obsolete gunboats was one of the answers: although many of these vessels can no longer venture into the open sea, nor reach the speeds that they once could, they are still reliable enough to perform the duties of low speed inshore surveying tasks within the confines of river mouths and bays of Chinese coastlines. Contrary to the commonly held, but erroneous belief that the Chinese Navy is following the tradition of maintaining weaponry on many of its auxiliaries (though there is certainly some degree of this), the retention was primarily for economic reasons: to avoid conversion costs, the original armament(s) were retained unless they were no longer serviceable. Consequently, many of the range support, surveying boats, and other auxiliary craft still maintain some of their former fighting capabilities. This class was exported to the Democratic Republic of Vietnam and was in service with its navy during the Vietnam War, including service at the time of the Gulf of Tonkin incident (see Edwin E. Moise, Tonkin Gulf and the Escalation of the Vietnam War, University of North Carolina Press, Chapel Hill 1996:701-1. References Bibliography Moise, Edwin E. Tonkin Gulf and the Escalation of the Vietnam War. (1996) The University of North Carolina Press. . Gunboat classes Gunboats of the People's Liberation Army Navy Ships of the Vietnam People's Navy