Prototype British submarine HMS/m D1, the forerunner to the Royal Navy’s patrol submarines of WW1, has been designated a Protected Wreck. Scuba divers can visit the 50m-deep site but the wreck and its contents must remain in situ.
DI sits upright and largely intact one nautical mile south-east of the eastern Blackstone, off Dartmouth in Devon. It was identified in 2018, following investigations by a team of technical divers diving from Wey Chieftain IV.
They had thought they were diving a U-boat wreck, for a project initiated by historian Michael Lowrey for a book he was writing about German submarines.
The main body of the wreck lay exposed, the lower conning-tower hatch open and the bow partly buried. The divers reported a combination of two forward and a single stern torpedo-tube, two propellers and a single rudder, ruling out previous U-boat identifications. Overall dimensions and the design of the conning tower, torpedo-tubes and deck-fixtures pointed instead to D1.
“Every diver dreams of identifying a historically important wreck,” said lead diver Steve Mortimer. “Expecting to find the remains of a German U-boat, we were thrilled to discover a ground-breaking British submarine instead. It’s tremendous that D1 is now protected, but divers can still visit.”
Built by Vickers at Barrow-in-Furness, D1 was the secret prototype for the Royal Navy’s first diesel-powered submarines, the D-class. Launched in 1908 and commissioned the following September, it was a significant development on the smaller, less-powerful C-class.
At the start of WW1, HMS/m D1 patrolled to protect the Kent coast before venturing beyond English waters to monitor German shipping.
In September 1917 it joined the Portsmouth Local Defence Flotilla and a year later was relegated to training duties. Decommissioned and scuttled the following October, it was used for target practice in naval training exercises.
Considered vulnerable to uncontrolled salvage, more than a century later the rare example of a pre-WW1 submarine has now been scheduled for protection by the Department for Digital, Culture, Media & Sport on the advice of Historic England (HE).
“The D-class submarine was superior to the C-class, with innovations that became integral parts of future Royal Navy submarines,” said HE chief executive Duncan Wilson.