Displacement Hull

WestMarine.com

This hull type is supported exclusively or predominantly by the pressure of water displaced by the hull. The speed at which the hull moves through the water is limited by the waterline length. As opposed to a planing or semi-displamcement hull, the displacement hull is not designed to provide dynamic lift. Semi-displacement or planing hulls can be identified by their buttock angle and shape of their run. Vessels with buttock angles that are flatter, less than 7 degrees, would be considered planing or semi-displacement vessels. See semi-displacement or planing hull types for more details. A typical example of a displacement hull would be a sail boat or a canoe. A sailing catamaran would simply be an example of two displacement hulls, although the hulls have less beam than its monohull counterpart would, they are still displacement hulls due to the shape of the run.

The SL ratio (speed length ratio) is key in determining the practical speed potential of a hull.

SL ratios of higher than 1.3 to 1.4 are not practical nor economical for most displacement hulls.

Boat Hull Types :