HMS D3

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 feet 7 inches (50.2 m) overall, a beam of 20 feet 5 inches (6.2 m) and a mean draught of 11 feet 5 inches (3.5 m). They displaced 495 long tons (503 t) on the surface and 620 long tons (630 t) submerged.[1] The D-class submarines had a crew of 25 officers and other ranks and were the first to adopt saddle tanks.[2]

For surface running, the boats were powered by two 600-brake-horsepower (447 kW) diesels, each driving one propeller shaft. When submerged each propeller was driven by a 275-horsepower (205 kW) electric motor. They could reach 14 knots (26 km/h; 16 mph) on the surface and 9 knots (17 km/h; 10 mph) underwater. On the surface, the D class had a range of 2,500 nautical miles (4,600 km; 2,900 mi) at 10 knots (19 km/h; 12 mph).[2]

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.[2]

D3 was laid down on 15 March 1910 by Vickers at their Barrow shipyard and commissioned on 30 August 1911. During her career, D3 returned from the second Heligoland Bight patrol along with D2, E5 and E7.

William McKinstry Heriot-Maitland-Dougall Plaque, CFB Halifax

D3 was mistakenly bombed and sunk by a French airship AT-0 off Fecamp in the English Channel and lost with all hands on 12 March 1918. AT-0 was patrolling when at 14:20 a vessel was spotted to her north east. The airship drew close for recognition purposes and according to her commander, Lieutenant (RCN) William McKinstry Heriot-Maitland-Dougall the submarine fired rockets at her. Four 52-kg bombs were dropped by the airship. The submarine disappeared but several minutes later men were seen in the water. Attempts were made by the airship to rescue the men but it proved too difficult. The airship withdrew to seek help but all the men had drowned by the time it arrived. It is clear that D3 was the victim of a serious identification error on the part of the French airship, with identification rockets being mistaken for aggressive gunfire.

• Akermann, Paul (2002). Encyclopaedia of British Submarines 1901–1955 (reprint of the 1989 ed.). Penzance, Cornwall: Periscope Publishing. ISBN 1-904381-05-7.
• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8.
• Gardiner, Robert & Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships: 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN 0-85177-245-5.
• Harrison, A. N. (January 1979). "The Development of HM Submarines From Holland No. 1 (1901) to Porpoise (1930) (BR3043)". Submariners Association: Barrow in Furness Branch. Archived from the original on 19 May 2015. Retrieved 19 August 2015.

• MaritimeQuest HMS D-3 Pages
• HMS D-3 Roll of Honour
• MaritimeQuest 12 March 2006 Daily Event HMS D-3