Bow thruster

Bow thruster

A bow thruster, is a propulsion device built into, or mounted to, the bow of a ship or boat to enhance its maneuverability. Bow thrusters make docking easier, since they allow the Captain to turn the vessel to port or starboard without using the main propulsion mechanism which requires some forward motion for turning.

Tunnel thrusters

Large vessels usually have one or more tunnels built into the bow below the waterline. An impeller in the tunnel can create thrust in either direction which makes the ship turn. Most tunnel thrusters are driven by electric motors, but some are hydraulically powered. These bow thrusters, also known as tunnel thrusters, may allow the ship to dock without the assistance of tugboats, saving the costs of such service. Ships equipped with tunnel thrusters typically have a sign above the waterline over each thruster on both sides, a big white cross in a white circle.

Tunnel thrusters increase the vessel's resistance to forward motion through the water, but this can be mitigated through proper fairing aft of the tunnel aperture (see below photo). Ship operators should take care to prevent fouling of the tunnel and impeller, either through use of a protective grate or by cleaning. During vessel design, it is important to determine whether tunnel emergence above the water surface is commonplace in heavy seas. Tunnel emergence hurts thruster performance, and may damage the device and the hull around it.

Externally mounted bow thrusters

Instead of a tunnel thruster, boats from 30 to 80 feet in length may have an externally mounted bow thruster. As its name suggests, an externally mounted bow thruster attaches to the bow making it suitable for boats where it is impossible or undesirable to install a tunnel thruster due to hull shape or outfitting. Externally mounted bow thrusters have one or more propellers driven by a small reversible electric motor which provides thrust in either direction. The added control provided by a bow thruster helps the Captain avoid accidents while docking.

Waterjet bow thrusters

A Waterjet thruster is a special type of bow thruster that utilizes a pumping device instead of a conventional propeller. The water is discharged through specially designed nozzles which increase the velocity of the exiting jet. Waterjets generally have the advantage of smaller hull penetrations for an equivalent size thruster. Additionally, the higher exit velocity of the discharged water increases the relative efficiency as speeds of advance, or currents, increase, as compared to standard tunnel thrusters. Some waterjet bow thrusters can be configured to provide forward and aft auxiliary propulsion, or even full 360 degree thrust.


Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • bow thruster — noun : an auxiliary propulsion device at the bow of a ship to aid in maneuvering * * * /bow/ a propeller located in a ship s bow to provide added maneuverability, as when docking. [1965 70] * * * bow thruster, an auxiliary propeller in a ship s… …   Useful english dictionary

  • bow thruster — /bow/ a propeller located in a ship s bow to provide added maneuverability, as when docking. [1965 70] * * * …   Universalium

  • bow thruster — noun a) a propulsion unit mounted in or on the bow of a vehicle b) a sideways pointing thruster mounted in a tunnel in the bow or under the bow in a pod, for increased maneuverability …   Wiktionary

  • bow thruster — /ˈbaʊ θrʌstə/ (say bow thrustuh) noun a propeller near the bow of a ship, usually in a tube running athwart, which permits the bow to be pushed sideways when the ship is mooring …  

  • Thruster — A thruster is a small propulsive device used by spacecraft and watercraft for station keeping, attitude control, or long duration low thrust acceleration.Thruster (surfing) is a surfboard fin design.Spacecraft thrusters,*Electrohydrodynamic… …   Wikipedia

  • thruster — noun a) A device for propelling an object, especially a spacecraft or a ship (marine vessel). b) A bow thruster …   Wiktionary

  • thruster — thrust•er [[t]ˈθrʌs tər[/t]] n. 1) rkt a small rocket attached to a spacecraft and used for producting thrust to control attitude or translational motion 2) a propeller located in a ship s bow or stern to provide added maneuverability, as when… …   From formal English to slang

  • ship — shipless, adj. shiplessly, adv. /ship/, n., v., shipped, shipping. n. 1. a vessel, esp. a large oceangoing one propelled by sails or engines. 2. Naut. a. a sailing vessel square rigged on all of three or more masts, having jibs, staysails, and a… …   Universalium

  • Newport class tank landing ship — USS Newport (LST 1179) Class overview Builders: Philadelphia Naval Shipyard National Steel and Shipbuilding Company …   Wikipedia

  • USS Harlan County (LST-1196) — The USS Harlan County (LST 1196) was a United States Navy tank landing ship of the Newport class. Harlan County (LST 1196) was named after Harlan County, Kentucky as reflected in her unit patch. Her keel was laid on 7 November 1970 at San Diego,… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”