[1] The new design incorporated a low superstructure fore and aft, providing additional accommodations for police or troops.

A lightly armed version with 25 mm main guns received NATO reporting name Beihai class.

The reason is that originally, majority of the hydrographic surveys were conducted by civilian fishing vessels with the additional scientific equipment, naval and governmental crews on board.

However, since the Chinese economic reform and the depletion of the fishery resources, the civilian fishing vessels must venture much further out into open ocean and staying longer at the sea, thus could no longer afford to stay in home waters and performing the heavy inshore surveying duties previously assigned under the planned economy era in China prior to the Chinese economic reform.

Consequently, the PLAN must come up with their own means to meet such huge demand, and converting former gunboats was one of the answers: although these boats can no longer venture out into open ocean and cruise at their maximum speed like they used to do, they are still quite capable of low speed inshore surveying tasks within the confines of river mouths and bays of Chinese coastlines.