HMS D2 was one of eight D-class submarine built for the Royal Navy during the first decade of the 20th century.
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. D2 was slightly smaller than her sister ships and had a length of 162feet overall, a beam of 20feet and a mean draught of 10feet. She displaced 489LT on the surface and 603LT submerged.[1] The D-class submarines had a crew of 25 officers and ratings and were the first to adopt saddle tanks.[2]
For surface running, the boats were powered by two 6000NaN0 diesels, each driving one propeller shaft. When submerged each propeller was driven by a 275hp electric motor. They could reach 14kn on the surface and underwater. On the surface, the D class had a range of 2500nmi at .[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]
D2 was laid down by Vickers on 10 July 1909 at their Barrow shipyard and commissioned on 29 March 1911. During her career, D2 returned from the second Heligoland Bight patrol along with, and . On 28 August 1914, D2, D3 and fought in the Battle of Heligoland Bight. Then, two days before D2 met her fate, Lieutenant Commander Jameson was washed overboard off Harwich. Lt. Cdr. Head was his replacement. D2 was rammed and sunk by a German patrol boat off Borkum on 25 November 1914, leaving no survivors.
The Coplestone Memorial Window in Chester Cathedral is in memory of "F. Lewis Coplestone, Lt-Commander, Royal Navy, HM Submarine D2" and Commander A.F. Coplesone-Boughey, RN, HMS Defence.[3] It depicts St Anselm, Archbishop of Canterbury and shows at the bottom three coats of arms of the Coplestone family, which originated at the manor of Copleston in Devon.