Japanese aircraft carrier Shinano: Wikis

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Shinano photo.jpg
Shinano underway during her sea trials in Tokyo Bay
Career (Japan)
Laid down: 4 May 1940
Launched: 5 October 1944
Commissioned: 19 November 1944
Fate: Sunk on 29 November 1944 by the submarine USS Archer-Fish
General characteristics
Class and type: Converted Yamato class battleship
Displacement: 62,000 tons (standard)
72,000 tons (loaded)[1]
Length: 266.0 m (872.7 ft)[1]
Beam: 36.3 m (119 ft) waterline
40 m (131.3 ft) flight deck[1]
Draught: 10.3 m (33.9 ft)
Draft: 10.8 m (35.4 ft)[1]
Propulsion: 12 Kampon oil-fired boilers,[1]
geared steam turbines,[1]
4 shafts,[1] 153,000 shp
Speed: 27 knots (51 km/h)[1]
Range: 10,000 nm. at 27 knots
  (18,400 km at 50 km/h)[1]
Complement: 2,400[2]
Armament: Sixteen 127 mm (5' inch)[2]
145 - 25 mm antiaircraft guns[2]
twelve 28-barreled 127 mm (5 inch) AA rocket launchers[2]
Armour: 127 mm (5 inch) side belt,
100 mm (4 inch) deck,
79 mm (3.1 inch) flight deck
Aircraft carried: 47 (capable of storing 139)[1]

Shinano (Japanese:信濃), named after the ancient Shinano Province, was an aircraft carrier of the Imperial Japanese Navy during World War II. Initially laid down as the third of the Yamato class battleships, Shinano's partially complete hull was converted to an aircraft carrier in 1942, midway through construction. Over the next two years, Shinano was heavily modified to act as a large support carrier. When completed, she had a full-load displacement of 72,000 tons, the largest aircraft carrier ever built at the time.

Commissioned in November 1944, Shinano was to transfer from the Yokosuka Naval Shipyard to Kure Naval Base to complete her outfitting. While en-route, Shinano was sunk by the submarine USS Archer-Fish ten days after her commissioning; the result of severe design flaws, crew inexperience and poor damage control. To date, it is the largest warship to be sunk by a submarine.

Contents

Design and construction

Shinano was initially designed as the third battleship of the Yamato class of super battleships. Her keel was laid down in June 1940 at the Yokosuka Naval Dockyard.[1] Named after the ancient Shinano Province, the vessel would have been one of the three largest battleships ever constructed.[1] In Summer 1941, construction on Shinano's hull was temporarily suspended, so as to allow personnel and equipment to be utilized for other naval projects in response to approaching hostilities.[3] Had she been completed as a battleship, her armament and armour would have been nearly identical to that of Yamato and Musashi.[1]

Following Japan's disastrous losses at the Battle of Midway—in which four of Japan's six fleet carriers were lost—the decision was made to convert Shinano's unfinished hull to an aircraft carrier.[3] The conversion began in June 1942.[4] The conversion process placed a heavy emphasis on flight-deck armour, similar to the design of the British Illustrious class aircraft carriers. The flight-deck was designed to withstand 1,000 pound bombs, the largest in the arsenal of the United States Navy that could be carried by dive-bombers.[1] Shinano was primarily designed as a support carrier, with extensive facilities for aircraft repair and refitting.[3] Shinano herself was intended to have a small fighter complement for defensive purposes, but was not intended to act as a fleet carrier despite her size.[2][3] Shinano was officially launched 5 October 1944, with Captain Toshio Abe in overall command of the vessel. With a full-load displacement of 72,000 tons,[2] Shinano was the largest aircraft carrier ever built—a rank it would hold until the USS Forrestal, with a displacement of 80,000 tons, was launched in 1954.[5]

The ship's very existence was kept a closely-guarded secret. A tall fence was erected on three sides of the graving dock, and those working on the conversion were confined to the yard compound. Serious punishment—up to and including death—awaited anyone who breathed a word about Japan's new carrier. As a result, Shinano was the only major warship built in the 20th century to have never been officially photographed during its construction.[6]

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Armament

Shinano's armament differed radically from that of Japan's other aircraft carriers.[3] Shinano's primary defensive armament took the form of 16 5-inch (13 cm) guns.[2] Her antiaircraft armament was also significant: 125 1-inch (25 mm) antiaircraft guns,[2] and 336 5-inch (13 cm) antiaircraft rocket launchers in 12 28-barrel turrets.[1] Shinano was also built to contain a maximum of 120 aircraft within her 870-foot hull.[1]

Commissioning and sinking

On 19 November 1944, Shinano was formally commissioned at Yokosuka, having spent the previous two weeks fitting out and performing minor trials.[4] As a result of growing worry for her safety, due to a U.S bomber fly-over, Japanese Naval Command ordered Shinano to Kure, where the remainder of her fitting-out would take place.[4] Naval Command wanted Shinano moved to Kure no later than 28 November. However, her commanding officer, Captain Toshio Abe, asked for a delay in the sailing date. The majority of her watertight compartment doors had yet to be installed,[2] and the ship had not been tested for watertightness. He also wanted more time to train his new crew.[6]

