Among the many small craft developed or adapted during World War II for British Commandos and Special Forces, one at least must be described here. If it had been committed to action as planned, the Vosper Boom Patrol Boat would have been as extra-hazardous, if not properly suicidal, as the Italian EMB which inspired it.
The suicidal attack on Valletta, Malta, made by Italian MTM explosive boats in July 1941. After close study of an intact MTM captured there, the British firm of Vosper was asked to construct a similar boat – with the added capability of being air-dropped, with its pilot, into a target area. This requirement was probably originated by LtCol H. G. “Blondie” Hasler, RM, commander of the raiding force with the innocent cover-name of Royal Marine Boom Patrol Detachment (RMBPD) and best known as the planner and leader of the “Cockleshell” canoeists’ assault on shipping at Bordeaux in December 1942.
The Vosper-built EMB, cover-named the Boom Patrol Boat (BPB), closely resembled its Italian model. It weighed c.1.5 tons and was 18ft (5.5m) in length and 5ft (1.52m) in beam. Its internal combustion engine, an American-built, 12-cylinder, 140hp Gray Fireball, gave a maximum speed of above 30kt (34.5mph, 55.5kmh), with an action radius of some 60nm (69 miles, 111km) at cruising speed. Its bow-mounted charge of c.500lb (226kg) of TNT was somewhat smaller than that of the Italian boat, but its fuzing system – impact, hydrostatic or time-fuze – was electrical rather than mechanical, thus allowing the pilot to select a system at any time during an attack. Operational procedure was the same as that of the MTM: in the target area, the pilot would select his victim, aim his boat, bring it to maximum speed, and then ditch with his back-rest/life-raft (called a “flutterboard”).