# Sokuten-class minelayer

The Sokuten-class minelayer (測天型敷設特務艇,, Sokuten-gata Fusetsu-Tokumutei) 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-inch (76 mm) 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.

## Ships in class

| Ship | Builder | Launched | Completed | Fate |
| Natsushima (夏島) (ex-Natsushima Maru) | Yokohama Dock Company | March 1911 | June 1911 | Renamed Nastushima on 1 July 1920. Sold on 27 August 1927. Later scrapped. |
| Sokuten (測天) (ex-Sokuten Maru No. 1) | Maizuru Naval Arsenal | March 1913 | 4 July 1913 | Renamed Sokuten on 1 July 1920. Decommissioned on 25 August 1936. |
| Toshima (戸島) (ex-Toshima Maru) | Maizuru Naval Arsenal | October 1914 | 20 March 1915 | Renamed Toshima on 1 July 1920. Sunk by aircraft at Maizuru on 30 July 1945. |
| Kuroshima (黒島) (ex-Kuroshima Maru) | Maizuru Naval Arsenal | October 1914 | 25 April 1915 | Renamed Kuroshima on 1 July 1920. Decommissioned on 5 October 1945. Surrendered to Republic of China on 3 October 1947. Decommissioned in 1960. |
| Ashizaki (葦埼) (ex-Ashizaki Maru) | Maizuru Naval Arsenal | October 1915 | 12 May 1916 | Renamed Ashizaki on 1 July 1920. Decommissioned on 5 October 1945. Aground at Kamikaifu on 17 November 1945. Later scrapped. |
| Katoku (加徳) (ex-Katoku Maru) | Maizuru Naval Arsenal | October 1915 | 4 April 1916 | Renamed Katoku on 1 July 1920. Decommissioned on 5 October 1945. Surrendered to United States on 3 October 1947. Sold to Japan on 8 March 1948. Transferred to Maritime Safety Agency and given the pennant number PS-29 (later PB-29) on 1 May 1948. Decommissioned on 16 April 1952. Sold to Setonaikai Kisen inc., and renamed Tsurumi. Retired in 1970. |
| Entō (円島) (ex-Entō Maru) | Maizuru Naval Arsenal | March 1917 | 16 May 1917 | Renamed Entō on 1 July 1920. Heavy damaged by aircraft at Fangliao on 15 January 1945, later sank in shallow water. |
| Kurokami (黒神) (ex-Kurokami Maru) | Kure Naval Arsenal | February 1917 | 1 May 1917 | Renamed Kurokami on 1 July 1920. Decommissioned on 5 October 1945. Surrendered to United Kingdom on 14 November 1947. Later scrapped. |
| Katashima (片島) (ex-Katashima Maru) | Maizuru Naval Arsenal | February 1917 | 19 May 1917 | Renamed Katashima on 1 July 1920. Decommissioned on 5 October 1945. Surrendered to Soviet Union on 3 October 1947. Transferred to PLAN in 1956 at Dalian. |
| Enoshima (江之島) (ex-Enoshima Maru) | Maizuru Naval Arsenal | | 31 March 1919 | Renamed Enoshima on 1 July 1920. Decommissioned on 30 April 1946. |
| Ninoshima (似島) | Kure Naval Arsenal | May 1920 | 15 October 1920 | Decommissioned on 30 November 1945. |
| Kurosaki (黒埼) | Uchida Zōsen | | 24 December 1921 | Aground at Hachinohe on 18 November 1945. Later scrapped. |
| Washizaki (鷲埼) (ex-Minelayer No. 45) | Yokohama Iron Works | | 30 September 1921 | Renamed Washizaki on 16 May 1926. Decommissioned on 30 November 1945. Surrendered to United Kingdom on 24 November 1947. Later scrapped. |

## Photos

* Natsushima (as Natsushima Maru) on 10 October 1912
* Enoshima in 1930

## Footnotes

* ↑ Editorial Committee of the Navy (1981), p. 146