A marine thruster is a device for producing directed hydrodynamic thrust on a marine vehicle. The thrust direction may be fixed or steerable. Examples of marine thrusters include screw propellers, Voith-Schneider propellers, waterjets, ducted propellers, tunnel bow thrusters and stern thrusters, azimuth thrusters, rim-driven thrusters, ROV and submersible drive units. Marine thrusters may be used for propulsion, maneuvering and steering, attitude control and dynamic positioning.
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Marine thruster Wikipedia(Text) CC BY-SA