SM UB-21

	SM UB-45, a U-boat similar to UB-21
History
German Empire
Name	UB-21
Ordered	30 April 1915
Builder	Blohm & Voss, Hamburg
Yard number	251
Launched	26 September 1915
Completed	18 February 1916
Commissioned	20 February 1916
Fate	Sunk as target 30 September 1920
General characteristics
Class & type	Type UB II submarine
Displacement	263 t (259 long tons) surfaced; 292 t (287 long tons) submerged;
Length	36.13 m (118 ft 6 in) o/a; 27.13 m (89 ft) pressure hull;
Beam	4.36 m (14 ft 4 in) o/a; 3.85 m (13 ft) pressure hull;
Draught	3.70 m (12 ft 2 in)
Propulsion	1 × propeller shaft; 2 × 6-cylinder diesel engine, 284 PS (209 kW; 280 bhp); 2 × electric motor, 280 PS (210 kW; 280 shp);
Speed	9.15 knots (16.95 km/h; 10.53 mph) surfaced; 5.81 knots (10.76 km/h; 6.69 mph) submerged;
Range	6,450 nmi (11,950 km; 7,420 mi) at 5 knots (9.3 km/h; 5.8 mph) surfaced; 45 nmi (83 km; 52 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged;
Test depth	50 m (160 ft)
Complement	2 officers, 21 men
Armament	2 × 50 cm (19.7 in) torpedo tubes; 4 × torpedoes (later 6); 1 × 5 cm SK L/40 gun;
Notes	45-second diving time
Service record
Part of:	I Flotilla; 14 April 1916 – 1 February 1917; II Flotilla; 1 February – 10 September 1917; V Flotilla; 10 September 1917 – 29 April 1918; I Flotilla; 29 April – 7 October 1918; Training Flotilla; 7 October – 11 November 1918;
Commanders:	Kptlt. Ernst Hashagen; 20 February – 26 November 1916; Oblt.z.S. Franz Walther; 27 November 1916 – 9 September 1917; Oblt.z.S. Walter Scheffler; 10 September 1917 – 28 April 1918; Oblt.z.S. Bruno Mahn; 29 April – 7 October 1918;
Operations:	26 patrols
Victories:	33 merchant ships sunk ; (36,764 GRT); 1 merchant ship damaged ; (3,734 GRT); 4 merchant ships taken as prize ; (2,722 GRT);

SM UB-21 was a German Type UB II submarine or U-boat in the Imperial German Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 30 April 1915 and launched on 26 September 1915. She was commissioned into the German Imperial Navy on 20 February 1916 as SM UB-21. The submarine sank 33 ships in 26 patrols for a total of 36,764 gross register tons (GRT). Surrendered to Britain in accordance with the requirements of the Armistice with Germany, UB-21 was sunk as a target by HMS Terror in the Solent on 30 September 1920; the wreck was sold in 1970 and most had been cleared by 1998, although some remnants survive.

History
SM UB-45, a U-boat similar to UB-21
German Empire
Name	UB-21
Ordered	30 April 1915
Builder	Blohm & Voss, Hamburg
Yard number	251
Launched	26 September 1915
Completed	18 February 1916
Commissioned	20 February 1916
Fate	Sunk as target 30 September 1920
General characteristics
Class & type	Type UB II submarine
Displacement	263 t (259 long tons) surfaced 292 t (287 long tons) submerged
Length	36.13 m (118 ft 6 in) o/a 27.13 m (89 ft) pressure hull
Beam	4.36 m (14 ft 4 in) o/a 3.85 m (13 ft) pressure hull
Draught	3.70 m (12 ft 2 in)
Propulsion	1 × propeller shaft 2 × 6-cylinder diesel engine, 284 PS (209 kW; 280 bhp) 2 × electric motor, 280 PS (210 kW; 280 shp)
Speed	9.15 knots (16.95 km/h; 10.53 mph) surfaced 5.81 knots (10.76 km/h; 6.69 mph) submerged
Range	6,450 nmi (11,950 km; 7,420 mi) at 5 knots (9.3 km/h; 5.8 mph) surfaced 45 nmi (83 km; 52 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	50 m (160 ft)
Complement	2 officers, 21 men
Armament	2 × 50 cm (19.7 in) torpedo tubes 4 × torpedoes (later 6) 1 × 5 cm SK L/40 gun
Notes	45-second diving time
Service record
Part of:	I Flotilla 14 April 1916 – 1 February 1917 II Flotilla 1 February – 10 September 1917 V Flotilla 10 September 1917 – 29 April 1918 I Flotilla 29 April – 7 October 1918 Training Flotilla 7 October – 11 November 1918
Commanders:	Kptlt. Ernst Hashagen 20 February – 26 November 1916 Oblt.z.S. Franz Walther 27 November 1916 – 9 September 1917 Oblt.z.S. Walter Scheffler 10 September 1917 – 28 April 1918 Oblt.z.S. Bruno Mahn 29 April – 7 October 1918
Operations:	26 patrols
Victories:	33 merchant ships sunk (36,764 GRT) 1 merchant ship damaged (3,734 GRT) 4 merchant ships taken as prize (2,722 GRT)