Oyashio (SS 590) at Pearl Harbour.
JMSDF Oyashio Class submarines docked at Yokosuka, Japan.
Oyashio is one of the quietest and largest submarine classes of the JMSDF.
The Oyashio Class submarine can launch UGM-84 Harpoon anti-ship missiles.

Oyashio is an advanced diesel-electric patrol submarine class operated by the Japanese Maritime Self-Defence Force (JMSDF).

Eleven submarines of this tupe were built by Kawasaki Shipbuilding Corporation and Mitsubishi Heavy Industries between 1994 and 2006. The Oyashio Class is preceded by the Harushio Class and succeeded by the Soryu Class.

Oyashio Class submarines can conduct both anti-submarine and anti-surface warfare missions. Oyashio is one of the quietest and largest submarine classes of the JMSDF.

The keel for lead submarine in the class, also known as Oyashio (SS 590), was laid down in January 1994. It was launched in October 1996 and commissioned in March 1998.

Other submarines in the class are: Michishio (SS 591), Uzushio (SS 592), Makishio (SS 593), Isoshio (SS 594), Narushio (SS 595), Kuroshio (SS 596), Takashio (SS 597), Yaeshio (SS 598), Setoshio (SS 599), and Mochishio (SS 600).

Mochishio was the final ship of the Oyashio Class to be built, and was commissioned into the JMSDF in March 2008.

Design and features

The Oyashio Class incorporates a leaf coil hull design in place of the tear drop hull form used in previous submarines of the JMSDF. The earlier bow mounted sensor arrangement was also changed and conformal sonar was fitted on the hull side to achieve improved detection capability.

“Oyashio Class submarines can conduct both anti-submarine and anti-surface warfare missions.”

The Oyashio Class has higher displacement over the Harushio Class due to its large flank sonar arrays. Anechoic rubber tiles were installed on the high tensile steel hull to improve acoustic stealth efficiency, while cigar-shaped hull enhances underwater operations and propulsion performance.

The Oyashio Class also features an advanced combat intelligence processing system, and the placement of the torpedo tube was changed due to a new sensor arrangement.

Submarines of this class are operated by a smaller crew compared to similar types of submarine operated by other nations, due to their highly automated systems.

Oyashio Class submarines have an overall length of 82m, a beam of 8.9m, a depth of 10.3m, a draft of 7.4m and a standard displacement of 2,750t. The submarine can complement a crew of 70.

Weapon systems

The Oyashio Class is fitted with six HU-605 533mm torpedo tubes with 20 reloads for Type 89 torpedoes and UGM-84D Harpoon anti-ship missiles. Harpoon missiles can travel at a speed of 864km/h and have a range of over 124km.

Type 89 is a wire-guided torpedo operating in active and passive homing modes. It has a maximum speed of 130km/h. The torpedoees can carry a warhead of 267kg have a maximum range of 50km.

“The class is powered by a diesel-electric propulsion system.”

Sensors and radars

The Oyashio Class features Japanese-designed radar and electronics, and are equipped with JRC ZPS six I-band search radar. The sonar suite consists of a Hughes/Oki ZQQ 5B/6 hull-mounted sonar, a towed array sonar and four flank arrays.


The class is powered by a diesel-electric propulsion system. The propulsion system integrates two Kawasaki 12V25S diesel engines, two Kawasaki alternators and two Toshiba main motors. The power plant provides a total power output of 7,700hp. The propulsion system provides a surfaced speed of 12kt and submerged speed of 20kt.