Bow thruster

A bow thruster or stern thruster is a transversal propulsion device built into, or mounted to, either the bow or stern, of a ship or boat, to make it more maneuvrable. Bow thrusters make docking easier, since they allow the captain to turn the vessel to port or starboard side, without using the main propulsion mechanism which requires some forward motion for turning; indeed, the effectiveness of a thruster is curtailed by any forward motion due to the Coandă effect. A stern thruster is of the same principle, fitted at the stern. Large ships might have multiple bow thrusters and stern thrusters.