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Icebreaker

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{{otheruses}} ---- Image:IcebreakerNasa.jpg thumb|right|300px|thumb|US Coast Guard icebreakers near [[McMurdo Station, February 2002]]Image:Polarstern.gif thumb|right|300px|Icebreaker ''[[Polarstern'']] An '''icebreaker''' is a special purpose ship designed to move and navigate through ice-covered marine environments. For a ship to be considered an icebreaker it requires three components: an ice strengthened hull, an ice clearing shape, and the power to push through. An ordinary ship with no strengthening will not risk touching ice at all, no matter how gently. An icebreaker needs a specially strengthened Hull (ship) hull to work in ice conditions. These ships break ice by using their momentum and power to push the bow up on the ice. The weight of the ship causes the ice to be pushed down which in turn causes the ice to split and break off in chunks. An icebreaker's specially designed hull must direct the ice around the vessel or under the ice to allow the icebreaker to proceed forward. A buildup of broken ice will stop a vessel much faster than breaking the ice itself. At a greater risk of damage from ice is a ship's propulsion system. Essential to an icebreaking vessel is the ability to propel itself onto the ice, breaking it, and then successfully clearing the ice debris from its path. One powerful kind is the nuclear powered icebreaker.

History
Image:SS Sankt Erik.jpg thumb|left|200px|An early 20th Century icebreaker — [[SS Sankt Erik|''Sankt Erik'' launched in 1915. Note the shape of the bow, designed to ride up over the ice]] Even in the earliest days of polar exploration, ice-strengthened ships were used. These were originally wooden and based on existing designs, but reinforced, particularly around the waterline with double planking to the hull and strengthening cross members inside the ship. Bands of iron were wrapped around the outside. Sometimes metal sheeting was placed at the bows, stern and along the keel. Such strengthening was designed to help the ship push through ice and also to protect the ship in case it was "nipped" by the ice. Nipping occurs when ice floes around a ship are pushed against the ship trapping it as if in a vice and causing damage. This vice-like action is caused by the force of winds and tides transmitted through ice formations that, although many miles distant, transmit the pressure. It is supposed that the first icebreaker equipped by steam engine was built in Kronshtadt in 1864. The steam-powered icebreaker was known as ''Pilot''. At the beginning of the 20th Century several countries began to operate purpose-built icebreakers; most were coastal icebreakers, but Russia and later the Soviet Union also built several oceangoing icebreakers of around 10,000 tonnes displacement. Several technological advances were introduced over the years, but it was not until the introduction of nuclear power in the Soviet icebreaker Lenin Soviet icebreaker ''Lenin'' in 1959 that icebreakers developed their full potential.

Function of icebreakers
Image:CCGS Louis S St Laurent.jpg right|thumb|250px|Canadian Coast Guard icebreaker ''Louis S. St Laurent'' Icebreakers are needed to keep trade routes open where there are either seasonal or permanent ice conditions. Icebreakers are expensive to build and very expensive to run, whether the icebreaker is powered by gas turbines, diesel-electric powerplant or nuclear powered icebreaker nuclear energy. They are uncomfortable to travel in on the open sea: almost all of them have thick, rounded keels and with no protuberances for stability they can roll even in light seas. They are also uncomfortable to travel in when breaking through continuous thick ice due to constant motion, noise, and vibration caused by banging against the ice. A modern icebreaker typically has shielded propellers both at the bow and at the stern, as well as side thrusters; pumps to move water ballast from side to side; and holes on the hull below the waterline to eject water bubbles, all designed to allow an icebreaker stuck amidst thick ice to break free. Many icebreakers also carry aircraft (formerly seaplanes and now helicopters) to assist in reconnaissance and liaison.

