was the lead ship of her class of two aircraft carriers built for the Imperial Japanese Navy (IJN) shortly before the Pacific War. Along with her sistership , she took part in several key naval battles during the war, starting the attack on Pearl Harbor where she destroyed air fields and other land facilities. During the Indian Ocean Raid, April 1942, Shōkaku dive bombers sank the armed merchant cruiser HMS Hector and helped to sink the light carrier HMS Hermes and the steamship SS Sagaing. At the battle of the Coral Sea later that May - assisted by Zuikaku - Shōkaku aircraft scored primary credit for sinking the aircraft carrier USS Lexington. Shōkaku dive bombers also sank the destroyer USS Sims and helped to sink the fleet oilier USS Neosho. However, she was in turn crippled by bomb hits and taken out of action.
In August, Shōkaku saw action again at the battle of the Eastern Solomons where she helped to cripple the aircraft carrier USS Enterprise but failed to score an overall victory. This was made up for later that October at the Battle of the Santa Cruz Islands where Shōkaku aircraft helped to sink the aircraft carrier USS Hornet and badly damaged the Enterprise; taking several bomb hits but remaining combat capable. However, throughout 1943 Shōkaku was mainly reserved for the Kantai Kessen plan and primarily transited between naval ports and rendezvoused in failed attempts to enact a large scale battleline engagement. Shōkaku finally saw action again at the battle of the Philippine Sea, 19 June 1944, where she damaged the battleship USS South Dakota but was finally torpedoed and sunk by the submarine USS Cavalla.
Design
The Shōkaku-class carriers were part of the same program that also included the s. No longer restricted by the provisions of the Washington Naval Treaty, which expired in December 1936, the Imperial Japanese Navy (IJN) was free to incorporate all those features they deemed most desirable in an aircraft carrier, namely high speed, a long radius of action, heavy protection and a large aircraft capacity. Shōkaku was laid down at Yokosuka Dockyard on 12 December 1937, launched on 1 June 1939, and commissioned on 8 August 1941.
With an efficient modern design, a displacement of about , and a top speed of , Shōkaku could carry 70–80 aircraft. Her enhanced protection compared favorably to that of contemporary Allied aircraft carriers and enabled Shōkaku to survive serious damage during the battles of the Coral Sea and Santa Cruz.Stille, p.17
Hull In appearance, Shōkaku resembled an enlarged , though with a longer overall length, wider beam and a larger island. As in Hiryū, the forecastle was raised to the level of the upper hangar deck to improve seakeeping. She also had a wider, more rounded and heavily flared bow which kept the flight deck dry in most sea conditions.Brown, p.23
The carrier's forefoot was of the newly developed bulbous type, sometimes referred to informally as a Taylor pear, which served to reduce the hull's underwater drag within a given range of speeds, improving both the ship's speed and endurance. Unlike the larger bulbous forefeet fitted to the battleships and , however, Shōkakus did not protrude beyond the ship's stem.
Shōkaku was 10,000 tons heavier than , mainly due to the extra armor incorporated into the ship's design. Vertical protection consisted of on the main armor deck over the machinery, magazines and aviation fuel tanks, while horizontal protection consisted of along the waterline belt abreast the machinery spaces, reducing to outboard of the magazines.
Shōkaku normally stowed 150,000 gallons of avgas for operational use. Unlike British carriers, whose aviation fuel was stored in separate cylinders or coffer-dams surrounded by seawater, all pre-war Japanese carriers had their aviation fuel tanks built integral with the ship's hull, and Shōkaku was no exception. The dangers this posed, however, did not become evident until wartime experience demonstrated these were often prone to cracking and leaking as the shocks and stresses of hits or near-misses to the carrier's hull were inevitably transferred to and absorbed by the fuel tanks. Following the debacle at Midway in mid-1942, the empty air spaces around Shōkakus aviation fuel tanks, normally pumped full of inert carbon dioxide, were instead filled with concrete in an attempt to protect them from possible damage. But this did little to prevent volatile fumes spreading to the hangar decks in the event damage did occur, particularly demonstrated when Cavalla torpedoed and sank her.Brown, p.6
Machinery The geared turbines installed on Shōkaku were essentially the same as those on Sōryū, maximum power increasing by to . In spite of all the additional armor, greater displacement and a increase in draught, Shōkaku was able to attain a speed of just over during trials. Maximum fuel bunkerage was 4100 tons, giving her a radius of action of at . Two same-sized downward-curving funnels on the ship's starboard side, just abaft the island, vented exhaust gases horizontally from the boilers and were sufficiently angled to keep the flight deck free of smoke in most wind conditions.Brown, p.23–24
Flight deck and hangars Shōkakus long wood-planked flight deck ended short of the ship's bow and, just barely, short of the stern. It was supported by four steel pillars forward of the hangar box and by two pillars aft.
The flight deck and both hangars (upper and lower) were serviced by three elevators, the largest being the forward one at by , the middle and the rear elevators measured by . All three were capable of transferring aircraft weighing up to and raising or lowering them took approximately 15–20 seconds.Brown, p.24
Shōkakus nine Type 4 electrically operated arrester wires followed the same standard arrangement as that on Hiryū, three forward and six aft. They were capable of stopping a aircraft at speeds of . A third crash barrier was added and a light collapsible wind-break screen was installed just forward of the island.
