Azimuth thruster

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An Azimuth thruster is a configuration of ship propellers placed in pods that can be rotated in any horizontal direction. A conventional rudder is not needed. These give ships better maneuverability than a fixed propeller and rudder system. Primary advantages are electrical efficiency, better use of ship space, and lower maintenance costs. Ships with azimuth thrusters do not need tugs to dock, though they still require tugs to maneuver in difficult places.

There are two major variants, based on the location of the motor:

Mechanical transmission, where the motor is inside the ship and power gets transmitted to the propeller via bevel gears. The motor may be either a directly mechanically connected diesel engine, or an electrical motor getting its power from generators run by an electricity producing engines (usually diesel engines) elsewhere in the ship.
Electrical transmission, where the electrical motor is in the pod itself, directly connected to the propeller without gearboxes. The energy used to drive the motor in the pod is produced by machinery inside the vessel, usually by diesel engines or gas turbines which drive electric generators, in a system comparable to that used by diesel-electric locomotives. Invented in 1955 by Mr. F.W. Pleuger and Mr. Friedrich Busmann (Pleuger Unterwasserpumpen GmbH), ABB Azipod was the first product using this technology.