SM U-81

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]

For other ships with the same name, see German submarine U-81.

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 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 the SS Mantola 143 nautical miles (265 km; 165 mi) off Fastnet, forcing her crew to abandon her. She then shelled the drifting hulk until being chased away by the Acacia-class sloop HMS Laburnum.[4] Laburnum took the floating hulk under tow, but the line parted in the rough seas, and Mantola was left to sink, which she did on 9 February.[4][5] She was torpedoed and sunk west of Ireland on 1 May 1917 by HMS E54; 31 of her crew died, there were seven survivors.[1]

Design

German 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
Date Name Nationality Tonnage[Note 2] Fate[6]
1 December 1916 Douglas  Sweden 1,177 Sunk
19 December 1916 Nystrand  Norway 1,397 Sunk
2 February 1917 Songdal  Norway 2,090 Sunk
3 February 1917 Port Adelaide  United Kingdom 8,181 Sunk
4 February 1917 Maria  Kingdom of Italy 992 Sunk
5 February 1917 Wartenfels  United Kingdom 4,511 Sunk
7 February 1917 Gravina  United Kingdom 1,242 Sunk
8 February 1917 Mantola  United Kingdom 8,253 Sunk
10 February 1917 Netherlee  United Kingdom 4,227 Sunk
12 February 1917 Hugo Hamilton  Sweden 2,577 Sunk
10 March 1917 Algol  Norway 988 Sunk
10 March 1917 Skreien  Norway 415 Sunk
13 March 1917 Coronda  United Kingdom 2,733 Sunk
14 March 1917 Paignton  United Kingdom 2,017 Sunk
18 March 1917 Pola  United Kingdom 3,061 Sunk
18 March 1917 Trevose  United Kingdom 3,112 Sunk
19 March 1917 Alnwick Castle  United Kingdom 5,900 Sunk
19 March 1917 Frinton  United Kingdom 4,194 Sunk
22 March 1917 Attika  Norway 2,306 Sunk
25 March 1917 C. Sundt  Norway 1,105 Sunk
25 March 1917 Garant  Norway 735 Sunk
25 March 1917 Laly  Norway 1,880 Sunk
24 April 1917 Amulree  United Kingdom 1,145 Sunk
25 April 1917 Glenesk  Norway 1,369 Sunk
25 April 1917 Heathfield  United Kingdom 1,643 Sunk
25 April 1917 Invermay  United Kingdom 1,471 Sunk
27 April 1917 Uranus  Kingdom of Italy 3,978 Sunk
28 April 1917 Jose De Larrinaga  United Kingdom 5,017 Sunk
28 April 1917 Terence  United Kingdom 4,309 Sunk
30 April 1917 Elisabeth  Denmark 217 Damaged
1 May 1917 Dorie  United Kingdom 3,264 Damaged
1 May 1917 San Urbano  United Kingdom 6,458 Sunk

References

Notes
  1. "SM" stands for "Seiner Majestät" (English: His Majesty's) and combined with the U for Unterseeboot would be translated as His Majesty's Submarine.
  2. Tonnages are in gross register tons

Citations
  1. Helgason, Guðmundur. "WWI U-boats: U 81". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 25 January 2010.
  2. Gröner 1991, pp. 12–14.
  3. Helgason, Guðmundur. "WWI U-boat commanders: Raimund Weisbach". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 20 January 2015.
  4. "SS Mantola (1916)". clydesite.co.uk. Archived from the original on 4 May 2005. Retrieved 11 October 2011.{{cite web}}: CS1 maint: unfit URL (link)
  5. "SS Mantola WWI shipwreck reveals silver haul". BBC News. 10 October 2011. Retrieved 11 October 2011.
  6. Helgason, Guðmundur. "Ships hit by U 81". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 20 January 2015.

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.
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