Nos. 6 and 7.
(Completed 1906.)
These two vessels were the first submarine boats to be built in Japan, but are of the same type as Nos. 1–5, only larger and faster. They have a submerged displacement of 180 tons, a length of 100 feet and a beam of 10 feet. The petrol engines are of 300 H.-P. and the electric motors of 100 H.-P. The surface and submerged speed is 10 knots and 8 knots an hour, respectively. Their armament consists of one torpedo tube with three 18-inch Whitehead torpedoes.