Voith Schneider Propeller

Voith Schneider Propeller

The Voith Schneider propeller (VSP), also known as a cycloidal drive (CD) is a specialized marine propulsion system (MPS). It is highly maneuverable, being able to change the direction of its thrust almost instantaneously. It is widely used on tugs and ferries.

Operation

From a circular plate, rotating around a vertical axis, a circular array of vertical blades (in the shape of hydrofoils) protrude out of the bottom of the ship. Each blade can rotate itself around a vertical axis. The internal gear changes the angle of attack of the blades in sync with the rotation of the plate, so that each blade can provide thrust in any direction, very similar to the collective and cyclic of helicopter flight controls.

Operational principle of Voith-Schneider propeller

Unlike a Z-drive (where a conventional propeller is tilted on a vertical rudder axis) changing the direction of thrust, a Voith-Schneider drive merely requires changing the pattern of orientation of the vertical blades. In a marine situation this provides for a drive which can be directed in any direction and thus does away with the need for a rudder. It is highly efficient and provides for an almost instantaneous change of direction. These drives are becoming increasingly common in work boats such as fireboats and tugboats where extreme manoeuvrability is needed.

Z-drives (and Kort nozzles) have both advantages and disadvantages when compared to cycloidal drives. The Z-drive is less efficient and slower to manoeuvre, but is likely to be cheaper in the short term. Life cycle costs favour the Voith solution, something reflected in the residual value of a Voith water tractor. A choice is made on the basis of perceived performance requirements. Also, the blades of the drive protrude from the bottom of the hull making shallow water operation a problem.

A low acoustic signature favours the device's use in minesweepers.

History

The Voith Schneider propeller was originally a design for a hydro-electric turbine. Its Austrian inventor, Ernst Schneider, had a chance meeting with an employee of Voith's subsidiary St. Pölten works; this led to the turbine being investigated by Voith's engineers. Although it worked no better than other water turbines, it was found that Schneider's design worked well as a pump; by changing the orientation of the vertical blades, it could function as a propellor.

Twin Voith Schneider Propeller on a tug's hull.

In 1928 a prototype was installed in a 60-hp motor launch named Torqueo (Latin:I spin) and trials were carried out on Lake Constance. A number of German minesweepers (R boats) were fitted with VSPs; the first of these was the R8, built in 1929 by Lürssen. By 1931 VSPs were being fitted in new vessels on Lake Constance run by the German State Railways. The first such ship to use the Voith Schneider propeller was the excursion boat Kempten. Two German 1935-type M class minesweepers M1 and M2 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. Some 80 ships had been installed with VSPs by the end of the 1930s, including the 1938 German aircraft carrier Graf Zeppelin (two auxiliary units in the bow), and the Japanese submarine cable laying ship Toyo-maru (also 1938).

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  Lift forces imparted to the VSP from the water body

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  Path of a blade in the water

See also

• Azipod
• Azimuth thruster
• Dynamic positioning
• Cycloid

References

Brown, R. Allen (1988); Lymington: The Sound of Success, Allan T Condie Publications. ISBN 978-0907742623

External links

• San Diego iBotics Autonomous Underwater Vehicle uses Voith Schneider Propulsion
• Voith Schneider Propeller