Abstract: A capstan for towing a rope which leads a marine vessel to a berth comprises a cylindrical drum having a negative crown and around which the rope is wrapped, an electric motor and a cycloid reduction gearing which connects the drum with the motor, both the motor and gearing being disposed within the drum. The motor has a shaft disposed in alignment with the axis of the drum. The reduction gearing comprises an eccentric cam mounted on one end of the shaft, a planet gear slidably mounted around the cam, and an inner gear mounted inside the drum. The inner gear meshes with the planet gear and has a number of teeth which is greater than that of the planet gear by one or more teeth. The planet gear is formed with a plurality of circular openings which are disposed on a circle of a given radius struck from the center thereof while the motor firmly carries a plurality of pins which extend upwardly through the openings.