Japanese aircraft carrier Shinano
Encyclopedia
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 battleship
s, 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 72000 LT (73,155.6 t), 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 and transfer a load of 100 Yokosuka MXY7 Ohka rocket-propelled kamikaze
aircraft. While en route, Shinano was sunk by the American
submarine
10 days after her commissioning — the result of severe design flaws, crew inexperience and poor damage control. To date, she is the largest warship to be sunk by a submarine.
with her keel
being laid down in June 1940 at the Yokosuka Naval Dockyard. Named after the ancient Shinano Province
, the vessel would have been one of the three largest battleships ever constructed. In mid-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. Had she been completed as a battleship, her armament and armor would have been nearly identical to that of her sister ship
s and .
As with Yamato and Musashi, Shinano's 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 never to have been officially photographed during its construction. Only a single photograph is known to exist of the ship, taken by a civilian photographic technician aboard a harbor tug during Shinano's initial sea trials in Tokyo Bay on 11 November 1944.
Following Japan's disastrous loss of four fleet carriers at the Battle of Midway
in June 1942, the decision was made to convert Shinano's unfinished hull into an aircraft carrier. Fortuitously, her hull was only 45 percent complete by that time, with structural work complete up to the lower deck and only major machinery parts installed. Conversion planning began that same month under the direction of Vice Admiral Keiji Fukuda of the Imperial Japanese Navy Technical Department
(or Kampon).
Shinano's launch on 8 October 1944 was marred by what some considered an ill-omened accident. During the floating-out procedure, one of the caissons at the end of the dock unexpectedly lifted as the water rose to the level of the harbor (no one had checked to insure that all the caissons were properly ballasted with seawater). The sudden inrush of water into the graving dock pushed the carrier into the forward end, damaging the bow structure below the waterline and necessitating another dry-dock for repairs. These were completed by 26 October. With a full-load displacement of 72000 LT (73,155.6 t), Shinano was the largest aircraft carrier ever built — a record she would hold until —with a displacement of 80000 LT (81,284 t)—was launched in 1954.
Shinano was primarily designed as a support carrier, with extensive facilities for aircraft repair and refitting. 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; instead, she was to carry reserve aircraft, fuel and ordinance in support of carrier task forces. Shinano was officially launched on 8 October 1944, with Captain
Toshio Abe in overall command of the vessel.
at that time that could be carried by dive bomber
s. The deck consisted of a 96 mm (3.8 in) layer of steel under which was a second layer of 19 mm (0.748031496062992 in) steel plate. The 840 mm (33.1 in) void between these two layers was reinforced with I-beams and the spaces between the beams filled with a composite mixture of cement, sawdust and latex.
Shinano's armored flight deck copied British practice as seen in their carriers but, whereas the hangars on British carriers formed an armored box with sides equal in width to the flight deck armor, the Japanese provided only an armored lid with unarmored sides.
Due to the great weight of Shinano's flight deck armor, only a single aircraft hangar could be built atop the hull in order to maintain adequate stability. The hangar was 163 m (534.8 ft) long, 5.08 m (16.7 ft) high and 33.8 m (110.9 ft) wide, tapering down to just 20.08 m (65.9 ft) fore and aft due to the sheer of the hull.
The new design for Shinano gave her hangar decks a lot of open space to facilitate jettisoning aircraft and ordnance in case of need, and her amidships belt armor was lightened somewhat. Special attention was given to the on board gasoline tanks, even though built to withstand a 155mm shell. Many lessons had been learned from the loss of the carrier Taihō
, on which Shinano´s flight deck would be modeled, which showed the fuel tank arrangement to be faulty. Torpedo hits in the vicinity could potentially permit gasoline vapors to leak beyond the cofferdam and there were also the worry of puncture by debris. Both of these worries were alleviated by pouring 2,400 metric tons of cement into the void spaces around the tanks as protection. Little else could be done due to the advanced state of construction. Another lesson from the Taiho resulted in the decision to install large ventilation fans on the hangar deck in case of damage to the gasoline system. Portable canvas wind scoops could also be rigged over the elevator opening to force more air inside.
s mounted on projecting sponsons and arranged in eight batteries, four on either side of the flight deck. Her close-range anti-aircraft armament
was made up of 145 25 mm (0.984251968503937 in) Type 96 anti-aircraft guns, and 336 127 mm (5 in) anti-aircraft rocket launcher
s in 12 28-barrel turrets.
