Abstract: An apparatus is provided for extracting energy from the motion of water waves during both the ebb and flow of such waves. The apparatus includes a screw propeller which is disposed to contact the waves and to be driven thereby in opposite directions depending on the direction of movement of the waves. A pair of ratchet wheel and pawl assemblies, mounted on a common drive shaft with the propeller, provide transmission of the rotational forces for both directions of rotation. A pair of force transmitting connections disposed between the drive shaft and a driven shaft provide rotation of the driven shaft in the same direction for both directions of rotation of the drive shaft. A plurality of such apparatus are preferably used to drive a single common shaft which serves as a drive shaft for an utilization device such as a dynamo.