propulsion by use of any desired engine or motor using any desired energy source or fuel including that captured converted and stored by the vessel itself specifically a renewable energy such a wind power the term propulsion as used herein refers generally to and includes the positioning moving driving navigation motorization and or directing of the vessel at sea the term wind power system as used herein refers to any system or device to convert wind energy into electrical power wind machines such as turbines and towers disposed on offshore vessels are capable of capturing the most reliable winds at and near the sea level the term wind machine as used herein refers to any device with a mechanism for converting the movement of air into a mechanical motion which may then be converted by a generator into electrical power wind machines include turbines where the turbine is perpendicular to the wind and mounted on a tower turbines may have a horizontal axis where the rotor faces the wind and typically two or three blades catch the wind and spin the blades are connected to a drive shaft that turns an electric generator to produce electricity turbines may have a vertical axis which can accept wind from any direction such as the darrieus wind turbine which consists of several aerofoils vertically mounted on a rotating shaft or framework in.