W-13-class minesweeper

The No.13 class minesweeper (第十三号型掃海艇,) was a class of minesweepers of the Imperial Japanese Navy (IJN), serving during the 1930s and World War II. 6 vessels were built in 1931-36 under the Maru 1 Keikaku. They have two sub classes, this article handles them collectively.

Background

 * Improved model of the No.1-class. The IJN tried to a small hull than No.1-class to give a performance the same as No.1-class. And this attempt failed when the vessels were discovered to be top heavy by an investigation of the fleet in the aftermath of the Tomozuru Incident.

No.13 class

 * Project number I3A. 4 vessels were built in 1931-1934. No.15 and No.16 were behind with the completed by the Tomozuru Incident. They had clipper-bow.

No.17 class

 * Project number I3B. 2 vessels were built in 1935-1936. Improved model of the No.13-class. About their appearance, bow was changed to double-curvature bow and fitted Kampon geared turbine.