, where the remainder of her fitting-out would take place. Naval Command wanted Shinano moved to Kure no later than 28 November. However, Abe asked for a delay in the sailing date. The majority of her watertight compartment doors had yet to be installed, the compartment air tests had not been conducted, and many holes for electrical cables, ventilation ducts and pipes had not been sealed. Nor had the fire mains or drainage systems been completed as pumps had not been delivered. He also wanted more time to train his new crew, and to give the crews of the destroyers a rest after returning from battle.
Abe's request was denied, and Shinano departed as scheduled at 18:00 on 28 November escorted by the destroyers Isokaze, Yukikaze and Hamakaze. Abe commanded a crew of 2,176 officers and men. Also on board were 300 shipyard workers and 40 civilian employees. Watertight doors and hatches were left open for ease of access to machinery spaces, as were some manholes in the double and triple bottomed hull. Abe would have preferred a daytime passage, but was unable to get Naval Command to provide air support; all available planes were needed for combat duty. She also carried six Shinyo suicide boats, and 50 Ohka
suicide rockets. Her orders were to go to Kure, where she would complete her fitting-out and commence to the Inland Sea after which Shinano was to take the Ohka east for "the relief of the Philippines". 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. 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 the carrier's 12 boiler
s were not in service due to lack of parts. This cut her top speed from 27 kn (52.9 km/h; 32.9 mph) to 21 kn (41.2 km/h; 25.6 mph) — too slow for planes to launch without a headwind.
At 21:00, the American submarine —commanded by Commander
Joseph F. Enright
—picked up Shinano′s task group on her radar
. Normally, Shinano would have been able to outrun Archer-Fish. However, the submarine was able to remain in pursuit of Shinano because the zig-zagging pattern of Shinano and her escorts—intended to avoid submarine attack—inadvertently turned the task group back into the sub's path on several occasions. Abe's zig-zagging was guided by his assumption that Archer-Fish was part of an American "wolfpack". He believed that Archer-Fish was being used as a decoy to lure away one of the escorting destroyer
s, 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. Additionally, Shinano was slowed because it was only running on four of her six operational boilers on two propeller shafts. Shinano was slowed further mid-pursuit after a bearing
overheated one of the shafts, forcing lower operating RPMs of that engine. As a result, Shinano was forced to reduce its top speed to the same speed as most American subs.
On November 29 Abe was still worrying about the submarine spotted 48 hours earlier, and all three following destroyers kept changing course erratically. Once again the zig-zagging put Shinano into the path of Archer-Fish. At 3:05 am, Archer-Fish dived. Enright quickly moved Archer-Fish in front of the carrier group. However, just as Enright was about to loose his torpedoes, one of the destroyers on Shinanos starboard beam broke away and set course straight for Archer-Fish. Expecting depth charge
s, Enright ordered a descent to 62 feet, but the destroyer passed overhead seemingly unaware of them, after which Archer-Fish rose back to 60 feet. At 3:15 am, Archer-Fish fired six shallow-running torpedoes in sequence before diving to 400 feet to escape a depth charge attack from the escorts. Enright later said he set the torpedoes to run shallow in hopes of capsizing it.
Four of the six torpedoes found their mark. The first torpedo struck Shinano towards the stern, ripping through the hull into refrigerated areas and one of the empty aviation gasoline-storage tanks. The explosion also killed the sleeping engineering personnel in the compartments above. The second torpedo struck some 8 seconds after the first and 50 yards ahead into the starboard outboard propeller shaft, flooding the outboard engine-room. The third torpedo took out the No. 3 fireroom, killing every man on watch. The fourth and final torpedo detonating against the starboard air compressor room, flooding it and neighboring magazines while also rupturing the starboard oil-tank.
