Voith-Schneider
Encyclopedia
Voith
The Voith GmbH, which is headquartered in Germany, is a family-run corporation in the mechanical engineering sector with worldwide operations....
Schneider propeller
Propeller
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...
(VSP), also known as a cycloidal drive (CD) is a specialized marine
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
propulsion
Marine propulsion
Marine propulsion is the mechanism or system used to generate thrust to move a ship or boat across water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting a motor or engine turning a propeller, or less frequently, in jet...
system (MPS). It is highly maneuverable, being able to change the direction of its thrust
Thrust
Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a force of equal magnitude but opposite direction on that system....
almost instantaneously. It is widely used on tug
Tug
Tuğ is a village in the Khojavend Rayon of Azerbaijan....
s and ferries
Ferry
A ferry is a form of transportation, usually a boat, but sometimes a ship, used to carry primarily passengers, and sometimes vehicles and cargo as well, across a body of water. Most ferries operate on regular, frequent, return services...
.
Operation
From a circular plate, rotating around a vertical axis, a circular array of vertical blades (in the shape of hydrofoilHydrofoil
A hydrofoil is a foil which operates in water. They are similar in appearance and purpose to airfoils.Hydrofoils can be artificial, such as the rudder or keel on a boat, the diving planes on a submarine, a surfboard fin, or occur naturally, as with fish fins, the flippers of aquatic mammals, the...
s) 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
Angle of attack
Angle of attack is a term used in fluid dynamics to describe the angle between a reference line on a lifting body and the vector representing the relative motion between the lifting body and the fluid through which it is moving...
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
Helicopter flight controls
A helicopter pilot manipulates the helicopter flight controls in order to achieve controlled aerodynamic flight. The changes made to the flight controls are transmitted mechanically to the rotor, producing aerodynamic effects on the helicopter's rotor blades which allow the helicopter to be...
.
Unlike a Z-drive
Z-drive
A Z-drive is a type of marine propulsion unit. Specifically, it is an azimuth thruster. The pod can rotate 360 degrees allowing for rapid changes in thrust direction and thus vessel direction...
(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
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...
. It is highly efficient and provides for an almost instantaneous change of direction. These drives are becoming increasingly common in work boats such as fireboat
Fireboat
A fireboat is a specialized watercraft and with pumps and nozzles designed for fighting shoreline and shipboard fires. The first fireboats, dating to the late 18th century, were tugboats, retrofitted with firefighting equipment....
s and tugboat
Tugboat
A tugboat is a boat that maneuvers vessels by pushing or towing them. Tugs move vessels that either should not move themselves, such as ships in a crowded harbor or a narrow canal,or those that cannot move by themselves, such as barges, disabled ships, or oil platforms. Tugboats are powerful for...
s where extreme manoeuvrability is needed.
Z-drives (and Kort nozzle
Kort nozzle
The Kort nozzle is a shrouded, ducted propeller assembly for marine propulsion. The hydrodynamic design of the shroud, which is shaped like a foil, offers advantages for certain conditions over bare propellers....
s) 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
Hull (watercraft)
A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...
making shallow water operation a problem.
A low acoustic signature
Acoustic signature
Acoustic signature is used to describe a combination of acoustic emissions of ships and submarines.-Contributing factors:The acoustic signature is made up of a number of individual elements...
favours the device's use in minesweepers
Minesweeper (ship)
A minesweeper is a small naval warship designed to counter the threat posed by naval mines. Minesweepers generally detect then neutralize mines in advance of other naval operations.-History:...
.
History
The Voith Schneider propeller was originally a design for a hydro-electric turbineTurbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
. 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.
Lake Constance
Lake Constance is a lake on the Rhine at the northern foot of the Alps, and consists of three bodies of water: the Obersee , the Untersee , and a connecting stretch of the Rhine, called the Seerhein.The lake is situated in Germany, Switzerland and Austria near the Alps...
. A number of German minesweepers (R boats) were fitted with VSPs; the first of these was the R8, built in 1929 by Lürssen
Lürssen
Lürssen is a German shipbuilding company based in Bremen-Vegesack.Lürssen designs and constructs yachts, naval ships and special vessels...
. By 1931 VSPs were being fitted in new vessels on Lake Constance run by the German State Railways
Deutsche Reichsbahn
Deutsche Reichsbahn was the name of the following two companies:* Deutsche Reichsbahn, the German Imperial Railways during the Weimar Republic, the Third Reich and the immediate aftermath...
. The first such ship to use the Voith Schneider propeller was the excursion boat Kempten. Two German 1935-type M class minesweeper
M class minesweeper (Germany)
The M class were the standard minesweeper of the German Navy during World War II.-M1935:The first series; the M1935 were ordered in the late 1930s to replace worn out World War I vintage boats. These ships proved versatile and seaworthy. The vessels could also undertake convoy escort,...
s 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
MV Lymington
MV Lymington is a former ro-ro ferry, built in 1938, for serve the Isle of Wight. She is Britain's earliest example of a Voith Schneider driven ferry. Renamed MV Sound of Sanda in 1974, she served Western Ferries on the Upper Clyde until 1993....
, 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
German aircraft carrier Graf Zeppelin
German aircraft carrier Graf Zeppelin was the lead ship in a class of two carriers ordered by the Kriegsmarine. She was the only aircraft carrier launched by Germany during World War II and represented part of the Kriegsmarine's attempt to create a well-balanced oceangoing fleet, capable of...
(two auxiliary units in the bow), and the Japanese submarine cable laying ship Toyo-maru (also 1938).