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A merchant aircraft carrier (also known as a MAC) was a limited purpose aircraft carrier built on a British hull designed for bulk grain ships and oil tankers. This was adapted by adding a flight deck enabling it to operate anti-submarine aircraft in support of Allied convoys during the Battle of the Atlantic. Despite their quasi-military function, MACs retained their mercantile status, continued to carry cargo and operated under civilian command. MACs began entering service in May 1943 and although originally intended as an interim measure pending the introduction of escort carriers, they remained operational until the end of the war in Europe. ==Development== In 1940, Captain M. S. Slattery RN, Director of Air Material at the Admiralty, proposed a scheme for converting merchant ships into aircraft carriers as a follow-up to the CAM Ship project.〔The National Archives: Public Record Office (TNA:PRO), ADM 234/383, ''The Development of British Naval Aviation'', Volume I.〕 Slattery proposed fitting a flight deck equipped with two arrester wires and a safety barrier onto an existing merchant ship hull. The resulting 'auxiliary fighter carrier' would be capable of operating six Hurricane fighters while retaining its cargo-carrying ability. The stumbling block for Slattery's proposal turned out to be objections from the Ministry of Supply that combining the merchant and aircraft carrier roles would be too complicated.〔 While this would turn out to be over-stated, it seems to have had the effect of diverting attention away from the idea of hybrid merchant-warships towards the alternative of converting merchant ships into fully-fledged warships designated 'auxiliary aircraft carriers', the first of which, converted from the captured German cargo ship ''Hannover'', entered service as ''Empire Audacity'' (later ''HMS Audacity'') in June 1941.〔 The hybrid concept re-emerged early in 1942 when, in the face of mounting losses from U-boat attacks, it became apparent that escort carriers building in the US could not be delivered quickly enough in the numbers required.〔TNA:PRO, ADM 234/384, ''The Development of British Naval Aviation'', Volume II.〕 Various people have been credited with re-inventing the idea, including Captain B. B. Schofield RN, Director Trade Division, and John Lamb, Marine Technical Manager of the Anglo-Saxon Petroleum Company.〔Schofield, B. B., 'The Defeat of the U-Boats During World War II' in ''Journal of Contemporary History'' Vol. 16, No. 1 (January 1981), p. 125.〕 Sir James Lithgow, Controller of Merchant Shipbuilding and Repair and joint-owner of Lithgows Ltd, the Clyde-based shipbuilders, also helped overcome Admiralty reservations about MACs. Lithgow is said to have sketched a rough design for one on the back of an envelope and offered to convert two ships about to be built at his family's shipyard on condition that "I am not interfered with by the Admiralty".〔 〕 While the timing of Lithgow's possibly apocryphal intervention is uncertain, his deputy, Sir Amos Ayre, the Director of Merchant Shipbuilding, was certainly discussing the requirements for MACs by May 1942.〔National Maritime Museum (NMM), Ship's Cover 667Y, ''Escort Carriers Converted from Grain Ships etc.''〕 Ayre himself credits Sir Douglas Thomson of Ben Line and the Ministry of War Transport with having first suggested the idea.〔 There was some initial resistance to the MAC concept, in particular through concerns about operating aircraft from short, relatively slow ships. The Admiralty considered that a flight deck length of 460 ft. was needed for safe take-offs and landings and a speed of 15 kts. to provide a sufficient margin over convoy speeds and they were especially doubtful that tankers, with their low freeboards and volatile cargoes, could be utilised.〔〔TNA:PRO, MT 59/1966, Minute dated 29 June 1942〕 As the U-boat situation worsened, however, such concerns were out-weighed by the urgent need to provide convoy air support, and once it was accepted that the grain ship variant at least could be made to work, the Admiralty became more enthusiastic about the project. By September 1942, the Admiralty was asking for 'about 50' MACs to be made available, to allow one to be included in every North Atlantic convoy and in October the requirement was set at 52.〔TNA:PRO, MT 59/1966, Admiralty to Ministry of War Transport dated 1 September 1942.〕〔NMM, Ship's Cover 667Y, Controller to ACNS(T) dated 1 October 1942.〕 This ambitious target had been scaled back to 40 by the time the MAC project was formally endorsed by the War Cabinet in October 1942, but it was apparent that even this reduced number could not be produced sufficiently quickly without American help.〔〔TNA:PRO, FO 371/32584, Construction of Merchant Aircraft Carriers: Joint Memorandum by First Lord of the Admiralty and Minister of War Transport dated 27 October 1942.〕 The US was therefore asked to begin construction of 30 MACs to be delivered during the first half of 1943, but a Navy Department committee specially formed to consider the request turned it down because of concerns about the experimental nature of the ships.〔TNA:PRO, CAB 65/28.17, War Cabinet Conclusions 147(42) of 29 October 1942.〕〔TNA:PRO, MT 59/1966, BADW to Admiralty dated 27 November 1942.〕 In the event, all the MACs were built and/or converted in British shipyards. 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「Merchant aircraft carrier」の詳細全文を読む スポンサード リンク
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