Abstract: Apparatus for converting energy contained in surface waves on a body of water to useful energy comprises a float from which is suspended a fully or effectively fully submerged inverted cup-shaped member having a closed top end and an open bottom end. Disposed within the top space is a compressible fluid separated by a flexible membrane from a column of water filling the bottom open end of the submerged member. Passing surface waves cause pressure variations at the bottom end of the member causing changes in the water column height and corresponding changes in the buoyancy of the member. The buoyancy changes induce vertical oscillations of the member relative to the float and known means are used for converting the relative movements of the float and submerged member to useful energy. Preferably, the float vertically oscillates in synchronization with the passing waves, and the vertical movements of the float increase the relative movements between the float and the submerged member.

Abstract: Apparatus for converting energy contained in surface waves on a body of water to useful energy comprises a float from which is suspended a fully or effectively fully submerged inverted cup-shaped member having a closed top end and an open bottom end. Disposed within the top space is a compressible fluid separated by a flexible membrane from a column of water filling the bottom open end of the submerged member. Passing surface waves cause pressure variations at the bottom end of the member causing changes in the water column height and corresponding changes in the buoyancy of the member. The buoyancy changes induce vertical oscillations of the member relative to the float or, alternatively, relative movements of parts within the member. Known means are used for converting the relative movements of the float and submerged member, and the member parts, to useful energy.