Abe quickly ordered a damage report and sounded battle stations. He initially thought Shinano had enough armor to withstand the damage, since American torpedoes had smaller warheads and fewer explosives than their Japanese counterparts. With this in mind, he ordered the navigator to maintain full speed. However, within minutes Shinano had already listed roughly 10 degrees to starboard. Archer-Fishs crew later reported seeing Shinano listing only minutes after the last torpedo hit. The executive officer
later reported that only minutes after the last torpedo hit, he heard air rushing through gaps in the watertight doors which had been left untested before departure—a sign that seawater was rapidly entering the ship, proving the doors unfit. Though severe, the damage to Shinano was at first judged to be manageable, and the carrier continued under way. The crew were confident in Shinano´s armor and its strength, which translated into lax efforts to save the ship initially. Captain Abe ordered a change of course towards Shiono Point and for the ship to be righted by counter-flooding, which reduced the list to 7 degrees.
At dawn Shinano was still making 18 knots with the remaining boilers and machinery when the starboard boiler-room flooded completely and increased the list to 20 degrees, at which point the port trimming tanks valves rose above the waterline and became ineffective. Speed dropped to 10 knots and the port boiler rooms were ordered flooded in desperation, stemming the list momentarily before it continued. All efforts to control the flooding failed, in part because most of the crew was not well trained in damage control. No flooding boundaries were set up either, which would be the norm, and few portable pumps were available or properly used by the inexperienced crew.
At 06:00, Shinanos boiler feed water was exhausted. At 7:45 am, she lost all power, and ceased all forward motion shortly afterward. Panic increasingly spread among the crew, who were also confused by the mix of civilian personnel in similar uniform who were "disobeying" orders given to them. At 08:50, Captain Abe messaged the destroyers Hamakaze and Isokaze to take her in tow, to attempt beaching her on Cape Ushio. However, the two escorts only displaced 5000 LT (5,080.3 t) between them, not nearly enough to overcome the list. The first cables snapped under the strain from pulling the waterlogged ship, and the second attempt was aborted for fear of injury to the men.
At 10:18, Abe gave the order to abandon ship; by this time Shinano was listing 30 degrees to starboard. As she heeled her flightdeck touched the water, which flowed into the open deck elevator; sucking mobs of sailors back into the ship as she sunk. At 10:57 Shinano finally capsized and sank 200 km (108 nmi; 124.3 mi) southeast of Shingū
(32°0′N 137°0′E), her stern slipping under first with the bow pointing skyward. She took 1,435 men and officers to their deaths, including Abe and both of his navigators. Rescued were 55 officers, 993 petty officers and men, plus 32 civilians for a total of 1,080 survivors. The survivors of Shinanos sinking were quarantined in Japan for several months following her sinking.
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. Survivors claimed that they were unable to control the flooding because the water poured in too fast; some claimed to have seen rivet
s between seams burst and allow water to surge through. The executive officer blamed the large amount of water that entered the ship so soon after the last hit 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 had worked properly.
Shinano Province
or is an old province of Japan that is now present day Nagano Prefecture.Shinano bordered on Echigo, Etchū, Hida, Kai, Kōzuke, Mikawa, Mino, Musashi, Suruga, and Tōtōmi Provinces...
, was an aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
of the Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...
during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. Initially laid down as the third of the battleship
Battleship
A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...
s, 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 72000 LT (73,155.6 t), the largest aircraft carrier ever built at the time.
Commissioned in November 1944, Shinano was to transfer from the Yokosuka Naval Shipyard
Yokosuka Naval Arsenal
was one of four principal naval shipyards owned and operated by the Imperial Japanese Navy, and was located at Yokosuka city, Kanagawa prefecture on Tokyo Bay, south of Yokohama...
to Kure Naval Base
Kure, Hiroshima
is a city in Hiroshima prefecture, Japan.As of October 1, 2010, the city has an estimated population of 240,820 and a population density of 681 persons per km². The total area is 353.74 km².- History :...
to complete her outfitting and transfer a load of 100 Yokosuka MXY7 Ohka rocket-propelled kamikaze
Kamikaze
The were suicide attacks by military aviators from the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, designed to destroy as many warships as possible....
aircraft. While en route, Shinano was sunk by the American
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
10 days after her commissioning — the result of severe design flaws, crew inexperience and poor damage control. To date, she is the largest warship to be sunk by a submarine.
