Abstract: This invention relates to a method of and device for generating energy from waves in water. The device includes a cylindrical buoyant body which has a regular shape in cross-section and annular tracks on its end faces. Gears adapted to constrain the body for rotation about its axis in one direction only are engaged in axial alignment with the tracks on one side of the center of gravity of the body and movable and rotatable means such as a cam or the like is engaged with the track on the opposite side of the center of gravity of the body to inhibit buoyant upward movement of the body on that side of its center of gravity and encourage rotary movement of the other side of the body relatively to the constraining gears.