The submarine sank 27 ships in 25 patrols. UB-31 was depth charged and sunk by British warships HMS Lord Leitrim, HMS Loyal Friend, and HMS Ocean Roamer in the English Channel on 2 May 1918.[2] Alternatively she may have been sunk by a mine on that date.[6]
Design
A Type UB II submarine, UB-31 had a displacement of 274 tonnes (270 long tons) when at the surface and 303 tonnes (298 long tons) while submerged. She had a total length of 36.90 m (121 ft 1 in), a beam of 4.37 m (14 ft 4 in), and a draught of 3.69 m (12 ft 1 in). The submarine was powered by two Benz six-cylinder diesel engines producing a total 270 metric horsepower (270 shp; 200 kW), two Siemens-Schuckert electric motors producing 280 metric horsepower (210 kW; 280 shp), and one propeller shaft. She was capable of operating at depths of up to 50 metres (160 ft).[2]
The submarine had a maximum surface speed of 9.06 knots (16.78 km/h; 10.43 mph) and a maximum submerged speed of 5.71 knots (10.57 km/h; 6.57 mph). When submerged, she could operate for 45 nautical miles (83 km; 52 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 7,030 nautical miles (13,020 km; 8,090 mi) at 5 knots (9.3 km/h; 5.8 mph). UB-31 was fitted with two 50 centimetres (20 in) torpedo tubes, four torpedoes, and one 8.8 cm (3.5 in) Uk L/30deck gun. She had a complement of twenty-one crew members and two officers and a 42-second dive time.[2]
^Helgason, Guðmundur. "WWI U-boat commanders: Wilhelm Braun". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 1 February 2015.
^Helgason, Guðmundur. "UB-31". U-Boat.net. Retrieved 8 May 2018.
^Helgason, Guðmundur. "Ships hit by UB-31". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 1 February 2015.
