JDS ''Oyashio'' (SS-511) was a

submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...

of the

Japan Maritime Self-Defense Force , abbreviated , also simply known as the Japanese Navy, is the maritime warfare branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. The JMSDF was formed following the dissolution of the Imperial Japanese Navy (IJN) ...

, named after the Oyashio Current, a cold current that comes down through the Bering Strait.

Development

The Maritime Self-Defense Force did not own a submarine at the time of its inauguration, but in January 1955, it was announced that a submarine would be rented as an addition to the Japan-US Ship Lending Agreement signed in May 1954. As a result, the

Gato-class submarine The ''Gato'' class of submarines was built for the United States Navy and launched in 1941–1943; they were the first mass-production U.S. submarine class of World War II. Together with their near-sisters the and es, their design formed the ma ...

USS Mingo was lent and recommissioned as JDS ''Kuroshio''. The ship was a conventional ship type mainly for surface navigation, and although it was inferior to the underwater high-speed submarines that appeared at the end of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

, it played a very important role as the beginning of submarine force development. However, on the other hand, based on the achievements of the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

, which built and operated more than 200 submarines before the war, the Japanese side began to aim for domestic production of submarines from around the beginning of 1954. At this time, aiming for an underwater speed of 20

knots A knot is a fastening in rope or interwoven lines. Knot may also refer to: Places * Knot, Nancowry, a village in India Archaeology * Knot of Isis (tyet), symbol of welfare/life. * Minoan snake goddess figurines#Sacral knot Arts, entertainme ...

, three types of 250 ton type, 500 ton type, and 1,000 ton type were examined, but since it was the first domestic ship after the war, ease of construction was prioritized and the 1000 ton type was selected. After that, we proceeded with the development by taking into account the achievements of ''Kuroshio'' and the reports of the US inspection team, and finally the size was increased to 1,100 tons.

Design

Having had a vast submarine fleet before and during World War II, the Japanese had built no subs for over ten years, so JDS ''Oyashio'' was based on the wartime

''I-201'' with some US innovations. However, as for the hull structure, while I-201 adopted the internal rib type, the ship was a saddle tank type semi-double shell type with only the bottom of the ship as a single shell type. SM52 high-strength steel (yield strength 30 kgf / mm2) was used for the pressure hull, and it was constructed by welding. The upper deck is covered with teak wood in a slatted shape, which is the only example of the JMSDF submarine adopting a wooden deck. The main engine system was a diesel-electric system modeled after ''Kuroshio''. A snorkel was planned to be installed on this ship, but since the operation record in the former Navy was short and it was not equipped in ''Kuroshio'', careful consideration was given to the diesel engine. First, aptitude studies were conducted, including when combined with a snorkel, by comparing

Kawasaki Heavy Industries (or simply Kawasaki) is a Japanese Public company, public multinational corporation manufacturer of motorcycles, engines, Heavy equipment (construction), heavy equipment, aerospace and Military, defense equipment, rolling stock and ships, headq ...

' 4-stroke engines, Shin-Mitsubishi Heavy Industries' 4-stroke and 2-stroke engines, and Mitsui Zosen's 2-stroke engines. As a result, the Kawasaki MAN V8 V200 / is a 4-stroke V-type 16-cylinder engine because it has the ability to extrude exhaust gas, has little performance degradation at high exhaust pressure, and has a low fuel consumption rate and combustion air consumption rate. A 30mAL medium-speed diesel engine (850 rpm, water 1,350 horsepower / snorkel operation 1,250 horsepower) was selected. It was also equipped with a turbocharger that was mechanically driven from the crankshaft to avoid operation at high exhaust pressure and low intake pressure.

Service history

''Oyashio'' was

laid down Laying the keel or laying down is the formal recognition of the start of a ship's construction. It is often marked with a ceremony attended by dignitaries from the shipbuilding company and the ultimate owners of the ship. Keel laying is one o ...

on 25 December 1957 and launched on 25 May 1959 by

Kobe Kobe ( , ; officially , ) is the capital city of Hyōgo Prefecture Japan. With a population around 1.5 million, Kobe is Japan's seventh-largest city and the third-largest port city after Tokyo and Yokohama. It is located in Kansai region, whic ...

Shipyard. She was commissioned on 30 June 1960. On 1 August 1962 ''Oyashio'' was assigned to Subron 1, Kure district. From June to August 1963 she visited

Pearl Harbor Pearl Harbor is an American lagoon harbor on the island of Oahu, Hawaii, west of Honolulu. It was often visited by the Naval fleet of the United States, before it was acquired from the Hawaiian Kingdom by the U.S. with the signing of the Re ...

. Assigned to Subron 2, Submarine Flotilla 1 together with JDS Kuroshio on 1 February 1965. Assigned to Submarine Flotilla 1 on 31 March 1975. ''Oyashio'' was finally decommissioned on 30 September 1976. Currently, her anchor and screw propeller are stored and exhibited at the Kota Town Folk Museum in Kota Town,

Aichi Prefecture is a prefecture of Japan located in the Chūbu region of Honshū. Aichi Prefecture has a population of 7,552,873 () and a geographic area of with a population density of . Aichi Prefecture borders Mie Prefecture to the west, Gifu Prefectur ...

Gallery

File:Launching ceremony of Oyashio (SS-511) in JMSDF in 1959 No.2.png, Launching of JDS ''Oyashio'' on 25 May 1959 File:Launching ceremony of Oyashio (SS-511) in JMSDF in 1959 No.1.png File:Anchor and screw of the SS511 Oyashio.jpg, Anchor and propeller of JDS ''Oyashio'' File:Parts of JDS Oyashio (21032009095).jpg File:Parts of JDS Oyashio (21032009100).jpg

References

External links