Specification
The craft was about 51 feet (15.5 m) long, 5.5 feet (1.68 m) in maximum diameter and displaced 27 tons surfaced and 30 tons submerged. Propulsion was by a 4-cylinder Gardner 42 hp diesel engine, converted from a type used in London buses, and a 30 hp electric motor, giving a maximum surface speed of 6.5 knots (12 km/h), and a submerged speed of 5.5 knots (10.1 km/h). The crew initially numbered three—commander, pilot and ERA (Engine Room Artificer, i.e. engineer) but soon a specialist diver was added, for which an airlock, known as a wet and dry compartment, was provided. The ERA, usually a Navy Chief Petty Officer, operated most of, and maintained all of, the machinery in the vessel.
The weapons on the "X-Craft" were two side-cargoes - explosive charges held on opposite sides of the hull with two tons of amatol in each. The intention was to drop these on the sea bed underneath the target then escape. The charges were detonated by a time fuse.
The craft were fitted with electro-magnets to evade detection by anti-submarine detectors on the sea bed.
Read more about this topic: X Class Submarine