military knowledge: German Type U 31 submarine

SM U-38, a Type U 31 U-boat

U 31 was a class of U-boats built during World War I by the Kaiserliche Marine.

Between 1912 and 1915 eleven were built on Germaniawerft in Kiel, amongst these top-three-scoring U-35 with the famous Lothar von Arnauld de la Perière as commander, U-39 with Walter Forstmann and U-38 with Max Valentiner. Together these U-boats sunk more than 1,244,204 gross register tons (GRT).

Later Admiral and head of the Abwehr from 1935 to 1944 Wilhelm Canaris also served as commander on two different U 31 U-boats. He first took over from Max Valentiner on U-38 and later on U-34.

List of Type U 31 submarines

There were eleven Type U 31 submarines commissioned into the Kaiserliche Marine.

Boat	Armament	Fate
U-31	no deck gun	lost in January 1915 in the North Sea - Discovered 2012 off the East Anglia Coast and identified September 2015
U-32	two 8.8 cm guns, from 1916/17 one 10.5 cm gun	sunk 5 May 1918 north-west of Malta
U-33	one 8.8 cm gun, from 1916/17 one 10.5 cm gun	surrendered 1919, scrapped
U-34	one 8.8 cm gun, from 1916/17 one 10.5 cm gun	sunk October 1918 in the Mediterranean Sea
U-35	one 7.5 cm gun (1914), one 10.5 cm gun (1916)	surrendered 1918, scrapped
U-36	two 8.8 cm guns, from 1916/17 one 10.5 cm gun	sunk 24 July 1915 west of Rona, Hebrides
U-37	two 8.8 cm guns, from 1916/17 one 10.5 cm gun	sunk by mine in April 1915 in the English Channel
U-38	one 8.8 cm gun, from 1916/17 one 10.5 cm gun	surrendered 1919, scrapped
U-39	one 8.8 cm gun, from 1916/17 one 10.5 cm gun, from 1916/17 one 10.5 cm gun	sunk 18 May 1918 off El Ferrol
U-40	one 8.8 cm gun	sunk 23 June 1915 in the North Sea
U-41	one 8.8 cm gun	sunk 24 September 1915 in the English Channel

Class overview

Builders:	Germaniawerft, Kiel
Operators:	Kaiserliche Marine
Preceded by:	Type U 27
Succeeded by:	Type U 43
In commission:	3 September 1914
Completed:	11
Lost:	7
General characteristics
Displacement:	685 t (674 long tons) (surfaced) 878 t (864 long tons) (submerged)
Length:	64.70 m (212 ft 3 in) (o/a) 52.36 m (171 ft 9 in) (pressure hull)
Beam:	6.32 m (20 ft 9 in) (o/a) 4.05 m (13 ft 3 in) (pressure hull)
Draught:	3.56 m (11 ft 8 in)
Installed power:	2 × 1,850 PS (1,361 kW; 1,825 shp) diesel engines 2 × 1,200 PS (883 kW; 1,184 shp) Doppelmodyn
Propulsion:	2 × shafts 2 × 1.60 m (5.2 ft) propellers
Speed:	16.4 knots (30.4 km/h; 18.9 mph) (surfaced) 9.7 knots (18.0 km/h; 11.2 mph) (submerged)
Range:	8,790 nmi (16,280 km; 10,120 mi) at 8 knots (15 km/h; 9.2 mph) (surfaced) 80 nmi (150 km; 92 mi) at 5 knots (9.3 km/h; 5.8 mph) (submerged)
Test depth:	50 m (164 ft 1 in)
Boats & landing craft carried:	1 dinghy
Complement:	4 officers, 31 enlisted
Armament:	four 50 cm (20 in) torpedo tubes (2 each bow and stern) 6 torpedoes one or two 8.8 cm (3.5 in) SK L/30 – 10.5 cm (4.1 in) SK L/45 deck guns