The first photograph, taken by a Japanese aircraft in mid-October 1944, was intended to review the camouflage efforts made to conceal the carrier while in drydock.

[5][6] Later, on 1 November 1944, a Boeing B-29 Superfortress reconnaissance aircraft captured Shinano near the entrance of Yokosuka Harbor from an altitude of 9,800 meters (32,000 ft).

She was not expected to be completed until 1945, and the sinking of the British capital ships Prince of Wales and Repulse by IJN bombers had called into question the viability of battleships in the war.

The ships had a designed speed of 27 knots (50 km/h; 31 mph), but Shinano never conducted full-speed sea trials so her actual performance is unknown.

[12] A large island, modeled on that fitted on the earlier Taihō, was sponsoned off the starboard side and integrated with the ship's funnel.

[15] Shinano's primary armament consisted of sixteen 40-caliber 12.7-centimeter (5 in) Type 89 dual-purpose guns in eight twin mounts, two at each corner of the hull.

The maximum effective rate of fire was only between 110 and 120 rounds per minute because of the frequent need to change the fifteen-round magazines.

[17] This was the standard Japanese light AA gun during World War II, but it suffered from severe design shortcomings that rendered it largely ineffective.

According to historian Mark Stille, the weapon had many faults including an inability to "handle high-speed targets because it could not be trained or elevated fast enough by either hand or power, its sights were inadequate for high-speed targets, it possessed excessive vibration and muzzle blast"....[18] These guns were supplemented by a dozen 28-round AA rocket launchers.

[14] The ship was originally scheduled for completion in April 1945, but construction was expedited after the defeat at the Battle of the Philippine Sea in June 1944 as the IJN anticipated that the United States would now be able to bomb Japan with long-range aircraft from bases in the Mariana Islands.

[21] Shinano's launch on 8 October 1944, with Captain Toshio Abe [ja] in command, 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 that had not been properly ballasted with seawater unexpectedly lifted as the water rose to the level of the harbor.

The sudden inrush of water into the graving dock pushed the carrier into the forward end, damaging the bow structure below the waterline and requiring repairs in drydock.

[21] On 19 November 1944, Shinano was formally commissioned at Yokosuka, having spent the previous two weeks fitting out and performing sea trials.

[22] Worried about her safety after the fly-over,[22] the Navy General Staff ordered Shinano to depart for Kure by no later than 28 November, where the remainder of her fitting-out would take place.

[25] The escorting destroyers, Isokaze, Yukikaze and Hamakaze, had just returned from the Battle of Leyte Gulf and required more than three days to conduct repairs and to allow their crews to recuperate.

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.

Traveling at an average speed of 20 knots (37 km/h; 23 mph), she needed sixteen hours to cover the 300 miles (480 km) to Kure.

As a measure of how important Shinano was to the naval command, Abe was slated for promotion to rear admiral once the fitting-out was complete.

Abe ordered the destroyer to return to the formation without attacking because he believed that the submarine was part of an American wolfpack.

He assumed Archerfish was being used as a decoy to lure away one of the escorts to allow the rest of the pack a clear shot at Shinano.

A few minutes later, Shinano turned south, exposing her entire side to Archerfish—a nearly ideal firing situation for a submarine.

[34] When it became apparent the damage was more severe than first thought, Abe ordered a change of course towards Shiono Point, the southernmost tip of Honshu's Kii Peninsula.

Fifty minutes later, Abe ordered the empty port outboard tanks to be counter-flooded, reducing the list to 12 degrees for a brief time.

At 06:00 her list had increased to 20 degrees after the starboard boiler room flooded, at which point the valves of the port trimming tanks rose above the waterline and became ineffective.

At 10:18, Abe released the crew to save themselves, refusing to issue any orders to abandon ship; by this time Shinano had a list of 30 degrees.

As she heeled water flowed into the open elevator well on her flight deck, sucking many swimming sailors back into the ship as she sank.

[36] At 10:57 Shinano finally capsized and sank stern-first at coordinates (33°07′N 137°04′E / 33.117°N 137.067°E / 33.117; 137.067), 65 miles (105 km) from the nearest land, in approximately 4,000 meters (13,000 ft) of water, taking 1,435 officers, men and civilians to their deaths.

In addition, the failure to test for watertightness in each compartment played a role as potential leaks could not be found and patched before Shinano put to sea.

[40] The executive officer blamed the large amount of water that entered the ship on the failure to air-test the compartments for leaks.