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''PT-109'' was a PT boat (Patrol Torpedo boat) last commanded by Lieutenant, junior grade (LTJG) John F. Kennedy (later President of the United States) in the Pacific Theater during World War II. Kennedy's actions to save his surviving crew after the sinking of ''PT-109'' made him a war hero, which proved helpful in his political career. The incident may have also contributed to Kennedy's long-term back problems. After he became president, the incident became a cultural phenomenon, inspiring a song, books, movies, various television series, collectible objects, scale model replicas, and toys. Interest was revived in May 2002, with the discovery of the wreck by Robert Ballard. ''PT-109'' earned two battle stars during World War II operations. == Specifications == ''PT-109'' belonged to the ''PT-103'' class, hundreds of which were completed between 1942 and 1945 by Elco in Bayonne, New Jersey. ''PT-109''s keel was laid 1942 as the seventh Motor Torpedo Boat (MTB) of the -class built by Elco and was launched on . She was delivered to the Navy on 1942, and fitted out in the New York Naval Shipyard in Brooklyn. The Elco boats were the largest PT boats operated by the U.S. Navy during World War II. At and , they had strong wooden hulls of two layers of mahogany planking. Powered by three 12-cylinder Packard gasoline engines (one per propeller shaft), their designed top speed was .〔(PT Boat 127 ).〕 For space and weight-distribution reasons, the center engine was mounted with the output end facing forward, with power transmitted through a Vee-drive gearbox to the propeller shaft. Because the center propeller was deeper, it left less of a wake, and was preferred by skippers for low-wake loitering. Both wing engines were mounted with the output flange facing aft, and power was transmitted directly to the propeller shafts.〔(PT Boat 127 ).〕 The engines were fitted with mufflers on the transom to direct the exhaust under water, which had to be bypassed for anything other than idle speed. These mufflers were used not only to mask their own noise from the enemy, but to improve the crew's chance of hearing enemy aircraft, which were rarely detected overhead before firing their cannons or machine guns or dropping their bombs. ''PT-109'' could accommodate a crew of three officers and 14 enlisted, with the typical crew size between 12 and 14. Fully loaded, ''PT-109'' displaced . The principal offensive weapon was her torpedoes. She was fitted with four 21-inch torpedo tubes containing torpedoes. They weighed each, with warheads and gave the tiny boats a punch at least theoretically effective even against armored ships. Their typical speed of was effective against shipping, but because of rapid marine growth buildup on their hulls in the South Pacific and austere maintenance facilities in forward areas, PT boats ended up being slower than the top speed of the Japanese destroyers and cruisers they were assigned to attack in the Solomons. Torpedoes were also useless against shallow-draft barges, which were their most common targets. With their machine guns and cannon, the PT boats could not return the large-caliber gunfire carried by destroyers, which had a much longer effective range, though they were effective against aircraft and ground targets. Because they were fueled with aviation gasoline, a direct hit to a PT boat's engine compartment sometimes resulted in a total loss of boat and crew. In order to have a chance of hitting their target, PT boats had to close to within for a shot, well within the gun range of destroyers. At this distance, a target could easily maneuver to avoid being hit. The boats approached in darkness, fired their torpedoes, which sometimes gave away their positions, and then fled behind smoke screens. Sometimes retreat was hampered by seaplanes dropping flares to render the boats visible in darkness. They would then attack the boats with bombs and machine gun fire. The firing of the boats' torpedoes imposed an additional risk of detection. The Elco launch tubes used black powder charges to expel the torpedoes. Firing of the charge could sometimes ignite the grease with which the torpedoes were coated to facilitate their release from the tubes. The resultant flash could give away the position of the boat. Crews of PT boats relied on their smaller size, speed and maneuverability, and darkness, to survive. Ahead of the torpedoes on ''PT-109'' were two depth charges, omitted on most PTs, one on each side, about the same diameter as the torpedoes. These were designed to be used against submarines, but were sometimes used by PT commanders to confuse and discourage pursuing destroyers. ''PT-109'' lost one of her two depth charges a month before Kennedy showed up when the starboard torpedo was inadvertently launched during a storm without first deploying the tube into firing position. The launching torpedo sheared away the depth charge mount and some of the footrail. ''PT-109'' had a single Oerlikon anti-aircraft mount at the rear with "109" painted on the mounting base, two open rotating turrets (designed by the same firm that produced the Tucker automobile), each with twin M2 .50 cal anti-aircraft machine guns at opposite corners of the open cockpit, and a smoke generator on her transom. These guns were effective against attacking aircraft. The day before her final mission, ''PT-109''s crew lashed a U.S. Army 37 mm antitank gun to the foredeck, replacing a small, 2-man life raft. Timbers used to secure the weapon to the deck later helped save their lives when used as a float.〔(【引用サイトリンク】title=Scalecraft history )〕 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「Motor Torpedo Boat PT-109」の詳細全文を読む スポンサード リンク
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