Wikipedia

Tugboat

"Tug" redirects here. For other uses, seeTugboat (disambiguation)andTug (disambiguation).
"Tugs" redirects here. For the television series, seeTugs(TV series).

Atugboatortugis amarine vesselthat manoeuvres other vessels by pushing or pulling them, with direct contact or a tow line. Theseboatstypically tugshipsin circumstances where they cannot or should not move under their own power, such as in crowdedharborsor narrowcanals,[1]or cannot move at all, such asbarges,disabled ships,log rafts,oroil platforms.Some are ocean-going, and some areicebreakersorsalvage tugs.Early models were powered bysteam engines,which were later superseded bydiesel engines.Many havedeluge gunwater jets, which help infirefighting,especially in harbours.

TugboatCSSTeaseris captured byUSSMaratanza
Justine McAllister,a tug boat inNew York Harbor,January 2008
The tugboatsReid McAllisterandMcAllister Responderpush the LPG tankerBW Volansinto port at Marcus Hook on the Delaware River

Types

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Seagoing

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Fleet tugUSSTawasa(1,255 tons, 205 ft) which towed a nuclear depth charge as it was detonated inOperation Wigwamin 1955
Articulated tug and barge(ATB)

Seagoing tugs (deep-sea tugs or ocean tugboats) fall into four basic categories:

  1. The standard seagoing tug with model bow that tows almost exclusively by way of a wire cable. In some rare cases, such as some USN fleet tugs, a synthetic ropehawsermay be used for the tow in the belief that the line can be pulled aboard a disabled ship by the crew owing to its lightness compared to wire cable.
  2. The "notch tug" can be secured by way of cables, or more commonly in recent times, synthetic lines that run from the stern of the tug to the stern of the barge. This configuration is generally used in inland waters where sea and swell are minimal because of the danger of parting the push wires. Often, this configuration is employed even without a "notch" on the barge, but in those cases it is preferable to have "push knees" on the tug to stabilize its position. Model bow tugs employing this method of pushing nearly always have a towing winch that can be used if sea conditions render pushing inadvisable. With this configuration, the barge being pushed might approach the size of a small ship, with the interaction of the water flow allowing a higher speed with a minimal increase in power required or fuel consumption.
  3. The "integral unit", or "integrated tug and barge" (ITB), comprises specially designedvesselsthat lock together in such a rigid and strong method as to be certified as such by authorities (classification societies) such as theAmerican Bureau of Shipping,Lloyd's Register of Shipping,Indian Register of Shipping,Det Norske Veritasor several others. These units stay combined under virtually any sea conditions and the tugs usually have poorsea-keepingdesigns for navigation without their barges attached. Vessels in this category are legally considered to be ships rather than tugboats and barges must be staffed accordingly. These vessels must show navigation lights compliant with those required of ships rather than those required of tugboats and vessels undertow.
  4. "Articulated tug and barge" (ATB) units also utilize mechanical means to connect to their barges. The tug slips into a notch in the stern and is attached by a hinged connection, becoming anarticulated vehicle.ATBs generally utilize Intercon andBludworthconnecting systems. ATBs are generally staffed as a large tugboat, with between seven and nine crew members. The typical American ATB displays navigational lights of a towing vessel pushing ahead, as described in the 1972ColRegs.

Harbour

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Svitzer Tyr,a Danish tugboat, built inChinain 2011, pictured in 2018 inYstadharbour

Compared with seagoing tugboats,harbourtugboats that are employed exclusively as ship assist vessels are generally smaller and their width-to-length ratio is often higher, due to the need for the tugs' wheelhouse to avoid contact with the hull of a ship, which may have a pronounced rake at the bow and stern. In some ports there is a requirement for certain numbers and sizes of tugboats for port operations withgas tankers.[2]Also, in many ports, tankers are required to have tug escorts when transiting in harbors to render assistance in the event of mechanical failure. The port generally mandates a minimum horsepower or bollard pull, determined by the size of the escorted vessel. Most ports will have a number of tugs that are used for other purposes than ship assist, such as dredging operations, bunkering ships, transferring liquid products between berths, and cargo ops. These tugs may also be used for ship assist as needed. Modern ship assist tugs are "tractor tugs" that employ azimuthing stern drives (ASD), propellers that can rotate 360 degrees without a rudder, or cycloidal drives (as described below).

