HMS D6

HMS D6 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. D3 and subsequent boats were slightly larger than the earlier boats. They had a length of 164 ft overall, a beam of 20 ft and a mean draught of 11 ft. They displaced 495 LT on the surface and 620 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
D6 was laid down on 24 February 1910 by Vickers at their Barrow shipyard, launched 23 October 1911 and was commissioned on 19 April 1912. She was the first British submarine to be equipped with a deck gun when built, a 12-pounder (3-inch/76mm) gun. D6 was sunk by UB-73 73 miles north of Inishtrahull Island off the west coast of Ireland on 24 or 28 June 1918. There were only two survivors who were taken prisoner; one of whom was F. S. Bell, the second-in-command who would go on to command HMS Exeter (68) at the Battle of the River Plate. The post-war report apparently led the British to conclude that the torpedo that sank her had employed a magnetic pistol.