Abstract: An apparatus for extracting power from ocean waves comprises a number of buoyant cylindrical body members (2, 3, 4) connected together at their ends to form an articulated chain-like structure (1). Each pair of adjacent cylindrical members is connected to each other by a coupling member (5a, 5b) which permits relative rotational movement of the cylindrical members about at least one transverse axis (40). Adjacent coupling members may permit relative rotation about mutually orthogonal transverse axes (A, B). Each coupling member is provided with elements such as a set of hydraulic rams (33, 34, 35) which resist and extract power from the relative rotational movement of the body members, and which can provide applied constraints to rotation about one or both of the transverse axes. The transverse axes of rotation (A, B) are skewed from the horizontal axis (104) and vertical axis (100) by a roll bias angle (&psgr;), selected to optimize the dynamic response of the apparatus to incoming waves.