No.31-class patrol boat
The No. 31-class patrol boats were a class of patrol boats of the Imperial Japanese Navy, serving during World War II. 9 vessels were converted from s and 1 vessel was converted from a in 1940.
Background
In 1939, the IJN was liberated from London Naval Treaty, and they built many s. On the other hand, aging of the Momi-class destroyers was serious. Their boilers were degraded due to the operating conditions present in destroyers. Some Momi-class destroyers were not able to show 30 knots speed. The Navy General Staff made the Confidential Document No. 456. It was an order to rebuild them into patrol boats - about four s and six Momi-class destroyers. The IJN chose nine Momi class and one Wakatake class. Three Momis and one Wakatake were increased, because two Minekazes were decreased.Rebuilding
- Ten vessels were sent to dockyards for rebuilding. "Q" turret, all of torpedo tubes and one boiler were removed in 1940.
- In the second half of 1941, the IJN rebuilt them once again for war preparations. They were rebuilt to the landing craft carrier. The Y turret was moved to a place of the "Q" turret. Furthermore, a slope for was installed to their stern, and added deck house for one company of Navy Landing Force. As for the No. 31 and the No. 46, those rebuilt were not done.
Service
- 10 and 23 December 1941: Sortie for the Battle of Wake Island.
- 12 December 1941: Sortie for the invasion of Legazpi.
- 20 December 1941: Sortie for invasion of Davao.
- 25 December 1941: Sortie for invasion of Jolo.
- 11 January 1942: Sortie for the Battle of Tarakan.
- 11 January 1942: Sortie for the Battle of Manado.
- 31 January 1942: Sortie for the Battle of Ambon.
- 20 February 1942: Sortie for invasion of Kupang.
- 1 March 1942: Sortie for invasion of Surabaya.
- 31 March 1942: Sortie for the Battle of Christmas Island.
- : The IJN which finished First Phase Operations allotted them to the convoy escort operations. Only No. 36 was survived war.
Ships in classes
''No. 31'' class
''No. 46'' class
No. 40 to No. 45 were a space to the vessels numbers. These numbers were going to be given to all of Wakatakes.| Ship | Completed as destroyer | Rebuilt completed | Fate |
| Patrol Boat No. 46 ex- | 31 May 1924 | First quarter of 1940 at Kure Naval Arsenal. Renamed Patrol Boat No. 46 on 1 April 1940. | Sunk by off Minamiizu on 10 November 1944; removed from naval ship list on 10 January 1945. |