudder by aiding in vertical displacement.

During this process, the balanced section will endure less torque pressure during swings. It will then return back to the centerline if the steering equipment fails, which is a critical aspect that balanced and unbalanced rudders did not originally have.

Semi-balanced rudders are also different from other types since they vary in size and shape. You will often hear sailors talk about the depth of the horn, which is the connection between the rudder and the boat.

A shallow horn rudder has a horn that extends less than half of the chord length from its top. In a deep horn rudder, the horn extends more than 50 percent of its chord length from the top.

Semi-balanced rudders have had some unique innovations over the years. They appear to be the best of both worlds between balanced and unbalanced.

Twin Rudders

Twin rudders have been used since 1980 among racing boats. Over the last decade or so, they have increased in popularity among cruising sailboats.

Twin rudders have a history of being difficult to operate in tight spaces if you do not have experience with them. This is true, especially since it navigates a little differently than one rudder.

When using a boat that has a twin rudder, the prop wash moves by both rudders and you cannot have the same maneuverability as with one rudder. One tactic you could do is to increase your boat speed to increase water flowing between the rudders. In doing so, it could cause some concern in tight spaces if you are unable to land exactly where you want.

One positive to twin rudders is that it performs well in reverse. You do not have as much prop walk as other boats and can handle better in lower speeds due to increased blade length on both rudders.

Another benefit is that it responds better to the wind. In single rudder boats, the wind can push the bow in one direction while the stern goes opposite. For twin rudders, the wind does not have as much of an impact in that regard.

Can Rudders Fail While in Use?

Just like anything in life that you use, it has a lifespan on it. For a rudder, some can fail while you are using them at sea.

Rudders failing at sea is actually a common hazard, so knowing what to do in that situation is very important. Sometimes cheaper boats, like a fiberglass boat, will experience a rudder failure likely before a more expensive boat.

The material of the rudder pole has to be a good blend of flexibility and strength. If it is too weak, it will break. If it is too strong, it might damage the hull since it cannot flex properly.

The framework inside the rudder should be a heavy-duty metal, because if it breaks, then it will be unusable. This is likely the case in cheaper boats, where costs have been cut in certain areas. Depending on the boat brand, you might see welding jobs that are not executed properly for rudders.

In addition, the type of rudder you use at sea can make a big difference. Full keel rudders might be the best option since it is protected from debris and offers the best stability. Depending on your sailing goals, the right rudder type will be different for everyone.

What are Rudders and Stocks Made out of?

Rudders have historically been crafted out of heavy duty stainless steel or aluminum. You want something that is non-corrosive and can withstand some beating.

If you were to look at high performance yachts, these typically have alloy since it is lighter but also strong. Stainless steel can handle swelling and debris, but crevice corrosion could be an issue.

Composite is another material that is used in mass production yachts or high performance boats. Some material is arguably better than others, but there is really not a perfect option out there. A proper inspection is needed before doing any long term use at sea.

Why a Tiller Could be Better than a Wheel for Rudders

If you have sailed a boat with a steering wheel and have never used a tiller, you could be missing out. Regardless if you are new to sailing or a seasoned pro, a tiller is very easy to use.

Tillers provide instant feedback when turning a boat, whereas steering wheels take a minute to get results. For newer sailors, a wheel could prove to be frustrating in rough conditions.

Depending on the size of your boat, a wheel might be the better option. In larger boats, a tiller does not perform the same.

Even though a tiller is harder to turn, it still offers an immediate reaction. This is why you will oftentimes see tillers on racing boats because they provide instant feedback.

What Happens if Your Rudder Fails?

While safety is a priority in everything you do while sailing, there are some situations you cannot avoid. No matter how much preventative maintenance you do, your rudder might still become damaged or unable to use.

If bearings have seized, the rudder can become difficult to move at first but will eventually lock up. Your steering capability will eventually be impossible and quite difficult to stop the boat from rounding into the wind.

If it were to fall off completely, then you will have quite a difficult time tracking the boat. The rotation of the boat might even be abrupt or rapid.

It is important to stay calm during a situation like this and to check on the crew. Drop your sails and attempt to gain some control.

You could even try pointing the bow into the wind and dropping anchor to reduce motion. Once the boat is under control, check for damage and call for assistance.

If you cannot phone for assistance, the best thing you can do is to create a makeshift rudder or potentially purchase one before a situation like this happens. For example, brands like Seabrake and Delta Drogue are quality rudders you could use in a pinch to safely make it back to shore.

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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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IMAGES

The Types of Sailboat Rudders
Kick Up Rudder
4 Rudder Types for Sailboats
Rudder Options For Lifting Keel And Centerboard Offshore Sailboats
mini transat sailing rudders retrofit
The Types of Sailboat Rudders

