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The ''Porpoise'' class were submarines built for the United States Navy in the late 1930s, and incorporated a number of modern features that would make them the basis for subsequent , , , , , and classes. Based on the s, enlarged to incorporate additional main diesels and generators,〔Alden, John D., Commander, USN (retired). ''The Fleet Submarine in the U.S. Navy'' (Annapolis, MD: Naval Institute Press, 1979), p.210.〕 the Portsmouth boats were all riveted while the other boats were welded.〔Alden, p.210.〕 In some references, the ''Porpoise''s are called the "P" class.〔Silverstone, pp. 189-190〕 ==Design== In general, they were around long and diesel-electric powered. Displacement was 1,934 tons submerged for the first four boats, 1,998 tons for the later ones. The goal of a 21-knot fleet submarine that could keep up with the standard-type battleships was still elusive. The relatively high surfaced speed of was primarily to improve reliability at lower cruising speeds.〔Friedman, pp. 198-200〕 A major improvement essential in a Pacific war was an increase in range from ''Perch'' onwards, nearly doubling from to at . This allowed extended patrols in Japanese home waters, and would remain standard through the ''Tench'' class of 1944.〔 Although it proved successful with improved equipment beginning with the ''Tambor'' class of 1940, the diesel-electric drive was troublesome at first. In this arrangement, the boat's four main diesel engines drove only electric generators, which supplied power to high-speed electric motors geared to the propeller shafts. The engines themselves were not connected to the propeller shafts. For submerged propulsion, massive storage batteries supplied electricity to the motors. Problems arose with flashover and arcing in the main electric motors. There was also a loss of in transmission through the electrical system.〔Alden, pp.58 and 65.〕 The Winton Model 16-201A 16-cylinder diesels also proved problematic, and were eventually replaced with 12-278As.〔Alden, p.58.〕 Five of the class received an additional pair of external bow torpedo tubes, probably early in World War II: ''Porpoise'', ''Pike'', ''Tarpon'', ''Pickerel'', and ''Permit''.〔Silverstone, p. 190〕〔Gardiner and Chesneau, p. 143〕 The original Mark 21 3 inch (76 mm)/50 caliber deck gun proved to be too light in service. It lacked sufficient punch to finish off crippled or small targets quickly enough to suit the crews. It was replaced by the Mark 9 4 inch (102 mm)/50 caliber gun in 1943-44, in most cases removed from an S-boat being transferred to training duty.〔Alden, p.93.〕 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「United States Porpoise-class submarine」の詳細全文を読む スポンサード リンク
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