Canting keel
A canting keel is a form of sailing ballast, suspended from a rigid canting strut beneath the boat, which can be swung to windward of a boat under sail, in order to counteract the heeling force of the sail. The canting keel must be able to pivot to either port or starboard, depending on the current tack.
Purpose and history
The traditional yacht keel performs four functions:
the development of lateral water force to resist lateral aerodynamic force from sails and superstructure,
the physical housing of ballast load as low as possible,
roll-damping to resist energy inputs from waves and disturbed water, and
a contribution to directional stability.
The traditional fin keel, pointing straight down from the boat, provides no righting moment when the boat is level. The heeling force of the wind on the sails is therefore not counteracted until the boat has heeled over by a certain amount, moving the fixed keel to windward of the centerline. The purpose of the canting keel is to allow the boat to sail closer to level which generates maximum speed, by swinging the keel to windward and developing an adequate righting moment to keep the boat's angle of heel closer to level.