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''Portmar'' was a United States-flagged merchant vessel that was constructed in response to World War I, operated by a succession of companies in the interwar period, then taken up for wartime shipping in World War II. The ship was built to Design 1013, as part of wartime orders by the United States Shipping Board (USSB). She was laid down by Northwest Steel of Portland, Oregon, with the name ''West Minsi''. The USSB order was cancelled during construction, but Northwest Steel completed the ship for private sale. She was sold to the Green Star Line before launching in November 1919, and was assigned the name ''Centaurus''. The freighter was sold to Nafra in 1920, then on to the Planet Steamship Company in 1923. In 1929, the ship was sold to the Calmar Steamship Company, who renamed the ship ''Portmar''. In late 1941, ''Portmar'' was chartered by the United States Department of War to carry supplies to the Philippines but due to the Japanese invasion of the Philippines was retained in Australia. She was used in February 1942 to carry reinforcements from Darwin for the defenders of Timor prior to the Japanese invasion. The reinforcement convoy was shadowed by Japanese planes and attacked, forcing its cancellation. ''Portmar'' returned to Darwin on 18 February, and was still in harbour the next day when Japanese carrier-based aircraft attacked the city in the first ever attack on Australia. The ship was heavily damaged, and run aground to prevent sinking. ''Portmar'' was later refloated, towed to Sydney, repaired, purchased by the United States Army and put back into service as an Army transport. In June 1943, she sailed as part of convoy GP55. On 15 June, off Smoky Cape, ''Portmar'' and the landing ship ''LST-469'' were torpedoed by the Japanese submarine ''I-174''. Due to a highly volatile cargo, ''Portmar'' was abandoned and sank in less than ten minutes. She was the last ship lost to the Japanese submarine campaign in Australian waters. == Design and construction == (詳細はDesign 1013 or the "''Robert Dollar'' type", a standardised freighter design ordered by the United States Shipping Board (USSB) from multiple west-coast shipyards during World War I.〔McKeller, ''Steel Shipbuilding under the U. S. Shipping Board, 1917–1921: Contract Steel Ships, Part I'', p. 475a〕 Standard dimensions were in length, with a beam of and a standard draft of .〔 This vessel varied a little from the standard, being long and beam. Depth was with a draft of . They had a deadweight tonnage value of 8,800, and a gross register tonnage of 5,551.〔〔 Her net register tonnage was 3,418.〔 Propulsion machinery varied across the type: this ship used oil-fuelled boilers, connected to triple-expansion steam engines.〔〔(【引用サイトリンク】title=Lloyd's Register, Steamers & Motorships )〕 The engine was built by the Hooven, Owens & Rentschler Company of Hamilton, Ohio. It had cylinders of , and diameter by stroke. It was rated at 582 NHP.〔 One hundred and five vessels were completed for the USSB, while this ship and four others were cancelled but completed and sold privately by the shipyards, and others cancelled outright.〔 The ship was laid down by Northwest Steel of Portland, Oregon as yard number 38 and USSB number 2373, with the name ''West Minsi''.〔McKeller, ''Steel Shipbuilding under the U. S. Shipping Board, 1917–1921: Contract Steel Ships, Part I'', pp. 477–8〕 During construction, the order for this ship was cancelled by the USSB Emergency Fleet Corporation, but construction continued for private sale.〔McKeller, ''Steel Shipbuilding under the U. S. Shipping Board, 1917–1921: Contract Steel Ships, Part I'', p. 478〕 By the time the ship was launched on 17 November 1919, she had been sold to the Green Star Line and assigned the name ''Centaurus''. The ship was completed in December 1919, and assigned the United States official number 219283 and Code Letters LTVH.〔〔 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「SS Portmar (1919)」の詳細全文を読む スポンサード リンク
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