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The G3 battlecruisers were a class of battlecruisers planned by the Royal Navy after the end of World War I in response to naval expansion programs by the United States and Japan. The four ships of this class would have been larger, faster and more heavily armed than any existing battleship (although several projected foreign ships would be larger). The G3s have been considered to be proper "fast battleships" since they were well-balanced designs with adequate protection. Nonetheless the class was officially designated as a "battlecruiser" due to their higher speed and lesser firepower and armour relative to the planned N3 class battleship design. The G3s carried nine guns and were expected to achieve , while the N3s would carry nine guns on the same displacement at the expense of a slower speed.〔Raven and Roberts, p. 90〕 The G3 design was approved by the Board of Admiralty on 12 August 1921. Orders were placed in October—November, but were suspended later in November with the beginning of the Washington Naval Conference which limited battleship numbers. The orders were cancelled in February 1922 with the ratification of the Washington Naval Treaty which limited construction to ships of no more than displacement. ==Background== In 1916 the US had declared its intention to create a Navy "second to none"; the United States Congress had authorized the building of a large number of battleships and battlecruisers. In the aftermath of the First World War, the Japanese government were also embarking on a large programme of warship building. Meanwhile, in Great Britain, the needs of the First World War had led to the pre-war s being followed by the slower and cheaper . Two improved ''Revenge''-class hulls were converted during construction into the two s as emergency builds during the war. The only new capital ships laid down in the war were the s. Their design had been called into question after the Battle of Jutland in 1916. Three of this class were cancelled, leaving only to be completed to an altered design.〔Campbell, Part 1, p. 4〕 The US plan had been delayed by the wartime need to build smaller vessels. Nevertheless, estimates by the Admiralty were that by the early 1920s the UK would be behind in ships. The British did have access to German technology through ships such as the battleship which had been saved from the scuttling of the interned German High Seas Fleet in Scapa Flow and the experiences of the war. A committee concluded that any new ship should be able to match the speed of the new US s, expected to make 32 knots. Consequently, a series of designs was prepared of ships with displacements ranging from , the only limitations being the ability to use British dockyards and passage through the Suez Canal. These designs were given letters of the alphabet running backwards from K to G. The related battleship designs under consideration at the same time had design letters from L upwards.〔Campbell, Part 2, p. 13〕 The first two design proposals, 'K2' and 'K3', had a general layout similar to ''Hood'', but were armed with either eight or nine 18-inch guns, in four twin or three triple gun turrets, respectively. The numeral in the designation came from the number of guns in each turret. These ships were very large, displacing , could only reach , and could only be docked in a single ex-German floating dock and one dock, Gladstone Dock, in Liverpool. 'J3', the next proposal, saved nearly by reducing the main armament to nine 50-calibre guns and the main deck armour to . This reduction in size allowed the ship to dock anywhere that ''Hood'' could dock and to pass through the Suez and Panama Canals. 'I3' took another route in saving weight and concentrated the main armament amidships with 'X' turret placed between the forward superstructure and the funnels. The consequent weight savings were negated by additional hull and machinery weights and the ship displaced only slightly less than 'K3'. It had the advantage, however, that it could be docked in Rosyth and Portsmouth and pass through both canals, once the Suez Canal had been deepened. The primary drawback was that the main armament had a blind spot towards the rear of the ship of no less than 40°. Several variations were evaluated of the 'H3' design with the number of turrets reduced. In 'H3a' both turrets were forward of the superstructure while in 'H3b' one was forward and the other was aft of the forward superstructure. 'H3c' retained the layout of 'H3b', but lowered the turrets by one deck and saved over the of 'H3b'. All three 'H3' designs had a maximum speed of , but the reduced number of main guns was disliked so the 'G3' was proposed with the three triple turrets, armed with guns to save weight.〔Raven and Roberts, pp. 93–94〕 This design was accepted at the end of 1920, but changes were made as the design was finalized in early 1921, including the reduction of the ship's horsepower from 180,000 to 160,000 and the reduction of the main armament from 16.5 inches to .〔Raven and Roberts, p. 95〕 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「G3 battlecruiser」の詳細全文を読む スポンサード リンク
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