The Type 625C oceanographic survey ships were built by Shanghai-based Hudong Shipyard (now Hudong-Zhonghua Shipyard) in the late 1970s, with a total four hulls launched. The ship was used for both military and civil purposes.
The PLA Navy signed an agreement with Hudong to build two Type 625C ships in March 1979. The design proposal was submitted and approved in January 1980. Hudong began the construction of the two hulls in September 1980. The first hull Haiyang 11 was launched in June 1981, followed by the second hull Haiyang 12 in July. Both ships were commissioned by the South Sea Fleet of the PLA Navy in November 1981.
The two Type 625C ships were operated by the 1st Oceanographic Survey Group of the South Sea Fleet under the cover name of 2nd Oceanographic Survey Group of the Chinese Ministry of Geology and Mineral Resources. The two ship were operating in the South China Sea region for oceanographic survey and research roles. Their operations included survey activities near the east coast of Philippine and collection of hydrological data near the Spratly Islands to be used by Chinese navy submarines. One of the ship is now known as Nandiao 411.
Hudong also built two Type 625C ships for the China Academy of Science (CAS) in the early 1980s. Construction of the first hull Kexue 1 began in December 1979, and the ship was launched in January 1981. The ship has been serving with CAS’s Institute Oceanology at Qingdao. The second hull Shijian 3 has been operated by CAS’s South China Sea Institute of Oceanology (SCSIO) at Guangzhou.
