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''Jääkarhu'' was a Finnish and later Soviet steam-powered icebreaker. Built in 1926 by P. Smit Jr. Shipbuilding and Machine Factory in Rotterdam, Netherlands, she was the last and largest steam-powered state-owned icebreaker of Finland. After two decades of successful service, ''Jääkarhu'' was handed over to the Soviet Union as war reparation in 1945 and renamed ''Sibiryakov''. She remained in service until the 1970s and was broken up in 1972. == Background and construction == When the Treaty of Tartu was signed on 14 October 1920, Finland agreed to return the Russian icebreakers that the Finnish White Guard had seized during the Civil War in 1918. As a result the largest and most powerful state-owned icebreaker of Finland at that time, ''Wäinämöinen'', was handed over to Estonia in 1922. Since both the size of the ships calling at the Finnish winter ports and the amount of exported goods, especially forest products, had increased considerably since the First World War, there was a definite need for a large and powerful icebreaker. One of the key issues was the beam of the existing icebreakers, , which was not enough for the new ships used to transport goods across the Atlantic Ocean.〔Laurell 1992, pp. 133–139.〕 In 1923, the state allocated FIM 10 million for the design and development of a new icebreaker based on the experiences gained during the four years that ''Wäinämöinen'' had spent under the Finnish flag. The basic design of the new vessel, which was to have a beam of at least , was awarded to experienced Finnish naval architects K. Albin Johansson and Ossian Tybeck.〔 By June 1923, bids ranging from FIM 20.2 to 35.5 million had been received from 24 shipyards representing eight nationalities. The most expensive offer was received from the Finnish Sandvikens Skeppsdocka och Mekaniska Verkstads Ab that was already building another new icebreaker, ''Voima'', in Helsinki. In the end, the contract was awarded to the Dutch shipbuilder P. Smit Jr. Shipbuilding and Machine Factory from Rotterdam. The shipyard had recently constructed four ice-strengthened ships for the Finland Steamship Company and the technical director of the company had personally spent several weeks on board the Finnish icebreaker ''Sampo'' during the past winter.〔 The contract for the construction of a new icebreaker was signed on 17 April 1924 after the Dutch government and the town council of Rotterdam agreed to subsidize the construction costs by 175,000 Dutch guilders, bringing the final cost to ƒ1,563,000 (FIM 26,000,000). She was launched on 26 August 1925〔Nieuwe Rotterdamsche Courant (26 August 1925 and 17 January 1926) and Het Centrum (24 December 1925). Excerpts available at ("The building of the Finnish icebreaker Jääkarhu according to the Dutch newspapers in 1925–1926" ), Warshipresearch, 10 September 2011.〕 and given the name ''Jääkarhu'', Finnish for polar bear. Curiously, her namesake animal is not a native species to Finland.〔(Polar bear cub becomes tourist magnet ). YLE, 19 March 2012. 〕 As the new icebreaker was being built, Captain Johan Rosqvist, who has previously commanded ''Sampo'', was selected as the first captain of the new icebreaker, and in the summer of 1925 he travelled to Rotterdam together with a chief engineer and a second engineer to supervise the construction and outfitting of his new ship.〔 On 13 January 1926 ''Jääkarhu'' was ready for first sea trials in the North Sea. Although there were still issues with the oil-fired boilers by late February, it was agreed to take the delivery of the new icebreaker on 2 March 1926 and solve the problems later as the winter of 1926 had turned out to be very severe. Despite the best efforts of existing Finnish state-owned icebreakers, the ice conditions in the Gulf of Finland and the Sea of Åland were extremely difficult and vast pack ice fields closed off the shipping lanes outside the island of Utö at the edge of the Archipelago Sea.〔〔 Although sometimes called the largest and most powerful icebreaker in the world by the press in the 1920s, ''Jääkarhu'' was no match for the Soviet polar icebreakers ''Yermak'' and ''Svyatogor'' that had nearly twice the displacement and over twice the power of the Finnish icebreaker. However, as a Baltic escort icebreaker she was considered better than the giants and was often compared with the Soviet icebreaker ''Lenin'', which was roughly of the same size and was considered a very successful design.〔Ramsay 1949, p. 320–324.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Jääkarhu」の詳細全文を読む スポンサード リンク
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