Japanese cruiser Ōyodo

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Oyodo
Career IJN Ensign
Ordered: 1939
Laid down: 14 February 1941
Launched: 2 April 1942
Commissioned: 28 February 1943
Fate: Sunk 28 July 1945 during attack on Kure Naval Base by US Task Force 38
Sunk: 28 July 1945
Struck: 20 November 1945
General Characteristics
Displacement: 8,164 tons (standard)
11,433 tons (full load)
Length: 192 m (630 ft 0 in)
Beam: 15.7 m (51 ft 5 in)
Draught: 6 m (19 ft 6 in)
Propulsion: Geared turbines, 4 shafts
6 Kampon boilers
110,000 hp (82 MW)
Speed: 35 knots (64 km/h)
Range: 10,600 nautical miles (19,610 km) at 18 knots (33 km/h)
Complement: unknown
Armament: 6 × 155 mm (6.1 in)/60 cal. 3rd Year Type guns (3 × 2)
8 × 100 mm (3.9 in)/65 cal. Type 98 anti-aircraft guns (4 × 2)
12 × 25 mm/60 cal. Type 96 AA guns
Aircraft: designed for 6, operationally carried 2
1 catapult

Ōyodo (Japanese:大淀, named after a river in Japan, literally means "big stagnant water") was a light cruiser of the Imperial Japanese Navy, the only ship of her class. Her design was basically an improved version of the Agano-class cruisers, though while the same general hull form as Agano was adopted, with flush deck and bulbous bow, the armament differed both in layout and weapons, and the armour protection scheme was reduced.

[edit] Design

The Ōyodo design was approved under the 1939 4th Replenishment Programme. However, out of the 2 ships authorised, only one, Ōyodo, was laid down; the second ship was to be named Niyodo. Immediately after she (Ōyodo) was completed, all available shipbuilding resources at that yard were used to build more aircraft carriers. In line with contemporary Japanese submarine tactics, the Ōyodo class were to be the flagships of scouting submarine flotillas. To this end, the Ōyodo class was to operate up to six of the upcoming Kawanishi E15K1 Shiun floatplanes; however, the requirements for these planes were issued only in mid-1939.

Ōyodo's main armament comprised six 155 mm (6.1 inch) 60 caliber 3rd Year Type guns in two triple-gun turrets arranged in conventional superfiring fashion. This gun was originally developed as a dual purpose (anti-surface and anti-aircraft) weapon for the Mogami-class cruisers; when those ships underwent reconstruction in the 1930s and had their triple 155 mm turrets replaced with 203 mm (8 inch) twin turrets, the now surplus triple 155 mm turrets were simply mounted on Ōyodo (as well as the Yamato-class battleships). Their slow rate of fire (about 5 to 6 rounds per minute) and limited elevation (up to only 55 degrees) made them unsuitable for the anti-aircraft role, but they were excellent anti-ship weapons.

The main armament was all located forward of the superstructure, much like the British Nelson-class battleships, French Dunkerque and Richelieu class and the Japanese navy's own Tone-class heavy cruisers. Like the Tone class, the Ōyodo-class ships were intended to be scouting cruisers and hence the entire deck of the ship aft of the superstructure was devoted to aircraft facilities. Indeed, again in view of their intended role, no torpedo tubes were fitted, making the Ōyodo class the sole class of cruisers in the Imperial Japanese Navy without them. The weight thus saved was invested instead in increased floatplane capacity (up to six) and a heavy-duty 45 m catapult that was necessary for the new E15K1 floatplane.

Ōyodo's heavy Anti-aircraft battery comprised eight 100 mm (3.9 inch)/65 caliber Type 98 guns in four twin mounts. These guns are the same as that carried by the Akizuki-class destroyers and the never-built B64 class cruisers. Their performance was superb, and is considered to be the best Japanese heavy AA gun of the war. Their only fault was a rather short service life, the result of high muzzle velocity (1,000 m/s) and a fast rate of fire (15–20 rounds per minute).

The remaining AA armament consisted of the ubiquitous (in the Japanese Navy) 25 mm/60 caliber Type 96 AA gun, which was based on a French Hotchkiss design but was a very mediocre AA weapon with low effective rate of fire, slow elevation and training, and lack of effective remote power control.

The E15K1 'Shiun' (Japanese for "violet cloud") floatplane (Allied codename "Norm") was intended to perform reconnaissance for the submarine flotilla in areas where the enemy had air superiority, and hence was to be able to take on land-based fighters. To achieve this, the plane was designed with two underwing stabilising floats that could be retracted, and a large central float that could be jettisoned, to increase performance during combat.

However, while incorporating this and several other innovations, the plane never really worked as designed and its troubled development resulted in only four aircraft entering service by 1942, and only fifteen were completed in total. Six were sent to Palau where Ōyodo was operating for operational testing. Despite a more powerful engine, the performance of the E15K1's (being about 500 kg heavier than the more common Aichi E13A1 "Jake") was poor and they were quickly lost to attacking fighters. As a result production of the aircraft, which had barely begun, was stopped and the entire E15K1 program shelved in early 1944. Ōyodo hence never operated more than two aircraft, particularly after her refit later in which her large hangar was converted to other uses.

As this class was larger had greater displacement than Agano, the installed powerplant was of an uprated design, producing 110,000 shp to achieve the same speed (35 knots) as the Agano class. Ōyodo's designed radius of action was also very large, at 10,500 nautical miles (18,500 km).

