China has apparently resumed construction of Type 039B Yuan-class diesel-electric attack submarines (SSK) after a three year hiatus, IHS Jane’s Defense Weekly reported on January 5. Images posted on Chinese online forums reportedly show three Type 039B Yuan-class boats in various stages of completion being out fitted out at the Wuchang Shipyard in Wuhan, central China. The last of the three subs, built by China State Shipbuilding Industrial Corp (CSIC), was purportedly launched on December 12.
The Yuan-class is purportedly one of the quietest submarine classes in the inventory of the People’s Liberation Army Navy (PLAN). The original Type 039A Yuan-class (also known as the Type 041) made its first public appearance in 2006 as the successor of the Type 039 Song-class of diesel-electric attack submarines. Analysts have identified a total of four Type 039 Yuan-class variants, with the Type 039B boats as the latest iteration of the SSK class.
There is very little open source data available on the Type 039B boats. With a length of 77 meters (254 feet) and a beam of 8.4 meters, they allegedly displace around 2,700 tons surfaced and 3,600 tons when submerged and hold a crew of 38. Type 039B boats feature a modified hull and redesigned conning tower, as well as a flank sonar array. “The hulls of the Yuan class are clad with anechoic tiles, to minimize any return echoes when pinged by active sonars,” according to IHS Jane’s Defense Weekly.
The subs are allegedly fitted with diesel-electric engines supplemented by an air independent propulsion (AIP) system. As I noted back in 2015:
Diesel-electric subs are usually significantly stealthier than their nuclear counterparts, mostly due to diesel engines that are specifically designed to minimize vibration and noise in order to evade sonar detection. For example, both the Song- and Yuan-class attack submarines are equipped with German-made state-of-the-art diesel engines — the 396 SE84 series — designed by MTU Friedrichshafen GmbH of Friedrichshafen, Germany.
Type 039B subs are also reportedly fitted with the Kockums Stirling AIP technology, which increases the boats’ submerged endurance from days to weeks.
It is unclear what combat control systems are installed aboard the latest Yuan-class boats. Fitted with six 533-millimeter torpedo tubes, the sub can reportedly launch YJ-2 (YJ-82) anti-ship cruise missiles, launched in a buoyant capsule, and a combination of Yu-4 (SAET-50) passive homing and Yu-3 (SET-65E) active/passive homing torpedoes.
There has also been speculation that some boats of the class will be fitted with a vertical launch system for newer anti-ship cruise missiles such as the YJ-18, China’s most modern supersonic anti-ship missile specifically designed to defeat the Aegis Combat System. The YJ-18 has allegedly already been deployed on PLAN surface warships.
The PLAN currently operates a fleet of 13 to 15 Yuan-class subs with a total of 20 boats of the class planned for production, according to a 2016 Pentagon study. The exact production schedule remains unknown. Chinese submarine technology is still generally considered to be a generation behind the West and the PLAN continues to rely on imported foreign technology for its SSK force, often license-built in China.