The bow thruster is mounted in an athwartship tunnel below the waterline at the bow. It usually is powered by an electric motor.
The bow thruster is used to maneuver the vessel. It enables lateral bow movement at low speeds, as when getting underway.
The bow thruster works in the same manner as any propeller. A motor turns the propeller blades, creating thrust as the result of the pressure differential between the blade faces. While some bow thrusters have variable pitch propellers, most use a simpler fixed pitch arrangement.
In large-displacement ships requiring significant force to maneuver the bow, such as merchant vessels, two bow thrusters are favored over a single large one.
