Imperial Japanese Navy submarine I-168 The Japanese Kaidai Types were based on the World War-I German U-139 submarine design. The Imperial Japanese Submarine I-168 was a KD6A type, faster than their predecessors, the KD5 type; these boats had the highest surface speed of any submarines in the world in the mid-1930s, although their speed was surpassed slightly by later Japanese boats.  The boat was originally numbered I-68, but was renumbered in 1942. These boats were quite successful. I-168 finished off the damaged USS Yorktown, airplane carrier, on 7 June 1942, also sinking USS Hammann, destroyer, with the same spread of torpedoes.  Specifications, I-168, Type KD6A: Displacement (srf/sub tons): 1,785/2,440 Dimensions (L*B*D feet): 343`6*27`0*15`0 Propulsion: 2*4,500hp diesel engines, 2*900hp electric motors, 2 shafts Speed (srf/sub knots): 23/8.25 Range (srf/sub n/miles@knots): 14,000@10/un known Diving depth (feet): 250 Complement: 70 officers and crew Torpedo: 4*21" (533mm) bow torpedo tubes, 2*21" aft torpedo tubes, total of 14 torpedoes Mines: none Armament: 1*100mm/65cal. Main deck gun Construction A total of 8 units were constructed under this type all completed between 1934 to 38. I-168 to I-173 of the KD6A type, I-174 and I-175 represent the KD6B type, and were about one foot (30cm) longer and 25 tons heavier than shown in the table. Their range is stated as 10,000 n/miles@16 knots. They, along with I-171, I-172, and I-173, received the 120 mm/50 cal. instead of the 100 mm weapon shown in the table. None survived the war. Back to History Index     Image Country Year Description Uganda 1991 Battle of Midway, Yorktown and Hammann torpedoed by Japanese sub I-168