History
German Empire
Name	U-4
Ordered	13 August 1907[1]
Builder	Kaiserliche Werft Danzig[1]
Cost	1,629,000 Goldmark
Yard number	3
Launched	18 May 1909[1]
Commissioned	1 July 1909[1]
Decommissioned	27 January 1919
Fate	Broken up in 1919
General characteristics [2]
Class and 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	5.60 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 4.5 knots (8.3 km/h; 5.2 mph) submerged
Test depth	30 m (98 ft 5 in)
Boats & landing craft carried	1 dingi
Armament	4 × 45 cm (18 in) torpedo tubes (2 bow, 2 stern) 6 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
Commanders:	Friedrich Lützow
Operations:	none
Victories:	No ships sunk or damaged

SM U-4 was one of the 329 submarines serving in the Imperial German Navy in World War I. She was partially broken up in 1919 with her hull being sold on.^[3]

• 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.