River

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River tug pushing alog raftinBritish ColumbianearVancouver(May 2012)

River tugs are also referred to astowboatsor pushboats. Their hull designs would make open ocean operations dangerous. River tugs usually do not have any significant hawser or winch. Their hulls feature a flat front or bow to line up with the rectangular stern of the barge, often with large pushing knees.

Propulsion

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A tugboat on theArakawa RiverinTokyo,Japan

The first tugboat,Charlotte Dundas,was built by William Symington in 1801. It had a steam engine and paddle wheels and was used on rivers in Scotland.Paddle tugsproliferated thereafter and were a common sight for a century. In the 1870s schooner hulls were converted to screw tugs. Compound steam engines and scotch boilers provided 300 Indicated Horse Power. Steam tugs were put to use in every harbour of the world towing and ship berthing.

Tugboat diesel engines typically produce 500 to 2,500kW(~680 to 3,400hp), but larger boats (used in deep waters) can have power ratings up to 20,000 kW (~ 27,200 hp)[citation needed].Tugboats usually have an extremepower:tonnage-ratio; normalcargoand passenger ships have a P:T-ratio (in kW:GRT) of 0.35 to 1.20, whereas large tugs typically are 2.20 to 4.50 and small harbour-tugs 4.0 to 9.5.[3]The engines are often the same as those used in railroadlocomotives,but typically drive thepropellermechanically instead of converting the engine output to power electric motors, as is common for diesel-electric locomotives. For safety, tugboat engines often feature two of each critical part for redundancy.[4]

A tugboat is typically rated by its engine's power output and its overallbollard pull.The largest commercial harbour tugboats in the 2000s–2010s, used for towing container ships or similar, had around 60 to 65 short tons-force (530–580 kN) of bollard pull, which is described as 15 short tons-force (130 kN) above "normal" tugboats.[5][6]

Diagram of components

Tugboats are highly manoeuvrable, and various propulsion systems have been developed to increase manoeuvrability and increase safety. The earliest tugs were fitted withpaddle wheels,but these were soon replaced by propeller-driven tugs.Kort nozzles(see below) have been added to increase thrust-to-power ratio. This was followed by the nozzle-rudder, which omitted the need for a conventionalrudder.Thecycloidal propeller(see below) was developed prior toWorld War IIand was occasionally used in tugs because of its maneuverability. After World War II it was also linked to safety due to the development of the Voith Water Tractor, a tugboat configuration that could not be pulled over by its tow. In the late 1950s, theZ-driveor (azimuth thruster) was developed. Although sometimes referred to as the Aquamasteror Schottelsystem, many brands exist:Steerprop,Wärtsilä,Berg Propulsion,etc. These propulsion systems are used on tugboats designed for tasks such as ship docking and marine construction. Conventional propeller/rudder configurations are more efficient for port-to-port towing.

Kort nozzle

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Main article:Ducted propeller

The Kort nozzle is a sturdy cylindrical structure around a special propeller having minimum clearance between the propeller blades and the inner wall of the Kort nozzle. The thrust-to-power ratio is enhanced because the water approaches the propeller in a linear configuration and exits the nozzle the same way. The Kort nozzle is named after its inventor, but many brands exist.

Cyclorotor

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Main article:Cyclorotor

The cycloidal propeller is a circular plate mounted on the underside of the hull, rotating around a vertical axis with a circular array of vertical blades (in the shape ofhydrofoils) that protrude out of the bottom of the ship. Each blade can rotate itself around a vertical axis. The internal mechanism 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, similar to the collective pitch control and cyclic in a helicopter.

Fenders

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Red Cloud(foreground), atype V2-ME-A1tug, alongsideUSNSDavid C. Shanks,outside theOakland Bay Bridgein San Francisco Bay, California, 1950s. On the bow is a traditional ropetugboat fender.

