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Oyashio class

Diesel-powered attack submarine

Oyashio class submarine

The Oyashio class submarines are as capable as most nuclear boats

Country of origin Japan
Entered service 1998
Crew 69 men
Diving depth (operational) 300 m
Diving depth (maximum) 500 m
Dimensions and displacement
Length 81.70 m
Beam 8.90 m
Draught 7.90 m
Surfaced displacement 2 700 tons
Submerged displacement 3 000 tons
Propulsion and speed
Surfaced speed 12 knots
Submerged speed 20 knots
Diesel engines 2 x 5 520 hp
Torpedoes 6 x 533 mm torpedo tubes with 20 torpedoes or Sub Harpoon anti-ship missiles


   The Oyashio, commissioned in 1998, was the first of advanced diesel-powered patrol submarines to enter service with the Japan Maritime Self-Defense Force. The new submarines are examples of the changing face of Japanese military equipment acquisition since the establishment of the Self-Defense Forces in the 1950s.

   The first generation of equipment was often second hand and generally acquired from the United States. By 1960, however, Japanese industry was up and running after the devastation of World War II, and the second stage saw American equipment or license-built Japanese copies of American equipment installed in Japanese-built platforms.

   From the late 1970s, and increasing proportion of JMSDF systems has been of Japanese origin. Even where those systems are based on state-of-the-art American or European designs, they have often been upgraded - at great cost - to be even more capable then the original.

   The Oyashio class is equipped with Japanese-designed radar and electronics. Its sonar systems are based on American designs, but have been modified to suit Japanese requirements. Outwardly the Oyashios have changed a little from preceding Japanese submarines. The revised outer casing gives them something of the look of British nuclear boats, while the fin is of a more efficient hydrodynamic shape.

   The new boats share the double hulls and anechoic coating of the previous class, but have been equipped with large flank sonar arrays, which according to some sources account for the increase in displacement over the Harushios.

   Kawasaki Heavy Industries have been conducting experiments in using Sterling-Cycle air-independent powerplants and fuel cells, and at one stage these were planned for the later Oyashios. Such systems, which allow boats to operate submerged for extended periods. The air independent propulsion system made its appearance in the follow-on Soryu class of Japanese submarines.

   The Oyashios replaced the older Yuushio class boats. A total of 11 Oyashio class boats are in service with the JMSDF. The last boat was commissioned in 2008.



Oyashio class submarine

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Oyashio class submarine

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