IMPROVEMENTS TO BOAT HULLS WHEN SLAMMING

摘要

The invention relates to hulls for boats. In heavy swell or chop, the hull of a fast motorboat travelling over the crest of a wave initially rises and, after travelling over the crest, drops heavily and makes contact with the downward slope of the wave. This is commonly known as "slamming" and is uncomfortable for the occupants of the boat and heavily loads the structure of the craft. On slamming, the boat also experiences a deceleration as the bow noses into the water causing further discomfort and stress to the hull. With the aid of under hull flaps, this invention improves the slamming phenomenon by reducing the deceleration and can actually achieve acceleration during the slam, alleviating discomfort and reducing hull loads. A plurality of flaps (2), which are preferably pivotally-mounted but may alternatively flex, extend from the hull surface, each flap being movable by the incident water flow between a first position and a second position, the flap having a greater angle from the centreline of the hull in the second position than in the first position. During slamming, the flap (2) adopts the second position, in which the angle of the flap from the centreline is constrained to be less than the angle of the water flow outward from the centreline of the hull, such that the impact of the water flow on the flap (2) produces a forward thrust to the flap and to the hull.