Submarine No.71

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Japanese No71 submarine in 1938.jpg
Submarine No.71 in 1938
Class overview
Name: Number 71
Completed: 1
Scrapped: 1
History
Empire of Japan
Name: Number 71
Builder: Kure Naval Arsenal
Laid down: December 1937
Launched: August 1938
Commissioned: 1938
Fate: scrapped, 1940
General characteristics
Class and type: Experimental high-speed submarine
Displacement:
  • 216 tonnes (213 long tons) surfaced
  • 244 tonnes (240 long tons) submerged
Length: 42.8 m (140 ft 5 in)
Beam: 3.3 m (10 ft 10 in)
Draft: 3.1 m (10 ft 2 in)
Installed power:
Propulsion:
Speed:
  • 13.25 knots (24.54 km/h; 15.25 mph) surfaced
  • 21.25 knots (39.36 km/h; 24.45 mph) submerged
Range:
  • 3,830 nmi (7,090 km; 4,410 mi) at 12 knots (22 km/h; 14 mph) surfaced
  • 33 nmi (61 km; 38 mi) at 7 knots (13 km/h; 8.1 mph) submerged
Test depth: 80 m (260 ft)
Complement: 11
Armament: 3 × bow 450 mm (17.7 in) torpedo tubes

Submarine No.71 (Number 71) was an experimental high-speed submarine built for the Japanese Imperial Navy (IJN) during the 1930s.

Design and description[edit]

Submarine No.71 was designed to test high-speed performance underwater. Intended to reach 25 knots (46 km/h; 29 mph) underwater and 18 knots (33 km/h; 21 mph) on the surface, she proved to be too underpowered to reach those goals. Nonetheless, the boat was the fastest submarine in the world underwater when built,[1] beating the previous record set by the similar World War I-era British R-class. She displaced 216 tonnes (213 long tons) surfaced and 244 tonnes (240 long tons) submerged. Submarine No.71 was 42.8 meters (140 ft 5 in) long, had a beam of 3.3 meters (10 ft 10 in) and a draft of 3.1 meters (10 ft 2 in).[1]

For surface running, the boat was powered by a single 1,200-brake-horsepower (895 kW) diesel engine that drove one propeller shaft. When submerged the propeller was driven by a 1,800-horsepower (1,342 kW) electric motor. She could reach 13.25 knots (24.54 km/h; 15.25 mph) on the surface and 21.25 knots (39.36 km/h; 24.45 mph) underwater. On the surface, Submarine No.71 had a range of 3,830 nautical miles (7,090 km; 4,410 mi) at 12 knots (22 km/h; 14 mph); submerged, she had a range of 33 nmi (61 km; 38 mi) at 7 knots (13 km/h; 8.1 mph). The boat was armed with three internal bow 45 cm (17.7 in) torpedo tubes; each was provided with one torpedo.[1]

Construction and career[edit]

Submarine No.71 was laid down by the Kure Naval Arsenal in December 1937 and was launched that same month by being lowered into the water by a crane. She was completed in August 1938; trials showed that her small size and low-powered diesel made her hard to handle on the surface. While incapable of her intended speeds, she exceeded a submerged speed of 21 knots,[1] almost five years before the famous German type XXI U-boats achieved speeds of around 18 knots (33 km/h; 21 mph).[2] After extensive evaluations the boat was scrapped in 1940, and the lessons learned contributed to the development of the Sen Taka-class, and the Sen Taka Sho-class.[1]

See also[edit]

Notes[edit]

  1. ^ a b c d e Carpenter & Dorr, p. 100
  2. ^ Bagnasco, p. 76

References[edit]

  • Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-962-6. 
  • Carpenter, Dorr B. & Polmar, Norman (1986). Submarines of the Imperial Japanese Navy 1904–1945. London: Conway Maritime Press. ISBN 0-85177-396-6. 
  • Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.