Tugboat fendersare made of high-abrasion-resistance rubber with good resilience properties. They are very popular with small port craft owners and tug owners. These fenders are generally made from cut pieces of vehicle tires strung together. Often the fendering on the sides of the tug is composed of large heavy equipment or aircraft tires attached to or hung on the side of the tug. Some fendering is compression moulded in high-pressure thermic-fluid-heated moulds and have excellent seawater resistance, but are not widely used owing to the cost. Tugboat bow fenders are also called beards or bow puds. In the past they were made of rope for padding to protect the bow, but rope rendering is almost never seen in recent times. Other types of tugboat fender include Tug cylindrical fender, W fender, M fender, D fender, and others.[7]

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A recentDutchinnovation is thecarousel tug,winner of the Maritime Innovation Award at the Dutch Maritime Innovation Awards Gala in 2006.[8]It adds a pair of interlocking rings to the body of the tug, the inner on the boat, the outer on the ship by winch or towing hook. Since the towing point rotates freely, the tug is very difficult to capsize.[9]

Races

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Vintage tugboat races have been held annually inOlympia, Washington,since 1974 during the Olympia Harbor Days Maritime Festival Tugboat races are held annually onElliott BayinSeattle,[10]on theHudson Riverat theNew York Tugboat Race,[11]theDetroit River,[12]and the Great Tugboat Race and Parade on theSt. Mary's River.[13]

Ballet

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South African Naval tugs perform a "ballet" when welcoming a new member of the fleet

Since 1980, an annual tugboat ballet has been held inHamburgharbour on the occasion of the festival commemorating the anniversary of the establishment of a port in Hamburg. On a weekend in May, eight tugboats perform choreographed movements for about an hour to the tunes ofwaltzand other sorts of dance music.[14]

Roundups

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The Tugboat Roundup is a gathering of tugboats and other vessels in celebration of maritime industry. The Waterford Tugboat Roundup is held in the late summer at the confluence of the Hudson and Mohawk Rivers in Waterford, New York. The tugs featured are river tugs and other tugs re-purposed to serve on the New York State Canal System.[15]

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Tugboat Anniewas the subject of a series ofSaturday Evening Postmagazine stories featuring the female captain of the tugboatNarcissusinPuget Sound,later featured in the filmsTugboat Annie(1933),Tugboat Annie Sails Again(1940) andCaptain Tugboat Annie(1945). The Canadian television seriesThe Adventures of Tugboat Anniewas filmed in1957.

Film and television

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Theodore Tugboat,the titular hero of a children's show, was popular enough that a fullsize replica was constructed

To date, there have been four children's shows revolving aroundanthropomorphictugboats.

"Tugger" is a tugboat in theanimated seriesSouth Park.He appears in theepisode"The New Terrance and Phillip Movie Trailer"as a sidekick forRussell Crowein a fictitioustelevision seriesentitledFightin' Round The World with Russell Crowe.Tugger follows Crowe as he engages various people in physical conflicts, providing emotional support and comic relief. At one point Tugger even attempts to commit suicide, upon being forced to hear Russell Crowe's new musical composition.

Literature

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(Alphabetical by author)

  • The children's bookScuffy the Tugboat,written byGertrude Cramptonand illustrated byTibor Gergelyand first published in1946as part of theLittle Golden Booksseries, follows the adventures of a young toy tugboat who seeks a life beyond the confines of a tub inside his owner's toy store.
  • TheDutchwriterJan de Hartogwrote numerous nautical novels, first inDutch,then inEnglish.
    • The novelHollands Glorie,written prior toWorld War II,was made into a Dutch miniseries in 1978 and concerned the dangers faced by the crews of Dutch salvage tugs.[16][17]
    • The novellaStella,concerning the dangers faced by the captains of rescue tugs in theEnglish Channelduring World War II, was made into a film entitledThe Keyin 1958.[18]
    • The novelThe Captain(1967), about the captain of a rescue tug during aMurmansk Convoy,sold over a million copies.[19]
    • Its 1986 sequel,The Commodore,features the narrator captaining a fleet of tugs in peace-time.
  • Little Toot(1939), written and illustrated byHardie Gramatky,is a children's story of an anthropomorphic tugboat child, who wants to help tow ships in a harbour nearHoboken.He's rejected by the tugboat community and dejectedly drifts out to sea, where he accidentally discovers a shipwrecked liner and a chance to prove his worth. This story was animated as part of the Disney movieMelody Time.
  • Farley Mowat's bookThe Grey Seas Undertells the tale of a legendary North Atlantic salvage tug, theFoundation Franklin.He later wroteThe Serpent's Coil,which also deals with salvage tugs in the North Atlantic.
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See also

