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What is a Boat Keel? & What Does It Do? – Detailed Explanation

Written by J. Harvey / Fact checked by S. Numbers

what is a boat keel

Knowing the different parts of a boat is important for any mariner. If you look at your vessel exterior, one of the things that’s noticeable is the keel. But what is a boat keel and what does it do?

The keel is a horizontal structure at the bottom section of the hull, which acts as the boat’s main support. We’ll cover keel definition boat use and other relevant information.

Keep reading to learn more.

The Boat Keel and What It Does


The keel of a boat is a beam that acts as structural support for the hull and entire vessel. It has many types, and varying designs lead to differences in appearance, with some being longer and extending deeper into the water.

However, serving as support for the hull is not the only purpose of a keel on a boat. It also counterbalances a vessel, which helps to keep it in place and not be displaced by external factors. It is also partially responsible for moving a boat forward and aids steering.

The keel of a ship functions similarly to the keel on boat, serving as the backbone and ballast. It is often the first thing to be constructed on a ship.

Types of Keels


1. Full

This type usually covers the entire length of the vessel and is one of the most common types used. This keel offers a high degree of safety, owing to its very stable performance along with the ability to run through sand without breaking off.

2. Fin

This is similar to the full keel but shorter, running less than 50% of the length of a vessel. This difference allows it to contribute to a boat’s ability to turn while also giving improvements to its speed. This type is commonly found in racing models.

3. Bulb

This keel boat part is similar to the fin, except for the bulb attachment at the bottom, which resembles a torpedo.

The shape of the bulb also makes it less likely to be damaged by contact with rocks, and this type is excellent for cruising.

4. Wing


This design extends the length of the keel, making it similar in appearance to an airplane wing. This design allows a vessel to turn and maneuver more easily, but it is more susceptible to breaking or digging into the ground.

5. Bilge

Instead of just one at the center, the bilge keel has one for each side of the hull. A vessel with this type of keel has less roll, which gives better comfort on the water. It also has a lower draft and allows easier anchoring on shallow waters.

6. Centerboard and Swing

These are two different types of keels but are grouped because of their similarities in design. These can adjust their length, making them usable for both deep and shallow water. However, centerboards only partially retract, while swing types have their entire length fully adjustable.

These have the advantage of adjustability but less performance, and they also have more components that require checking compared to fixed keels.

7. Canting

This is similar to the swing keel in that its entire length is connected to a hinge at the bottom of a sailboat but adjusts from side to side, starboard to port, and vice versa.

It can boost speed and maneuverability by wetted surface reduction and weight shifting. This is often used for racing vessels but is still considered experimental as there is a high rate of failure due to its reliance on hydraulics.

Frequently Asked Questions


Hull and keel: what is the difference?

The keel hull confusion likely stems from the fact that the keel is often part of the hull. However, they are two entirely different things, since the hull is the main body of the boat while the keel is a beam that is connected to the bottom of the hull and may extend farther down from it.

Do all boats have a keel?

Most boats do, but not all boats, as flat-bottomed ones are the exception. The keel boat Lewis and Clark Expedition used in 1803 is a well-known example. This was a barge, a type of flat-bottom vessel that was a boat without a keel.

How is the keel of the boat different from the keel at the bottom of a ship?

Both ships and boats have keels that function in similar ways, but how they are constructed and even the keel shape are different. While most types of sailboat keel are fin-like in appearance, a keel ship needs to be much wider to be able to support the entire ship’s size.


Knowing what is a boat keel is a very important matter that you should no longer have trouble with. Now, you can move on to learning other major parts of vessels. Just remember to consider the draft and use a boat keel guard to safeguard your vessel.

Which type of keel is best in your opinion? Tell us all about it in the comments section below. We’ll be waiting to hear from you.

Remember to boat safely.

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