What Is a Swing Keel?

What Is a Swing Keel? | Life of Sailing

Last Updated by

Daniel Wade

August 30, 2022

Swing keels are a robust and useful alternative to centerboards, and they’re common on variable draft sailboats.

Swing keels are retractable keels that are hinged in the front and swing into a slot called a trunk. Sailors lift and lower the keel with a crank, pulley, or hydraulic system. Sailboats with swing keels can reduce their draft for shallow water sailing or to make them fit on a trailer.

In this article, we’ll show you everything you need to know about swing keels and the sailboats that use them. We’ll go over the benefits and drawbacks of swing keel designs, compare them to centerboards, and cover the different variations you’re likely to find on common sailboats.

We sourced the information used in this article from sailboat design guides, sailboat plans, and from the sailing community.


Table of contents

What are Swing Keels For?

Swing keels are commonly outfitted on trailerable sailboats that need low clearance. These vessels are usually longer than 20 feet and would normally have a fixed keel if they weren’t designed to be towed.

Swing keels are used in applications where centerboards are cumbersome or have insufficient ballast. Also, a swing keel allows additional ballast to be placed underneath the hull and around the keel trunk.

What is a Keel Trunk?

A keel trunk is a simple rectangular box located on the bottom of the hull. The box, which is open on the bottom and closed on the top, houses the swing keel and its hinge mechanism. The keel retracts into and out from the keel trunk.

The keel trunk can be located inside or outside of the hull. Some vessels have an external keel trunk that protrudes a few inches from the bottom of the hull and usually contains ballast for stability. Most swing keel sailboats have a recessed keel trunk, which is flush with the bottom of the hull.

How a Swing Keel Works

Swing keels, also known as lifting keels, are simple. They act a lot like a lever. The keel is contained in a trunk-mounted to the hull with a pin, which serves as a hinge. The keel is raised and lowered by a system of ropes and pulleys or by a hydraulic system.

Some swing keels are retracted into the trunk using a crank. This system is common on some Catalina sailboats and has proven to be very reliable. These systems usually use a ratcheting pulley which can be locked in one direction for lifting and lowering.

The weight of the keel keeps it in the lowered position, but some vessels have a simple locking device to keep the keel in the down position. When raised, the keel or the raising mechanism is locked securely into place.

Swing Keel vs. Centerboard

Swing keels and centerboards are not the same, but they share some characteristics.

 Centerboards are distinguishable from fin keels because, unlike fixed fin keels, centerboards can be retracted into the hull. Swing keels may appear like fin keels from the bottom, but they also retract into the hull.

So then, how are they different from centerboards? Unlike centerboards, which must be lifted vertically out of the centerboard trunk, swing keels hang on a hinge and fold into the hull. Hence, they ‘swing’ instead of raise.

Benefits of Swing Keels

Swing keels have several distinct advantages over centerboards. Chiefly, swing keels don’t require a massive trunk in the center of the cabin or cockpit.

Most swing keels retract into a trunk located below the hull. Others retract into a trunk under the deck, and some require a small amount of cabin space.

Swing keels never need to be removed or lifted into the boat. Additionally, it’s physically easier to raise a swing keel. This is because the keel distributes some of its weight to the hinge, and lifting it is easier thanks to the physics of levers.

Additionally, swing keel trunks are usually sealed. This is good for a number of reasons—especially in rough weather. Water rarely floods a boat through the centerboard trunk.

But lifting out a centerboard can make a mess, and a pitching and rolling boat could allow water in through an open centerboard trunk. Swing keels don’t suffer from this issue, as the only hole they have is for the rope and block system used to lift and lower the keel.

Drawbacks of Swing Keels

Swing keels have a few notable drawbacks. For one, they’re not as strong or robust as fixed keels. They don’t provide the stability of a full or semi-displacement keel, and they don’t have the windward performance of bilge or fin keels.

Additionally, these keels still require a trunk, which can still take up cabin space on some models. The systems used to raise and lower a swing keel are prone to failure and add complexity where it otherwise wouldn’t exist.

Are Swing Keels Strong?

Swing keels are not as strong as fixed keels. This is because they’re usually smaller and lose rigidity at the hinge. Usually, the addition of mechanical complexity reduces the strength of a system, and that rule applies to swing keels.

A fixed keel can be mounted to a boat with numerous rigid bolts, whereas a swing keel is mounted to a pin and adds a level of complexity. That said, swing keels have an advantage in one respect, which we’ll cover next.

Advantages of Swing Keels in Shallow Water

Most swing keels swing down to the front, meaning their hinge is mounted forward. This is advantageous in shallow water, as it allows the keel to swing up into the boat instead of snapping off should the boat run aground. It’s like an automatic failsafe.

However, some swing keels lock into place in the lowered position. Sailboat owners should always proceed with caution in shallow water and lift the keel if the water isn’t deep enough.

Can You Beach a Sailboat with a Swing Keel?

One of the advantages of having a swing keel is that you can easily beach the boat. All you have to do is build up a bit of momentum, retract the keel, and head for the beach.

Sailboats with swing keels are particularly popular for island hopping due to their transformable flat bottoms. They can also utilize more seaworthy hull shapes than other shallow-draft vessels, thanks to their long retractable keels.

However, some sailboats with swing keels cannot be beached. If the keel retracts fully into the hull, and your rudder does too, you’re in luck. But if you have a fixed rudder, a prop, or any protrusion of the keel under the hull, you have to proceed with caution.

What Sailboats Have Swing Keels?

Dozens of different sailboat brands and models have utilized swing keel systems at some point. One notable and extremely popular example is the famous Catalina 22. The Catalina 22 is a trailerable coastal cruiser with a masthead sloop rig and a typical swing keel.

This small cruiser has a spacious cabin thanks to its keel, which retracts into a hidden trunk. The raising and lowering of the keel is performed by a pulley system and hides out of the way when not in use. The Catalina 22 keel is made of heavy metal.

The Catalina 22 is an example of a sailboat with a semi-hidden swing keel. The trunk only partially covers the keel, as the boat is designed for trailering—beaching abilities were not considered key in its development.

As a result, the keel swings up and still protrudes out from the bottom of the hull. But the swinging design gives the vessel a variable draft and a much deeper keel for stability. The boat otherwise wouldn’t have good handling characteristics if it weren’t for the swing keel.

Not all Catalina 22 sailboats came with a swing keel, but many of them did. It’s the most common boat of its type and a great example of the benefits of swing keels on smaller cruising sailboats.

Do Large Sailboats Have Swing Keels?

Large sailboats aren’t known for having any sort of retractable keel system. However, many ultra-modern big cruising vessels utilize some version of a retractable keel for performance and shallow water operations.

New sailboats that utilize swing keels usually do so for increasing hydrodynamic performance at high speeds and for reducing the draft of an otherwise deep keel.

For example, a vessel with a long 8-foot keel can reduce its draft to 4 feet or so when navigating a harbor and then extend the keel to increase performance offshore.

However, most large sailboats use fixed keels for strength, simplicity, and cost-effectiveness. This is also because most designers simply don’t bother with complex keel systems on larger cruising boats.

What are Swing Keels Made Of?

Swing keels are usually made of strong materials like steel. They’re extremely heavy, as they function as part of the sailboat’s ballast. Swing keels are typically made of a solid steel plate between one and one and one-half inches thick.

Some swing keels on high-performance yachts are made of composite materials like carbon fiber and filled with ballast, but this is exceedingly rare. Much of the sailboat’s ballast is usually internal on swing keel vessels.

What Is a Swing Keel?
Daniel Wade

Daniel Wade

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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