SM U-31 (Germany)

History
German Empire
Name	U-31
Ordered	29 March 1912
Builder	Germaniawerft, Kiel
Yard number	191
Laid down	12 October 1912
Launched	7 January 1914
Commissioned	18 September 1914
Fate	c. 13 January 1915 – Mined in the North Sea; all hands lost.
General characteristics
Class and type	German Type U 31 submarine
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 kW; 1,825 shp) diesel engines; 2 × 1,200 PS (883 kW; 1,184 shp) Doppelmodyn;
Propulsion	2 × shafts; 2 × 1.60 m (5 ft 3 in) 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;
Service record
Part of:	IV Flotilla; 18 September 1914 – 13 January 1915;
Commanders:	Oblt.z.S. Siegfried Wachendorff; 1 August 1914 – 13 January 1915;
Operations:	1 patrol
Victories:	None

SM U-31^{[Note 1]} was one of the 329 submarines serving in the Imperial German Navy in World War I. U-31 was engaged in the

First Battle of the Atlantic

.

U-31 sailed from Wilhelmshaven on 13 January 1915 but disappeared shortly thereafter. It was assumed, correctly, she had struck a mine, and sunk with all hands somewhere in the North Sea.

Design

Type 27 subs in dimensions and differed only slightly in propulsion and speed. They were considered very good high seas boats with average manoeuvrability and good surface steering.^[2]

U-31 had an

pressure hull was 52.36 m (171 ft 9 in) long. The boat's beam was 6.32 m (20 ft 9 in) (o/a), while the pressure hull measured 4.05 m (13 ft 3 in). Type 31s had a draught of 3.56 m (11 ft 8 in) with a total height of 7.68–8.04 m (25 ft 2 in – 26 ft 5 in). The boats displaced a total of 971 tonnes (956 long tons); 685 t (674 long tons) when surfaced and 878 t (864 long tons) when submerged.^[2]

U-31 was fitted with two

kW; 1,825 bhp) for use on the surface and two Siemens-Schuckert double-acting electric motors with a total of 1,200 PS (883 kW; 1,184 shp) for underwater use. These engines powered two shafts each with a 1.60 m (5 ft 3 in) propeller, which gave the boat a top surface speed of 16.4 knots (30.4 km/h; 18.9 mph), and 9.7 knots (18.0 km/h; 11.2 mph) when submerged. Cruising range was 8,790 nautical miles (16,280 km; 10,120 mi) at 8 knots (15 km/h; 9.2 mph) on the surface, and 80 nmi (150 km; 92 mi) at 5 knots (9.3 km/h; 5.8 mph) under water. Diving depth was 50 m (164 ft 1 in).^[2]

The U-boat was armed with four 50 cm (20 in)

bow and two in the stern, and carried 6 torpedoes. The boat's complement was 4 officers and 31 enlisted.^[2]

Wreck discovery

The wreck of U-31 had been discovered in 2012 about 55 miles (89 km) off the coast of East Anglia during surveys made in preparation for the construction of an offshore wind farm. However, the wreck was not formally identified until 9 September 2015 when the Dutch Lamlash wreck-diving team discovered the hull number engraved on a salvaged item of navigation equipment.^[3]

Summary

2012: Wreck found during sonar survey by Fugro for Offshore Windfarm Project by Scottish Power Renewables

2013 and 2014: Wreck surveyed by RNLNavy with divers and sonar in the course of the search for the wreck of HNLMS O13, lost on patrol in June 1940 in the North Sea. This wreck could be classified as a World War I SM U-31 series U-boat

2015: Wreck positively identified by Dutch divers from

mv Lamlash - Haarlem as the SM U-31 (Hull number found on a “Fahrt Tabelle” (Manoeuvring Settings Table)).^{[citation needed}

]

References

Notes

^ "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.

Citations

^ Helgason, Guðmundur. "WWI U-boat commanders: Siegfried Wachendorff". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 16 March 2015.
^ ^a ^b ^c ^d Gröner 1991, p. 6.
^ Gosden, Emily (20 January 2016). "WW1 U-boat mystery solved after wreck discovered by offshore wind farm developers". The Daily Telegraph. Archived from the original on 20 January 2016. Retrieved 20 January 2016.

Bibliography

Gröner, Erich; Jung, Dieter; Maass, Martin (1991). U-boats and Mine Warfare Vessels. German Warships 1815–1945. Vol. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press.
ISBN 0-85177-593-4
.

Kemp, Paul (1997). U-boats destroyed, German submarine losses in the World Wars. London: Arms & Armour Press. p. 11.
ISBN 1-85409-321-5
.

External links

Helgason, Guðmundur. "WWI U-boats: U 31". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net.

[2] "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.

[1] Helgason, Guðmundur. "WWI U-boat commanders: Siegfried Wachendorff". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 16 March 2015.

[FOOTNOTEGröner19916-3] Gröner 1991, p. 6.

[4] Gosden, Emily (20 January 2016). "WW1 U-boat mystery solved after wreck discovered by offshore wind farm developers". The Daily Telegraph. Archived from the original on 20 January 2016. Retrieved 20 January 2016.

[1]

[Note 1]

[2]

[3]

v t e German Type U 31 submarines
U-31 U-32 U-33 U-34 U-35 U-36 U-37 U-38 U-39 U-40 U-41
Preceded by: Type U 27 Followed by: Type U 43
List of U-boats of Germany

v t e Shipwrecks and maritime incidents in January 1915
Shipwrecks	1 Jan HMS Formidable 4 Jan: HMS C31 13 Jan: HMS Viknor, SM U-31 15 Jan: Saphir 18 Jan: HMS E10 21 Jan: SM U-7 24 Jan: SMS Blücher 26 Jan: Washingtonian 28 Jan: William P. Frye 30 Jan: Tokomaru
Other incidents	13 Jan: HMS Imperieuse 25 Jan: SMS Gazelle 26 Jan: HMS Britannia 31 Jan: Asama
1914 1915 1916 December 1914 February 1915