SM U-18

For other ships with the same name, see German submarine U-18.

SM U-18^{[Note 1]} was one of 329 submarines serving in the Imperial German Navy in World War I. U-18 engaged in the commerce warfare in the First Battle of the Atlantic.

SM U-18 (second row, second from the right)
History
Germany
Name	U-18
Ordered	May 6, 1910
Builder	Kaiserliche Werft Danzig
Cost	2,333,000 Goldmark
Yard number	12
Laid down	27 October 1910
Launched	25 April 1912
Commissioned	17 November 1912
Fate	Scuttled on 23 November 1914
General characteristics
Class & type	German Type U 17 submarine
Displacement	564 t (555 long tons) surfaced 691 t (680 long tons) submerged
Length	62.35 m (204 ft 7 in)
Beam	6 m (19 ft 8 in)
Height	7.30 m (23 ft 11 in)
Draught	3.40 m (11 ft 2 in)
Propulsion	2 shafts 2 × 2 Körting 8-cylinder two stroke paraffin motors with 1,400 PS (1,030 kW; 1,380 shp) 2 × AEG electric motors with 1,120 PS (820 kW; 1,100 shp) 550 rpm surfaced 425 rpm submerged
Speed	14.9 knots (27.6 km/h; 17.1 mph) surfaced 9.5 knots (17.6 km/h; 10.9 mph) submerged
Range	6,700 nmi (12,400 km; 7,700 mi) at 8 kn surfaced 75 nmi (139 km; 86 mi) at 5 kn submerged
Test depth	50 m (164 ft 1 in)
Boats & landing craft carried	1 dingi
Complement	4 officers, 25 men
Armament	4 × 45 cm (17.7 in) torpedo tubes (2 each bow and stern) with 6 torpedoes
Service record
Part of:	II Flotilla 1 August – 23 November 1914
Commanders:	Kptlt. Heinrich von Henning[1] 1 August – 23 November 1914
Operations:	3 patrols
Victories:	None

Service history

Beginning in October 1914, she was commanded by Kaptlt. von Hennig.^[2]

On her third mission, on 23 November U-18 penetrated the fleet anchorage of Scapa Flow via Hoxa Sound, following a steamer through the boom and entering the anchorage with little difficulty. However, the fleet was absent, being dispersed in anchorages on the west coast of Scotland and Ireland. As U-18 was making her way back out through Hoxa Sound to the open sea, her periscope was spotted by a guard boat. The trawler Dorothy Gray altered course and rammed the periscope, rendering it unserviceable. U-18 then suffered a failure of her diving plane motor and the boat became unable to maintain her depth, at one point even impacting the seabed. She was rammed a second time by destroyer HMS Garry and eventually, her captain was forced to surface and scuttle his command just outside the Hoxa Gate; all crew members, except one, were picked up by British boats.^[3][4] One crew member perished, while the remaining 22 were interned as prisoners of war.^[5]

The wreck lies 75 m (246 ft) below the surface just outside the Hoxa Gate, at 58°41′N 02°55′W.^[6]