The Type B1 submarine (巡潜乙型潜水艦, Junsen Otsu-gata sensuikan, lit. "Cruiser submarine type B"), also called I-15-class submarine (伊一五型潜水艦, I-jū-go-gata sensuikan) was the first group of boats of the
Type Bcruiser submarines built for the
Imperial Japanese Navy (IJN) during the 1940s. In total 20 were built, starting with
I-15, which gave the series their alternative name.
Design and description
The Type B submarines were derived from the earlier KD6 sub-class of the
Kaidai class and were equipped with an aircraft to enhance their scouting ability. They
displaced 2,631 tonnes (2,589 long tons) surfaced and 3,713 tonnes (3,654 long tons) submerged. The submarines were 108.7 meters (356 ft 8 in) long, had a
beam of 9.3 meters (30 ft 6 in) and a
draft of 5.1 meters (16 ft 9 in). They had a diving depth of 100 meters (330 ft).[1]
For surface running, the boats were powered by two 6,200-
brake-horsepower (4,623 kW)
diesel engines, each driving one
propeller shaft. When submerged each propeller was driven by a 1,000-horsepower (746 kW)
electric motor. They could reach 23.6
knots (43.7 km/h; 27.2 mph) on the surface and 8 knots (15 km/h; 9.2 mph) underwater.[2] On the surface, the B1s had a range of 14,000
nautical miles (26,000 km; 16,000 mi) at 16 knots (30 km/h; 18 mph); submerged, they had a range of 96 nmi (178 km; 110 mi) at 3 knots (5.6 km/h; 3.5 mph).[3]
The boats were armed with six internal bow 53.3 cm (21.0 in)
torpedo tubes and carried a total of 17
torpedoes. They were also armed with a single
140 mm (5.5 in)/40deck gun and two single mounts for
25 mm (1 in) Type 96anti-aircraft guns.[3] In the Type Bs, the aircraft
hangar was faired into the base of the
conning tower. A single
catapult was positioned on the forward deck. Late in the war, some of the submarines had their aircraft hangar removed, to replace it with an additional 14 cm gun. In 1944, I-36 and I-37 had their aircraft hangar and catapult removed so that they could carry four
Kaiten manned torpedoes, with I-36 later being further modified to carry six.[3]
Service
The series was rather successful, especially at the beginning of the war.
I-17 shelled an oil field up the beach from
Santa Barbara and damaged a pump house in Elwood in February 1942. She was sunk by the New Zealand trawler
Tui and two US Navy aircraft off
Noumea on 19 August 1943.
On 15 September 1942
I-19 fired six torpedoes at the aircraft carrier
USS Wasp, three of which hit the carrier and sank her. The three remaining torpedoes went on for several thousand meters and hit another carrier force,[citation needed] damaging the battleship
USS North Carolina and sinking the destroyer
USS O'Brien. I-19 was sunk with depth charges by
USS Radford[4] on 25 November 1943.
I-25 conducted one of the few attacks on the continental United States in September 1942. A year later she was sunk by destroyer
USS Patterson off the
New Hebrides on 3 September 1943.
I-26 sank the
US Army chartered merchant ship
SS Cynthia Olson about 1,000 miles[clarification needed] northeast of Pearl Harbor on 7 December 1941, causing 35 fatalities. She also crippled the aircraft carrier
USS Saratoga with one torpedo hit (out of six fired) on 31 August 1942. On 13 November 1942, she sank the cruiser
USS Juneau. She was sunk off
Leyte in October 1944.
I-27 Between June 1942 and February 1944, she sank several ships including:
SS Iron Crown near Gabo Island,
SS Fort Mumford and
SS Montanan in the Indian Ocean,
Liberty ship SS Sambridge, and the
SS Khedive Ismail near the Maldives on February 12, 1944. Following her last success, she was sunk by escorting British warships.
I-29 was used to conduct personnel, gold, and technology exchanges with
Germany during WW2. Her most famous
Yanagi mission was the successful transfer on 26 April 1943 off the coast of
Mozambique,
Africa, and safe return to Japan from
German U-180 with Netaji
Subhas Chandra Bose, leader of the Indian Independence Movement and
Indian National Army who was going from Berlin to Tokyo, and his Adjutant,
Abid Hasan, while two Japanese naval officers sent to study U-boat construction and 2 tons of gold were transferred to U-180 as Japanese payment for German wartime technology. Both submarines returned safely to their bases.
I-39 on 12 September 1943, torpedoed the 205 ft fleet tug
USS Navajo en route from
Pago Pago towing a gas barge.
Losses
I-15 was sunk off San Cristobol on 2 November 1942 by destroyer
USS McCalla.
I-21 made her final report on 27 November 1943, off the
Gilbert Islands, following which she was never heard from again.[5] At least one source attributes her sinking to aircraft from escort carrier
USS Chenango on 29 November 1943.[6]
I-23 was lost in February 1942, following a final report made from off
Oahu.
I-27 was sunk by the British destroyers
HMS Paladin and
HMS Petard off Addu Atoll on 12 February 1944 after it had sunk the
troopshipSS Khedive Ismail with the loss of about 1,300 lives. She was first rammed by Paladin then torpedoed by Petard.[5]
Altogether the Type B submarines (B1,
B2, and
B3 combined) are credited with sinking 56 merchant ships for a total of 372,730 tonnes, about 35% of all merchant shipping sunk by Japanese submarines during the war.
All B1 type submarines were lost during the conflict, except for I-36, which was scuttled off
Gotō Islands by the
US Navy on 1 April 1946.
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