Type 4 Ka-Tsu

The Type 4 Ka-Tsu was an amphibious tracked vehicle developed for the Imperial Japanese Navy during the Second World War. Although often listed alongside Japan's amphibious tanks, it was essentially an unarmoured carrier for supplies or troops rather than a tank.

Development

Work began in 1943, prompted by the Navy's difficulty in resupplying its troops in the Solomon Islands. Its main task was to carry cargo from ship to shore. To allow it to be transported submerged on the deck of a submarine, the engine compartment and the electric final drives were hermetically sealed. Trials took place off Kure in March 1944.

Design

The Ka-Tsu was about 11 m long and weighed around 16 tonnes, with a crew of five. Apart from some shields for the crew it had no armour; one source gives 10 mm. It could carry about 4 tonnes of cargo or 40 troops.

Attack role

Some in the Navy wanted to use the Ka-Tsu as an attack weapon armed with two torpedoes, and it is said to have been earmarked for a planned second raid on Pearl Harbor in which submarines would release the vehicles offshore. The concept suffered from many problems: the engine was not fully watertight and eventually flooded, it took some 20 minutes to launch a vehicle from its submarine, the engine was noisy and weak, the tracks slipped on obstacles, and crews were drafted from midget-submarine units with only about two weeks' training. The war ended before it could be used in this way.

About 49 are reported to have been built, and one survives at the US Marine Corps base at Camp Pendleton, California.