Bollard pull

Bollard pull is a value that allows the comparison of the pulling power of watercraft, particularly tugboats.

Unlike in ground vehicles, the statement of installed horsepower is not sufficient to understand how strong a tug is - this is because other factors, like transmission losses, propulsion type, propulsion system efficiency, have an influence as well.

The bollard pull test is easily understood: take the tug (or more generally, the vessel) in question and tie a rope between the aftermost clamp or cleat on the vessel (in a tug, this will be the pulling hook) and a bollard on shore. Set the water vessel's engines to "full ahead" and wait until the conditions have settled. Now measure the force in the rope.

Although it can be performed in practice, bollard pull is normally a hypothetical test. In reality, too many conditions would have a disturbing influence on the measurement:
  • depth of water
  • distance from shore
  • shape of shore wall
  • stream
  • salinity
Bollard pull figures for a tug are normally determined by means of simulation or computation when designing the ship.

Real-life bollard pull tests are conducted for human powered vehicles. There, bollard pull is often a category in competitions and gives an indication of the power train efficiency.

See also

Further reading

TUGboat (ISSN 0896-3207) is a journal published three times per year by the TeX Users Group. It covers a wide range of topics in digital typography relevant to the TeX typesetting system. The editor is Barbara Beeton.
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Horsepower (hp) is the name of several non-metric units of power. The most occurring conversion of horsepower to watt goes 1 horsepower = 745.7 watts. In scientific discourse, the term "horsepower" is seen as inferior and is rarely used because of its various definitions and
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rope (IPA: /rəʊp/) is a length of fibers, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength (i.e.
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Clamp may refer to:
  • Clamp (tool), a device used to hold an object in a fixed position.
  • Storage clamp, an agricultural root crop storage.
  • Clamp meter, a device for measuring electric current.

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Cleat may refer to:
  • Cleat (nautical), a fitting on ships, boats, and docks to which ropes are tied
  • Cleat (shoe), a type or part of a shoe
  • Cleats (comic strip), a comic strip by Bill Hinds

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A bollard is a short vertical post typically found where large ships dock. While originally it only meant a post [1] used on a quay for mooring, the word now also describes a variety of structures to control or direct road traffic.
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Human-powered transport is any vehicle for transport of person(s) and/or goods, powered by human muscle. Like animal-powered transport, human-powered transport has existed since time immemorial in the form of walking, running and swimming.
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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.
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The maximum tractive effort is the highest force that a vehicle can exert. The term tractive effort is usually used in connection with trains and rail locomotives. Like all forces, tractive effort is measured in newtons.
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