Japanese midget submarines of WW-II
Japanese Ko-Hyoteki, type A, B, and C midget submarine.
From 1934 to 1944, the Japanese Navy built several dozen midget submarines for combat use. They were originally intended to be carried by larger Japanese ships and deployed in the path of an enemy fleet, where they would disrupt its operations with torpedo attack.

The ko-hyoteki class of midget submarines had no names, but was referred to by the designations of their `mother` I-16, plus the suffix `tou` meaning `boat`. Thus, the midget carried by I-16 was known as I-16tou. They also had hull numbers beginning with the character "ha," which can only be seen on a builder`s plate inside the hull. They carried one commander and one crewman.

The first two, Ha-1 and Ha-2, were used only in testing. Ha-19 was used as I-24tou. The other hull numbers are unaccounted for.

The type A midget submarines had a series of basic design problems including trim and ballast control and problems both with battery life and battery monitoring. To increase endurance, the prototype Type B and production Type C boats were fitted with a diesel engine to recharge their electric batteries. They had an additional crew member, were slightly longer and heavier, but otherwise resembled the Type A.

Displacement (srf/sub tons):
un known/46
Dimensions (L*B*D feet): 78`6*6`0*10`2
Propulsion: one electric motor, 600hp at 1800 rpm, two screws conter-rotating on single shaft, leading prop 1.35 meters diameter, right-handed; trailing prop 1.25 meters diameter, left-handed . Batteries: 192 trays of 2.2-volt cells each, 136 trays forward, 56 trays aft
Speed (srf/sub knots): 23/19
Range (srf/sub n/miles@knots): 100@2, 80@6, 18@19
Diving depth (feet): 100
Complement: one commander, one crewman
Torpedo: 2*18" bow  torpedo tubs-loaded, total of 2 torpedoes
Mines: none
Armament: one 300-pound scuttling charge (big enough not only to destroy the sub but to disable any ship it was near)
Back to History index

Image Country Year Description
Dominica 1991 Minesweeper Breeze,dest' Medusa and Curtiss sinking a midget-submarine
Ghana 1998 Type "A" midget-submarine of Japan
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