Borodino-class battlecruiser

TheBorodino-class battlecruisers(Russian:Линейные крейсера типа «Измаил») were a group of fourbattlecruisersordered by theImperial Russian NavybeforeWorld War I. Also referred to as theIzmailclass, they werelaid downin late 1912atSaint Petersburgfor service with theBaltic Fleet. Construction of the ships was delayed by a lack of capacity among domestic factories and the need to order some components 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 forthe war effort.
Three of the four ships werelaunchedin 1915 and the fourth in 1916. Work on thegun turretslagged, and it became evident that Russian industry would not be able to complete the ships during the war. TheRussian Revolution of 1917halted all work on the ships, which was never resumed. Although some consideration was given to finishing the hulls that were nearest to completion, the three furthest from completion were sold forscrapby theSoviet Unionduring the early 1920s. TheSoviet Navyproposed to convertIzmail, the ship closest to completion, to anaircraft carrierin 1925, but the plan was cancelled after political manoeuvring by theRed Armycut funding and she was eventually scrapped in 1931.
After the end of theRusso-Japanese Warof 1905, theRussian Naval General Staffdecided that it needed a squadron of fastarmoured cruisersthat could use their speed to engage the leader of an enemy'sbattle line, asAdmiral Tōgōhad done against the Russian fleet during theBattle of Tsushima. The Naval General Staff initially called for a ship with high speed (28knots(52 km/h; 32 mph)), 305-millimetre (12 in) guns, and limited protection (awaterline beltof 190 mm or 7.5 in). TheTsar, head of the Russian government, approved construction of four such ships on 5 May 1911, but theState Dumasession 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. The Naval General Staff issued a new specification on 1 July 1911 for a ship with a speed of only 26.5 knots (49.1 km/h; 30.5 mph) and with armour increased to 254 mm (10 in). The armament was increased to nine 356-millimetre (14 in) guns in three non-superfiringtriple-gun turrets,based on a false rumour that the Germans were increasing the calibre of the guns in theirbattleships.The Imperial Russian Navy believed that widely separating the main gun turrets and theirmagazinesreduced the chance of a catastrophic ammunition explosion, reduced thesilhouetteof the ship and improvedstabilitywithout superfiring turrets and their tallbarbettes.
TheNaval Ministrysolicited new bids on 8 September from 23 shipbuilders, domestic and foreign, but only 7 responded, even after the deadline was extended by a month. Several 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 theAdmiralty ShipyardinSaint Petersburgwhich had the extra turret added to a newhullsection inserted into the original three-turret design.
The Duma approved construction in May 1912, before the design was finalised, and allocated 45.5 millionroublesfor each ship. The additional gun turret and consequent increase in the size of the ships led to the ships being overbudget by about 7 million roubles each, and some money was diverted from the budget for theSvetlana-classcruiserto cover the discrepancy. Orders were placed on 18 September 1912 for a pair of ships each from the Admiralty Shipyard and theBaltic Works, also of Saint Petersburg. The first pair was to be ready for trials on 14 July 1916, and the second pair on 14 September 1916.
Full-scale armourtrialsin 1913 revealed serious weaknesses in theBorodinos' proposed protection scheme. The obsoleteironcladChesmahad been modified with armour protection identical to that used by theGangut-classbattleships, then under construction. Thedeckand 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 theBorodinos' armour was similar in construction to that of theGanguts and therefore needed to be modified, which slowed construction. TheBorodinos' deck armour was reinforced with extra plates and the thickness of the turret roofs was increased. To offset this additional weight, a planned rearconning towerwas removed entirely and the thickness of the main belt was slightly reduced.Mortise and tenonjoints 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 many ship orders already in hand.
TheBorodino-class ships were 223.85 metres (734 ft 5 in) longoverall. They had abeamof 30.5 metres (100 ft 1 in) and adraughtof 8.81 metres (28 ft 11 in) atfull load. The shipsdisplaced32,500long tons(33,000t) normally and 36,646 long tons (37,234 t) at full load.High-tensile steelwas used throughout the hull withmild steelused only in areas that did not contribute to structural strength. The hull was subdivided by 25 transverse watertightbulkheadsand the engine room was divided by a longitudinal bulkhead. Thedouble bottomhad a height of 1.275 metres (4 ft 2 in), and the vitals of the ship were protected by a triple bottom that added an extra 875 millimetres (2 ft 10 in) of depth. The design called for afreeboardof 8.89 metres (29 ft 2 in) forward, 6.24 metres (20 ft 6 in) amidships and 6.49 metres (21 ft 4 in) aft. The ships were fitted with three Frahmanti-rolling tankson each side.
TheBorodinos were powered by four sets ofsteam turbines, each driving onepropeller shaftusing steam provided by 25 triangularYarrow boilerswith a working pressure of 17kg/cm(1,667kPa; 242psi). The turbines developed a total of 66,000shaft horsepower(49,000kW) and were designed to be overloaded to 90,000 shp (67,000 kW). The forward boilers were grouped into three compartments with three oil-fired boilers in each compartment. The rear boilers were in four compartments with each containing four coal-fired boilers fitted with oil sprayers to increase the burn rate. Maximum speed was estimated at 26.5 knots, although forcing the machinery would increase it to 28.5 knots (52.8 km/h; 32.8 mph). The ships were designed to carry 1,974 long tons (2,006 t) of coal and 1,904 long tons (1,935 t) offuel oil, which gave an estimated range of 2,280nautical miles(4,220 km; 2,620 mi) at full speed.
