Yup! A very fast, very nasty boat. Good for island defence and ripping into convoys. The Sen Taka's design was actually basically laid out in 1938 (!) with Experimental Vessel Number 71 (the IJN code name).
Here's a link to a thread on the Warship Projects Board discussing her, and a picture..
http://www.phpbbplanet.com/forum/viewto ... ipprojects
Number 71, experimental submarine
Displacement(normal): 213/240 tons
Dimensions: 42.8m x 3.3m x 3.15m(140'5" x 10'10" x 10'4")
Machinery: single shaft, 1 diesel engine(1,200hp) and 1 electric engine(1,800hp)
Speed: 14kt surfaced, 23-25kt submerged
Range: 3,830 miles @12.5kt/33 miles @7kt
Complement: 11
Maximum operational depth: 80m(256')
Armament: 3 18" torpedo tubes forward(no mention on reloads)
No 71 was to have had a Daimler-Benz diesels but actually was fitted with a Japanese diesels. Her actual speed was 21.3 kts sub, 13.2kts surfaced with endurance 2200nm at 12kts surfaced.
She was broken up in 1940 on completion of her trials, she was not a success because of her engines. Her designation Vessel No 71 was a security cover.
Her general design enlarged bacame the ST (Sen-Taka-Sho) (Small Fast Submarines) of 1945. 146ft 8in long, 13ft 1in beam, 11ft 3in draught, 400bhp diesel and 1250hp electric motor, 10.5kts sur, 13kts sub, 2x21in TT 4 torpedoes, 22 crew. On trials they actually made 13.5kts submerged. 71 were ordered and only 5 completed but saw no action.
Info from Warships of the Imperial Japanese Navy 1869-1945 by Jentschura, Jung and Mickel.