Koryu file photo

Type D-class Midget Submarine

CountryJapan
Launched1 Jan 1945
Displacement60 tons full
Length86 feet
Beam9 feet
Draft7 feet
Machinery500hp electric motor, 150hp diesel engine
Power Output500 SHP
Speed8 knots
Range1,000nm at 8 knots surfaced, 125nm at 16 knots submerged
Crew5
Armament2x457mm muzzle-loaded torpedoes
Submerged Speed16 knots
Number Built115

Contributor: David Stubblebine

This article refers to the entire Type D-class; it is not about an individual vessel.

In mid-1944, with coastal defense requirements becoming urgent, the Japanese Navy developed the Koryu Tei Gata Type D midget submarines. More than just another improved version of the Type A, this was a new design. They were the largest of Japan's midgets, displacing about 60 tons, 86 feet in length, with a five-man crew, featuring a more powerful diesel engine, and had improved operating endurance. Koryu's had the same armament as the Ko-hyoteki Type A's: two muzzle-loaded 17.7-inch torpedoes. As with the earlier types, individual boats had alpha-numeric names in the "Ha" series beginning with Ha-101. Some 115 units had been completed when Japan capitulated in August 1945. Nearly 500 more were under construction. Some of these submarines intended for training pilots for Kaiten type manned torpedoes, had an enlarged conning tower and two periscopes.

Type D boats were employed off Guadalcanal and the Solomon Islands in 1942-43, where they achieved modest success against U.S. shipping. They were deployed around Midway, the Aleutians, the Bismarck Islands, the Philippines, the Marianas, and Okinawa as shore-based defensive units, but their overall effectiveness was negligible at best.

Sources: Wikipedia; Naval History & Heritage Command; Combined Fleet; Japan-101.

Type D-class Midget Submarine Interactive Map

Photographs

Drawings of both Koryu and Kairyu submarines, copied from Koryu Type D submarines in an assembly shed at the Mitsubishi shipyard, Nagasaki, Japan, circa Sep 1945, photo 1 of 2Koryu Type D submarines in an assembly shed at the Mitsubishi shipyard, Nagasaki, Japan, circa Sep 1945, photo 2 of 2Koryu Type D submarine at the Yokosuka Naval Base, Japan, 8 Sep 1945, photo 1 of 3
See all 18 photographs of Type D-class Midget Submarine



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Document(s):
» Planned and Actual Tokko Naval Weapon Production, 1945-1946


Type D-class Midget Submarine Photo Gallery
Drawings of both Koryu and Kairyu submarines, copied from
See all 18 photographs of Type D-class Midget Submarine



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