SM UB-91

SM UB-91 was a German Type UB III submarine or U-boat in the German Imperial Navy (Kaiserliche Marine) during World War I. She was commissioned into the German Imperial Navy on 11 April 1918 as SM UB-91.

Surrender
UB-91 was surrendered to Britain on 21 November 1918 at Harwich and was toured around the South Wales ports of Cardiff, Newport, Swansea, Port Talbot and towed to Pembroke Dock, eventually being broken up in Briton Ferry in 1921. Her deck gun was presented to Chepstow by King George V in recognition of the bravery of William Charles Williams RN VC at Gallipoli in 1915.

Construction
She was built by AG Vulcan of Hamburg and following just under a year of construction, launched at Hamburg on 6 March 1918. UB-91 was commissioned later the same year. Like all Type UB III submarines, UB-91 carried 10 torpedoes and was armed with a 10.5 cm deck gun. UB-91 would carry a crew of up to 3 officer and 31 men and had a cruising range of 7120 nmi. UB-91 had a displacement of 510 t while surfaced and 640 t when submerged. Her engines enabled her to travel at 13 kn when surfaced and 7.4 kn when submerged.