Different rudder types and their advantages
Full keel rudders
Many sailboats have a full keel rather than a fin keel, which requires a particular type of rudder. A full keel is the standard type of keel, or flat blade at the bottom of a sailboat. A full keel is designed for stability, not speed - it can keep you safe in rough water.
A generation or two ago, nearly all cruising boats had full keels. However, this is no longer true. Many customers today prefer fin keels, which are designed with speed rather than stability in mind.
A fin keel is smaller than a full keel and shaped differently. Fin keels are more popular today because many sailors today never go far from the coast. If you are near the coast, fin keels are relatively safe.
With a full keel sailboat, the rudder appears to be part of the keel. It is attached with a hinge and looks like a continuation of the keel. There may be a hole between the keel and the rudder, where the propeller is, although not all boats use this design.
What is the advantage of a full keel rudder?
A full keel rudder is strong and protects the boat from harm. A full keel rudder helps a boat survive a storm. Any debris floating by will not snag on a full keel rudder as it will snag on some other rudders.
Do full keel rudders have any disadvantages?
It is harder to move a full rudder than to move other types of rudders. Water flowing by the boat puts a great deal of pressure on a full keel rudder and makes the rudder hard to move. It takes a lot of force to push the rudder against the water moving past the boat.
Spade rudders are for fin keel boats rather than full keel boats. A spade rudder sticks straight down into the water. A spade rudder can rotate left or right with a rudder post that extends into the hull.
Advantages and disadvantages of spade rudders
The most obvious advantage of the spade rudder is that it can be part of a fin keel boat. A full keel rudder requires a full keel - you could not attach a rudder of this type to another type of boat.
It is also not nearly as difficult to turn a spade rudder as it is to turn a full keel rudder. The water does not put all of its force on one side of the rudder, so it does not take as much force to turn it.
One disadvantage is that debris floating in the water can get caught on a spade rudder. Spade rudders are more delicate than full keel rudders in many ways. Debris can damage a spade rudder.
A spade rudder can also be damaged by rough water. Large waves may exert enough pressure on a spade rudder that it will break. A large wave can bend the rudder post, and after that happens, your rudder becomes useless.
An outboard rudder is not part of the boat's hull and is mounted outside of it, at the back of the boat. Usually, an outboard rudder is not hooked up to a steering wheel.
Instead, it is hooked up to a tiller, which is a steering lever. A tiller can take a bit of getting used to if you are used to a steering wheel, but a tiller is not hard to use. Many sailors prefer a tiller, especially for smaller boats.
Advantages and disadvantages of outboard rudders
If an outboard rudder is damaged, it is not likely to damage the rest of the boat. Since there is no rudder post running through the hull, damage to the rudder usually won't mean damage to anything else as well.
You may also be able to remove and fix a damaged outboard rudder while you are still out at sea. There is no way to remove a rudder that is part of the hull and beneath the boat, but a rudder attached to the boat with hinges may be possible to fix at sea.
Outboard rudders are not necessarily weaker than and can be stronger than other types of rudders. The hinges that hold an outboard rudder in place may be stronger than a rudder post.
In some ways, an outboard rudder is worse than either a spade rudder or a full keel rudder. Unlike a full keel rudder, things like rope floating in the water can get caught on an outboard rudder. Objects floating by can also hit and damage an outboard rudder more easily than they can damage a more durable full keel rudder.
Compared to a spade rudder, the outboard rudder is harder to turn. The water pressure will always be on one side of the rudder; this is not always the case with spade rudders.
Skeg mounted rudders
Skeg rudders are both durable and possible to use on fin keel rather than full keel boats. Skeg mounted rudders are more durable than the spade rudders you usually find on fin keel boats.
Skeg mounted rudders have the same disadvantage as full keel rudders and outboard rudders, which is that they require more energy to turn. The water will put all of its pressure on one side of the rudder. Only spade rudders avoid this problem.
Is a tiller better than a wheel?
Either for inexperienced or veteran sailors, a tiller can work better. With a tiller, you will get immediate feedback. If you turn a wheel, the boat won't turn right away, which can confuse or annoy a new sailor.
The tiller should be long enough, as it is harder to turn if it is shorter. In strong winds, you need a long lever to turn your boat without it taking a great deal of strength.
It is easier to turn a wheel than to turn a tiller, as there is more leverage with a steering wheel. Therefore, wheels are better for larger boats; as a tiller is harder to turn with a bigger boat.
A tiller's advantage is that it is more responsive than a wheel, even though it is harder to turn. The boat will start to change direction almost immediately if you use a tiller. In racing, it is normal to use a tiller because you can change direction more quickly.
How does a rudder work?
A rudder works through water pressure. If you turn the rudder, the pressure becomes higher on one side of the rudder than the other. The rudder then moves toward the side with the lower pressure, which causes the boat to change direction.
When a sailboat turns, it pivots around a point near the middle of the boat. Both the stern and the bow move simultaneously, with the middle of the boat not moving. You have to take this into account while sailing, or else you might swing the end of your ship into another boat.
What is the purpose of the keel?
The keel keeps the boat stable. Without a keel sticking down from the boat into the water, it would be easy for the wind to push the boat around. Without a keel, the wind could easily push you sideways and make the ship much harder to control.
A keel is also weighted. The keel is full of ballast, which is weight that keeps the boat from flipping over. Without ballast, a boat would be top-heavy and unsafe.
Keels are usually made out of the same material as the rest of the boat - if the boat is aluminum, the keel will be as well. The ballast is usually lead.
While full keels are better in rough weather in most ways, a fin keel does a better job of preventing the wind from blowing your boat around. Wind can create leeway, which is sideways movement of the boat. Leeway is most likely if you are sailing into the wind.
Do rudders often fail at sea?
Yes, a rudder failure is one of the more common hazards you might encounter at sea. Not every sailboat has a good, durable rudder. The rudders on cheap boats, especially cheap fiberglass boats, can fail.
The rudder pole should neither be too weak nor too strong. If the rudder pole is too weak, it will bend easily. If it is too strong, it may damage the hull rather than bend, which is even more dangerous.
A rudder has a metal framework inside of it. If the framework breaks, the rudder will become unusable. With a cheaper boat, the metal framework may not be welded together properly.
Make sure you buy a sailboat that has a reputation for safety. Don't buy the cheapest boat you can find - look into whether or not the boat is safe to take out to sea.