Updated at: 13-09-2021 - By: Lucas

A rudder is a steering device used on boats. It is usually attached to the stern (back) of the boat by a horizontal arm called a “rudder post”. The rudder is shaped like a wedge and it is this shape which allows it to effect a turning movement of the boat. 

A boat without a rudder is like a car with no steering wheel; it just goes wherever the driver wants it to go. A boat with a properly designed and working rudder can turn to the right or the left and change its heading as directed by the captain. Therefore, a properly designed and working rudder is one of the most important safety devices on any boat.

Spade Rudder


A spade rudder is a type of control you use when steering a boat with a center console. It’s also known as a “spud” or “spade” rudder. This type of rudder is attached to the stern of the boat and extends out past the transom. On many boats, there are two or more spade rudders. Each one steers a different direction. 

A boat with a center console has an easier time keeping its course because the captain or pilot can use the console to steer the boat. Without a center console, the spade rudders would be the only steering device available.

They are also very effective for heavy weather conditions. When you are running before the wind or in heavy seas, you can use the spade rudders to help keep the boat heading in the right direction. The spade rudders attach to a bracket that is bolted to the transom of the boat. 

They have a long handle so the captain or pilot can reach out and move them back and forth as needed. On some boats, you will see three or four of these brackets. This allows the boat to be steered from both the stern (where the engine is) and from the bow (where the deckhouse is).

Balanced Rudder


A balanced rudder is the most efficient type of rudder that you can use. It has two straight edges with a third edge that is curved up at an angle. This type of rudder allows for the least resistance and movement of the water over the surface of the rudder. This type of rudder is also called a “cathedral” or “teardrop” type of rudder.

It is the most common type of rudder used on commercial vessels. It is also used on many pleasure craft. It is the best type of rudder to use if you want to have the smoothest, most efficient ride possible. It will give the smoothest ride of all the types of rudders discussed in this book.

Semi- Balanced Skeg Rudder

Semi- Balanced Rudder

A semi-balanced Skeg rudder is one where the left and right sides are of equal length. This type of rudder is very common and it provides a smooth and balanced feel when you push the boat forward with an even stroke. A fully-balanced rudder is one where the left and right sides are of exactly the same length. This gives a much more responsive feeling to the rudder. It also makes it much easier to maneuver the boat because there is no resistance from the water.

A semi-balanced rudder works best for most people. If you are very strong or have very long arms, then you may want to get a fully-balanced rudder. Some manufacturers, such as Daiwa make a wide variety of rudders, including ones with different levels of balance. You may want to look at the options that are available and see which one feels the best to you.

Full Rudder


A full ruddered boat has three rudders instead of two.  This gives the boat much more stability and makes it easier to navigate in rough water.  It also allows the boat to be turned much faster in a tight circle.  The extra rudder also makes the boat much more responsive to the rudder pedals.

It is important to note that a full-rudder boat will have a significant handling advantage over a boat with only two rudders. However, it should not be assumed that a boat with three rudders is necessarily a better boat than one with two.

Skeg Rudder

A skeg rudders are small fins (usually triangular) attached to the bottom of a boat to increase its ability to steer. They also improve the boat’s stability and give it better resistance to capsizing. Skegs are usually made of metal or fiberglass.

A fin like this is sometimes called a “drift keel” or “hydraulic rudders”. The name comes from the fact that they were once used on riverboats to help control the boat’s drift when it was being pushed by the current. Nowadays, these types of fins are used on pleasure boats and commercial fishing vessels. They’re also used on some types of military craft.

Outboard Rudder


An outboard rudder is a small device that is attached to the stern of a boat. It helps guide the boat by acting like an extension of the rudder pedal of the boat. When you use the rudder pedal, it acts like a brake for the front of the boat. 

However, when you use the outboard rudders, it works like a gas pedal for the back of the boat. Outboard rudders are used on boats with outboard motors. They are very useful for maneuvering the boat when you are close to the dock or other objects.

They are also very useful when you are in shallow water since they give you more control over the boat. When you first get your boat, you should go to your local boating supply store and get some outboard rudders. Then, you should become familiar with how they work. 

