Shōkai Maru-class tugboat

The Shōkai Maru-class high-powered tugboat (照海丸型強力曳船,) was a class of gunboat of the Imperial Japanese Army, serving during World War II. The IJA official designation was high-powered tugboat, however, they did not have any towing facilities. They were actually gunboat and escort ships. Many records were lost after the Surrender of Japan.

Shōkai Maru (照海丸)

 * 20 April 1938; completed at Ōsaka Iron Works, Sakurajima Factory.
 * Hereafter, her record was not left to documents.

Eikai Maru (映海丸)

 * 27 February 1939; completed at Ōsaka Iron Works, Sakurajima Factory.
 * 20 to 26 October 1944; escort operation for Harukaze Convoy (Manila - Kaohsiung).
 * 22 to 27 November 1944; escort operation for TaKa-206 Convoy (Keelung - Naha).
 * Survived war in Kushigahama; later rebuilt as short-range passenger at Mitsubishi Heavy Industries, Hiroshima shipyard.
 * 1 May 1946; transferred to Japanese National Railways (later converted to training ship).
 * 1 September 1948; transferred to Japan Maritime Safety Agency as patrol boat (PB-31, later PS-31).
 * 23 June 1951; retired.