# SM UB-23

SM UB-23 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 30 April 1915 and launched on 9 October 1915. She was commissioned into the Imperial German Navy on 13 March 1916 as SM UB-23. The submarine sank 51 ships in 21 patrols for a total of 33,880 gross register tons (GRT). On 26 July 1917, UB-23 was badly damaged by a depth charge attack by HMS PC-60 off the Lizard; she put in at Corunna, Spain, on 29 July 1917 and was interned. On 22 January 1919 she was surrendered to France in accordance with the requirements of the Armistice with Germany, and she was broken up in Cherbourg in July 1921.

## Design

A Type UB II submarine, UB-23 had a displacement of 263 tonnes (259 long tons) when at the surface and 292 tonnes (287 long tons) while submerged. She had a total length of 36.13 m (118 ft 6 in), a beam of 4.36 m (14 ft 4 in), and a draught of 3.70 m (12 ft 2 in). The submarine was powered by two Körting six-cylinder, four-stroke diesel engines each producing a total 280 metric horsepower (280 shp; 210 kW), a Siemens-Schuckert electric motor producing 206 kilowatts (276 shp; 280 PS), and one propeller shaft. She was capable of operating at depths of up to 50 metres (160 ft).
The submarine had a maximum surface speed of 9.15 knots (16.95 km/h; 10.53 mph) and a maximum submerged speed of 5.81 knots (10.76 km/h; 6.69 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 6,650 nautical miles (12,320 km; 7,650 mi) at 5 knots (9.3 km/h; 5.8 mph). UB-23 was fitted with two 50 centimetres (20 in) torpedo tubes, four torpedoes, and one 5 cm (2.0 in) SK L/40 deck gun. She had a complement of twenty-one crew members and two officers and a 45-second dive time.

## Summary of raiding history

| Date | Name | Nationality | Tonnage | Fate |
| 4 July 1916 | Queen Bee | United Kingdom | 34 | Sunk |
| 5 July 1916 | Annie Anderson | United Kingdom | 77 | Sunk |
| 5 July 1916 | Peep O’ Day | United Kingdom | 52 | Sunk |
| 6 July 1916 | Girl Bessie | United Kingdom | 62 | Sunk |
| 6 July 1916 | Nancy Hunnam | United Kingdom | 58 | Sunk |
| 6 July 1916 | Newark Castle | United Kingdom | 85 | Sunk |
| 6 July 1916 | Petunia | United Kingdom | 58 | Sunk |
| 6 July 1916 | Watchful | United Kingdom | 52 | Sunk |
| 24 July 1916 | Mary | Norway | 560 | Sunk |
| 26 July 1916 | Kentigern | Norway | 796 | Sunk |
| 27 July 1916 | Agenda | Norway | 226 | Sunk |
| 28 July 1916 | Andrew Ina | United Kingdom | 50 | Sunk |
| 28 July 1916 | Good Design | United Kingdom | 40 | Sunk |
| 28 July 1916 | Jane Stewart | United Kingdom | 15 | Sunk |
| 28 July 1916 | Janet Overstone | United Kingdom | 15 | Sunk |
| 28 July 1916 | Johan | United Kingdom | 49 | Sunk |
| 28 July 1916 | Renown | United Kingdom | 61 | Sunk |
| 28 July 1916 | Speedwell | United Kingdom | 11 | Sunk |
| 28 July 1916 | Spero Meliora | United Kingdom | 11 | Sunk |
| 28 July 1916 | Volunteer | United Kingdom | 15 | Sunk |
| 3 September 1916 | General Archinard | France | 355 | Sunk |
| 6 September 1916 | Britannia | United Kingdom | 48 | Sunk |
| 7 September 1916 | Emma | France | 19 | Sunk |
| 7 September 1916 | Farfadet | France | 17 | Sunk |
| 7 September 1916 | Jeanne D’Arc | France | 17 | Sunk |
| 7 September 1916 | Leonine | France | 20 | Sunk |
| 8 September 1916 | Marie Louise | France | 157 | Sunk |
| 8 September 1916 | Mayo | Spain | 1,880 | Sunk |
| 9 September 1916 | Gemma | Kingdom of Italy | 3,111 | Sunk |
| 9 September 1916 | Remora | France | 92 | Sunk |
| 21 October 1916 | Julia | France | 166 | Sunk |
| 21 October 1916 | Snestad | Norway | 2,350 | Sunk |
| 23 October 1916 | Alf | Denmark | 196 | Sunk |
| 23 October 1916 | Antoine Allosia | France | 29 | Sunk |
| 23 October 1916 | Saint Pierre | France | 151 | Sunk |
| 23 October 1916 | Venus II | Norway | 784 | Sunk |
| 26 October 1916 | Saint Yves | France | 165 | Sunk |
| 30 November 1916 | Gaete | France | 170 | Sunk |
| 2 December 1916 | Harpalus | United Kingdom | 1,445 | Sunk |
| 4 December 1916 | Nervion | Norway | 1,921 | Sunk |
| 8 December 1916 | Conch | United Kingdom | 5,620 | Sunk |
| 7 January 1917 | Brenda | United Kingdom | 249 | Sunk |
| 2 February 1917 | Gabrielle | France | 1,410 | Sunk |
| 31 March 1917 | Hestia | Netherlands | 959 | Sunk |
| 31 March 1917 | Lisbeth | Norway | 1,621 | Sunk |
| 4 April 1917 | Trevier | Belgium | 3,006 | Sunk |
| 18 April 1917 | Marcel | Belgium | 24 | Sunk |
| 31 May 1917 | Dirigo | United States | 3,004 | Sunk |
| 2 June 1917 | Prudence | United Kingdom | 25 | Sunk |
| 5 June 1917 | Laura Ann | United Kingdom | 116 | Sunk |
| 30 June 1917 | Ilston | United Kingdom | 2,426 | Sunk |
| 4 July 1917 | Gloire à Dieu | France | 419 | Damaged |