SM UC-18

SM UC-18 was a German Type UC II minelaying submarine or U-boat in the German Imperial Navy (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 t when at the surface and 493 t while submerged. She had a length overall of 49.35 m, a beam of 5.22 m, and a draught of 3.65 m. The submarine was powered by two six-cylinder four-stroke diesel engines each producing 250 PS (a total of 500 PS), two electric motors producing 460 PS, and two propeller shafts. She had a dive time of 35 seconds and was capable of operating at a depth of 50 m.

The submarine had a maximum surface speed of 11.6 kn and a submerged speed of 7 kn. When submerged, she could operate for 55 nmi at 4 kn; when surfaced, she could travel 9430 nmi at 7 kn. UC-18 was fitted with six 100 cm mine tubes, eighteen UC 200 mines, three 50 cm torpedo tubes (one on the stern and two on the bow), seven torpedoes, and one 8.8 cm 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, some 64 km further west than the historical accounts of the battle described which was originally believed to have been 13 km west of the coast of Jersey.