Abstract: A water wave-to-hydraulic power converter pumps quantities of working liquid which are approximately proportional to the square of wave height. A reciprocating force pump is attached pivotally to a pair of hinged hulls, the cylinder to one hull and the piston rod to the other hull, so that the axis defined by the points of pivotal connection intersects the axis of the interhull hinge when the hulls are at rest, in the absence of waves.