Type 037-class submarine chaser

The Type 037 class submarine chaser, also known as the Hainan class, is a class of submarine chaser of the People's Republic of China's People's Liberation Army Navy, designed by China to replace the Soviet S.O.-1 class submarine chaser. Early units had Dual Purpose Mk.26 76.2 mm guns and Russian RBU-1200 ASW rocket launchers, but eventually, these were replaced by Chinese Type 66 twin 57 mm guns and Type 81 ASW rocket launchers (the Chinese version of RBU-1200).

The original Skin Head radar has been replaced by the Pot Head radar. In addition to ASW missions, these simple yet effective units are also capable of a wide variety of missions such as mine laying and patrol. These boats were first equipped with Soviet Soviet Tamir-11 (MG-11, with NATO reporting name Stag Hoof) hull mounted sonar with a typical range of 3 km, but in the 1970s, they were superseded by domestic Chinese SJD-3 sonar, which is modification of original MG-11: instead of being fixed to the hull, SJD-3 has a telescoping arm, so when not in use, the sonar is stored in the hull, and when deployed, the sonar is lowered into water several meter below the hull, thus increased detection range by avoiding baffles generated by the hull.

Exports and successors
Over 70 were built, but as newer submarine chasers enter service, this class is being transferred into the reserves. A number of these have been exported to Bangladesh, Egypt, North Korea, Pakistan and Myanmar. The Type 037 Hainan class is also the base of Type 206 class gunboat, also known as Huludao class.

Operational service
During the Sino-South Vietnamese naval clashes on January 19, 1974, two boats of this class, # 281 & # 282 (two out of the 8 total in Chinese inventory) participated in the latter half of the battle, the fastest Chinese units in the conflict. Originally the units were waiting at Yongxing Island, but due to the problem of communications (mainly due to the backwardness of the Chinese communication gear), they were not notified until the battle was already in progress.