Marine Electric/Hydraulic Mooring Rope Capstan is a vertical axled rotating machine used on sailing ships. It can apply force to ropes, cables, and hawsers. The principle is similar to that of the windlass, which owns a horizontal axle. Typically, it uses a gearbox which trades reduced speed, relative to the prime mover, for increased torque. Modern capstan winches are powered electrically, hydraulically, pneumatically, or via an internal combustion engine.