Japanese aircraft carrier Un'yō

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IJN CV Unyo in 1943 cropped.jpg
Un'yō in military service in 1943
Career (Japan) Civil naval ensign ([Hinmaru])
Name: Yawata Maru
Operator: Nippon Yusen (NYK)
Builder: Mitsubishi Shipbuilding & Engineering Co. Nagasaki, Japan
Yard number: 751
Laid down: 14 December 1938
Launched: 31 October 1939
Completed: 31 July 1940
In service: 1940
Out of service: October 1940
Fate: converted to military use, renamed as Un'yō
Career (Japan)
Name: Un'yō
Commissioned: 31 May 1942
Out of service: 17 September 1944
Fate: Sunk by the submarine USS Barb on 17 September 1944
General characteristics
Class and type: Taiyō-class escort carrier
Displacement: 17,830 long tons (18,120 t) (standard)
19,500 long tons (19,800 t) (full load)
Length: 173.7 m (569 ft 11 in) (w/l)
180.4 m (591 ft 10 in) (o/a)
Beam: 22.5 m (73 ft 10 in)
Draft: 7.74 m (25 ft 5 in)
Installed power: 25,200 shp (18,800 kW)
Propulsion: 2 × Kampon geared steam turbines
4 × Kampon water-tube boilers
2 × shafts
Speed: 21 kn (39 km/h; 24 mph)
Range: 6,500 nmi (12,000 km; 7,500 mi) at 18 kn (33 km/h; 21 mph)
Complement: 850
Armament: Upon completion as escort carrier: 4 × 120 mm (4.7 in) L/45 10th Year Type anti-aircraft guns
8 × 25 mm (0.98 in) L/60 Type 96 anti-aircraft cannons (4x2)

From 23 June 1942: 4 × 120 mm L/45 10th Year Type anti-aircraft guns
14 × 25 mm L/60 Type 96 anti-aircraft guns (2x3, 4x2)
From 1 February 1943: 4 × 120 mm L/45 10th Year Type anti-aircraft guns
30 × 25 mm L/60 Type 96 anti-aircraft cannons (6x3, 6x2)
8 × Type 95 depth charges

From 10 August 1944: 6 × 120 mm L/45 10th Year Type anti-aircraft guns
59 × 25 mm L/60 Type 96 anti-aircraft cannons (8x3, 2x2, 31x1)
8 × Type 95 depth charges
Armor: 2.5 cm (0.98 in) side belt over machinery spaces and magazines
Aircraft carried: 27
  • 9 × fighters
  • 18 × attack bombers

Un'yō (雲鷹 Hawk tear the cloud?) was a Taiyō-class escort carrier operated by the Imperial Japanese Navy in World War II. It was originally constructed as the passenger vessel Yawata Maru (八幡丸?).

Civilian Use[edit]

The Yawata Maru in passenger service

The Yawata Maru was a Japanese ocean liner owned by Nippon Yusen Kaisha. The ship was built in 1938-1940 by Mitsubishi Shipbuilding & Engineering Co. at Nagasaki, Japan. It was laid down in December 1938, launched in October 31, 1939 and left port on July 31, 1940 on her maiden voyage.[1] The vessel's pre-war design anticipated passenger service; but when work was completed, the onset of war had created somewhat different priorities.

The vessel was created as a sister ship of the Kasuga Maru, and the Nitta Maru. None of the three survived the Second World War. Each in succession was re-fitted as a troopship; and each was later converted to an aircraft carrier. In 1941, Kasuga Maru was re-commissioned as the Japanese aircraft carrier Taiyō and in late 1942, the Nitta Maru was recommissioned as the Japanese aircraft carrier Chūyō.[2]

When first launched, this ship was named after an important Shinto shrine.[3]

The 17,163-ton vessel had a length of 559.3 feet (170 m), and her beam was 74 feet (22.5 m). The ship had an average speed of 18.5 knots (34.3 km/h).[1]

Military Use[edit]

The ship was requisitioned by the Imperial Japanese Navy in October 1941. Initially, the ship was assigned for transporting prisoners of war. Between 25 November 1941 and 31 May 1942, Yawata Maru was rebuilt in Kure to be an auxiliary aircraft carrier. Her flight deck measured 150 m × 23 m (492 ft × 75 ft) and was equipped with two elevators. She had no island, catapults or arresting gear.[note 1] On 31 July 1942, she was reclassified as an escort carrier and renamed Un'yō.[2]

Un'yō was used primarily for flight training and aircraft transport. She often sailed with her sister ships Taiyō and Chūyō.

On 10 July 1943, off Truk, she was hit by a single torpedo fired by the American submarine USS Halibut.

On 19 January 1944, while en route to Yokosuka, she was hit and heavily damaged by three torpedoes fired by USS Haddock. While sheltering at Garapan Anchorage, Saipan on 23 January, a follow-up attack by Halibut was driven off. Following repairs, she was back in service by June 1944.

On 17 September, Un'yō was struck by two torpedoes fired by USS Barb. Her crew’s struggle to keep Un'yō afloat was in vain. Of the approximately 1,000 people aboard (crew and passengers), 761 were rescued. Its last position was 220 nautical miles (410 km) southeast of Hong Kong, 19°08′N 116°36′E / 19.133°N 116.600°E / 19.133; 116.600.


  1. ^ Many experts dispute the lack of arresting gear on the Unyo and her sisters, and while photographic evidence is lacking, the Unyo during her service life operated aircraft which required arresting gear to land aboard a carrier.


  1. ^ a b Haworth, R.B. Miramar Ship Index: ID #4047477.
  2. ^ a b CombinedFleet: Taiyō class, Imperial Japanese Navy.
  3. ^ Ponsonby-Fane, Richard. (1935). The Nomeclature of the N.Y.K. Fleet, p. 50.

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