[edit] Career

After her working up period, on 26 July 1943 Ōyodo joined the fleet at Truk, which was the Japanese Navy's main fleet base in the Pacific. In December 1943, she participated in an operation to reinforce the garrisons at Rabaul and Kavieng. At that time she had just become the flagship of Vice Admiral Jisaburo Ozawa's Third Fleet. While returning to Truk on 1 January 1944 she was slightly damaged by US aircraft of Task Group 50.2. The following month, Japanese radio intelligence learned of an impending massive US strike on Truk, and all heavy surface units (including Ōyodo) were quickly withdrawn from the base. Ōyodo transferred to Palau in the Western Caroline Islands. In March that base too became threatened, and Ōyodo withdrew to Singapore. During this movement the cruiser was one of the escorts of the battleship Musashi when the latter was torpedoed and damaged by the US submarine Tunny.

By 1944, it was recognized from the progress of the war and the failure of the floatplane programme that Ōyodo would not be able to fulfill her design role. Hence she returned to Yokosuka naval base in March of that year and had the heavy-duty catapult exchanged for the shorter (18 m), standard type, took on two of the standard Aichi E13A1 floatplanes, and the hangar converted to accommodate Fleet Headquarters staff. She was to become a Combined Fleet flagship. During this refit, six Type 96 triple-mount and 11 single-mount 25 mm AA guns were also installed, bringing the Ōyodo's 25 mm AA suite to a total of 47 barrels. A Type 22 surface-search radar was also fitted.

On 25 October 1944 during the Battle of Leyte Gulf, Ōyodo comes alongside the damaged Zuikaku (from which this photo was taken) so that Admiral Jisaburo Ozawa can transfer his flag.
Enlarge
On 25 October 1944 during the Battle of Leyte Gulf, Ōyodo comes alongside the damaged Zuikaku (from which this photo was taken) so that Admiral Jisaburo Ozawa can transfer his flag.

The refit/conversion work was completed at the end of March 1944, and after shuttling between a few ports in Japan, Ōyodo departed Yashima anchorage on 20 October 1944 towards the Philippines as part of Operation Sho-Ichi-Go ("Victory number 1") — what was to become the Battle of Leyte Gulf. The objective of the operation was to repel the American invasion of the Philippines. Ōyodo was part of Vice Admiral Jisaburo Ozawa's Northern Mobile ("Decoy") Force, which was to bait the American aircraft carrier strike force away from the main Japanese strike force. The decoy force included several old carriers (by now bereft of aircraft), cruisers and destroyers. Ōyodo was the only warship in Ozawa's force that had reconnaissance floatplanes, and both E13A1's performed reconnaissance and anti-submarine patrols over the fleet.

On 25 October 1944, off Cape Engaño, the Northern Mobile Force was attacked by Vice Admiral Marc A. Mitscher's Task Force 38 carrier planes in a massive strike consisting 527 sorties in five strikes. During the first strike, Ōyodo suffered two near-misses and at 0848 she was hit by a bomb that damaged her Number 4 boiler room. At 10:54, Vice Admiral Ozawa left the sinking carrier Zuikaku and transferred his flag to Ōyodo. Ozawa then ordered his force to retire northward. Later that day Ōyodo was hit by two rockets from F6F Hellcat fighter-bombers and damaged by the near-miss of a bomb. Ōyodo and the surviving ships arrived at Sakawa Bay, Amami-Oshima the next day. A few days later Ōyodo was sent to Manila on a transport run, arriving on 1 November 1944. Throughout the remainder of the year, Ōyodo was actively involved in numerous operations around Brunei, Camranh and the Philippines, attacking US convoys, bombarding landing sites and engaging US naval forces in the area. Although other ships with her were either damaged or sunk during the sorties, Ōyodo emerged unscathed.

By January 1945, Ōyodo had arrived at Singapore, where she took on 300 tons of rubber, zinc, mercury, tin and petrol. Other ships in her unit were similarly loaded with critical supplies bound for Japan. On 11 February 1945 Ōyodo's unit, the "Completion Force", left Singapore for Japan, and along the way escaped pursuit and dodged attacks by twenty-three Allied submarines. The Force arrived at the Kure naval base in Japan on 20 February 1945.

Oyodo sunk in shallow waters near Kure.
Enlarge
Oyodo sunk in shallow waters near Kure.

Ōyodo remained at Kure for the remainder of the war, and on 19 March 1945, Vice Admiral (later Admiral) Marc A. Mitscher's Task Force 58 aircraft carriers made the first carrier attack on the Kure Naval Arsenal. More than 240 aircraft (SB2C Helldiver dive bombers, F4U Corsair and F6F Hellcat fighter-bombers) attacked the Japanese fleet. Three 500 pound bombs hit Ōyodo; she started to flood, but was towed to Etajima and beached.

On 24 July 1945 US Task Force 38 launched a massive all-day-long attack to destroy any and all remaining units of the Japanese Navy. Ōyodo was strafed and hit by four 500 pound bombs and many near misses that left her listing to starboard. Four days later, another all-day-long attack was launched by the US carrier fleet. Ōyodo was hit by four more bombs and at 1000, hits near the bridge caused extensive flooding and Ōyodo took on a heavy list to starboard. At 1200, she capsized to starboard in shallow water. About 300 crewmen were killed, while her remaining crew abandoned ship that afternoon. Ōyodo was removed from the Navy List on 20 November 1945.

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