Images posted on Chinese online forums in December show three new Yuan-class (Type 039B) patrol submarines being fitted out in the water at the Wuchang Shipyard in Wuhan, central China: a clear indication that China has resumed production of these diesel-electric boats after a near-three-year hiatus.
The latest of the three submarines appears to have been launched around 12 December, according to online forums.
The initial variant of the Yuan class (Type 039A) entered service in 2006. Overall length is 77 m with a beam of 8.4 m, displacing around 2,700 tonnes when on the surface and 3,600 tonnes when dived, according to IHS Jane's Fighting Ships.
Equipped with six 533 mm (21 inch) torpedo tubes, weapon loads are likely to be a mix of anti-ship missiles, such as the YJ-82, and heavyweight torpedoes, such as the Yu-6.
Although not officially confirmed, most sources believe that the Yuan class has a conventional diesel-electric configuration supplemented with an air-independent propulsion (AIP) system.
The performance of the AIP is unknown but it should be expected to extend the interval between when the submarine has to run the diesel engines to charge the batteries from hours to days. This will enable it to maintain a minimal noise signature and thus makes it more difficult to detect.
The hulls of the Yuan class are clad with anechoic tiles, to minimise any return echoes when pinged by active sonars.
Establishing an accurate picture of the number of submarines built for China's People's Liberation Army Navy (PLAN) presents some difficulties. The PLAN is more secretive about its submarine force than about other platforms and the absence of pennant numbers in most photographs makes identification and monitoring the build/disposal programme susceptible to errors.
Most sources agree, however, that the first four Yuan-class submarines were of the same design (Type 039A) and entered service between 2006 and 2010.
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