Keel

The weighted vertical fin beneath the hull that resists leeway and, through its ballast, keeps the boat upright; modern variants include fin, bulb, winged, lifting, swing, and twin keels.

Test your knowledge

Know your nautical terms? Play the free SkipperCheck daily maritime quiz — COLREGs, navigation, VHF radio, seamanship. Earn points, climb the global leaderboard.

Play the Daily Quiz →

Related K-terms

Kedge off

To refloat a grounded vessel by laying a kedge anchor in deeper water and hauling the boat…

Kedge

A secondary anchor, smaller than the bower, carried for manoeuvring or for kedging the boa…

Kevlar

An aramid fibre used in high-performance laminate sails and safety gear; it is strong and …

Ketch

A two-masted rig whose shorter mizzen mast stands forward of the rudder post and is shorte…

Knockdown

A severe knock in which the boat is blown onto her side far enough that a spreader dips in…

Knot

One nautical mile per hour — the standard unit of speed at sea.

← Back to full glossary