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The United States Navy ''Gato''-class submarines were launched 1941-43 and were the first mass-production US submarine class of World War II. Together with their near-sisters the and es, their design formed the majority of the United States Navy's World War II submarine fleet.〔(Typical Gato-class submarine diagram ), USS ''MacKinnon'' website〕 Named after the first vessel of the class, , the ''Gato'' class and its successors formed the core of the submarine service that was largely responsible for the destruction of the Japanese merchant marine and a large portion of the Imperial Japanese Navy in World War II. ''Gato''s name comes from a species of small catshark. Like most other U.S. Navy submarines of the period, boats of the ''Gato'' class were given the names of marine creatures. In some references, the ''Gato''s are combined with their successors, especially the ''Balao'' class.〔Silverstone, pp. 195-204〕 ==Design== The ''Gato''-class boats were considered to be "Fleet Submarines". The original rationale behind their design was that they were intended to operate as adjuncts to the main battle fleet, centered around Standard-type battleships since World War I. They were to scout out ahead of the fleet and report on the enemy fleet's composition, speed, and course, then they were to attack and whittle down the enemy in preparation for the main fleet action, a titanic gun battle between battleships and cruisers. This was an operational concept born from experience in World War I. In order to operate effectively in this role, a submarine had to have high surface speed, long range and endurance, and a heavy armament.〔Friedman through 1945, pp. 99-104〕 State-of-the-art submarine design and construction in the 1920s and 1930s made this combination of qualities very difficult to achieve.〔Alden, p. 5〕 The USN experimented constantly with this concept in the post-World War I years, producing a series of submarines with less than stellar qualities and reliability, the (also known as the T class) and the V-boats, of which ''V-1'' through ''V-3'' were an unsuccessful attempt to produce a fleet submarine.〔Alden, Part I〕 By 1931, the experimental phase of fleet submarine development was over and the Navy began to make solid progress towards what would eventually be the ''Gato'' class. By 1940, a much better developed industrial base and experience gained from the ''Porpoise'', , and boats resulted in the ''Tambor'' and ''Gar'' classes. Finally, the USN had hit the right combination of factors and now had the long-desired fleet submarine.〔Alden, Part II〕 Timing, however, conspired against the actual use of these boats in their assigned role. The attack on Pearl Harbor on 7 December 1941 destroyed the Pacific Fleet battle line and along with it the concept of the battleship-led gun battle. The successful Pearl Harbor attack overturned 20 years of submarine strategic concept development and left the fleet submarine without a mission. Fortunately, the very same capabilities that would have enabled these submarines to operate with the fleet made them superbly qualified for their new mission of commerce raiding against the Japanese Empire.〔Friedman through 1945, p. 163〕 The ''Gato''-class design was a near duplicate of the preceding ''Tambor'' and ''Gar''-class boats. The only significant differences were an increase in diving depth from to , and an extra five feet in length to allow the addition of a watertight bulkhead dividing the one large engine room in two, with two diesel generators in each room. The ''Gatos'', along with nearly all of the USN fleet-type submarines of World War II, were of partial double hull construction. The inner pressure-resisting hull was wrapped by an outer hydrodynamic hull. The voids between the two hulls provided space for fuel and ballast tanks. The outer hull merged with the pressure hull at both ends in the area of the torpedo room bulkheads, thus the "partial" double hull. Operational experience with earlier boats led the naval architects and engineers at the Navy's Bureau of Construction and Repair to believe that they had been overly conservative in their estimates of hull strength. Without changing the construction or thickness of the pressure hull steel, they decided that the ''Gato''-class boats would be fully capable of routinely operating at 300 feet, a 50-foot increase in test depth over the preceding classes.〔Alden, p. 101〕 The ''Gato''s were slow divers when compared to some German and British designs, but that was mostly because the ''Gato''s were significantly larger boats. Sufficient fuel bunkerage to provide the range necessary for 75-day patrols from Hawaii to Japan and back could only be obtained with a large boat, which will take longer to submerge than a smaller one. Acknowledging this limitation, the Bureau designers incorporated a negative (sometimes called a "down express") tank into the design, which was flooded to provide a large amount of negative buoyancy at the start of the dive. Based on later wartime experience, the tank was normally kept full or nearly full at the surface, then emptied to a certain mark after the boat was submerged to restore neutral buoyancy. At the start of the war these boats could go from fully surfaced to periscope depth in approximately 45–50 seconds. The superstructure that sat atop the pressure hull provided the main walking deck when the boat was surfaced and was free flooding and full of water when the boat was submerged. When the dive began the boat would "hang" for a few extra seconds while this superstructure filled with water. In an attempt to speed this process, additional limber, or free flooding, holes were drilled and cut into the superstructure to allow it to flood faster. By mid war, these measures combined with improved crew training got dive times down to 30–35 seconds, very fast for such a large boat and acceptable to the boat's crew.〔Alden, p. 88〕 The large size of these boats did negatively affect both surfaced and underwater maneuverability when compared to smaller submarines. There was no practical fix for this due to the limitations of the installed hydraulic systems that were used to move the rudder. Although a point of concern, the turning radius was still good enough to be acceptable. After the war, a few fleet boats were fitted with an additional rudder topside at the very stern.〔Friedman through 1945, pp. 210, 214〕 These boats all had air conditioning, refrigerated storage for food, fresh water distilling units, clothes washers, and bunks for nearly every crew member; luxuries virtually unheard of in other navies. The Bureau designers felt that if a crew of 60–80 men were to be expected to conduct 75-day patrols in the warm waters of the Pacific, these types of features were vital to the health and efficiency of the crew. They could be added without impact to the boat's war fighting abilities due to the extra room of the big fleet boat. However, one feature in particular had a very practical side to it. Submerge a submarine for any length of time and the heat generated by the recently shut down engines, electronic gear, and 70 warm bodies will quickly raise internal temperatures above 100 Fahrenheit. High humidity generated by tropical waters will quickly condense and begin dripping into equipment, eventually causing electrical shorts and fires. Air conditioning, acting mostly as a dehumidifier, virtually eliminates this problem and greatly increases mechanical and electrical reliability. It proved to be a key factor in the success of these boats during World War II.〔Alden, p. 48,97〕 Twelve submarines of this class built by Electric Boat received what would be the final installations of the Hooven-Owens-Rentschler (HOR) double-acting diesel engine. The Navy had been tinkering with this engine off and on since 1937 because its unique design promised nearly twice the horsepower in a package the same size as other diesel engine types. Unfortunately, the HOR company ran into severe design and manufacturing problems and these engines proved to be operational and maintenance nightmares.〔Friedman through 1945, pp. 263, 360-361〕 Frequent breakdowns and utter unreliability had destroyed these engines' reputation with the Navy and they were all removed at the first opportunity and replaced by GM-Winton 16-278A V-type diesels. The other ''Gato''-class boats received either the Fairbanks-Morse 38D 8-1/8 nine-cylinder opposed piston engine or the GM-Winton 16-248 V-type as original installations. These engines were hardy, rugged and well liked by the crews and served the boats quite well.〔Alden, p. 90, 210–212〕 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「Gato-class submarine」の詳細全文を読む スポンサード リンク
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