Submarines of the Imperial Japanese Navy
In 1904 Kawasaki Dockyard Company purchased plans for a modified version directly from Holland, and built two boats (Hulls No. 6 and 7), with the help of two American engineers, Chase and Herbert, who had been assistants to Holland. The Kawasaki-type submarines displaced 63 and 95 tons when submerged, and measured in overall length, respectively. both vessels measured at the beam. This contrasted with the original five imported Hollands-type submarines which had arrived that same year, at over 100 tons submerged, in overall length and beam. The Kawasaki Type #6 and #7 submarines had gained extra speed and reduced fuel consumption by . However both boats could launch only one torpedo, and each was manned by 14 sailors, whereas the imported Holland-type submarines could fire two torpedoes and could be operated by 13 sailors. This new type was designated the Type 6 submarine by the Imperial Japanese Navy, and was used primarily for test purposes.
Japanese Type 6 submarine
The "Kaigun Holland" #6 was launched at Kobe on 28 September 1905 and was completed six months later at Kure as the first submarine built in Japan. It sank during a training dive in Hiroshima Bay on 15 April 1910. Although the water was only 58 feet deep, there were no provisions for the crew to escape while submerged. The commanding officer, Lieutenant Tsutomu Sakuma, patiently wrote a description of his sailor's efforts to bring the boat back to the surface as their oxygen supply ran out. All of the sailors were later found dead at their duty stations when this submarine was raised the following day. The sailors were regarded as heroes for their calm performance of their duties until death, and the submarine was preserved as a memorial in Kure until the end of World War II.