The upper hangar was and had an approximate height of ; the lower was and had an approximate height of . Together they had an approximate total area of . Hangar space was not greatly increased in comparison to Sōryū and both Shōkaku and Zuikaku could each carry just nine more aircraft than Sōryū, giving them a normal operating capacity of seventy-two plus room for twelve in reserve. Unlike on Sōryū, the reserve aircraft did not need to be kept in a state of disassembly, however, thereby shortening the time required to make them operational.Stille, p.18
After experimenting with port-side islands on two previous carriers, and Hiryū, the IJN opted to build both Shōkaku and her sister ship Zuikaku with starboard-side islands.
In September 1942, a Type 21 air-warning radar was installed on Shōkakus island atop the central fire control director, the first such device to be fitted on any Japanese carrier. The Type 21 had a "mattress" antenna and the initial prototypes were light enough that no major structural modifications were necessary. Later versions, however, were bulkier and required eventual removal of the fifth fire control director in order to accommodate the larger and heavier antenna.
Armament Shōkakus primary air defense consisted of sixteen Type 89 dual-purpose AA guns in twin mountings. These were sited below flight deck level on projecting sponsons with four such paired batteries on either side of the ship's hull, two forward and two aft. Four fire control directors were installed, two on the port side and two to starboard. A fifth fire control director was located atop the carrier's island and could control any or all of the heavy-caliber guns as needed.
Initially, light AA defense was provided by twelve triple-mount Type 96 AA guns.
In June 1942, Shōkaku had her anti-aircraft armament augmented with six triple 25 mm mounts, two each at the bow and stern, and one each fore and aft of the island. The bow and stern groups each received a Type 95 director. In October another triple 25 mm mount was added at the bow and stern and 10 single mounts were added before the Battle of the Philippine Sea in June 1944.
Operational history Shōkaku and Zuikaku formed the Japanese 5th Carrier Division, embarking their aircraft shortly before the Pearl Harbor attack. Each carrier's aircraft complement consisted of 18 Mitsubishi A6M2 "Zero" fighters, 27 Aichi D3A1 "Val" dive bombers, and 27 Nakajima B5N1 or B5N2 "Kate" torpedo bombers.
Shōkaku and Zuikaku joined the Kido Butai ("Mobile Unit/Force", the Combined Fleet's main carrier battle group) and participated in Japan's early wartime naval offensives, including Pearl Harbor and the attack on Rabaul in January 1942.
Indian Ocean Raid Main Article: Indian Ocean Raid
On 17 March, Shōkaku and Zuikaku left Yokosuka and arrived at Staring Bay on the 24th where they met with Akagi, Sōryū, and Hiryū, and an escort of the battleships Kongō, Hiei, Kirishima, and Haruna, the heavy cruisers Tone and Chikuma, the light cruiser Abukuma, and 11 destroyers in preparation for Operation C; a planned carrier raid to destroy British shipping in the Indian Ocean. The force departed Starting Bay on 3 April. The next day, they were spotted by a Catalina flying boat which was shot down by anti-aircraft fire from the destroyer Kagerō and six fighters, but not before radioing the presence of Japanese ships to Air Vice-Marshall D'Albiac whom ordered local British warships to sail out of harbor in expectation of an attack.
At 7:30 the next morning, Shōkaku lent 19 D3A "Val" dive bombers to a mass wave of attack aircraft to strike the port of Colombo, joining another 19 Vals from Zuikaku and 53 B5N "Kate" torpedo bombers from Sōryū, Hiryū and Akagi. The planes attacked at 7:40, and Shōkaku's air group singled out the 11,200-ton armed merchant cruiser HMS Hector. Hector was hit by five bombs that set her ablaze, and after uncontrollable fires ravaged Hector, she was abandoned and lef to sink over the course of several hours, earning Shōkaku her first kill. Her remaining aircraft then damaged the submarine depot ship HMS Lucia, while other carrier groups destroyed land position and sank the destroyer HMS Tenedos and the 6,838-ton Norwegian tanker Soli. Later in the afternoon, 53 dive bombers from Akagi, Sōryū, and Hiryu sank the heavy cruisers HMS Cornwall and HMS Dorsetshire.
On the 9th, Shōkaku joined the other carriers in raiding the port of Trincomalee. Dive bombers from Shōkaku and Zuikaku attacked the 8,000-ton British steamship Sagaing and gouged her with a pair of bomb hits that detonated ammunition stored throughout the ship, killing 5 sailors. They left Sagaing to burn out and drift into the Malay Cove where she was blasted apart by a massive explosion 15 minutes later. Shōkaku and Zuikaku also damaged the monitor HMS Erebus with 6 bomb near misses and killed at least 9 of her crew. Shōkaku only lost one Zero fighter during the attack.Shores, Cull & Izawa, Vol. II, pp. 395, 405
Sinking of HMS Hermes