It was also discovered that careful streamlining of the propeller shafts and the bilge keel added at least half a knot at full speed. It was found that the large bulbous bow reduced hull resistance by over 8 per cent, as well as increasing buoyancy forward in heavy seas. Prior to this, extensive research was conducted in hull model tank testing to develop the most efficient hull form possible. In fact, the US Navy’s Office of Naval Intelligence assumed that these vessels were armed with 16in guns and displaced 45,000 tons, and did not know the size of the main guns and the actual displacement of the battleships until after the war.Īfter the extensive modification to the Kure, Nagasaki, Yokosuka and even the Sasebo naval shipyards, which also included heavy lift equipment for the construction of these massive warships, Yamato’s keel was laid down in the dry dock at the Kure Navy Yard on 4 November 1937. These efforts to keep information from the Americans were generally successful, and by 1942, although the US Navy knew of the construction of at least two new battleships, they only had a rough sketch of the vessels. The Japanese wanted to keep the construction of this new class of warship a total secret, so there was a complete restriction on photography, as well as the construction of a roof over part of the building slip there was even a gigantic curtain of rope used to block any view of construction and at Nagasaki a 400-ton camouflage net. The construction facilities had to be widened, lengthened and the approaches dredged deeper. The navy yards were well set up to construct battleships, but not on the scale of these new behemoths. The final design was approved in March 1937, but the first vessel, Yamato, could not be laid down until improvements to the yard facilities could be completed. By early 1937 the final design of this new class of battleship was completely steam powered. The use of diesel engines was dropped from consideration, as the Japanese Navy was having trouble with some of their larger diesel power plants, and the complexity and cost of removing and replacing them in a capital ship would be too high. By late 1935 a design requirement of nine 18in guns in three triple turrets and a top speed of at least 27 knots had been established. Twin, triple and even quad mounts were proposed for the main armament, in different arrangements, including a layout similar to that of the British battleship Nelson. Displacements ranged from 49,000 to 69,000 tons, speeds from 24 to 31 knots, various forms of a combined steam and diesel power plant were considered, and main gun calibres from 16in to 18in. Already inferior in numbers, the Imperial Japanese Navy planned to redress the balance with ships more powerful than those of its rivals and likely enemies, so the designs for a new class of battleship that began at this point were unrestricted by any of the previous treaty limitations.ĭuring the years 1934 to 1937 about twenty-four different designs were drawn up. When Japan invaded Manchuria, China in 1934, the League of Nations imposed sanctions upon Japan, at which point Japan dropped out of the League and abandoned all naval treaties. These negotiations, in which Great Britain accepted parity with the United States, forced Japan to agree to a 5:5:3 ratio in capital ships – three for every five in the Royal and US Navies. The design of the Yamato class battleships grew out of Japanese resentment at the outcome the 1921 Washington Naval Treaty and the 1930 London Naval Treaty. Intended to enforce Japan’s mastery of the Pacific, they made a minimal contribution to the country’s war effort.
The class were to be ‘super-battleships’, bigger, more heavily armed and better-protected than anything else afloat. Around 2055 of the crew were killed or drowned. At 14:23 the ship capsized, one of the two fore magazines exploding at the same time. The attacks began at 12:37 and, hit by six bombs and 11 or more torpedoes, Yamato was progressively disabled and partially flooded, with little power and no steering. With nine escorting craft but no air protection, it was attacked on the 7th, southwest of the Kyushu Islands, by around 400 American bombers and torpedo bombers in three waves. Yamato was to be beached on the island to act as a fixed artillery fortress. ‘Suicide mission’ On 6 April 1945 it was sent to help repel the American landings on Okinawa in an operation code-named Ten-go, generally considered a large-scale suicide mission.