Boat rudders: Types and how they work

Boat rudders are an essential part of a vessel’s steering system and help you move left and right while out on the water.

In this guide, we’ll look at how you use a rudder, the difference between a tiller and a boat rudder, and the different types of rudders you might come across.

What is a boat rudder?

A boat rudder is a flat blade under the water at the back of a boat that helps you steer. When you turn the tiller or wheel, the rudder moves to one side, changing the way water flows past it. This causes the back of the boat to move one way, and the front to turn the other. Although it may appear simple, the rudder’s shape is carefully designed to allow the boat to turn smoothly without slowing it down excessively.

Different boats employ various types of rudders. Some are built for durability, while others focus on quick, easy turns. A good rudder also helps the boat maintain its course, even when waves or wind try to push it off course. With small, gentle movements, the rudder lets the sailor control the boat’s direction and keep it moving safely.

How do you use a rudder on a boat?

How you use a boat rudder depends on whether the vessel has a tiller or a wheel. If the boat has a tiller, pushing the tiller to the left causes the boat to turn right, and moving it to the right causes it to turn left. When using the tiller, make small, smooth movements and look in the direction you want the boat to go. When the boat begins to turn, return the tiller to the centre.

If the boat has a wheel, turning it to the left makes the boat go left, and turning it to the right makes the boat go right. Turn the wheel gently and centre it when you want to stop turning.

What’s the difference between a rudder and a tiller?

A rudder and a tiller are both parts of a boat’s steering system. The rudder is an underwater blade at the back of the vessel that moves the water and turns the boat. The tiller is the handle you hold. It attaches to the rudder at the top, and moving the tiller controls the rudder’s angle. Essentially, the rudder steers the boat, and the tiller lets you steer it.

On boats with a wheel, the wheel replaces the tiller, but the rudder still works in the same way.

The different types of boat rudders

There are many types of boat rudders, each with its own unique uses, advantages and disadvantages. Some of the most common boat rudders include:

1. Balanced spade rudder

A balanced spade runner is fully suspended, meaning it’s unattached at the bottom. Part of its surface area is placed forward of the stock to balance steering loads. Balanced spade runners are commonly found on modern performance sailboats, racing yachts, and some cruising yachts, as they enhance responsive handling.

Pros

• Very light helm effort
• Ideal for tight turns and performance sailing
• Efficient hydrodynamic shape

Cons

• Vulnerable to impact
• Complex bearings and stock systems
• Difficult and expensive to repair

2. Skeg-hung rudder

A skeg-hung rudder is mounted to a partial fin, or skeg, that extends down from the hull, providing structural support and directional stability. This type of boat rudder is typically found on offshore cruising boats and yachts, prioritising durability.

Pros

• Protection from grounding and debris
• More directional stability than a spade rudder
• Stronger mechanical support, which reduces strain on the rudder stock

Cons

• More drag than a spade rudder, resulting in a slightly slower performance
• Heavier steering
• Skeg repairs can be complicated after a hard impact

3. Keel-hung rudder

As its name suggests, a keel-hung rudder is mounted directly to the trailing edge of a full-length keel. This type of boat rudder is commonly used on traditional long-keel sailboats, cruisers designed for comfort, and classic vessels.

Pros

• Extremely robust, which makes them ideal for long-distance cruising
• Excellent straight-line tracking
• Very low maintenance due to their simple construction

Cons

• Slow to manoeuvre with a large turning radius
• Less responsive handling than other rudder types
• Increased drag compared to other designs

4. Outboard rudder

An outboard rudder is hung externally on the transom and is typically found on dinghies, small sailboats, and some traditional double-enders.

Pros

• Everything is accessible, which means it’s easy to inspect and repair
• Simple, lightweight construction
• Can be lifted or removed in shallow water, depending on its design

Cons

• Little protection, making it exposed to damage
• Can lose bite in heavy conditions
• Limited size and leverage for larger vessels

5. Vane rudder

A vane rudder is a self-steering system where a wind vane controls either a small auxiliary rudder or the main rudder by directing the flow of water. Vane rudders may be found on some cruisers and are useful for solo sailors who need mechanical self-steering.

Pros

• No electricity required as they work using force from wind and water
• Very reliable for long passages
• Reduces crew fatigue and can handle different conditions well

Cons

• Only works effectively when sailing, as it requires wind
• Can be vulnerable to breaking waves from astern
• Requires careful calibration

6. Duck rudder

A duck rudder pivots vertically or partially tucks up and is commonly used on dinghies and river craft operating in shallow or obstacle-prone waters.

Pros

• Automatically lifts on impact, protecting the rudder and its fittings
• Ideal for beaching or shallow water sailing
• Simple mechanical design

Cons

• Less efficient hydrodynamically due to its pivoting structure
• Can kick up unintentionally in rough water if not secured
• Only suitable for small or light vessels

7. Lifting rudder

A lifting rudder can be lifted vertically to reduce draft in shallow water and is ideal for trailer sailors, performance dinghies, and lightweight coastal cruisers.

Pros

• Adjustable draft, which is excellent for shallow water sailing and launching
• Usually features an efficient foil shape when fully down
• Simpler to service as it’s easy to remove

Cons

• Complex trunk and lifting gear compared to fixed rudders
• Can jam when it encounters sand or debris
• Higher maintenance due to moving parts

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Taking your boat out on the water can come with risks to you and your vessel, which is why you may want to consider getting specialist boat insurance.

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