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Notes

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  1. ^"How Pygmy Tugboats Dock a Giant Liner."Popular Science Monthly,March 1930, p. 22-23.
  2. ^Thoresen, Carl A (2003).Port Designer's Handbook: Recommendations and guidelines.Thomas Telford Books. p. 116.ISBN0-7277-3228-5.
  3. ^Poulsen, B Lund; et al. (1971).Teknisk Leksikon[The Technological Encyclopaedia] (in Danish). Vol. 2. København: A/S Forlaget for Faglitteratur København/Oslo. pp. 163–190.ISBN87-573-0023-2.
  4. ^Bilinski, Marcie B.:"The Workhorse of the Waterways"Massachusetts Office of Coastal Zone Management, Coastlines 2007
  5. ^"Rotor Tug" RT Zoe "".Marineline.com.13 September 2006.Retrieved19 August2013.
  6. ^"Western Marine to build tugboat, vessel for Ctg port".The Independent.4 June 2012. Archived fromthe originalon 15 April 2016.Retrieved19 August2013.
  7. ^"Tugboat Fender Types and Application - Marine Fender System".
  8. ^novatugnews."Novatug.nl news".Novatug.Archived fromthe originalon 2007-09-08.Retrieved2008-01-18.
  9. ^novatugprod."Novatug.nl product information".Novatug.Archived fromthe originalon 2008-01-19.Retrieved2008-01-18.
  10. ^"Port of Seattle".Portseattle.org. Archived fromthe originalon July 23, 2011.Retrieved2012-02-18.
  11. ^"In search of the toughest tug," by Laurel Graeber,New York Times,August 29, 2008.
  12. ^"tugrace.com".tugrace.com. 2013-06-22. Archived fromthe originalon 2014-04-17.Retrieved2014-03-23.
  13. ^"The Great Tugboat Race".Archived fromthe originalon 2011-08-28.Retrieved2012-06-13.
  14. ^"Schlepperballett: Kaiserwalzer der Kolosse – SPIEGEL ONLINE – Nachrichten – SPIEGEL TV".Der Spiegel.Spiegel.de. 19 May 2002.Retrieved2012-02-18.
  15. ^"Waterford Tugboat Roundup".Tugboatroundup.com.Retrieved2022-03-08.
  16. ^ "Hollands glorie".IMDb.Retrieved2008-01-20.
  17. ^ Mel Gussow(September 24, 2002)."Jan de Hartog, 88, Author of His Own Life".The New York Times.Retrieved2008-01-20.
  18. ^ "The Key".IMDb.Retrieved2008-01-20.
  19. ^ "Hartog, Jan De [1914 – 2002]".New York State Library.Retrieved2008-01-20.

References

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  • Jane's Ocean Technology 1979–80/ Jane's Yearbooks, 1979 –ISBN0-531-03902-1.
  • On Tugboats: Stories of Work and Life Aboard/ Virginia Thorndike – Down East Books, 2004.
  • Under Tow: A Canadian History of Tugs and Towing/ Donal Baird – Vanwell Publishing, 277 p., 2003 –ISBN1-55125-076-4
  • Pacific Tugboats/ Gordon Newell – Superior Publishing Company 1957, Seattle Washington.
  • Primer of Towing/ George H. Reid – Cornell Maritime Press, 1992.

Further reading

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  • Lehman, Charles F (2009).A riverman's lexicon: in Lehman's terms.Florissant, MO: J.R. Simpson & Associates.ISBN978-0-9841503-0-4.Nautical terminology specific to towboating on inland waterways.
  • Farrell, Paul (2016).Tugboats Illustrated History, Technology, Seamanship.New York: W. W. Norton & Company.ISBN978-0-393-06931-0.A gorgeously detailed guide to the evolution, design, and role of tugboats, from the earliest days of steam to today’s most advanced ocean-going workboats.
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