DN - Defence Notes

UDT Asia: Japan boosts submarine technologies

12th January 2017 - 04:01 GMT | by Koji Miyake in Tokyo


This year Japan will start building a Soryu-class submarine for the Japan Maritime Self-Defence Force (JMSDF) containing a host of new technologies and is scheduled to enter service in FY2021.

Funded under the budget announced in August 2016, the boat will feature four new technologies, the first of which is lithium ion batteries. Current Soryu-class submarines were equipped with an air-independent propulsion (AIP) system but this generates low power and occupies considerable space inside the hull. 

Lithium ion batteries on the other hand will improve the submarine’s underwater speed and free up internal space.

A second item of new technology is the G-RX6 heavyweight torpedo, optimised to detect and attack targets in shallow water where the acoustic environment is complicated. This is important because the average depth of the East China Sea is less than 200m, for example.

The G-RX6, designed to target both warships and submarines, is stealthy and will be fitted with updated sensors. It will also be more resistant to acoustic decoys and jammers. 

A third new element is a next-generation sonar system that analyses signal data transmitted from the bow array sonar, towed array sonar and side array sonar. It automatically analyses a target’s movements by using this data and then suggests suitable tactics.

A final area where technology is being applied is improved quietness. The Acquisition, Technology & Logistics Agency researched submarine hulls that reduce fluid noise and these research results will be applied to the new submarine.

For a long time the JMSDF possessed a fleet of 18 submarines, including two that were used for training. However, with increased activity by China’s navy in the East China Sea, the JMSDF is responding by expanding its submarine fleet to 22 hulls by FY2021. 

The JMSDF is achieving this target by extending the service life of Oyashio-class submarines instead of increasing the output of new-build submarines. Nevertheless, the JMSDF is anxious about a shortage of submarine crews who have requisite skill and aptitude.

Currently the JMSDF has 19 submarines: seven Soryu class, ten Oyashio class and two training submarines. In addition two Soryu-class boats are under outfitting, two are being constructed and the funding for one more has been approved. The eleventh and twelfth submarines will be equipped with lithium ion batteries instead of AIP.

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