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The ''Borodino''-class battlecruisers ((ロシア語:Линейные крейсера типа «Измаил»)) were a group of four battlecruisers ordered by the Imperial Russian Navy before World War I. Also referred to as the ''Izmail'' class, they were laid down in December 1912〔All dates used in this article are New Style (Gregorian).〕 at Saint Petersburg for service with the Baltic Fleet. Construction of the ships was delayed as many domestic factories were overloaded with orders and some components had to be ordered from abroad. The start of World War I slowed their construction still further as the imported components were often not delivered and domestic production was diverted into areas more immediately useful for the war effort. Three of the four ships were launched in 1915 and the fourth in 1916. Work on the gun turrets lagged, and it became evident that Russian industry would not be able to complete the ships during the war. The Russian Revolution of 1917 put a stop to their construction, which was never resumed. Although some consideration was given to finishing the hulls that were nearest to completion, they were all eventually sold for scrap by the Soviet Union. The Soviet Navy proposed in 1925 to convert ''Izmail'', the ship closest to completion, to an aircraft carrier, but the plan was cancelled after political maneuvering by the Red Army led to funding not being available. ==Design and development== After the end of the Russo-Japanese War of 1905, the Russian Naval General Staff decided that it needed a squadron of fast "armoured cruisers"〔McLaughlin, p. 244〕 that could use their speed to engage the leader of an enemy's battle line, much as Admiral Tōgō had done against the Russian fleet during the Battle of Tsushima. Initially the Naval General Staff wanted a ship with high speed (), guns, and limited protection (a waterline belt of ); the Emperor approved construction of four such ships on 5 May 1911, but the Duma session ended before the proposal could be voted on. Preliminary bids for the ships were solicited from private builders, but the bids proved to be very high,〔 leading to a reconsideration of the requirements. A new specification was issued on 1 July 1911 by the Naval General Staff for a ship with a speed of only and with armour increased to . Armaments were increased to nine guns in three non-superfiring triple-gun turrets,〔McLaughlin, p. 245〕 based on a false rumor that the Germans were increasing the caliber of their guns.〔Gardiner and Gray, p. 304〕 The Russian Navy believed that widely separating the main gun magazines improved the survivability of the ship, and that under a superfiring arrangement, muzzle blast would hurt the sailors manning the gun sights in the lower turrets through the open sighting hoods on the turret roofs. The Naval Ministry solicited new bids on 8 September from 23 shipbuilders, domestic and foreign, but only seven responded, even after the deadline was extended by a month. A number of designs were rejected for not meeting the revised criteria. In the meantime, the Artillery Section of the Main Administration of Shipbuilding had decided that it preferred a four-turret design, and new bids were solicited in May 1912 from the leading contenders from the first round of bidding.〔 The eventual winner was a design by the Admiralty Works in Saint Petersburg, which had the extra turret added to a new hull section inserted into the original three-turret design.〔McLaughlin, pp. 245–46〕 The Duma approved construction in May 1912, before the design was finalised, and allocated 45.5 million rubles for each ship. However, the increase in armaments and consequential increase in the size of the ships raised their estimated cost by seven million rubles each, and some money was diverted from the budget for the s. Orders were placed on 18 September 1912 for a pair of ships each from the New Admiralty Shipyard and the Baltic Works. The first pair was to be ready for trials on 14 July 1916 and the second pair on 14 September 1916.〔Watts, p. 65〕〔McLaughlin, p. 247〕 Full-scale armour trials revealed serious weaknesses in the proposed protection scheme. The trials employed the obsolete ironclad , modified with armour protection identical to that used by the s then under construction. The deck and turret roof armour proved to be too thin, and the structure supporting the side armour was not strong enough to withstand the shock of impact from heavy shells.〔 The design of the ''Borodino''-class ships was modified as a consequence, which slowed their construction. Deck armour was reinforced with extra plates, the turret roofs were increased to a thickness of , and the side and roof of the conning tower were increased by and respectively. To compensate for the additional weight, the rear conning tower was removed entirely and the thickness of the main belt was reduced by . Mortise and tenon joints were introduced between the armour plates along their vertical edges to better distribute the shock of a shell impact and to lessen the stress on the supporting hull structure. The launching of the first pair of ships was postponed by six months because of these changes, plus delays imposed by the large number of ship orders already in hand.〔The shipyards were overloaded with orders and simply lacked the capacity to maintain the original construction schedule.〕〔McLaughlin, pp. 247–48〕 The outbreak of the First World War in 1914 caused further delays as a number of components had been ordered from foreign manufacturers. As an example, the gun turrets rested on roller bearings made in Germany, but attempts to order replacements from the United Kingdom and Sweden proved futile, as no company was willing and able to make the bearings. Components for the turbines of ''Navarin'' and ''Izmail''〔 that had been ordered from AG Vulcan in Germany were seized by the German government at the beginning of the war and used in the construction of the two s.〔McLaughlin, pp. 248–249, 253〕 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「Borodino-class battlecruiser」の詳細全文を読む スポンサード リンク
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