# Sokuten-class minelayer (1938)

The Sokuten-class minelayer (測天型敷設艇,, Sokuten-gata Fusetsutei) 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.

## Ships in classes
### 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).
| Ship # | Ship | Builder | Laid down | Launched | Completed | Fate |
| 57 | Sokuten (測天) | Mitsubishi, Yokohama Shipyard | 24-06-1937 | 27-04-1938 | 28-12-1938 | Sunk by aircraft at Palau, 25-07-1944. |
| 58 | Shirakami (白神) | Tōkyō Ishikawajima Shipyard | 03-09-1937 | 25-06-1938 | 25-04-1939 | Clashed with Army troop transport and sunk off Urup, 03-03-1944. |
| 59 | Naryū (成生) | Mitsubishi, Yokohama Shipyard | 24-03-1939 | 28-08-1939 | 20-06-1940 | Sunk by USS Sennet off Kii Peninsula 32°10′N 135°58′E﻿ / ﻿32.167°N 135.967°E﻿ / 32.167; 135.967, 16-02-1945. |
| 60 | Kyosai (巨済) | Tōkyō Ishikawajima Shipyard | 22-06-1938 | 29-06-1939 | 27-12-1939 | Decommissioned on 05-09-1945. Surrendered to United Kingdom on 20-11-1947. Scrapped on 31-03-1948. |
| 61 | Ukishima (浮島) | Tōkyō Ishikawajima Shipyard | 28-07-1939 | 09-12-1939 | 31-10-1940 | Sunk by unknown submarine off Hatsushima, 16-11-1943. |

### 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.
| Ship # | Ship | Builder | Laid down | Launched | Completed | Fate |
| 170 | Hirashima (平島) | Mitsubishi, Yokohama Shipyard | 06-09-1939 | 06-06-1940 | 24-12-1940 | Sunk by USS Sawfish at west of Gotō Islands, 27-07-1943. |
| 171 | Hōko (澎湖) | Tama Shipyards | 07-11-1940 | 08-09-1941 | 20-12-1941 | Sunk by aircraft off Buka Island, 28-09-1943. |
| 172 | Ishizaki (石埼) | Mitsubishi, Yokohama Shipyard | 10-03-1941 | 13-08-1941 | 28-02-1942 | Decommissioned on 30-11-1945. Surrendered to United States on 01-10-1947. Sunk as target at 35°40′N 122°53′E﻿ / ﻿35.667°N 122.883°E﻿ / 35.667; 122.883 on 16-10-1947. |
| 173 | Takashima (鷹島) | Nihon Kōkan, Tsurumi Shipyard | 11-12-1940 | 18-10-1941 | 25-03-1942 | Sunk by aircraft at Okinawa Island, 10-10-1944. |
| 174 | Saishū (済州) | Ōsaka Iron Works, Sakurajima Factory | 15-01-1941 | 15-11-1941 | 25-04-1942 | Decommissioned on 22-10-1945. Surrendered to Republic of China on 03-10-1947, and renamed Yungtsin (PF-75). Decommissioned on 01-05-1960. |
| 175 | Niizaki (新井埼) | Mitsui, Tamano Shipyard | 12-07-1941 | 02-03-1942 | 31-08-1942 | Struck a naval mine at Muroran on 04-10-1945. Decommissioned on 05-10-1945. Scrapped 1947. |
| 176 | Yurijima (由利島) | Nihon Kōkan, Tsurumi Shipyard | 31-10-1941 | 04-07-1942 | 25-11-1942 | Sunk by USS Cobia off Kota Bharu, 14-01-1945. |
| 177 | Nuwajima (怒和島) | Ōsaka Iron Works, Sakurajima Factory | 26-11-1941 | 31-07-1942 | 15-11-1942 | Heavy damaged by aircraft at Saiki, 30-04-1945. Later sank in shallow water. Salvaged and scrapped on 01-09-1948. |
| 178 | Maeshima (前島) | Nihon Kōkan, Tsurumi Shipyard | 20-07-1942 | 18-04-1943 | 31-07-1943 | Sunk by aircraft at Laoag City, 21-10-1944. |
| 179 | Moroshima (諸島) | Hitachi Zōsen | | | | Cancelled on 11 August 1943. |

### 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.
| Ship # | Ship | Builder | Laid down | Launched | Completed | Fate |
| 460 | Ajiro (網代) | Hitachi Zōsen, Innoshima Shipyard | 06-09-1943 | 08-04-1944 | 31-07-1944 | Sunk by USS Snapper at northwest of Chichi-jima, 01-10-1944. |
| 461–473 | Futtsu (富津) Hamizaki (波見埼) Hikoshima (彦島) Himeshima (姫島) Kamishima (神島) Kyobun (巨文) Musō (無双) Niijima (新島) Shinoshima (篠島) Sugashima (菅島) Tateshima (立島) Terajima (寺島) Torai (虎井) | | | | | Cancelled on 11 August 1943. |
| 5421–5432 | Arashima (荒島) Awashima (粟島) Hayashima (早島) Hosojima (細島) Kurushima (来島) Makishima (牧島) Michishima (満島) Mishima (見島) Ōshima (大島) Toshima (利島) Tobishima (飛島) Tsunoshima (角島) | | | | | Cancelled on 5 May 1944. |

## Footnotes

* ↑ Senshi Sōsho Vol.31 (1969), p.501
* ↑ Senshi Sōsho Vol.31 (1969), p.544
* ↑ Senshi Sōsho Vol.31 (1969), p.815
* ↑ Senshi Sōsho Vol.88 (1975), p.37
* 1 2 Senshi Sōsho Vol.88 (1975), p.71–74
* ↑ Senshi Sōsho Vol.88 (1975), p.95