Design and construction
Shinano was initially designed as the third battleshipBattleship
A battleship is a large armored warship with a main battery consisting of heavy caliber guns. Battleships were larger, better armed and armored than cruisers and destroyers. As the largest armed ships in a fleet, battleships were used to attain command of the sea and represented the apex of a...
with her keel
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
being laid down in June 1940 at the Yokosuka Naval Dockyard. Named after the ancient Shinano Province
Shinano Province
or is an old province of Japan that is now present day Nagano Prefecture.Shinano bordered on Echigo, Etchū, Hida, Kai, Kōzuke, Mikawa, Mino, Musashi, Suruga, and Tōtōmi Provinces...
, the vessel would have been one of the three largest battleships ever constructed. In mid-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. Had she been completed as a battleship, her armament and armor would have been nearly identical to that of her sister ship
Sister ship
A sister ship is a ship of the same class as, or of virtually identical design to, another ship. Such vessels share a near-identical hull and superstructure layout, similar displacement, and roughly comparable features and equipment...
s and .
As with Yamato and Musashi, Shinano's 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 never to have been officially photographed during its construction. Only a single photograph is known to exist of the ship, taken by a civilian photographic technician aboard a harbor tug during Shinano's initial sea trials in Tokyo Bay on 11 November 1944.
Following Japan's disastrous loss of four fleet carriers at the Battle of Midway
Battle of Midway
The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...
in June 1942, the decision was made to convert Shinano's unfinished hull into an aircraft carrier. Fortuitously, her hull was only 45 percent complete by that time, with structural work complete up to the lower deck and only major machinery parts installed. Conversion planning began that same month under the direction of Vice Admiral Keiji Fukuda of the Imperial Japanese Navy Technical Department
Imperial Japanese Navy Technical Department
The was the externally operating division of the Ministry of the Navy of Japan responsible for the administration of naval vessel construction. From 1923 onward, it took on the role of a research institution for the research and development of naval technologies and engineering...
(or Kampon).
Shinano's launch on 8 October 1944 was marred by what some considered an ill-omened accident. During the floating-out procedure, one of the caissons at the end of the dock unexpectedly lifted as the water rose to the level of the harbor (no one had checked to insure that all the caissons were properly ballasted with seawater). The sudden inrush of water into the graving dock pushed the carrier into the forward end, damaging the bow structure below the waterline and necessitating another dry-dock for repairs. These were completed by 26 October. With a full-load displacement of 72000 LT (73,155.6 t), Shinano was the largest aircraft carrier ever built — a record she would hold until —with a displacement of 80000 LT (81,284 t)—was launched in 1954.
Shinano was primarily designed as a support carrier, with extensive facilities for aircraft repair and refitting. Shinano herself was intended to have a small fighter
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
complement for defensive purposes, but was not intended to act as a fleet carrier despite her size; instead, she was to carry reserve aircraft, fuel and ordinance in support of carrier task forces. Shinano was officially launched on 8 October 1944, with Captain
Captain (naval)
Captain is the name most often given in English-speaking navies to the rank corresponding to command of the largest ships. The NATO rank code is OF-5, equivalent to an army full colonel....
Toshio Abe in overall command of the vessel.
Hull
While the ship's original 410 mm (16.1 in) belt armor was halved to 205 mm (8.1 in), the armor over the machinery and magazine spaces, ranging from 102 mm (4 in) to 190 mm (7.5 in), was retained, forming the floor of the hangar deck. Large bulges on either side of the hull, below the waterline, provided the main defense against torpedoes, backed up by an armored bulkhead attached to and extending down from the belt armor. The bulkhead was intended to prevent splinters from piercing the main hull and, though not water-tight, was backed by a second one which was.Machinery
Shinano's 150000 shp steam turbines, fed by 12 boilers, were of the same type as installed on Yamato. With greater fuel oil bunkerage than she would have had as a battleship, the carrier had a calculated cruising range of 10000 miles (16,093.4 km) at 18 knots (9.8 m/s).Flight deck & hangar
Given the destruction wrought by American dive bombers at Midway, naval architect Fukuda opted to provide Shinano with an armored flight deck, capable of withstanding the impact of 454 kg (1,000.9 lb) bombs, the largest in the arsenal of the United States NavyUnited States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
at that time that could be carried by dive bomber
Dive bomber
A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy for the bomb it drops. Diving towards the target reduces the distance the bomb has to fall, which is the primary factor in determining the accuracy of the drop...
s. The deck consisted of a 96 mm (3.8 in) layer of steel under which was a second layer of 19 mm (0.748031496062992 in) steel plate. The 840 mm (33.1 in) void between these two layers was reinforced with I-beams and the spaces between the beams filled with a composite mixture of cement, sawdust and latex.