Once you understand how they work, you will be able to adjust them so you can fine tune their performance for maximum efficiency. This is especially important if you are going to use your boat for sport fishing. If you don’t do this, you could end up with a boat that is extremely difficult to control.

Unbalanced Rudder


An unbalanced rudder is a control surface attached to the stern of a boat that acts like an elevator. It is controlled by the helmsman using a tiller. An unbalanced rudder will cause the boat to list to one side or the other.

Unbalanced rudders are often used in small boats to help the boat turn in a tight circle. This type of rudder is usually located on the stern of a boat and it is used when you want to make a tight circle. If you do a lot of water skiing or other types of watersports, then you may see people using unbalanced rudders on their boats.

Schilling Rudder


The schilling rudder is a boat steering device consisting of a long wooden pole with a weighted, rounded end. The rudder is attached to the stern of the boat with a short length of rope or chain. When the rope or chain is tightened around the pole, the weighted end of the pole is pulled toward the center of the boat, causing the boat to turn in the desired direction.

The schilling rudder was originally designed to help a fisherman steer his boat when he was fishing in shallow water. It was invented in the 16th century by German sailors who were sailing along the coast of what is now Germany.

Fishtail Rudder

A fishtail rudder is a type of control surface found on the rear of many sailboats. It consists of a flexible piece of material attached to the rear of the boat which hangs down below the water line. As the boat turns, the rudder swings back and forth, like a tail on a dog, and helps guide the boat around the corner.

They are always designed to be used with a rudder post (a vertical wooden pole located just behind the stern of the boat), and 

They are always designed to be “flopped” (turned) by hand from the cockpit. This is true of all types of rudders, including centerboard rudders, skeg rudders, and genoa rudders. A fishtail rudder is simply the most efficient and popular type of rudder for small boats.

Flap Rudder


A flap rudder is a device that is attached to the rear of a boat and helps it turn in a straight line. It consists of a horizontal blade that is hinged to the bottom of the vertical blade of a V-shaped rudder. When the blades are moved together, they form a “V” shape that helps the boat turn in a straight line. When they are moved apart, they form a “U” shape which allows the boat to turn in a circle. This allows you to make the boat turn in any direction whatsoever.

You can attach a pair of these to the back of your boat to make it go in any direction whatsoever. You can use one on each side of your boat or even on the front if you want to. They are extremely useful for learning how to turn a boat and are a must-have for anyone who plans on taking their boat out on the water at all. These are very inexpensive and easy to install. You should be able to find them almost anywhere.


Distance of the rudder from the stern frame should be how much?

The distance from the stern frame to the rudder should be 20% to 25% of the boat length. If the boat is 12 feet long the rudder should be from 2.4 to 2.5 feet from the stern frame.

Why is the rudder angle limited to 35 degrees?

When designing a rudder we should remember that rudder is a part of a boat that can be damaged in a collision with a submerged object. That is why the rudder should be as long as possible and as big as possible to increase its strength.

But it’s also important not to make it too strong because then it will be hard to move when you want to maneuver the boat. So the compromise is to make it strong enough so that it will not break or bend in a normal situation but at the same time not so strong that it will damage your boat in a collision.

Why is the rudder situated aft of the ship?

When a ship starts to move, the rudder is the only surface which resists the force of the water. The rudder should be aft of the center of gravity. This way, when a ship has a turning moment the rudder will be the only surface which resists the force.

If the rudder were forward of the center of gravity, then when the ship turns, the rudder would be pushed sideways by the turning moment and it would no longer be able to resist the force of the water. Therefore, the ship would heel over and possibly capsize.

How does a rudder work?

A rudder works by deflecting the flow of water and creating a force called the rudder force (which will be explained in the next section). This force causes a reaction on the ship and causes the ship to turn. 

The more rudder force you create, the faster your boat will turn. The faster your boat turns, the less resistance you will experience from the water and the easier it will be for you to maintain your speed. 


Rudders are used to steer the boat in the right direction. They are very important in order to avoid accidents. If you don’t know how to use rudders properly, you may end up steering your boat in the wrong direction which may lead to an accident. It is really important to know how to use rudders in boats. 

Hopefully, after reading this article, you will have a good understanding about what a rudder is and how it works.