Recent advances
Image:USCGC Healy.gif left|thumb|200px|[[USCG Cutter C ''Healy'' (WAGB-20)]] The shape which allows icebreakers to move through ice also makes them uncomfortable in open water and means they have poor fuel efficiency. Icebreakers tend to roll side to side causing discomfort to the crew. Some new icebreakers such as the USCGC Healy USCGC ''Healy'' make use of anti-roll tanks. Anti-roll tanks use computer controlled pumps to rapidly shift ballast water side to side to keep the vessel upright. This same technology can be very hazardous if used improperly. A greater concern is how well a ship cuts through waves. The ability of a ship to cut through waves can greatly affect its fuel efficiency and even its safety in a storm. Most ships use a sharp bow to cut through waves and help prevent waves from slamming the bow of the ship. However, icebreakers have a round sled-like bow. They tend to slam into waves, which can be a risk in high seas. Recent advances in ship propulsion have produced new experimental icebreakers. Electrically driven propellers are mounted to steerable pods under the ship. These Azimuth thruster Azimuthing Podded Propulsors, or ''Azi-pods'', improve fuel efficiency, ship steering, ship docking, and remove the need for rudders. Azipods also allow a ship to travel backwards as easily as it travels forwards. The double acting icebreaker is unique because its stern is shaped like an icebreaker's bow. Normally travelling forward, a double acting icebreaker uses a conventional ship bow for a more comfortable ride. When ice is encountered, the ship turns around and travels backwards through the ice. The MT Mastera MT ''Mastera'' and MT Tempera MT ''Tempera'' are two vessels using this new technology. In the 1980s hovercraft were shown to be effective as icebreakers on rivers. Instead of displacing or crushing the ice from above, they work by injecting a bubble of air under the ice sheet, causing it to break off and be swept downstream by the current. The purpose is usually not to provide navigation channels, rather, to prevent ice dams from forming on bridge structures, thus damaging them and causing local flooding. :''Media: :Image:Ship_in_ice,_animation.gif This computer simulation shows a ship transit through an ice-filled channel.

Notable icebreakers

Argentina
Argentine Navy *ARA Almirante Irízar (Q-5) ARA ''Almirante Irízar'' (Q-5)

Australia
*Aurora Australis (icebreaker) ''Aurora Australis''

Canada
Image:CCGS_TERRY_FOX.jpg thumb|right|250px|Icebreaker [[CCGS Terry Fox|CCGS ''Terry Fox'']] Image:CCGS Pierre Radisson.JPG.jpg thumb|right|250px|CCGS ''Pierre Radisson'' Image:MV ArcticIceProbeAnaktalakBayFebruary2005.jpg right|thumb|250px|Icebreaker MV ''Arctic'' Image:CCGS Henry Larsen 1.jpg right|thumb|250px|Icebreaker [[CCGS Henry Larsen|CCGS ''Henry Larsen'']] Image:MV_Caribou.jpg thumb|right|250px|[[MV Caribou|MV ''Caribou'', the largest icebreaker ferry in the world]] '''Canadian Coast Guard''' '''Heavy Icebreaker''' * CCGS Louis S. St-Laurent CCGS ''Louis S. St-Laurent'' * CCGS Terry Fox CCGS ''Terry Fox'' '''Icebreaker''' * CCGS Alexander Henry CCGS ''Alexander Henry'' * CCGS Amundsen CCGS ''Amundsen'' * CCGS Des Groseilleirs CCGS ''Des Groseilleirs'' * CCGS Henry Larsen CCGS ''Henry Larsen'' * CCGS Labrador CCGS ''Labrador'' (''decomissioned'') * CCGS Pierre Radisson CCGS ''Pierre Radisson'' * CCGS Sir John Franklin CCGS ''Sir John Franklin'' '''Light Icebreaker''' * CCGS Samuel Risley CCGS ''Samuel Risley'' * CCGS Ann Harvey CCGS ''Ann Harvey'' * CCGS Edward Cornwallis CCGS ''Edward Cornwallis'' * CCGS George R. Pearkes CCGS ''George R. Pearkes'' * CCGS Griffon CCGS ''Griffon'' * CCGS J.E. Bernier CCGS ''J.E. Bernier'' * CCGS Martha L. Black CCGS ''Martha L. Black'' * CCGS Sir Wilfred Laurier CCGS ''Sir Wilfred Laurier'' * CCGS Sir William Alexander CCGS ''Sir William Alexander'' * CCGS Earl Grey CCGS ''Earl Grey'' * CCGS Bartlett CCGS ''Bartlett'' * CCGS Provo Wallis CCGS ''Provo Wallis'' * CCGS Simco CCGS ''Simco'' * CCGS Tracy CCGS ''Tracy'' * CCGS Cygnus CCGS ''Cygnus'' * CCGS Leonard J. Cowley CCGS ''Leonard J. Cowley'' * CCGS Sir Wilfred Grenfell CCGS ''Sir Wilfred Grenfell'' '''Marine Atlantic''' *MV Caribou MV ''Caribou'' (''Gulfspan'' ferry) *MV Joseph and Clara Smallwood MV ''Joseph and Clara Smallwood'' (''Gulfspan'' ferry) *MV Leif Ericson MV ''Leif Ericson'' '''Newfoundland and Labrador''' ''Dept. of Transportation'' *Northern Ranger MV ''Northern Ranger'' '''Ontario Hydro''' *''Niagara Queen II'' '''FedNav''' *MV Arctic (icebreaker) MV ''Arctic'' '''Other''' *Icebreaker Arctic Kalvik ''Arctic Kalvik''

