Patent ID: 7083382

Claim:
A prime mover for harnessing energy from flow of a fluid, the prime mover comprising a shaft having a rotational axis, arranged to be rotatably mounted to a substructure, the shaft comprising at least one arm extending radially from the shaft, the at least one arm comprising at least one blade, wherein the at least one blade is oriented such that fluid flow acting on the at least one blade effects rotation of the shaft, wherein the at least one blade is movably mounted on an arm and wherein each blade is movable from a first position, wherein the each blade is substantially perpendicular to the flow of fluid and has a first drag, to a second position, wherein the each blade is substantially parallel with the flow of fluid and has a second drag, wherein the first drag is higher than the second drag, and wherein the at least one blade is provided with a trim tab, attached to or integral with the blade and partly or completely spanning blade tip or the trailing edge of the at least one blade wherein each arm and/or blade comprises means to prevent each blade moving between the first and second position until the shaft has rotated a prescribed distance.