Ships in Brief #002: IJN Shinano

The only known photograph of Shinano, taken while she was undergoing trials

What was to be the last of the massive Yamato Class Battleships was laid down in May of 1940 at the Yokosuka Naval Yard on Tokyo Bay. Like her sisters, the Japanese maintained strict secrecy in the construction of Shinano, with tall fences around the dockyards and harsh punishments to any worker who spoke of the ship. In mid 1942, following the loss of the bulk of the Imperial Navy’s fleet carriers at Midway the decision was made to convert the still incomplete battleship into a massive supercarrier.

The huge vessel still boasted its planned armor, and its lower speed meant that the Japanese intended to relegate Shinano to support other carriers by bringing extra aircraft, fuel and stores as needed. She would carry some aircraft for defensive purposes as well.

When launched in late 1944, she was the largest aircraft carrier in the world, with a length of 872 feet and displacing 69,000 tons. Her armored flight decks were designed to resist attacks by dive bombers such as those that destroyed the fleet at Midway, and her hangars were also redesigned from earlier IJN carriers to allow for better safety during attacks. Shinano carried 47 aircraft for her own use, and could store an additional 120 aircraft for her supply role.

On November 28, 1944 the Shinano departed from the Yokosuka Naval Yard with a small destroyer screen, despite the fears of her captain, Toshio Abe, regarding the state of his vessel, which had not yet been fitted with watertight doors and still had harbor crew aboard for fitting out, leaving most of the interior hatches open for construction. Despite this, Naval Command feared that the Americans had become aware of the ship, and thus needed her moved quickly to prevent destruction in air raids.

After night fell, as the ship was making its way to Kure she was spotted by the patrolling submarine USS Archerfish, which began to tail her. Fearing that several submarines were in the area, Captain Abe ordered his destroyer screen to stay close rather than engage the submarine, which the carrier could outrun at any rate. This was not to be, however, as failures in Shinano’s unproven engines caused a reduction in speed as the clock turned into November 29th, and the zig-zag pattern being performed by the Japanese ships soon resulted in the Shinano presenting a broadside to the Archerfish at close range.

Archerfish fired a spread of six torpedoes and dived to avoid the destroyers, peppering the carrier with four hits along her hull. Believing that American torpedoes could not cause significant damage to his ship, Captain Abe ordered a continuation of top speed, even as water gushed into the ruptured compartments. The ship rapidly began to take on a list to port, and over the next few hours this continued to worsen as Captain Abe changed course, having realized the severity of the situation. Not long after dawn the ship’s engines failed as the flooded boilers shut down, and attempts to tow the massive hulk with the destroyers were unsuccessful.

As the dead ship continued to list Captain Abe ordered his crew to abandon ship just after 1000, and within the hour the largest aircraft carrier in the world capsized and sank, never having seen action. She remains the largest warship ever sunk by a submarine, and was the largest aircraft carrier ever built until the launch of the American USS Enterprise in the late 1960s.

Specifications: Shinano Class Aircraft Carrier - IJN Shinano

Builder: Yokosuka Naval Arsenal
Operator: Imperial Japanese Navy
Commissioned: November 19, 1944
Lost: November 29, 1944
Length: 872 feet
Beam: 119 feet
Draft: 33 feet
Powerplant: 12x Kampon RO Boilers powering 4x Geared Turbines
Armament: 16x 5’’ AAA, 35x Triple Type 96 AA Cannons, 12x 120mm AA Rocket Launchers
Crew: 2,400
Commanding Officer: Captain Toshio Abe, IJN