Shinano's armored flight deck copied British practice as seen in their carriers but, whereas the hangars on British carriers formed an armored box with sides equal in width to the flight deck armor, the Japanese provided only an armored lid with unarmored sides.
Due to the great weight of Shinano's flight deck armor, only a single aircraft hangar could be built atop the hull in order to maintain adequate stability. The hangar was 163 m (534.8 ft) long, 5.08 m (16.7 ft) high and 33.8 m (110.9 ft) wide, tapering down to just 20.08 m (65.9 ft) fore and aft due to the sheer of the hull.
The new design for Shinano gave her hangar decks a lot of open space to facilitate jettisoning aircraft and ordnance in case of need, and her amidships belt armor was lightened somewhat. Special attention was given to the on board gasoline tanks, even though built to withstand a 155mm shell. Many lessons had been learned from the loss of the carrier Taihō
Japanese aircraft carrier Taiho
was an aircraft carrier of the Imperial Japanese Navy during World War II. With a heavily armored hull and flight deck , she represented a major departure in Japanese carrier design and was expected to not only survive multiple bomb, torpedo or shell hits but also continue fighting effectively...
, on which Shinano´s flight deck would be modeled, which showed the fuel tank arrangement to be faulty. Torpedo hits in the vicinity could potentially permit gasoline vapors to leak beyond the cofferdam and there were also the worry of puncture by debris. Both of these worries were alleviated by pouring 2,400 metric tons of cement into the void spaces around the tanks as protection. Little else could be done due to the advanced state of construction. Another lesson from the Taiho resulted in the decision to install large ventilation fans on the hangar deck in case of damage to the gasoline system. Portable canvas wind scoops could also be rigged over the elevator opening to force more air inside.
Armament
Shinano's primary defensive armament consisted of sixteen 127 mm (5 in) paired dual purpose gunDual purpose gun
A dual purpose gun is a naval artillery mounting designed to engage both surface and air targets.-Description:Second World War-era capital ships had four classes of artillery: the heavy main battery, intended to engage opposing battleships and cruisers ; a secondary battery for use against enemy...
s mounted on projecting sponsons and arranged in eight batteries, four on either side of the flight deck. Her close-range anti-aircraft armament
Anti-aircraft warfare
NATO defines air defence as "all measures designed to nullify or reduce the effectiveness of hostile air action." They include ground and air based weapon systems, associated sensor systems, command and control arrangements and passive measures. It may be to protect naval, ground and air forces...
was made up of 145 25 mm (0.984251968503937 in) Type 96 anti-aircraft guns, and 336 127 mm (5 in) anti-aircraft rocket launcher
Rocket launcher
A rocket launcher is any device that launches a rocket-propelled projectile, although the term is often used in reference to mechanisms that are portable and capable of being operated by an individual....
s in 12 28-barrel turrets.
Aircraft
Shinano was also built to contain a maximum of 120 aircraft within her 265 m (869.4 ft) hull.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. By 1 October the crew had reported on board, 70 to 75 percent of which had no previous sea duty experience. As a result of growing worry for her safety, due to a U.S. bomber fly-over, Japanese Naval Command ordered Shinano to KureKure, Hiroshima
is a city in Hiroshima prefecture, Japan.As of October 1, 2010, the city has an estimated population of 240,820 and a population density of 681 persons per km². The total area is 353.74 km².- History :...
, where the remainder of her fitting-out would take place. Naval Command wanted Shinano moved to Kure no later than 28 November. However, Abe asked for a delay in the sailing date. The majority of her watertight compartment doors had yet to be installed, the compartment air tests had not been conducted, and many holes for electrical cables, ventilation ducts and pipes had not been sealed. Nor had the fire mains or drainage systems been completed as pumps had not been delivered. He also wanted more time to train his new crew, and to give the crews of the destroyers a rest after returning from battle.
