Fin keel

The fin keel is a stationary foil positioned amidships and projecting downwards under the hull of a sailing vessel. A fin keel is relatively short in a fore-aft direction, and relatively deep, located near the center of the boat. A fin keel is a fixed element, unlike a centerboard, which is retractable. The design purpose of the fin keel[1] is to provide lateral resistance to wind forces applied to the boat via the sails and to facilitate the placement of ballast below the hull while presenting less wetted surface area than a full keel, which helps to reduce drag and leeway. The fin keel was invented by James Brown Herreshoff (1834–1930).[2]