SM U-3 in the Harbour of Kiel (second boat right)
History
German Empire
Name	U-3
Ordered	13 August 1907[1]
Builder	Kaiserliche Werft Danzig[1]
Cost	1,629,000 Goldmark
Yard number	2
Launched	27 March 1909[1]
Commissioned	29 May 1909[1]
Fate	Surrendered on 1 December 1918. Sank on the way to be broken up at Preston.
General characteristics [2]
Type	German Type U 3 submarine
Displacement	421 t (414 long tons) surfaced 510 t (500 long tons) submerged
Length	51.28 m (168 ft 3 in) (o/a) 45.00 m (147 ft 8 in) (pressure hull)
Beam	5.6 m (18 ft 4 in)
Draught	3.05 m (10 ft)
Propulsion	2 shafts 2 × Körting 8-cylinder two stroke paraffin motors with 600 PS (440 kW; 590 shp) 2 × Siemens-Schuckert electric motors with 1,030 PS (760 kW; 1,020 shp) 550 rpm surfaced 600 rpm submerged
Speed	11.8 knots (21.9 km/h; 13.6 mph) surfaced 9.4 knots (17.4 km/h; 10.8 mph) submerged
Range	1,800 nmi (3,300 km; 2,100 mi) at 12 knots (22 km/h; 14 mph) surfaced 50 nmi (93 km; 58 mi) at 5 knots (9.3 km/h; 5.8 mph)
Test depth	30 m (98 ft)
Boats & landing craft carried	1 dinghy
Complement	3 officers, 19 men
Armament	4 × torpedo tubes (2 bow, 2 stern) 6 × 45 cm (18 in) torpedoes 1 × 5 cm (2.0 in) SK L/40 gun (from 1915)
Service record
Part of:	Training Flotilla 1 August 1914 - 11 November 1918
Operations:	none
Victories:	No ships sunk or damaged

SM U-3 was the third German U-boat created by the German Empire in their history, and the first of two submarines in its class. The boat was built by Kaiserliche Werft Danzig and was launched on 27 March 1909.

On 17 January 1911, U-3 sank near Kiel harbour in Heikendorfer Bay because of an unclosed ventilation shaft valve. Its entire 30-man crew was rescued by SMS Vulkan via torpedo tube. Amongst the saved crew was Otto Weddigen, the later commander of U-9 and Paul Clarrendorf, the commander of U-boot-Abnahme-Kommando in Kiel which enlisted U-boat crews.

U-3 began her World War I career as a training boat from 1 August 1914 to 11 November 1918. On 1 December 1918, the surrendered boat was being towed to Preston to be broken up when she sank. Unlike the first two U-boat designs, the third design was fitted with a 5 cm (2.0 in) SK L/40 deck gun.

• SM U-4
• List of U-boats of Germany

• 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.
• Rössler, Eberhard (1985). Die deutschen U-Boote und ihre Werften: U-Bootbau bis Ende des 1. Weltkriegs, Konstruktionen für das Ausland und die Jahre 1935–1945 [The German Submarines and Their Shipyards: Submarine Construction Until the End of the First World War] (in German). Vol. I. Koblenz: Bernard & Graefe. ISBN 3-7637-5213-7.

• Helgason, Guðmundur. "WWI U-boats: U 3". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 3 August 2009.