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A marine thruster is a device for producing directed
Positioning thrusters come in applications,
Propulsion thrusters are those thrusters which provide longitudinal motion for vessels as an alternative to traditional propellers. There are a variety of types of propulsion thrusters but the most common form is the azimuth thruster, that can rotate 360 degrees on a vertical axis to optionally produce thrust for maneuvering. (Lindborg, 1997). The amount of thrust produced is controllable. There are variants of azimuth thrusters such as CRP thrusters which have two contra-rotating Azimuth thrusters or Swing-Up Azimuth thrusters that can be retracted when not in use to reduce drag on the vessel (Wartsila Encyclopedia). Other propulsion thrusters like outboard thrusters which can be easily put in and out of service, rim drive thrusters that are driven via the external ring with the blades mounted on the inner face of the ring with their tips towards the center, or tilted thrusters pointed away from the hull to minimize interaction with the ship and increase thruster efficiency.{{clarify, tilted thruster, date=November 2020 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. They have this versatility at the cost of complexity and lower efficiency – they are not as robust as propellers and typically have applications on smaller vessels that don't require as much power.
A marine thruster is a device for producing directed hydrodynamic thrust
In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids—liquids and gases. It has several subdisciplines, including '' aerodynamics'' (the study of air and other gases in motion) ...
mounted on a marine vehicle
A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles ( motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles ( trains, trams ...
, 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 propeller
A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) 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 ...
s, Voith-Schneider propellers, waterjets, ducted propeller
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 diam ...
s, tunnel bow thrusters
Bow often refers to:
* Bow and arrow, a weapon
* Bowing, bending the upper body as a social gesture
* An ornamental knot made of ribbon
Bow may also refer to:
* Bow (watercraft), the foremost part of a ship or boat
* Bow (position), the rower s ...
, and stern thrusters, azimuth thrusters, rim-driven thrusters, ROV
ROV may refer to:
*Real options valuation
*Recreational Off highway Vehicle, also known as ''Side by side'' or UTV (''Utility Task Vehicle'')
*''Realm of Valor'', Thai-marketed version of multiplayer online video game ''Arena of Valor''
*Remotely ...
and submersible
A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of in ...
drive units. A marine thruster consists of a propeller
A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) 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 ...
or impeller
An impeller or impellor is a rotor used to increase the pressure and flow of a fluid. It is the opposite of a turbine, which extracts energy from, and reduces the pressure of, a flowing fluid.
In pumps
An impeller is a rotating componen ...
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
Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...
and maneuvering, the maneuvering thruster typically in the form of bow or stern thrusters and propulsion thrusters ranging from Azimuth thruster
An azimuth thruster is a configuration of marine propellers placed in pods that can be rotated to any horizontal angle (azimuth), making a rudder unnecessary. These give ships better maneuverability than a fixed propeller and rudder system.
Ty ...
s to Rim Drive thrusters.
Positioning Thrusters
Positioning thrusters come in applications, Bow thrusters
Bow often refers to:
* Bow and arrow, a weapon
* Bowing, bending the upper body as a social gesture
* An ornamental knot made of ribbon
Bow may also refer to:
* Bow (watercraft), the foremost part of a ship or boat
* Bow (position), the rower s ...
at the forward end of the vessel, and stern thrusters mounted aft on the boat. Their purpose is to maneuver or position the boat to a greater precision than the propulsion device can accomplish. Their positioning along the length of the vessel allows for directed lateral thrust ahead and astern of the centre of lateral resistance so that the vessel may be maneuvered away from obstructions in its path, or towards a desired position, especially when coming to or away from a dock
A dock (from Dutch ''dok'') is the area of water between or next to one or a group of human-made structures that are involved in the handling of boats or ships (usually on or near a shore) or such structures themselves. The exact meaning va ...
. These positioning thrusters are usually significantly smaller than the main propulsion thrusters because they only have to do small adjustments rather than moving the whole vessel at speed. Both bow and stern thrusters may be housed in through-hull tunnels. Depending on the size of the motors driving these propellers, they could draw an insignificant amount of power or a large amount of power that requires much caution to operate. Another smaller subset of positioning thrusters is those used for maneuvering unmanned aquatic vehicles like Guanay II AUV tested by scientists from Spain (Masmitja, 2018).
Propulsion Thrusters
Propulsion thrusters are those thrusters which provide longitudinal motion for vessels as an alternative to traditional propellers. There are a variety of types of propulsion thrusters but the most common form is the azimuth thruster, that can rotate 360 degrees on a vertical axis to optionally produce thrust for maneuvering. (Lindborg, 1997). The amount of thrust produced is controllable. There are variants of azimuth thrusters such as CRP thrusters which have two contra-rotating Azimuth thrusters or Swing-Up Azimuth thrusters that can be retracted when not in use to reduce drag on the vessel (Wartsila Encyclopedia). Other propulsion thrusters like outboard thrusters which can be easily put in and out of service, rim drive thrusters that are driven via the external ring with the blades mounted on the inner face of the ring with their tips towards the center, or tilted thrusters pointed away from the hull to minimize interaction with the ship and increase thruster efficiency.{{clarify, tilted thruster, date=November 2020 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. They have this versatility at the cost of complexity and lower efficiency – they are not as robust as propellers and typically have applications on smaller vessels that don't require as much power.
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