SM UB-33^{[Note 1]} was a German Type UB II submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 22 July 1915 and launched on 5 December 1915. She was commissioned into the German Imperial Navy on 22 April 1916 as SM UB-33.

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SM UB-45, a U-boat similar to UB-33
History
German Empire
Name	UB-33
Ordered	22 July 1915[1]
Builder	Blohm & Voss, Hamburg[1]
Cost	1,152,000 German Papiermark[2]
Yard number	257[1]
Launched	5 December 1915[1]
Completed	20 April 1916[1]
Commissioned	22 April 1916[2]
Fate	Sunk 11 April 1918[2]
General characteristics [2]
Class and type	German Type UB II submarine
Displacement	274 t (270 long tons) surfaced 303 t (298 long tons) submerged
Length	36.90 m (121 ft 1 in) o/a 27.90 m (91 ft 6 in) pressure hull
Beam	4.37 m (14 ft 4 in) o/a 3.85 m (12 ft 8 in) pressure hull
Draught	3.69 m (12 ft 1 in)
Propulsion	1 × propeller shaft 2 × 6-cylinder diesel engine, 270 PS (200 kW; 270 bhp) 2 × electric motor, 280 PS (210 kW; 280 shp)
Speed	9.06 knots (16.78 km/h; 10.43 mph) surfaced 5.71 knots (10.57 km/h; 6.57 mph) submerged
Range	7,030 nmi (13,020 km; 8,090 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 × 8.8 cm (3.5 in) Uk L/30 deck gun
Notes	42-second diving time
Service record
Part of:	Baltic Flotilla 22 June 1916 - 24 October 1917 Flandern Flotilla 24 October 1917 - 11 April 1918
Commanders:	Oblt. Herbert Lefholz 22 April 1916 – 30 January 1917 Oblt. Waldemar von Fischer 1 February – 21 March 1917 Oblt. Karl Ruprecht 22 March – 16 September 1917 Oblt. Fritz Gregor 17 September 1917 – 11 April 1918
Operations:	17 patrols
Victories:	13 merchant ships sunk (5,390 GRT) 2 merchant ships damaged (6,575 GRT) 3 merchant ships taken as prize (1,527 GRT)

Close

The submarine sank thirteen ships, damaged two others, and took a further three as prizes in seventeen patrols.^[3]

A German Type UB II submarine, UB-33 had a displacement of 274 tonnes (270 long tons) when at the surface and 303 tonnes (298 long tons) while submerged. She had a total length of 36.90 m (121 ft 1 in), a beam of 4.37 m (14 ft 4 in), and a draught of 3.69 m (12 ft 1 in). The submarine was powered by two Benz six-cylinder diesel engines producing a total 270 metric horsepower (270 shp; 200 kW), two Siemens-Schuckert electric motors producing 280 metric horsepower (210 kW; 280 shp), and one propeller shaft. She was capable of operating at depths of up to 50 metres (160 ft).^[2]

The submarine had a maximum surface speed of 9.06 knots (16.78 km/h; 10.43 mph) and a maximum submerged speed of 5.71 knots (10.57 km/h; 6.57 mph). When submerged, she could operate for 45 nautical miles (83 km; 52 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 7,030 nautical miles (13,020 km; 8,090 mi) at 5 knots (9.3 km/h; 5.8 mph). UB-33 was fitted with two 50 centimetres (20 in) torpedo tubes, four torpedoes, and one 8.8 cm (3.5 in) Uk L/30 deck gun. She had a complement of twenty-one crew members and two officers and a 42-second dive time.^[2]

UB-33 was mined and sunk around the Varne Bank on 11 April 1918.^[4] The wreck of UB-33 lies 77 feet (23 m) below the surface of the water. The amount of clearance between the submarine and ships' keels passing directly overhead is very small, making it a risk for the heavy cross-channel ship traffic in the area. The wreck is officially classified as a war grave and therefore it cannot be deliberately destroyed.