HIGH SPEED BOAT

PROBLEM TO BE SOLVED: To store a roll damping wing in contact with a bottom part of a hull when the roll damping wing is not necessary by providing the roll damping wing on the bottom part of the hull in an elevating/lowering manner, and providing an elevating/lowering equipment to elevate/lower the roll damping wing within the hull. SOLUTION: When the sea is in rough condition a roll damping wing 2 is lowered (projected) by the prescribed elevating/lowering quantity downwardly from a bottom part of a hull 1 by a cylinder unit 4. The pitching of the hull l can be effectively controlled, and the high-speed navigation can be performed in a stable condition. When the sea is in calm condition, the roll damping wing 2 is elevated at the position in contact with the bottom part of the hull 1 by the cylinder unit 4. That means, the roll damping wing does not cause any propulsion resistance during the navigation. The propulsion resistance can be further reduced by forming a recessed part of depth equal to the thickness of the roll damping wing 2 on the bottom part of the hull 1, and storing the roll damping wing 2 in the recessed part.