Sokuten-class minelayer

The Sokuten-class minelayer (測天型敷設特務艇,) was a class of auxiliary minelayers of the Imperial Japanese Navy (IJN), serving during the 1910s and World War II. They were called the Sokuten class from their nameship. They were also called the Toshima class after Sokuten was retired. In some sources Natsushima was included in this class. Their official class name was not mentioned in IJN official documents.

Background

 * The IJN intended to update their mineboats for local guards.

Construction

 * In 1911, the IJN built the first experimental boat Natsushima (Natsushima Maru). Natsushima attached importance to gun-fights. Therefore, she was equipped with two 3 in Armstrong guns.
 * In 1913, the IJN built the second experimental boat Sokuten (Sokuten Maru No. 1). She was an improved model of Natsushima, and her equipment was almost the same as Natsushima.
 * The IJN adopted Sokuten's hull design, and started production.
 * Kuroshima, Kurokami and Kurosaki were equipped with netlayer facilities. However, those armaments were not announced.

Service history
Natsushima was retired in 1927, and Sokuten was retired in 1936. The other sisters participated to World War II, and nine boats survived the war.