Asia Defense

Japan to Commission 10th Soryu-Class Attack Sub This Month

Recent Features

Asia Defense

Japan to Commission 10th Soryu-Class Attack Sub This Month

The Japan Maritime Self-Defense Force’s latest diesel-electric attack submarine will be commissioned on March 18.

Japan to Commission 10th Soryu-Class Attack Sub This Month
Credit: KHI

The Japan Maritime Self-Defense Force (JMSDF) will commission its tenth Soryu-class diesel-electric attack submarine (SSK) during an official ceremony to be held at the Kawasaki Heavy Industries (KHI) shipyard in Kobe in Hyogo Prefecture on March 18, the service announced in a statement.

The new SSK, the future JS Shuriyu, was laid down in January 2015 and launched in November 2017. It is the fifth Soryu-class SSK built by KHI and the 28th boat overall constructed by the shipbuilder since 1945. Two more SSKs are expected to be commissioned in 2020 and 2021 respectively, which will bring the total number of Soryu-class boats to 12.

The ninth Soryu-class SSK, the JS Seiryu, was commissioned in March 2018. The boat was built by Mitsubishi Heavy Industries (MHI) and is the fifth Soryu-class and the 27th SSK built overall by MHI since the end of World War II. The future Shuriyu and the Seiryu each cost around 53 billion yen ($496 million) to built.

The Soryu class is thought to be one of the most advanced SSKs currently in service with any Navy in the world. As I explained previously:

The 4,200-ton (submerged) Soryu-class boats are the JMSDF’s first SSKs to be fitted with air-independent propulsion (AIP) systems, enabling the submarines to stay underwater for up to two weeks. (…) In 2015, Japan’s Ministry of Defense (MoD) announced that it intends to equip the last two boats of the class with lithium-ion batteries. (According to some reports, the other boats of the class will be retrofitted with the batteries as well.)

Soryu-class SSKs are powered by two Kawasaki 12V 25/25 SB-type diesel engines and four Kawasaki Kockums V4-275R Stirling AIP engines for silent running. The boats have an estimated range of 6,100 nautical miles (11,297 kilometers) with a maximum surface speed of 13 knots and a subsurface travelling speed of 20 knots. The maximum diving depth of the sub is around 650 meters.

The Soryu-class is fitted with six HU-606 533 mm torpedo tubes that can accommodate Type 89 heavyweight homing torpedoes and UGM-84 Harpoon anti-ship missiles. Next to bow-and-flank-mounted Hughes/Oki ZQQ-7 sonar arrays, the sub is also equipped with a towed array sonar capable of detecting ships over 70 kilometers away.

As a result of the Soryu-class SSKs’ high degree of automation, the boat’s crew is smaller than on previous JMSDF subs and consists of nine officers and 56 sailors.

Additionally, I noted:

The Soryu-class boats’ hydrodynamic design is based on the older Oyashio-class diesel-electric attack submarines currently in service with the JMSDF. It is (…)  fitted with a computer-controlled, Swedish-designed X rudder to increase the submarine’s maneuverability when operating in shallow waters close to the seabed.

Notably, the first Soryu-class SSK fitted with lithium-ion batteries, the future JS Oryu, was launched in October 2018.