Type 037I-class (Haiqing)

The Type 037I (NATO reporting name: Haiqing class) is a submarine chaser developed for the People's Liberation Army Navy as a follow-on to the Type 037 Hainan class. The vessels were produced at the Qiuxin Shipyard in Shanghai and the Huangpu Shipyard. The class consists of the base Type 037I and the improved Type 037IS variant.

The design is configured for general-purpose patrol duties and limited anti-submarine warfare. For underwater detection, the class utilizes a Chinese version of the French Thomson-Sintra medium frequency variable depth sonar. The configuration of the primary guns evolved during the production cycle, with earlier units carrying manually operated hardware and later variants utilizing automatic systems. The ships are also equipped with anti-submarine mortar launchers and heavy machine guns. A related modification, referred to in some sources as the Type 037 Mod or Haijiu class, integrated a variable depth sonar system with a towing cable to improve detection ranges, although limited vessel endurance impacted the operation of this system.

The class entered service in 1982. Twenty-seven vessels were completed for the People's Liberation Army Navy. In 1996, the Sri Lanka Navy acquired one unit from this class. Commissioned as SLNS Parakramabahu, the vessel was deployed during the Sri Lankan Civil War.