HMS D1

HMS D1 was one of eight D-class submarine built for the Royal Navy during the first decade of the 20th century.

Description
The D-class submarines were designed as improved and enlarged versions of the preceding C class, with diesel engines replacing the dangerous petrol engines used earlier. The submarines had a length of 163 ft overall, a beam of 20 ft and a mean draught of 10 ft. They displaced 483 LT on the surface and 595 LT submerged. The D-class submarines had a crew of 25 officers and ratings and were the first to adopt saddle tanks.

For surface running, the boats were powered by two 600 bhp diesels, each driving one propeller shaft. When submerged each propeller was driven by a 275 hp electric motor. They could reach 14 kn on the surface and 9 kn underwater. On the surface, the D class had a range of 2500 nmi at 10 kn.

The boats were armed with three 18-inch (45 cm) torpedo tubes, two in the bow and one in the stern. They carried one reload for each tube, a total of six torpedoes.

Construction and career
D1 was laid down by Vickers on 14 May 1907 and was launched on 16 May 1908 at Barrow. She was commissioned in September 1909. In 1910, D1 took part in the annual manoevures, during which she "torpedoed" two "Blue Fleet" cruisers off Colonsay. This showed that the D class could operate a considerable distance from their base at Fort Blockhouse.

D1 was sunk as a target on 23 October 1918 near Dartmouth.

Wreck discovery
The wreck was discovered by divers looking for the remains of German U-Boats and has been afforded protected status.