No.31-class patrol boat

	No. 35 in 1940
Class overview
Name	No. 31-class patrol boat
Builders	Kure Naval Arsenal; Sasebo Naval Arsenal; Hakodate Dock Corporation;
Operators	Imperial Japanese Navy; People's Security Army Navy;
Succeeded by	Matsu-class destroyer; No.1-class landing ship;
Subclasses	No. 31 class (ex-Momi class); No. 46 class (ex-Wakatake class);
Built	1940
In commission	1940 – 1946
Planned	6
Completed	10
Lost	9
Retired	1
General characteristics No. 31 class
Type	Patrol boat
Displacement	940 long tons (955 t) standard
Length	April 1940; 88.39 m (290 ft 0 in) overall;
Beam	7.93 m (26 ft 0 in)
Propulsion	2 × geared turbines; 2 × Kampon water tube boilers; 2 shafts, 4,000 shp;
Speed	18.0 knots (20.7 mph; 33.3 km/h)
Armament	April 1940; 2 × 120 mm (4.7 in) L/45 naval guns; 1 × Type 96 25 mm AA gun; 1 × paravane; No. 32 in 1941; 2 × 120 mm L/45 naval guns; 2 × Type 96 25 mm AA guns; 2 × depth charge throwers; 18 × depth charges; 1 × landing craft and one companie of Navy Landing Force, or 42 × depth charges;
General characteristics No. 46
Type	Patrol boat
Displacement	925 long tons (940 t) standard
Length	88.39 m (290 ft 0 in) overall
Beam	8.08 m (26 ft 6 in)
Propulsion	2 × Escher Wyss & Cie Zoelly geared turbines; 2 × Kampon water tube boilers; 2 shafts, 4,000 shp;
Speed	18.0 knots (20.7 mph; 33.3 km/h)
Armament	2 × 120 mm L/45 naval guns

The No. 31-class patrol boats (第三十一号型哨戒艇,, Dai Sanjūichi Gō-gata Shōkaitei) were a class of patrol boats of the Imperial Japanese Navy (IJN), serving during World War II. 9 vessels were converted from Momi-class destroyers and 1 vessel was converted from a Wakatake-class destroyer in 1940. During WW2 all were lost except one.