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fighting ships of the world

IMPERIAL JAPANESE NAVY (JAPAN)

SUBMARINES

"Tei-Hyoteki D" ("KORYU") midget submarines (1945)

HA77 1944

Names

77 <HA77> and others, 570 boats at all (115 completed)

Builders

Ourazaki, Kure: HA77

Harima, Aioi: 39 boats

Hitachi, Mukazima: 30 boats (2 completed)

Kawasaki, Kobe: 47 boats

Kure K K: 100 boats (60 completed)

Maizuru K K: 50 boats (14 completed)

Mitsubishi, Kobe: 17 boats

Mitsubishi, Nagasaki: 69 boats (3 completed)

Mitsubishi, Yokohama: 32 boats

Mitsui, Tamano: 50 boats (30 completed)

Niigata, Niigata: 12 boats

Yokosuka K K: 50 boats (6 completed)

Commissioned

1/1945 - 7/1945

Losses

unknown

Transfers

none

Discarding surrendered 8/1945 and BU: all survived

 

Displacement standard, t

 

Displacement normal, t

59.3

Length, m

26.3

Breadth, m

2.04

Draught, m

2.00

No of shafts

1

Machinery

1 diesel-generator, 1 electric motor

Power, h. p.

150 / 500

Max speed, kts

8 / 16

Fuel, t

4.5

Endurance, nm(kts) 1000(8) / 125(2.5)
Armament

2 - 450 TT (bow, 2) or explosive charge (for "special" attacks)

Complement

5

Diving depth operational, m

100

Ship project history: In December, 1943 on the basis of C type submarine designing of larger D or Koryu type has begun. The basic changes, in comparison with C type, consisted in fitting of more powerful diesel-generator for acceleration of process of battery recharging (its time was decreased to eight hours), raise of seaworthiness and improvement of conditions of habitability of the crew which has increased to five persons. Besides, the hull became notably more strongly, that has raised a diving depth to 100m.

In spring 1945, even before the end of lead boat trials, serial building had been developed. According to plans of Naval staff, by September, 1945 it was supposed to receive 570 submarines, with subsequent rate of building of 180 boats in a month. The section method (the boat shared on five sections), shranking the building period to 2 months, has been applied to acceleration of works. Despite attraction of the big number of builders to Koryu program, to maintain rate of delivery it was not possible and by August, 1945 only 115 boats were commissioned, 496 more were at various stages of building.

Modernizations: None.

Naval service: Fates are unknown.

D type

Ivan Gogin, 2008-14