Two sets of steam turbines were ordered on 22 April 1913 from theFranco-Russian Worksin Saint Petersburg for the Admiralty Shipyard-built ships, and the Baltic Works built the turbines for its ships, although some components were ordered from abroad.However, Western sources have long stated incorrectly that the turbines forNavarinhad been ordered fromAG Vulcan, and that they were taken over at start of the war for use in theBrummer-classlight cruisers. As well as being contradicted by original Russian and German records, this is technically impossible, as the turbines actually specified forNavarinwere of the Parsons type, while those actually employed in the German cruisers were of the Curtis pattern. In fact, theBrummerclass engines had been ordered for thelead shipof theSvetlana-class cruisers.
TheBorodinoclass had sixturbo generatorsand twodiesel generators, each rated at 320 kilowatts (430 hp). These were in four compartments below themain deck, two each fore and aft of theboilerandengine rooms. The generators powered a complex electrical system that combinedalternating currentfor most equipment withdirect currentfor heavy-load machinery such as the turret motors.
The ships' primary armament consisted of a dozen 52-calibre356-millimetre (14 in) Model 1913 guns mounted in four electrically powered turrets. The turrets were designed toelevateandtraverseat a rate of 3° per second. The guns had an elevation range from −5° to +25°. They could be loaded at any angle between −5° and +15°; the expected rate of fire was threeroundsper minute. Space was provided for a maximum of 80 rounds per gun. The guns fired 747.6-kilogram (1,648 lb) projectiles at amuzzle velocityof 731.5 m/s (2,400 ft/s), with a maximum range of 23,240 metres (25,420 yd).
Thesecondary armamentconsisted of twenty-four 55-calibre130 mm (5.1 in) Pattern 1913 gunsmounted incasematesin the hull, twelve per side.The guns had a maximum elevation of +20° which gave them a range of 15,364 metres (16,802 yd). They fired 36.86-kilogram (81.3 lb) projectiles at a muzzle velocity of 823 m/s (2,700 ft/s).
Theanti-aircraftarmament was intended to be four 38-calibre 64-millimetre (2.5 in)anti-aircraft gunsfitted on the upper deck with 220 rounds carried for each gun.They fired 4.04-kilogram (8.9 lb) projectiles at a muzzle velocity of 686 m/s (2,250 ft/s).Four 75-millimetre (3.0 in) guns were to be mounted in pairs on the main turret roofs forsub-calibre trainingwith the main guns. Six underwater 450-millimetre (17.7 in)torpedo tubeswere fitted, three on eachbroadside; they were provided with a total of eighteen torpedoes.
The fore and aft main gun turrets were given a 6-metre (19 ft 8 in)rangefinder, and there was another 5-metre (16 ft 5 in) unit on top of the conning tower.These would provide data for the Geislercentral artillery postanalogue computer, which would then transmit commands to the gun crew.The mechanical fire-control computer would have been either aPollen Argorange clock, which had been bought in 1913, or a domestically designed Erikson system.
Thetrials withChesmagreatly affected the armour protection design of theBorodino-class ships. TheKrupp cemented-armourplates were resized to match the frames and provide support for their joints; they were also locked together with mortise-and-tenon joints to better distribute the shock of a shell's impact. The 237.5-millimetre (9.4 in)waterline beltcovered the middle 151.2 metres (496 ft 1 in) of the ship. It had a total height of 5.015 metres (16 ft 5 in), of which 3.375 metres (11 ft 1 in) was above the designwaterlineand 1.64 metres (5 ft 5 in) below. The remaining portion of the waterline was protected by 125-millimetre (4.9 in) plates. The upper belt was 100 millimetres (3.9 in) thick and had a height of 2.89 metres (9 ft 6 in). It thinned to 75 millimetres forward of the casemates and extended all the way to thebow. The rear portion of theforecastledeck was protected by an upward extension of the upper belt in the area of the forward barbettes and the upper casemates. Those casemates were protected by 100-millimetre transverse bulkheads. Behind the side armour was an inboard longitudinal splinter bulkhead that was 50 millimetres (2.0 in) thick between the middle and lower decks and decreased to 25 millimetres (0.98 in) between the middle and upper decks. The bulkhead sloped away from the edge of the lower deck to the lower edge of the armour belt with a total thickness of 75 millimetres divided between a 50-millimetre plate ofKrupp non-cemented armour(KNC) layered above a 25-millimetrenickel-steelplate. The forward end of thearmoured citadelwas protected separately and the transverse bulkhead was therefore only 75 millimetres thick. The rear bulkhead had no other protection and was 300 millimetres (11.8 in) thick between the middle and lower decks, decreasing to 75 millimetres at the level of the armour belt.
