A wave energy converter comprising: a float intended to lie along the surface of a body of water and designed to move in-phase with the waves present in the body of water; a spar intended to extend vertically, generally perpendicular to the float and the surface of the body of water, said spar extending below the surface of the body of water and intended to move vertically up and down generally out-of-phase with the waves; a power take off device, connected between the spar and the float, responsive to their relative motion to convert their relative motion to useful energy; and a heave plate centrally connected to a submerged portion of the spar, said heave plate extending in a plane perpendicular to the spar, and the plate moves uniformly up and down with the spar for effectively adding mass to the spar as the spar tends to move up and down and causing the spar to move generally out-of-phase relative to the float for increasing the energy produced by the WEC, characterized in that at least one of rods and wires are connected between the outer periphery of the heave plate and the spar for ensuring a structurally firm connection between the heave plate and the spar, wherein the spar has an upper portion and a lower portion, wherein the float moves up and down along the upper portion of the spar, and wherein the heave plate is attached via at least one of rods and wires to a region along the spar; the region on the spar along which said rods and wires are connected being made sufficiently long to increase the structural strength and reduce any movement between the heave plate and the spar, and in that the upper and lower portion of the spar are formed separately and are interconnected via a flexible coupling in order to reduce the magnitude of the forces between the heave plate and the upper portion of the spar translated through the flexible coupling. a float intended to lie along the surface of a body of water and designed to move in-phase with the waves present in the body of water; a spar intended to extend vertically, generally perpendicular to the float and the surface of the body of water, said spar extending below the surface of the body of water and intended to move vertically up and down generally out-of-phase with the waves; a power take off device, connected between the spar and the float, responsive to their relative motion to convert their relative motion to useful energy; and a heave plate centrally connected to a submerged portion of the spar, said heave plate extending in a plane perpendicular to the spar, and the plate moves uniformly up and down with the spar for effectively adding mass to the spar as the spar tends to move up and down and causing the spar to move generally out-of-phase relative to the float for increasing the energy produced by the WEC, characterized in that at least one of rods and wires are connected between the outer periphery of the heave plate and the spar for ensuring a structurally firm connection between the heave plate and the spar, wherein the spar has an upper portion and a lower portion, wherein the float moves up and down along the upper portion of the spar, and wherein the heave plate is attached via at least one of rods and wires to a region along the spar; the region on the spar along which said rods and wires are connected being made sufficiently long to increase the structural strength and reduce any movement between the heave plate and the spar, and in that the upper and lower portion of the spar are formed separately and are interconnected via a flexible coupling in order to reduce the magnitude of the forces between the heave plate and the upper portion of the spar translated through the flexible coupling.