Abe's request was denied, and Shinano departed as scheduled on 28 November, escorted by three destroyers. Abe commanded a crew of 2,176 officers and men. Also on board were 300 shipyard workers and 40 civilian employees.[1][6] She also carried six Shinyo suicide boats, and fifty Ohka suicide rockets.[4] Her orders were to go to Kure, where she would complete her fitting-out and commence in the Inland Sea. Shinano was to take the Ohkas east for "the relief of the Philippines".[7] Abe was due to be promoted to rear admiral once Shinano completed her fitting-out, and take command of a fleet of attack carriers being built up in the east.[6] Although Shinano was to act as a support carrier, she was also assigned her own air group, commanded by Lieutenant Commander Yoshio Shiga, a veteran of the attack on Pearl Harbor. Shiga's air group would have already been aboard when Shinano sortied for Kure, but four of her 12 boilers were not in service for want of parts. This cut her top speed from 27 knots to 21 knots — too slow for planes to launch without a headwind.[6]

At 21:00 on 28 November, the American submarine Archer-Fish, commanded by Commander Joseph F. Enright, picked up Shinano's taskgroup on her radar.[8] Although Shinano was faster than Archer-Fish, the sub was able to remain in pursuit of Shinano due to the zig-zagging pattern of Shinano and her escorts.[8] Shinano was also slowed by having only 4 out of 12 boilers running, as the rest were still unoperational. Shinano was slowed further mid-pursuit due to the fact that a bearing had overheated on a propeller shaft, forcing lower operating R.P.M's of that engine. Abe's zig-zagging was guided by his assumption that Archer-Fish was part of an American wolf pack. He believed that Archer-Fish was being used as a decoy to lure away one of the destroyer escorts, allowing the rest of the pack a clear shot at Shinano. He actually ordered one of the destroyers to turn back when he spotted it trying to ram Archer-Fish, in part because he believed it left Shinano's bow exposed to an ambush.[6]

At 03:05 on 29 November, Archer-Fish dived, and ten minutes later fired six shallow-running torpedoes at Shinano, with four striking the starboard side between the anti-torpedo bulge and the waterline.[4] Enright later said he'd deliberately set the torpedoes to run shallow (10 feet) in order to capsize the target.[6] Shinano's destroyer escorts pursued Archer-Fish, forcing the sub to go deep.[8]

Though severe, the damage to Shinano was at first judged to be manageable, and the carrier continued under way.[4] However, progressive flooding over the next four hours caused Shinano to list to starboard. Archer-Fish's crew later reported that Shinano was already listing minutes after the last torpedo hit.[6] At dawn, Captain Abe ordered three of the outboard boiler rooms counter-flooded. Thirty-six miles from where the torpedoes struck, Shinano's boiler water feed failed shortly afterwards.[4] All efforts to control the flooding failed, in part because most of the crew was not well-trained in damage control.[6]

At 07:45, Shinano lost all power, and ceased all forward motion shortly afterward. At 08:50, two of Shinano's escorts took her under tow, attempting to beach her on Cape Ushio. However, the two escorts only displaced 5,000 tons between them, not nearly enough to overcome the list. After two attempts, the towing effort had to be abandoned.[4][6] At 10:18, Abe gave the order to abandon ship; by this time Shinano was listing 30 degrees to starboard. At 10:57 on 29 November, Shinano capsized and sank at 32°0′N 137°0′E / 32°N 137°E / 32; 137, taking 1,400 sailors and civilian workers with her. The dead included Abe and both of his navigators.[9] The survivors of Shinano's sinking were quarantined in Japan for several months following her sinking.[4]

Postwar analysis of the sinking

Postwar analysis by the US Naval Technical Mission to Japan claimed that Shinano had serious design flaws.[10] Specifically, the joint between the antiprojectile armor on the hull and the anti-torpedo bulge on the underwater body was poorly designed; Archer-Fish's torpedoes all exploded along this joint. Also, the force of the torpedo explosions dislodged an H-beam in one of the boiler rooms. The dislodged beam turned into a giant battering ram that punched a hole between two of the boiler rooms. In addition, the failure to test for watertightness played a role.[11] Survivors claimed that they were unable to control the flooding because the water poured in too fast; some claimed to have seen rivets between seams burst and allow water to surge through. The executive officer reported hearing large amounts of water entering the ship only minutes after the last torpedo hit, and blamed this on the failure to air-test the compartments. Additionally, the ship's list to starboard caused the pumping valves to rise above sea level, which would have made it impossible to counter-flood and right the ship even if they'd worked properly.[6]

Footnotes

  1. ^ a b c d e f g h i j k l m n o p q Preston, p. 84
  2. ^ a b c d e f g h i "Shinano class aircraft carrier". Parshall, Jon; Bob Hackett, Sander Kingsepp, & Allyn Nevitt. http://combinedfleet.com/ship.php?q=shinan_c.htm. Retrieved 27 January 2009.  
  3. ^ a b c d e Preston, p. 91
  4. ^ a b c d e f g h i "Combined Fleet - tabular history of Shinano". Parshall, Jon; Bob Hackett, Sander Kingsepp, & Allyn Nevitt. http://combinedfleet.com/Shinano.htm. Retrieved 27 January 2009.  
  5. ^ Preston, p. 91.
  6. ^ a b c d e f g h i j k Enright, Joseph; James W. Ryan (2000). Sea Assault. New York: St. Martin's Press. ISBN 0-312-97746-8.   Originally published as Shinano! (ISBN 031200186X) in 1987.
  7. ^ Reynolds, p. 284.
  8. ^ a b c Wheeler, p. 184
  9. ^ Wheeler, p. 185
  10. ^ Technical Reports, p. 26
  11. ^ Technical Reports, p. 27

References


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