The main gun turrets were designed with 300-millimetre sides and 150-millimetre roofs. Thegun portswould have been protected by 50-millimetre plates with 25-millimetre bulkheads separating each gun inside the turrets. The barbettes were 247.5 millimetres (9.7 in) thick and decreased to 147.5 millimetres (5.8 in) when behind other armour. They were shaped like truncated cones which matched the trajectories of descending shells and thus lessened their protective value. The conning tower was 400 millimetres (15.7 in) thick and reduced to 300 millimetres below the upper deck. Thefunneluptakes were protected by 50 millimetres of armour. The upper deck was 37.5 millimetres (1.5 in) thick and the middle deck consisted of 40-millimetre (1.6 in) plates of KNC on 25 millimetres of nickel-steel over the armoured citadel. The sides of the conning tower were fitted with armour plates 400 millimetres (15.7 in) thick and its roof was 250 millimetres (9.8 in) thick. Underwater protection was minimal: there was only a 10-millimetre (0.4 in) watertight bulkhead behind the upward extension of the double bottom, and this became thinner as the hull narrowed towards the end turrets.
All four ships were officially laid down on 19 December 1912, and work began in March–April 1913. After a progress review on 4 June 1914,launchingof the first pair of ships was delayed until October. When World War I began in August, the hull ofIzmailwas judged as being 43per cent complete, the others lagging considerably behind.The war caused further delays as some components had been ordered from foreign manufacturers. For example, the gun turrets were intended to rest on 203 mm (8 in)roller bearingsmade 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.The war caused other delays, including competition for scarce resources needed by other production deemed necessary for the war. Three of the four ships were launched in 1915, but it was clear that Russian industry would not be able to complete them during the war, mostly because the turrets were seriously delayed by non-delivery of foreign-built components and a shortage of steel. They were reclassified as second rank projects by the Main Administration of Shipbuilding in 1916 and construction virtually stopped.
Various plans were made by the Naval General Staff and the Main Administration of Shipbuilding for the post-war completion of the ships, including modifying the turrets to load at a fixed angle of +4° to reduce the weight and complexity of the loading equipment. Another intended change was to lengthen the funnels by 2 metres (6 ft 7 in) to minimise smoke interference with thebridge, which had been a problem on theGangut-classdreadnoughts. There were suggestions to improve the machinery with geared turbines,turbo-electric drive, orFöttinger's hydraulic transmission, but these were more theoretical than practical.
After theFebruary Revolution, the condition of the ships was assessed on 28 April 1917. The ship that was furthest along was stillIzmail: her hull, engines, and boilers were around 65per cent complete, and her armour was 36per cent complete. Her turrets were not expected to be completed until 1919. TheCongress of Shipyard Workersdecided to continue work on theIzmailin mid-1917, but only to provide jobs. TheProvisional Governmenthalted all work onBorodino,Kinburn, andNavarinon 24 October 1917, and theBolsheviksordered work onIzmailhalted on 14 December 1917.
After the end of theRussian Civil Warwas in sight by October 1921, the victorious Bolsheviks considered finishingIzmail, and possiblyBorodino, to their original design. It would have taken at least two years to build all ofIzmail's turrets, even if enough guns had been available. Ten had been delivered byVickersbefore the Revolution and one gun had been completed domestically in 1912, but the prospects for more guns were not promising, given the poor state of Soviet heavy industry in the wake of the civil war. Another problem was their complicated electrical system; it could not be completed under current conditions, and at least twenty months would be required to replace it with a simpler system.
The Soviets also considered finishingKinburnandNavarinto a modified design that featured 410-millimetre (16 in) guns; a two-gun turret weighed slightly less than a triple 354 mm (13.9 in) gun turret. The proposal was rejected because the prospects of actually acquiring such guns were minimal. Domestic industry was incapable of building such large guns and the Soviets were not able to purchase the guns from any foreign company. Other ideas were examined for the three less complete ships. These included converting the hulls tocargo ships,passenger liners, or 22,000-long-ton (22,000 t) oilbarges, but the hulls were thought to be too large and unwieldy for the proposed uses. None of the proposals was accepted, and all three of the less complete ships were sold to a German company for scrap on 21 August 1923 to raise much-needed cash for the government.
In May 1925, the Operational Administration of the Soviet Navy contemplated convertingIzmailinto an aircraft carrier with a top speed of 27 knots (50 km/h; 31 mph) and a capacity of 50 aircraft. She would have been armed with eight 183-millimetre (7.2 in) guns and her armour reduced to a maximum of 76 millimetres (3.0 in). This proposal was approved byAlexey Rykov, Chairman of theCouncil of the People's Commissarson 6 July 1925, but the Red Army was strongly opposed to spending more money on naval projects. They managed to block the project by gaining control of a commission appointed to review the needs of the Navy in December, which cancelled the project on 16 March 1926.After most of her boilers were used during the reconstructions of the battleshipsParizhskaya KommunaandOktyabrskaya Revolyutsiya,Izmailwas scrapped beginning in 1931 inLeningrad.
The ships were named after battles fought by the Russian Empire: