Abstract: A self-governing, vertically oriented wind driven assembly is provided by a pair of open, semicylindrically shaped wind scoops with elongated edges which face each other in a nearly closed position at times of high or maximum wind speeds, and partically face each other and partially exposed into the wind at lower wind speeds. The scoops are pivotally attached to posts oppositely located at the edges of a rotating frame. The amount of exposure of the scoops into the wind is dynamically balanced by springs which tend to open the scoops and by weights which tend to close the scoops proportional to the rotational speed of the assembly. The ends of the scoops are modified to permit the scoops to cooperatively slide from an open to close position. The assembly is connected to an electrical generating means and can be used for producing electrical power on sailboats.