Finland
Finnish Maritime Administration *MS Fennica *MS Nordica *MS Kontio *Jääkarhu (icebreaker) icebreaker Jääkarhu Commercial *MV Sampo *MT Tempera and MT Mastera

Germany
*PFS Polarstern ''Polarstern'' *Stettin (icebreaker) ''Stettin''

International
*Greenpeace **MV Arctic Sunrise

Japan
*Shirase (icebreaker) ''Shirase''

Norway
*Vidar Viking icebreaker and drill ship

Russia
Image:NSF picture of Yamal.gif thumb|right|250px|Russian nuclear icebreaker ''Yamal'' Image:HMS Endurance.jpg thumb|right|250px|HMS ''Endurance'' Image:Polar sea.jpg thumb|right|250px|USCGC ''Polar Sea'' *Icebreaker Arktika ''Arktika'' (nuclear-powered) *Kapitan Dranitsyn (icebreaker) ''Kapitan Dranitsyn'' *Kapitan Khlebnikov (icebreaker) ''Kapitan Khlebnikov'' *Krasin (icebreaker) ''Krasin'' *Soviet icebreaker Lenin ''Lenin'' (nuclear-powered) *Icebreaker Saint Alexander Nevsky ''Saint Alexander Nevsky'' *Yamal (icebreaker) ''Yamal'' (nuclear-powered) *Icebreaker Yermak ''Yermak'' *Icebreaker Vladimir Ignatyuk ''Vladimir Ignatyuk'' *Nuclear marine propulsion NS Taimyr (icebreaker) ''Taimyr'' (nuclear-powered) *NS Vaigach (icebreaker) ''Vaigach'' (nuclear-powered)

Sweden
*''Ale (icebreaker) Ale'' *''Atle (icebreaker) Atle'' *''Frej (icebreaker) Frej'' *''Oden (icebreaker) Oden'' *''Ymer (icebreaker) Ymer'' *''SS Sankt Erik Sankt Erik''

United Kingdom
*HMS_Endurance_(A171) HMS ''Endurance'' * RRS James Clark Ross

United States
National Science Foundation *Nathaniel B. Palmer (icebreaker) ''Nathaniel B. Palmer'' United States Coast Guard *Heavy Icebreaker USCGC Healy (WAGB-20) *Heavy Icebreaker USCGC Polar Star (USCGC Polar Star WAGB-10) *Heavy Icebreaker USCGC Polar Sea (USCGC Polar Sea WAGB-11) *Icebreaker USCGC Mackinaw *Icebreaker [http://www.cgcwestwind.net USCGC Westwind] (decommissioned)

=External Links
=
- "Ice heroes": Read a Q&A with Canadian Coast Guard acting commanding officer
- Canadian Geographic: View a Canadian Coast Guard slideshow Category:Ship types Category:Icebreakers * cs:Ledoborec da:Isbryder de:Eisbrecher et:Jäälõhkuja es:Rompehielos fr:Brise-glace it:Rompighiaccio he:שוברת קרח ms:Kapal pemecah air batu nl:IJsbreker ja:砕氷船 nn:Isbrytar pl:Lodołamacz pt:Quebra-gelo ru:Ледокол sh:Ledolomac sl:Ledolomilec fi:Jäänmurtaja sv:Isbrytare

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