The Voith Schneider Propeller (VSP) is a specialized marine propulsion system (MPS) manufactured by the Voith Group based on a cyclorotor design. It is highly maneuverable, being able to change the direction of its thrust almost instantaneously. It is widely used on tugs and ferries.
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.
Unlike the azimuth thruster (where a conventional propeller is rotated about the vertical axis to direct its thrust, allowing a vessel to steer without the use of a rudder), the 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 maneuverability is needed.
Azimuth thrusters (and Kort nozzles) have both advantages and disadvantages when compared to cycloidal drives. The azimuth thruster 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. Instead of a Kort nozzle, VSPs are often fitted with a "thrust plate" or "propeller guard" which acts as a nozzle at low speed, protects the VSP against grounding and provides another blocking location during drydocking.
A low acoustic signature favours the device's use in minesweepers by minimising cavitation (usually produced at the tips of axial propellers) as the rotor does not need to rotate as fast for a given thrust. The underwater sound signature of the MV North Sea Giant (IMO: 9524073, MMSI: 248039000) dynamic positioning vessel was measured by the International Centre for Island Technology (ICIT) whilst installing a foundation monopile for the Voith tidal energy device in the Fall of Warness, Orkney (Ref Beharie and Side, 2011).
VSPs are offered with an input power range of 160 kW to 3900 kW [1]
The Voith Schneider propeller was originally a design for a hydro-electric turbine. [2] Its Austrian inventor, Ernst Schneider, had a chance meeting on a train with a manager at Voith's subsidiary St. Pölten works; this led to the turbine being investigated by Voith's engineers, who discovered that although it was no more efficient than other water turbines, Schneider's design worked well as a pump by reversing the flow through the device. By changing the orientation of the vertical blades, it could be made to function as a combined propeller and rudder.
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. [3] 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 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. Some 80 ships had been installed with VSPs by the end of the 1930s, including the uncompleted 1938 German aircraft carrier Graf Zeppelin (two auxiliary units in the bow), and the Japanese submarine cable laying ship Toyo-maru (also 1938).
The three vessels (John Burns, Ernest Bevin, and James Newman) which were in service for the Woolwich Ferry until 2018 featured Voith-Schneider propulsion systems. They were built in 1963 by the Caledon Shipbuilding & Engineering Company of Dundee and featured one VSP in the bow and a second in the stern for remarkable maneuverability. The Tay Ferries Scotscraig which were built by the Caledon in the 1950s also used VSPs.It was essentially a replacement copy of the earlier Abercraig ferry, which was built by Fleming and Ferguson Paisley yard for Dundee Harbour crossings and launched in 1938. The "Abercraig" also featured VSPs. [4]
The US Navy built twelve VSP-equipped Osprey-class coastal minehunters in the 1990s. [5] These vessels have been decommissioned, six were sold to foreign navies.[ citation needed ] and six were sold for "dismantlement purposes only." [6] The French Navy operates sixteen tugboats of the RPC12 type, that can provide a 12-tonne bollard pull thanks to two Voith Schneider propellers. [7]
The same device, mounted on a horizontal rather than a vertical axis, has been used to provide lift and propulsion on a few experimental aeroplanes, known as "cyclogyros". None of them were very successful. [8] It has also more recently been proposed as an alternative to rotors for drone applications. [9]
A propeller is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working fluid such as water or air. Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a boat through water or an aircraft through air. The blades are shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade by Bernoulli's principle which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a propeller shaft with an approximately horizontal axis.
A tugboat or tug is a marine vessel that manoeuvres other vessels by pushing or pulling them, with direct contact or a tow line. These boats typically tug ships in circumstances where they cannot or should not move under their own power, such as in crowded harbors or narrow canals, or cannot move at all, such as barges, disabled ships, log rafts, or oil platforms. Some are ocean-going, and some are icebreakers or salvage tugs. Early models were powered by steam engines, which were later superseded by diesel engines. Many have deluge gun water jets, which help in firefighting, especially in harbours.
A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller, a centrifugal pump, or a mixed flow pump which is a combination of both centrifugal and axial designs. The design also incorporates an intake to provide water to the pump and a nozzle to direct the flow of water out of the pump.
An azimuth thruster is a configuration of marine propellers placed in pods that can be rotated to any horizontal angle (azimuth), making a rudder redundant. These give ships better maneuverability than a fixed propeller and rudder system.
A propulsor is a mechanical device that gives propulsion. 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.
In marine propulsion, a variable-pitch propeller is a type of propeller with blades that can be rotated around their long axis to change the blade pitch. Reversible propellers—those where the pitch can be set to negative values—can also create reverse thrust for braking or going backwards without the need to change the direction of shaft revolution.
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. This eliminates the need for a conventional rudder.
Azipod is a trademarked azimuth thruster pod design, a marine propulsion unit consisting of a fixed pitch propeller mounted on a steerable gondola ("pod") containing the electric motor driving the propeller, allowing ships to be more maneuverable. They were developed in Finland in the late 1980s jointly by Wärtsilä Marine, Strömberg and the Finnish National Board of Navigation.
Manoeuvering thrusters are transversal propulsion devices built into or mounted to either the bow or stern of a ship or boat to make it more manoeuvrable. Bow thrusters make docking easier, since they allow the captain to turn the vessel to port or starboard side, without using the main propulsion mechanism which requires some forward motion for turning; The effectiveness of a thruster is curtailed by any forward motion due to the Coandă effect. A stern thruster is of the same principle, fitted at the stern. Sufficiently large vessels often have multiple bow thrusters and stern thrusters.
Astern propulsion is a maneuver in which a ship's propelling mechanism is used to develop thrust in a retrograde direction. Astern propulsion does not necessarily imply the ship is moving astern ; astern propulsion is used to slow a ship by applying a force in the direction of the bow of the ship, instead of the stern. The equivalent concept for an airplane is thrust reversal.
The Kitchen rudder is the familiar name for "Kitchen's Patent Reversing Rudders", a combination rudder and directional propulsion delivery system for relatively slow speed displacement boats which was invented in the early 20th century by John G. A. Kitchen of Lancashire, England. It turns the rudder into a directional thruster, and allows the engine to maintain constant revolutions and direction of drive shaft rotation while altering thrust by use of a control which directs thrust forward or aft. Only the rudder pivots; the propeller itself is on a fixed shaft and does not.
The Pleuger rudder is a power assisted ship's rudder. It creates a flow of water in the direction the rudder points powered by an auxiliary electric motor. This aids maneuverability at low speeds greatly, since it operates on a similar principle to a thruster.
Marine propulsion is the mechanism or system used to generate thrust to move a watercraft through water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of an electric motor or internal combustion engine driving a propeller, or less frequently, in pump-jets, an impeller. Marine engineering is the discipline concerned with the engineering design process of marine propulsion systems.
A Schilling rudder is a specific type of profiled rudder used on certain boats and ships. The rudder is typically described as 'shaped like a fishtail'.
An L-drive is a type of azimuth thruster where the electric motor is mounted vertically, removing the second bevel gear from the drivetrain. Azimuth thruster pods can be rotated through a full 360 degrees, allowing for rapid changes in thrust direction and eliminating the need for a conventional rudder. This form of power transmission is called a L-drive because the rotary motion has to make one right angle turn, thus looking a bit like the letter "L". This name is used to make clear the arrangement of drive is different from Z-drive.
A ducted propeller, also known as a Kort nozzle, is a marine propeller fitted with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited diameter. It was developed first by Luigi Stipa (1931) and later by Ludwig Kort (1934). The Kort nozzle is a shrouded propeller assembly for marine propulsion. The cross-section of the shroud has the form of a foil, and the shroud can offer hydrodynamic advantages over bare propellers, under certain conditions.
Schottel is a manufacturer of propulsion and steering systems for ships and offshore applications. The company founder Josef Becker invented the rudderpropeller, a z-drive, in 1950. Today the company develops and manufactures azimuth propulsion, maneuvering and steering systems. In 2014 the subsidiary Schottel Hydro was founded to bundle up the company activities in the hydrokinetic energy segment.
Sanmar Denizcilik is a Turkish firm that operates its own fleet of tugboats, and builds tugboats for its own fleet, and for other shipping firms. The firm was founded in 1976 by Orhan Gürün and Gökҫen Seven. It remains a privately held firm, with its board of directors chaired by Ali Gürün.
A cyclorotor, cycloidal rotor, cycloidal propeller or cyclogiro, is a fluid propulsion device that converts shaft power into the acceleration of a fluid using a rotating axis perpendicular to the direction of fluid motion. It uses several blades with a spanwise axis parallel to the axis of rotation and perpendicular to the direction of fluid motion. These blades are cyclically pitched twice per revolution to produce force in any direction normal to the axis of rotation. Cyclorotors are used for propulsion, lift, and control on air and water vehicles. An aircraft using cyclorotors as the primary source of lift, propulsion, and control is known as a cyclogyro or cyclocopter. A unique aspect is that it can change the magnitude and direction of thrust without the need of tilting any aircraft structures. The patented application, used on ships with particular actuation mechanisms both mechanical or hydraulic, is named after German company Voith Turbo.
A marine thruster is a device for producing directed hydrodynamic thrust mounted on a marine vehicle, primarily for maneuvering or propulsion. There are a variety of different types of marine thrusters and each of them plays a role in the maritime industry. Marine thrusters come in many different shapes and sizes, for example screw propellers, Voith-Schneider propellers, waterjets, ducted propellers, tunnel bow thrusters, and stern thrusters, azimuth thrusters, rim-driven thrusters, ROV and submersible drive units. A marine thruster consists of a propeller or impeller which may be encased in some kind of tunnel or ducting that directs the flow of water to produce a resultant force intended to obtain movement in the desired direction or resist forces which would cause unwanted movement. The two subcategories of marine thrusters are for propulsion and maneuvering, the maneuvering thruster typically in the form of bow or stern thrusters and propulsion thrusters ranging from Azimuth thrusters to Rim Drive thrusters.
