The Japanese midget submarine captured at Hawaii according to the U.S. Joint Intelligence Committee. Daily summary dated 16 December 1941

An item referred to CNO 14 December reporting that the at Hawaii captured Japanese two man submarine had as dimensions 41 x 5 feet, height conning tower 4.6 feet, thickness hull plates 0.25”, speed 21 (actual)-4 to 24.31 (design) knots, range of 175 nautical miles/5 knots, 85 nautical miles/10 and 18 nautical miles/20 knots; all speeds surface. Propulsion consisted of electric batteries and motors. Fitted out with periscope, radio transmitter and receiver, gro, magnetic compasses, listening gear, 2-45.72cm/18 torpedoes and 300 pound TNT under stern hooked up to batteries for a suicide attack.

Source

Map Room Papers (Roosevelt Administration) mr0422a. U.S. Joint Intelligence Committee. Daily summary No. 6 Dated 16 December 1941.