Submarine No.71
Introduction '''''Submarine No.71''''' (Number 71) was an experimental high-speed submarine built for the Imperial Japanese Navy (IJN) during the 1930s.
Design and description Submarine ''No.71'' was designed to test high-speed performance underwater. Intended to reach  underwater and  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, beating the previous record set by the similar World War I-era British R-class. She displaced  surfaced and  submerged. Submarine ''No.71'' was  long, had a beam of  and a draft of .For surface running, the boat was powered by a single  diesel engine that drove one propeller shaft. When submerged the propeller was driven by a  electric motor. She could reach  on the surface and  underwater. On the surface, Submarine ''No.71'' had a range of  at ; submerged, she had a range of  at . The boat was armed with three internal bow  torpedo tubes; each was provided with one torpedo.
Construction and career 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, almost five years before the famous German type XXI U-boats achieved speeds of around . 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.
See also * German submarine V-80* British R-class submarine
Notes
References * **