What Is a Keel?
The ballast-filled foil beneath a sailing boat’s hull - the balancing element that counters heel and one of the most commonly overlooked inspection points.
The keel is the weighted vertical foil beneath a sailing boat. It serves two purposes: to resist the heeling force from the sails with ballast, and to stop the boat sliding sideways. The boat’s entire stability calculation is built around the keel.
There are several types; the table below sets out the main ones.
Keel types
Type | Features |
|---|---|
Full keel | Long, robust, slow to turn, seamanlike |
Fin keel | Short and deep, nimble, modern standard |
Bulb keel | Weight at the tip, low centre of gravity, performance |
Swing/lifting keel | Can be used in shallow water, but the mechanism needs maintenance |
On modern boats, the keel is bolted to the hull, and those bolts, together with the joint area, are among the most heavily loaded structural points on the boat. The cost of groundings brushed off as ‘nothing happened’ often shows up here.
Every grounding, even a soft one, deserves a check of the keel joint at the next haul-out, along with the bolt area from the bilge. A sealant crack opening up along the joint line (‘keel smile’) is only caught early by comparing photos year by year.