Abstract: A trimaran has its floats displaceable from normal extended positions to retracted positions close to the central hull and is arranged to have improved stability at large angles of heel with the floats retracted. The retraction is actuable responsively to the heel of the craft so that if the heel angle becomes undesirably large, the retraction of the floats produces a self-righting moment. The floats are also extendable when the craft has righted itself and as it continues underway. The crew can also effect retraction from a central position independently of the sailing attitude of the craft.