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English inventor Francis Ronalds described what he called a propelling rudder in 1859 that combined the propulsion and steering mechanisms of a boat in a single apparatus. . The propeller was placed in a frame having an outer profile similar to a rudder and attached to a vertical shaft that allowed the device to rotate in plane while spin was transmitted to the propell
ABB provided an azimuth thruster for ShinNihonkai Ferries in form of the CRP Azipod, [2] claiming efficiency gains from the propeller (about 10% increase [3]) and a simpler hull design. Volvo Penta have launched the IPS (Inboard Performance System), [4] an integrated diesel, transmission and pulling contra-rotating propellers for motor yachts.
Other vessels may have twin, triple or quadruple screws. Power is transmitted from the engine to the screw by way of a propeller shaft, which may be connected to a gearbox. The propeller then moves the vessel by creating thrust. When the propeller rotates the pressure in front of the propeller is lower than the pressure behind the propeller.
[clarification needed] The choice between using thrusters or traditional propellers to propel marine vessels is a compromise between versatility and efficiency. Propellers are designed to work in-line with a propulsion plant and produce one-directional thrust while thrusters are more customizable and have a more versatile application.
In the conventional azimuth thrusters such as Z-drive and L-drive thrusters, the propeller is driven by an electric motor or a diesel engine inside the ship's hull. The propeller is coupled to the prime mover with shafts and bevel gears that allow rotating the propeller about a vertical axis. This type of propulsion system has a long tradition ...
As early as 1804, the American John Fitch is credited with a screw propeller, which was unsuccessful. In 1836, the Englishman Francis Pettit Smith tested a screw propeller similar to Ressel's. The first transatlantic journey of a ship powered by a screw-propeller was by the SS Great Britain in 1845. Propeller design stabilized in the 1880s.
The word is commonly used in the marine vernacular, and implies a mechanical assembly that is more complicated than a propeller. The Kort nozzle, pump-jet and rim-driven thruster are examples. An example propulsor is shown in the accompanying picture. It has a shroud which cuts down on blade-tip cavitation and radiated noise.
The first such ship to use the Voith Schneider propeller was the excursion boat Kempten. Two German 1935-type M class minesweepers M-1 and M-2 were fitted with VSPs. The first British ship to use Voith Schneider propellers was the double-ended Isle of Wight ferry MV Lymington , launched in 1938.