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Kontio (icebreaker)
''Kontio'' is a Finnish state-owned icebreaker. Built by Wärtsilä Helsinki shipyard in 1987 as a replacement for the aging ''Karhu''-class icebreakers, she and her sister ship ''Otso'' were the first Finnish post-war icebreaker to be built without bow propellers.
In addition to icebreaker duties, ''Kontio'' has been fitted for oil spill response by the European Maritime Safety Agency.
== Development and construction ==
In the early 1980s, the Finnish National Board of Navigation began looking for a replacement for the aging ''Karhu''-class icebreakers ''Karhu'', ''Murtaja'' and ''Sampo'' which had been built in the late 1950s and were no longer wide enough to escort modern merchant ships.〔Karhu II - A new-generation icebreaker. Shipping World & Shipbuilder, October 1985.〕 Furthermore, the old icebreakers were expensive to operate and, despite their small size, required a relatively large crew of 53.〔Kaukiainen (1992), page 330.〕 The development of the new class of icebreakers, dubbed ''Karhu II'' in the preliminary papers, intensified when Wärtsilä opened a new ice model test facility in 1983. The first new icebreaker, ''Otso'', was ordered from Wärtsilä Helsinki shipyard on 19 March 1984 with a price of FIM 235 million and commissioned in January 1986.〔〔Uusi murtaja tilattu. Suomen Merenkulku 6/1984. Page 43.〕 The second ship, identical to the first one, was ordered in December 1985 and delivered to the owners on 29 January 1987.〔Helsingin Sanomat, 31 January 1986.〕 Her name, ''Kontio'', is one of the many epithets for bear in the Finnish language. Afterwards, the three ''Karhu'' class icebreakers were decommissioned and sold.〔
In terms of performance, ''Kontio'' is identical to her sister ship ''Otso''. During extensive ice trials in the Bothnian Bay in March 1986, ''Otso'' was put through a series of test to determine her icebreaking capability. In a race against the 1975-built ''Urho'' in level ice, ''Otso'' beat the older but more powerful four-propelled icebreaker by a ship's length,〔Turunen (2011), pages 37–39.〕 showing that in terms of ice resistance the new icebreaker was superior to her predecessor.〔〔 In ice, she could easily maintain a speed of and small ice ridges along the way appeared to be of no consequence to the vessel. However, the strength of the new icebreaker was put to the ultimate test when she encountered a large pressure ridge reaching all the way to the seafloor some below the surface. After preparations, ''Otso'' was accelerated to a speed of and rammed into the ridge at full power. Since the new icebreaker had a smooth inclined stem and lacked the bow propellers of her predecessors, she rode up the ridge and began listing to the port side as the hull rose from the water. After coming to a stop, ''Otso'' slid back by herself without utilizing the engines, and the ridge was penetrated on the second charge.〔〔 The robustness of the ship and its propulsion system were further proven when the icebreaker was backed into a ridge at "to prove to the customer it doesn't break".〔(Icebreakers! ) Popular Mechanics, February 1989. 〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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