SM U-81

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

History

German Empire
Name:	U-81
Ordered:	23 June 1915
Builder:	Germaniawerft, Kiel
Yard number:	251
Laid down:	31 August 1915
Launched:	24 June 1916
Commissioned:	22 August 1916
Fate:	1 May 1917 - Torpedoed W of Ireland at 51°33′N 13°38′W / 51.550°N 13.633°W / 51.550; -13.633Coordinates: 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:	70.06 m (229 ft 10 in) (o/a) 55.55 m (182 ft 3 in) (pressure hull)
Beam:	6.30 m (20 ft 8 in) (oa) 4.15 m (13 ft 7 in) (pressure hull)
Height:	8.00 m (26 ft 3 in)
Draught:	4.02 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
Propulsion:	2 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 depth:	50 m (164 ft 1 in)
Complement:	4 officers, 31 enlisted
Armament:	6 × 50 cm (19.7 in) torpedo tubes (four bow, two stern) 12-16 torpedoes 1 × 10.5 cm (4.1 in) deck gun
Service record
Part of:	Imperial German Navy IV Flotilla 18 October 1916 – 1 May 1917
Commanders:	Kptlt. Raimund Weisbach^[3] 22 August 1916 – 1 May 1917
Operations:	4 patrols
Victories:	30 ships sunk 88,483 GRT 2 ships damaged 3,481 GRT^[1]

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]

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] Laburnam 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] It had a total length of 229 ft 10 in (70.05 m), a pressure hull length of 182 ft 3 in (55.55 m), a beam of 20 ft 8 in (6.30 m), a height of 26 ft 3 in (8.00 m), and a draught of 13 ft 2 in (4.01 m). 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. It had two 1.7 m (5.6 ft) propeller shafts. It 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, it could operate for 56 nautical miles (104 km; 64 mi) at 5 knots (9.3 km/h; 5.8 mph); when surfaced, it could travel 11,220 nautical miles (20,780 km; 12,910 mi) at 7 knots (13 km/h; 8.1 mph). U-81 was fitted with six 50 centimetres (20 in) torpedo tubes (one at the starboard bow and one starboard stern), twelve to sixteen torpedoes, and one 10.5 centimetres (4.1 in) deck machine gun. It 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

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

Citations

1 2 3 4 5 Helgason, Guðmundur. "WWI U-boats: U 81". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 25 January 2010.
1 2 3 4 5 Gröner 1991, pp. 12-14.
↑ 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.
1 2 "SS Mantola (1916)". clydesite.co.uk. Retrieved 2011-10-11.
↑ "SS Mantola WWI shipwreck reveals silver haul". BBC News Online. Retrieved 2011-10-11.
↑ 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. 2. Translated by Thomas, Keith; Magowan, Rachel. London: Conway Maritime Press. ISBN 0-85177-593-4.

German Type U 81 submarines

U-81 U-82 U-83 U-84 U-85 U-86

Preceded by: Type UE I Followed by:Type U 87 List of U-boats of Germany

Shipwrecks and maritime incidents in May 1917

Shipwrecks	1 May: SM U-81 2 May: HMS Derwent 4 May: Ilva, Transylvania 6 May: Hebble 7 May: SM UB-39 8 May: SM UC-26 14 May: SM U-59 15 May: Boutefeu 20 May: HMS Paxton 21 May: Lanthorn, SM UC-36 24 May: SM UC-24 25 May: HMS Hilary 26 May: HMHS Dover Castle 28 May: Asters 30 May: SS Italia 31 May: Miyazaki Maru Unknown date: HMS C17, SM UB-36

Other incidents	16 May: HMS Dartmouth Unknown date: HMS Lurcher

1916 1917 1918 April 1917 June 1917

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