Sokuten-class minelayer (1938)

The Sokuten-class minelayer (測天型敷設艇,) was a class of minelayers of the Imperial Japanese Navy (IJN), serving during and after World War II. The class consists of three subclasses, which this article handles collectively.

Background

 * In 1937, the IJN planned this class as a replacement for the timeworn Natsushima and the Sokuten-class auxiliary minelayer.

Sokuten class

 * Project number H11. Original model of the Sokuten class. Five vessels were built in 1937–40 under the Maru 3 Programme (Ship # 57–61).

Hirashima class

 * Project number H11B. Second production model of the Sokuten-class. Nine vessels were built in 1939–43 under the Maru 4 Programme (Ship # 170–178). They were equipped with a 76.2 mm anti-aircraft gun. The Nuwajima had its ballast tank replaced with a fuel tank for convoy escort operations. These nine vessels were classed in the Sokuten-class in the IJN official documents.

Ajiro class

 * Project number H13 at first. The IJN hoped urgent building for her. The Navy Technical Department revised the Hirashima drawings. Twenty-six vessels were planned under the Maru Kyū Programme (Ship # 460–473, 14 vessels) and the Kai-Maru 5 Programme (Ship # 5421–5432, 12 vessels), but only Ajiro was completed. The Ajiro-class were classified separately from the Sokuten-class in the IJN official documents.