PREMIUM: Japan Commissions Ocean Surveillance Ship

As Chinese submarines venture farther afield, neighbours such as Japan need new naval assets to see whether they are intruding.
The Japan Maritime Self-Defense Force (JMSDF) commissioned a 67m-long ocean surveillance vessel – the third in its class – on 4 March. Mitsui Engineering & Shipbuilding (E&S) built the ship.
Christened JS Aki (AOS 5203), the catamaran-hulled vessel belongs to the Hibiki class. The commissioning ceremony took place in the city of Tamano in Okayama Prefecture, with the ship joining Ocean Surveillance Division 1 stationed at Kure Naval Base in Hiroshima.
Laid down in March 2019, the vessel was launched on 15 January 2020 under a contract signed in February 2018. It comes nearly 30 years after the last ocean surveillance ship was built for the JMSDF.
The 3,048t Hibiki class utilises a small waterplane area twin hull with a beam of 29.9m, which reduces wave resistance and results in greater stability.
The American-installed AN/UQQ-2 Surveillance Towed Array Sensor System (SURTASS) on JS Aki is more advanced than the sensors aboard the preceding two ships, as they were commissioned in 1991 and 1992 respectively.
Data from the SURTASS is shared with the US via the Defense Satellite Communications System as part of the Integrated Undersea Surveillance System. SURTASS is also used on five USN ocean surveillance ships (USNS Victorious, Able, Effective, Loyal and Impeccable). With Japan and the US alarmed by China’s growing naval might, such surveillance vessels help monitor hostile submarines.
A crew of 40 operate the Hibiki class. Their range is 3,800nm (with a 90-day endurance), and their top speed is 11kt via four Mitsubishi S6U-MPTK diesel-electric engines. They possess a flight deck for helicopters.
A day earlier, Mitsubishi Heavy Industries (MHI) launched a 3,900t multirole frigate at its Nagasaki shipyard. Oddly, although it is the first-of-class, this ship called JS Mogami was the second such frigate to be launched. Indeed, Mitsui E&S launched Kumano on 19 November 2020.
JS Mogami should enter service next year. Its launch was …