Abe's request was denied, and Shinano departed as scheduled at 18:00 on 28 November escorted by the destroyers Isokaze, Yukikaze and Hamakaze. Abe commanded a crew of 2,176 officers and men. Also on board were 300 shipyard workers and 40 civilian employees. Watertight doors and hatches were left open for ease of access to machinery spaces, as were some manholes in the double and triple bottomed hull. Abe would have preferred a daytime passage, but was unable to get Naval Command to provide air support; all available planes were needed for combat duty. She also carried six Shinyo suicide boats, and 50 Ohka
Ohka
The Yokosuka MXY-7 Ohka was a purpose-built, rocket powered human-guided anti-shipping kamikaze attack plane employed by Japan towards the end of World War II...
suicide rockets. Her orders were to go to Kure, where she would complete her fitting-out and commence to the Inland Sea after which Shinano was to take the Ohka east for "the relief of the Philippines". Abe was due to be promoted to rear admiral
Rear Admiral
Rear admiral is a naval commissioned officer rank above that of a commodore and captain, and below that of a vice admiral. It is generally regarded as the lowest of the "admiral" ranks, which are also sometimes referred to as "flag officers" or "flag ranks"...
once Shinano completed her fitting-out, and take command of a fleet of attack carriers being built up in the east. Although Shinano was to act as a support carrier, she was also assigned her own air group, commanded by Lieutenant Commander
Lieutenant Commander
Lieutenant Commander is a commissioned officer rank in many navies. The rank is superior to a lieutenant and subordinate to a commander...
Yoshio Shiga
Yoshio Shiga
was an officer, ace fighter pilot, and leader in the Imperial Japanese Navy during the Second Sino-Japanese War and the Pacific theater of World War II. At the December 1941 Attack on Pearl Harbor, Shiga led one of the aircraft carrier Kaga's fighter divisions during the first strike on American...
, a veteran of the attack on Pearl Harbor
Attack on Pearl Harbor
The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941...
. Shiga's air group would have already been aboard when Shinano sortied for Kure, but four of the carrier's 12 boiler
Boiler
A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...
s were not in service due to lack of parts. This cut her top speed from 27 kn (52.9 km/h; 32.9 mph) to 21 kn (41.2 km/h; 25.6 mph) — too slow for planes to launch without a headwind.
At 21:00, the American submarine —commanded by Commander
Commander
Commander is a naval rank which is also sometimes used as a military title depending on the individual customs of a given military service. Commander is also used as a rank or title in some organizations outside of the armed forces, particularly in police and law enforcement.-Commander as a naval...
Joseph F. Enright
Joseph F. Enright
Joseph Francis Enright was a submarine captain in the United States Navy...
—picked up Shinano′s task group on her radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
. Normally, Shinano would have been able to outrun Archer-Fish. However, the submarine was able to remain in pursuit of Shinano because the zig-zagging pattern of Shinano and her escorts—intended to avoid submarine attack—inadvertently turned the task group back into the sub's path on several occasions. Abe's zig-zagging was guided by his assumption that Archer-Fish was part of an American "wolfpack". He believed that Archer-Fish was being used as a decoy to lure away one of the escorting destroyer
Destroyer
In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...
s, 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. Additionally, Shinano was slowed because it was only running on four of her six operational boilers on two propeller shafts. Shinano was slowed further mid-pursuit after a bearing
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
overheated one of the shafts, forcing lower operating RPMs of that engine. As a result, Shinano was forced to reduce its top speed to the same speed as most American subs.
On November 29 Abe was still worrying about the submarine spotted 48 hours earlier, and all three following destroyers kept changing course erratically. Once again the zig-zagging put Shinano into the path of Archer-Fish. At 3:05 am, Archer-Fish dived. Enright quickly moved Archer-Fish in front of the carrier group. However, just as Enright was about to loose his torpedoes, one of the destroyers on Shinanos starboard beam broke away and set course straight for Archer-Fish. Expecting depth charge
Depth charge
A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...
s, Enright ordered a descent to 62 feet, but the destroyer passed overhead seemingly unaware of them, after which Archer-Fish rose back to 60 feet. At 3:15 am, Archer-Fish fired six shallow-running torpedoes in sequence before diving to 400 feet to escape a depth charge attack from the escorts. Enright later said he set the torpedoes to run shallow in hopes of capsizing it.
