Name UC-21 Yard number 271 Launched 1 April 1916 Draft 3.68 m | Ordered 26 August 1915 Commissioned 12 September 1916 Length 49 m Builder Blohm + Voss | |
Fate disappeared September 1917 Class and type German Type UC II submarine | ||
SM UC-21 was a German Type UC II minelaying submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 26 August 1915 and was launched on 1 April 1916. She was commissioned into the German Imperial Navy on 12 September 1916 as SM UC-21.
In eleven patrols UC-21 was credited with sinking 100 ships, either by torpedo or by mines laid. They included the British hospital ship Donegal, which UC-21 torpedoed in the English Channel on 17 April 1917, killing 29 already wounded soldiers and 12 crew.
UC-21 disappeared after departing Zeebrugge for the Bay of Biscay on 13 September 1917.
Design
Like all pre-UC-25 German Type UC II submarines, UC-21 had a displacement of 417 tonnes (410 long tons) when at the surface and 493 tonnes (485 long tons) while submerged. She had a total length of 49.35 m (161 ft 11 in), a beam of 5.22 m (17 ft 2 in), and a draught of 3.65 m (12 ft). The submarine was powered by two six-cylinder four-stroke diesel engines each producing 250 metric horsepower (180 kW; 250 shp) (a total of 500 metric horsepower (370 kW; 490 shp)), two electric motors producing 460 metric horsepower (340 kW; 450 shp), and two propeller shafts. She had a dive time of 35 seconds and was capable of operating at a depth of 50 metres (160 ft).
The submarine had a maximum surface speed of 11.6 knots (21.5 km/h; 13.3 mph) and a submerged speed of 7 knots (13 km/h; 8.1 mph). When submerged, she could operate for 55 nautical miles (102 km; 63 mi) at 4 knots (7.4 km/h; 4.6 mph); when surfaced, she could travel 9,430 nautical miles (17,460 km; 10,850 mi) at 7 knots (13 km/h; 8.1 mph). UC-21 was fitted with six 100 centimetres (39 in) mine tubes, eighteen UC 200 mines, three 50 centimetres (20 in) torpedo tubes (one on the stern and two on the bow), seven torpedoes, and one 8.8 centimetres (3.5 in) Uk L/30 deck gun. Her complement was twenty-six crew members.