# SM UC-18

SM UC-18 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 29 August 1915 and was launched on 4 March 1916. She was commissioned into the German Imperial Navy on 15 August 1916 as SM UC-18. In 6 patrols UC-18 was credited with sinking 34 ships, either by torpedo or by mines laid. UC-18 was sunk by the British Q ship HMS Lady Olive on 19 February 1917.

## Design

Like all pre-UC-25 Type UC II submarines, UC-18 had a displacement of 417 tonnes (410 long tons) when at the surface and 493 tonnes (485 long tons) while submerged. She had a length overall 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-18 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 cm (3.5 in) Uk L/30 deck gun. Her complement was twenty-six crew members.

## Discovery

In March 2024, it was announced that the wreck of UC-18 had been discovered by a team of divers off the island of Guernsey at a depth of 70 m (230 ft), some 64 km (40 mi) further west than the historical accounts of the battle described which was originally believed to have been 13 km (8 mi) west of the coast of Jersey.

## Summary of raiding history

| Date | Name | Nationality | Tonnage | Fate |
| 3 November 1916 | HMT Glenprosen | Royal Navy | 224 | Sunk |
| 5 November 1916 | HMT Cantatrice | Royal Navy | 302 | Sunk |
| 9 November 1916 | HMS Fair Maid | Royal Navy | 432 | Sunk |
| 9 November 1916 | Marga | United Kingdom | 674 | Sunk |
| 10 November 1916 | H.m.w. | United Kingdom | 93 | Sunk |
| 13 November 1916 | Lilloise | France | 165 | Sunk |
| 15 November 1916 | Lake Michigan | United Kingdom | 9,288 | Damaged |
| 16 November 1916 | Trevarrack | United Kingdom | 4,199 | Sunk |
| 11 December 1916 | Inger | Denmark | 786 | Sunk |
| 14 December 1916 | Glencoe | United Kingdom | 2,560 | Sunk |
| 14 December 1916 | Leca | Portugal | 1,911 | Sunk |
| 15 December 1916 | Rogn | Norway | 1,028 | Sunk |
| 17 December 1916 | Cascais | Portugal | 835 | Sunk |
| 17 December 1916 | Immaculee Conception | France | 246 | Sunk |
| 17 December 1916 | Prima | Norway | 1,233 | Sunk |
| 17 December 1916 | Prosper Leon | France | 42 | Sunk |
| 17 December 1916 | Saint Yves | France | 325 | Sunk |
| 18 December 1916 | Kansan | United States | 7,913 | Damaged |
| 22 December 1916 | Amedee | France | 130 | Sunk |
| 22 December 1916 | Dansborg | Denmark | 2,242 | Sunk |
| 22 December 1916 | Hroptatyr | Denmark | 1,300 | Sunk |
| 12 January 1917 | Saint Michel | France | 419 | Sunk |
| 13 January 1917 | Toftwood | United Kingdom | 3,082 | Sunk |
| 14 January 1917 | Martin | United Kingdom | 1,904 | Sunk |
| 15 January 1917 | Bernadette | France | 128 | Sunk |
| 15 January 1917 | Otto | Norway | 401 | Sunk |
| 16 January 1917 | City of Tampico | Norway | 1,513 | Sunk |
| 17 January 1917 | Jeune France | France | 126 | Sunk |
| 17 January 1917 | Valle | Spain | 2,365 | Sunk |
| 18 January 1917 | Louis Joseph | France | 197 | Sunk |
| 18 January 1917 | Louise | France | 101 | Sunk |
| 19 January 1917 | Klampenborg | Denmark | 1,785 | Sunk |
| 19 January 1917 | Parahyba | Uruguay | 2,606 | Sunk |
| 20 January 1917 | Phoebe | France | 3,956 | Damaged |
| 22 January 1917 | Aurelie | France | 89 | Sunk |
| 18 February 1917 | Netherton | United Kingdom | 199 | Sunk |
| 19 February 1917 | HMS Lady Olive | Royal Navy | 701 | Sunk |