Four of the six torpedoes found their mark. The first torpedo struck Shinano towards the stern, ripping through the hull into refrigerated areas and one of the empty aviation gasoline-storage tanks. The explosion also killed the sleeping engineering personnel in the compartments above. The second torpedo struck some 8 seconds after the first and 50 yards ahead into the starboard outboard propeller shaft, flooding the outboard engine-room. The third torpedo took out the No. 3 fireroom, killing every man on watch. The fourth and final torpedo detonating against the starboard air compressor room, flooding it and neighboring magazines while also rupturing the starboard oil-tank.
Abe quickly ordered a damage report and sounded battle stations. He initially thought Shinano had enough armor to withstand the damage, since American torpedoes had smaller warheads and fewer explosives than their Japanese counterparts. With this in mind, he ordered the navigator to maintain full speed. However, within minutes Shinano had already listed roughly 10 degrees to starboard. Archer-Fishs crew later reported seeing Shinano listing only minutes after the last torpedo hit. The executive officer
Executive officer
An executive officer is generally a person responsible for running an organization, although the exact nature of the role varies depending on the organization.-Administrative law:...
later reported that only minutes after the last torpedo hit, he heard air rushing through gaps in the watertight doors which had been left untested before departure—a sign that seawater was rapidly entering the ship, proving the doors unfit. Though severe, the damage to Shinano was at first judged to be manageable, and the carrier continued under way. The crew were confident in Shinano´s armor and its strength, which translated into lax efforts to save the ship initially. Captain Abe ordered a change of course towards Shiono Point and for the ship to be righted by counter-flooding, which reduced the list to 7 degrees.
At dawn Shinano was still making 18 knots with the remaining boilers and machinery when the starboard boiler-room flooded completely and increased the list to 20 degrees, at which point the port trimming tanks valves rose above the waterline and became ineffective. Speed dropped to 10 knots and the port boiler rooms were ordered flooded in desperation, stemming the list momentarily before it continued. All efforts to control the flooding failed, in part because most of the crew was not well trained in damage control. No flooding boundaries were set up either, which would be the norm, and few portable pumps were available or properly used by the inexperienced crew.
At 06:00, Shinanos boiler feed water was exhausted. At 7:45 am, she lost all power, and ceased all forward motion shortly afterward. Panic increasingly spread among the crew, who were also confused by the mix of civilian personnel in similar uniform who were "disobeying" orders given to them. At 08:50, Captain Abe messaged the destroyers Hamakaze and Isokaze to take her in tow, to attempt beaching her on Cape Ushio. However, the two escorts only displaced 5000 LT (5,080.3 t) between them, not nearly enough to overcome the list. The first cables snapped under the strain from pulling the waterlogged ship, and the second attempt was aborted for fear of injury to the men.
At 10:18, Abe gave the order to abandon ship; by this time Shinano was listing 30 degrees to starboard. As she heeled her flightdeck touched the water, which flowed into the open deck elevator; sucking mobs of sailors back into the ship as she sunk. At 10:57 Shinano finally capsized and sank 200 km (108 nmi; 124.3 mi) southeast of Shingū
Shingu, Wakayama
is a city located in Wakayama, Japan.As of May 1, 2011, the city has an estimated population of 32,288, with a household number of 16,003, and the density of 126.41 persons per km². The total area is 255.43 km²....
(32°0′N 137°0′E), her stern slipping under first with the bow pointing skyward. She took 1,435 men and officers to their deaths, including Abe and both of his navigators. Rescued were 55 officers, 993 petty officers and men, plus 32 civilians for a total of 1,080 survivors. The survivors of Shinanos sinking were quarantined in Japan for several months following her sinking.
Post-war analysis of the sinking
Post-war analysis by the U.S. Naval Technical Mission to Japan claimed that Shinano had serious design flaws. Specifically, the joint between the anti-projectile armor on the hull and the anti-torpedo bulgeAnti-torpedo bulge
The anti-torpedo bulge is a form of passive defence against naval torpedoes that featured in warship construction in the period between the First and Second World Wars.-Theory and form:...
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. Survivors claimed that they were unable to control the flooding because the water poured in too fast; some claimed to have seen rivet
Rivet
A rivet is a permanent mechanical fastener. Before being installed a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the buck-tail. On installation the rivet is placed in a punched or pre-drilled hole, and the tail is upset, or bucked A rivet...
s between seams burst and allow water to surge through. The executive officer blamed the large amount of water that entered the ship so soon after the last hit 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 had worked properly.