Half a century of experience in the production of sophisticated marine propulsion systems. A shaftline is the classic form of marine propulsion system. Originally, only fixed-pitch propellers were used on a shaftline for marine propulsion. The blades were mounted in a fixed position on the hub — a simple mechanical system, but one which necessitated complex measures, such as a reversing gearbox, in the vessel. Added to this are further disadvantages, including restricted manoeuvrability.