SM U-81[Note 1] was one of the 329 submarines serving in the Imperial German Navy (Kaiserliche Marine) in World War I.U-81 was engaged in naval warfare and took part in the First Battle of the Atlantic.[1]

History
German Empire
NameU-81
Ordered23 June 1915
BuilderGermaniawerft, Kiel
Yard number251
Laid down31 August 1915
Launched24 June 1916
Commissioned22 August 1916
Fate1 May 1917 - Torpedoed W of Ireland at 51°33′N 13°38′W / 51.550°N 13.633°W / 51.550; -13.633 by HM Sub E54. 31 dead, seven survivors.[1]
General characteristics [2]
Displacement
  • 808 t (795 long tons) surfaced
  • 946 t (931 long tons) submerged
Length
Beam
  • 6.30 m (20 ft 8 in) (oa)
  • 4.15 m (13 ft 7 in) (pressure hull)
Height8.00 m (26 ft 3 in)
Draught4.02 m (13 ft 2 in)
Installed power
  • 2 × 2,400 PS (1,765 kW; 2,367 shp) surfaced
  • 2 × 1,200 PS (883 kW; 1,184 shp) submerged
Propulsion2 shafts, 2 × 1.70 m (5 ft 7 in) propellers
Speed
  • 16.8 knots (31.1 km/h; 19.3 mph) surfaced
  • 9.1 knots (16.9 km/h; 10.5 mph) submerged
Range
  • 11,220 nmi (20,780 km; 12,910 mi) at 8 knots (15 km/h; 9.2 mph) surfaced
  • 56 nmi (104 km; 64 mi) at 5 knots (9.3 km/h; 5.8 mph) submerged
Test depth50 m (160 ft)
Complement4 officers, 31 enlisted
Armament
Service record
Part of:
  • IV Flotilla
  • 18 October 1916 – 1 May 1917
Commanders:
Operations:5 patrols
Victories:
  • 30 merchant ships sunk
    (88,483 GRT)
  • 2 merchant ships damaged
    (3,481 GRT)[1]

U-81 had one 10.5 cm gun with 140–240 rounds.[1] On 8 February 1917 she torpedoed Mantola 143 nautical miles (265 km; 165 mi) off Fastnet, forcing her crew and passengers to abandon her. She then shelled the drifting hulk until being chased away by the Acacia-class sloop HMS Laburnum. Mantola sank the next day.[4][5] HMS E54 sank U-81 by torpedo west of Ireland on 1 May 1917. 31 of U-81's crew were killed; seven survived.[1]

Design

Type U 81 submarines were preceded by the shorter Type UE I submarines. U-81 had a displacement of 808 tonnes (795 long tons) when at the surface and 946 tonnes (931 long tons) while submerged.[2] She had a total length of 70.06 m (229 ft 10 in), a pressure hull length of 55.55 m (182 ft 3 in), a beam of 6.30 m (20 ft 8 in), a height of 8 m (26 ft 3 in), and a draught of 4.02 m (13 ft 2 in). The submarine was powered by two 2,400 metric horsepower (1,800 kW; 2,400 shp) engines for use while surfaced, and two 1,200 metric horsepower (880 kW; 1,200 shp) engines for use while submerged. She had two propeller shafts. She was capable of operating at depths of up to 50 metres (160 ft).[2]

The submarine had a maximum surface speed of 16.8 knots (31.1 km/h; 19.3 mph) and a maximum submerged speed of 9.1 knots (16.9 km/h; 10.5 mph).[2] When submerged, she could operate for 56 nautical miles (104 km; 64 mi) at 5 knots (9.3 km/h; 5.8 mph); when surfaced, she could travel 11,220 nautical miles (20,780 km; 12,910 mi) at 8 knots (15 km/h; 9.2 mph). U-81 was fitted with four 50-centimetre (20 in) torpedo tubes (one at the starboard bow and one starboard stern), twelve to sixteen torpedoes, and one 10.5 cm (4.1 in) SK L/45 deck gun. She had a complement of thirty-five (thirty-one crew members and four officers).[2]

Summary of raiding history

DateNameNationalityTonnage[Note 2]Fate[6]
1 December 1916Douglas  Sweden1,177Sunk
19 December 1916Nystrand  Norway1,397Sunk
2 February 1917Songdal  Norway2,090Sunk
3 February 1917Port Adelaide  United Kingdom8,181Sunk
4 February 1917Maria  Kingdom of Italy992Sunk
5 February 1917Wartenfels  United Kingdom4,511Sunk
7 February 1917Gravina  United Kingdom1,242Sunk
8 February 1917Mantola  United Kingdom8,253Sunk
10 February 1917Netherlee  United Kingdom4,227Sunk
12 February 1917Hugo Hamilton  Sweden2,577Sunk
10 March 1917Algol  Norway988Sunk
10 March 1917Skreien  Norway415Sunk
13 March 1917Coronda  United Kingdom2,733Sunk
14 March 1917Paignton  United Kingdom2,017Sunk
18 March 1917Pola  United Kingdom3,061Sunk
18 March 1917Trevose  United Kingdom3,112Sunk
19 March 1917Alnwick Castle  United Kingdom5,900Sunk
19 March 1917Frinton  United Kingdom4,194Sunk
22 March 1917Attika  Norway2,306Sunk
25 March 1917C. Sundt  Norway1,105Sunk
25 March 1917Garant  Norway735Sunk
25 March 1917Laly  Norway1,880Sunk
24 April 1917Amulree  United Kingdom1,145Sunk
25 April 1917Glenesk  Norway1,369Sunk
25 April 1917Heathfield  United Kingdom1,643Sunk
25 April 1917Invermay  United Kingdom1,471Sunk
27 April 1917Uranus  Kingdom of Italy3,978Sunk
28 April 1917Jose De Larrinaga  United Kingdom5,017Sunk
28 April 1917Terence  United Kingdom4,309Sunk
30 April 1917Elisabeth  Denmark217Damaged
1 May 1917Dorie  United Kingdom3,264Damaged
1 May 1917San Urbano  United Kingdom6,458Sunk

References

Notes

Citations

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.