Japanese submarine tender Chōgei

	Chōgei in 1923
History
Empire of Japan
Name	Chōgei
Ordered	1923 Fiscal Year
Builder	Mitsubishi Nagasaki Shipyards
Laid down	11 March 1922
Launched	24 March 1924
Completed	20 August 1924
Out of service	30 July 1945
Stricken	5 October 1945
Reinstated	October 1945 – August 1946 (reparation transport)
Fate	Scrapped 1947
General characteristics initial
Class and type	Jingei-class submarine tender
Displacement	5,160 long tons (5,243 t) standard; 7,678 long tons (7,801 t) trial;
Length	125.40 m (411 ft 5 in) overall; 123.00 m (403 ft 7 in) waterline;
Beam	16.215 m (53 ft 2.4 in)
Draught	6.283 m (20 ft 7.4 in)
Installed power	7,500 shp (5,600 kW)
Propulsion	2 × Parsons geared turbines; 5 × Kampon coal/oil-fired boilers , 2-shafts;
Speed	16 knots (18 mph; 30 km/h)
Range	10,400 nmi (19,300 km) at 14 kn (16 mph; 26 km/h)
Capacity	40 torpedoes, 1700 tons of fuel
Complement	399
Armament	4 × 14 cm/50 3rd Year Type naval guns; 2 × 8 cm/40 3rd Year Type naval guns; 2 × 7.7 mm machine guns;
Aircraft carried	1927-1942; 1 × float plane;
Aviation facilities	derrick and deck
General characteristics after 1935
Displacement	6,240 long tons (6,340 t) standard; 8,288 long tons (8,421 t) trial;
Length	123.47 m (405 ft 1 in) waterline
Beam	17.15 m (56 ft 3 in)
Draught	6.60 m (21 ft 8 in)
Speed	16.0 knots (18.4 mph; 29.6 km/h)
Electronic warfare ; & decoys	1 × 21-Gō early warning radar
Armament	4 × 14 cm/50 3rd Year Type naval guns; 2 × 8 cm/40 3rd Year Type naval guns; 2 × Type 96 25 mm AA guns; 4 × Type 93 13 mm AA guns;

Chōgei (長鯨, Long Whale),^[1] was the second and final vessel of the Jingei-class submarine tenders operated by the Imperial Japanese Navy, from the 1920s through World War II. Along with her sister ship Jingei, she was the first purpose-built submarine tender in the Imperial Japanese Navy.

Background

Under the

Eight-eight fleet plan, the Imperial Japanese Navy planned to acquire 100 submarines for long-distance scouting operations, which would also be used to conduct attrition warfare against any enemy fleet approaching Japan. Chōgei was intended to serve as a flagship

for the Submarine Division Commander and as a depot ship for the nine submarines in a submarine division.

Initially, Chōgei was planned as a 14,500-ton vessel; however, her specifications were scaled down to 8,500-tons due to restrictions imposed by the Washington Naval Treaty.

Design

Chōgei was built by

Nagasaki, and the contractor was given an unusually free hand in her design. In order to keep costs to a minimum, the basic design of her hull was adapted from that of a standard civilian merchant vessel, of which Mitsubishi had considerable experience in building. Her coal/oil-fired boilers were taken from the cancelled Tosa-class battleship project. As Mitsubishi was also working on the Katori-class cruiser

at the same time, many design innovations that had been developed by Mitsubishi engineers were shared between the two classes, and as a result, the Katori-class cruisers came bear a superficial resemblance to the Jingei-class submarine tenders.

Operational career

Chōgei was

First Shanghai Incident of 1932, and was assigned to the IJN 1st Fleet

from November 1933.

Following the

Kaidai-class submarines, they were reassigned to the Training Fleet around this time, and their duties as submarine tenders were taken up by the new Kuma-class

cruisers.

After the

Marco Polo Bridge Incident of 7 July 1937, Chōgei was assigned to transport troops of the IJA 10th Division to northern China, as well as a thousand troops of the 1st Special Naval Landing Force. On arrival at Port Arthur, word was received that Japanese positions in Shanghai were in danger of being overrun, so Chōgei quickly reembarked the same troops and transported them to Shanghai. Aside from duty as a troop transport, shuttling between Shanghai and Port Arthur, Chōgei took no further combat role in the Second Sino-Japanese War.^[2]

On 15 November 1940, in preparation for the coming conflict with the United States, both Jingei-class ships were returned to active combat status, replacing

IJN 3rd Fleet at the time of the attack on Pearl Harbor.^[2]

Following the start of the

Torres Straits. She was based at Staring-baai

in February 1942 and was recalled to Japan in March. On 6 May 1942, Chōgei was involved in a collision with the submarine I-153 off the coast of Shikoku, which required repairs until the end of June. She was then based at Kure Naval Arsenal.

On 7 November 1942, Chōgei relieved Jingei as submarine tender for the IJN 8th Fleet based in Rabaul. The Japanese base at Rabaul came under attack by American forces on 12 October 1943, but Chōgei was undamaged. She suffered minor damage due to strafing during the subsequent attack on 2 November 1943, and none during the third raid of 5 November 1943. However, the repeated air raids led the Imperial Japanese Navy to order the withdrawal of Chōgei back to Japan.

On 18 November 1943, north of Truk, Chōgei and her escorts were attacked by the American submarine USS Sculpin, which was sunk by the destroyer Yamagumo

Chōgei returned to front-line combat status on 1 January 1944 as flagship of Submarine Squadron 11, under the IJN 6th Fleet. In summer, her main guns were replaced with 18

Okinawa

as a transport for supplies and reinforcements in August and September 1944.

On 1 January 1945, Chōgei was assigned to the Maizuru Naval District. On 30 July 1945, Maizuru came under attack by a combined Royal Navy / United States Navy air raid. Chōgei took a direct hit which destroyed her bridge.

Following the

Onomichi, Hiroshima

.