HMS G8  HMS "G8" was a G-class submarine of the Royal Navy that saw service during World War I, costing an estimated £125,000 (£ in 2020). The G-class submarines were designed by the Admiralty in response to a rumour that the Germans were building double-hulled submarines for overseas duties. The submarines had a length of overall, a beam of and a mean draft of . They displaced on the surface and submerged. The G-class submarines had a crew of 30 officers and other ranks. They had a partial double hull. For surface running, the boats were powered by two Vickers two-stroke diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the G class had a range of at . The boats were intended to be armed with one 21-inch (53.3 cm) torpedo tube in the bow and two 18-inch (45 cm) torpedo tubes on the beam. This was revised, however, while they were under construction, the 21-inch tube was moved to the stern and two additional 18-inch tubes were added in the bow. They carried two 21-inch and eight 18-inch torpedoes. The G-class submarines were also armed with a single deck gun. Like the rest of her class, "G8"′s role was to patrol the North Sea in search of German submarines. "G8" belonged to the 10th Flotilla during her war service, but also operated out of Scapa Flow during most of 1917. Her patrol areas were from north of Shetland to Norway, the Skagerrak, the Kattegat, and the Horns Reef. She also made one patrol out of Harwich for the 9th Flotilla in August 1916 before joining the Tees Flotilla. Her two commanding officers were Lieutenant Charles de Burgh from 30 June 1916 to 30 July 1917 and Lieutenant John F. Tryon from 30 July 1917 until her loss. Her last patrol began from Tees on 27 December 1917, leaving with the submarine and the destroyer for the Kattegat. She was ordered to start her voyage back on 3 January 1918 or possibly 48 hours later, returning to Tees on or around 6 January 1918. She did not return and was never heard from again. She was officially declared missing on 14 January 1918. The cause remains unknown, but she was found with depth rudders pointing towards the surface, which suggests that the men aboard were trying to get to the surface.