COMMENTS

4 Rudder Types for Sailboats
Learn about the different types of rudders for sailboats, such as full keel, spade, outboard, and skeg-mounted rudders. Compare their advantages and disadvantages, and how they affect the boat's performance and stability.
Replacement Rudders and Centerboards
Foss Foam Products is a family owned company that produces and sells sailboat rudders and centerboards for over 40 years. They are the original equipment manufacturer for many sailboat companies and offer quality and expertise in rudder repair and custom molds.
Rudder Craft
Rudder Craft offers hydrofoil sailboat rudders, tillers, and accessories for various sailboat models. Learn how hydrofoil design improves steering performance, reduces drag, and enhances sailing experience.
What is a Sailboat Rudder?
A sailboat rudder steers the boat. A rudder is a hinged fin or blade mounted on the stern of the vessel that turns side to side, and it's controlled by a tiller or a helm. A rudder is one of the primary controls of a sailboat. When the boat moves forward through the water, the rudder causes friction on one side and changes the direction of the ...
Foss Rudders
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.
The Types of Sailboat Rudders
On a sailboat, as the rudder is moved to one side by means of the tiller or steering wheel, the force of the water striking one edge of the rudder turns the stern in the other direction to turn the boat. Different types of rudders have different advantages and disadvantages. The type of rudder is often related to the boat's type of keel ...
Four Types of Rudders On Sailboats
The boat will rest safely on its side until the tide returns and lifts the boat off the shoal. Spade Rudder. The spade rudder rests below the transom separate from the keel. A spade rudder turns easily because the water rushes both against its fore and aft edges - good when using a tiller. There's less wet area so the spade rudder is fast.
Know Your Rudder
Know Your Rudder. After hull integrity, rudder integrity is the most vital component of a seaworthy vessel, yet most sailors pay more attention to LED lighting or smartphone apps than they do to their boat's rudder. Before you shrug off rudder failure as a remote concern, consider that the incidence of mid-ocean rudder failures is close to 1 ...
The Foss Company Makes Quality Sailboat Rudders and Dagger Boards that
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 ...
How To Repair a Rudder
6. Fill small cracks above the water line with Capt. Tolley's Creeping Crack Cure. Top rear crack sealed and painted. 7. Last, re-apply ablative paint or a polyurethane topcoat to match the rest of the rudder or hull. If you keep your sailboat in the water, ablative paint can minimize algae growth.
What Is a Sailboat Rudder? An Overview of Its Function and Design
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 ...
All About the Rudder on a Sailboat
Obviously, the rudder is a pretty important part of a sailboat. Without it, the boat cannot counter the forces put into the sails and cannot steer in a straight line. It also cannot control its direction, even under power. A rudder failure of any kind is a serious emergency at sea.
Building a Faster Rudder
A boat with poorly trimmed sails and a crudely finished rudder will miss tacks and roll like a drunkard downwind when the waves are up. On the other hand, a rudder that is properly tuned will agilely swing the boat through tacks even in rough weather, and provide secure steering that helps prevents broaching when things get rolly.
Sailboat Rudder Types
The boat will sit comfortable on its side until the tide returns and floats the boat back up. A spade rudder meets the water on both edges for easy turning action. 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.
Sailboat Rudders
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. These twin high-aspect ratio rudders on an all-out race boat are clearly optimised for their hydrodynamic ...
The Rudimentaries of Rudders
Walking around a boatyard one day and measuring a few cruising sailboat rudders, I came up with aspect ratios of between 1.7 and 2.1, while one high-performance sailing vessel's rudder came in at 3.5. The 20-knot semi-displacement lobster yacht's rudder I measured yielded an even 2.0 aspect ratio, which is considered respectable for this ...
Rudder Mods for Low-speed Docking
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.
Making a Sailboat Rudder for an Offshore Yacht
This design of sailboat rudder is something of a compromise between the spade rudder and the full skeg rudder. Supported at its mid-point by a half-depth skeg, it benefits by the area forward of the stock, below the skeg. This applies a balancing force as the rudder is turned making the steering lighter than it would otherwise be.
Know how: Fixing a Loose Rudder
Problem No. 1: A Bad Design for the Rudder Bearing. While most of the systems on the Niagara 35 are overbuilt and well designed, for whatever reason, the rudder post bearing is simply not. Despite the thousands of pounds of force on the rudder being magnified at the fulcrum where the post comes up through a bearing in the cockpit floor, the ...
Replacement Rudders We Carry In Stock
Watkins - 23 Centerboard - Rudders - 27, 29, 33, 36. Rudder Order Guidelines. Foss Foam ships sailboat rudders all over the world. It is important to verify the dimensions of the rudder and shaft before we begin production. In many cases we have drawings/sketches.
Custom kick-up rudders
The Kick-Up rudder design includes a 316 stainless steel nitrogen charged gas strut (patent-pending) which keeps the rudder blade in the ideal position for top performance. These rudders shrug off obstacles and groundings, returning to position automatically, predictably, every time. The rudders can be raised 180 degrees for easy and safe ...
Rudder Types for Sailboats
Today's sailboats use various rudders that serve unique purposes in steering or performance. You are probably wondering which rudder type you have on your boat and which one is best. There are four types of rudders, which are skeg, spade, outboard, and full. Depending on the size of the boat and the hull will determine which rudder it will need.
How to Build a Sailboat Rudder From Scratch
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.

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Identifying the Rudder

Rudder Design

How Does a Sailboat Rudder Work?

Can a Sailboat Rudder Steer in Reverse?

Sailboat Steering Characteristics

Tiller Steering

Benefits of a Tiller

Tiller Self-Steering

Helm Steering

Hydraulic Rudder Control

Rudder Maintenance

What to Do if the Rudder is Damaged

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The Types of Sailboat Rudders

Full Keel Rudder

Rudder on Full-Keel Sailboat

Advantages of Full Keel Rudder

Disadvantage of Full Keel Rudder

Spade Rudder

Advantages of Spade Rudder

Disadvantage of Spade Rudder

Balanced Spade Rudder

Skeg-Mounted Rudder

Outboard Rudder

Advantages of Outboard Rudder

Disadvantages of Outboard Rudder

The $tingy Sailor

How To Repair a Rudder

It’s just like doing auto body work

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

Quick Facts

Components of a Sailboat Rudder

Different Types of Rudders

Materials Used in Rudder Construction

The Function of a Sailboat Rudder

Balancing the Sailboat

Rudder Effectiveness in Different Conditions

Design Considerations for Sailboat Rudders

Rudder Size and Shape

Rudder Placement and Configuration

Rudder Shaft Turned