. Explosive motorboats were designed to make a silent approach to a moored warship, set a collision course and run into full gear until the last 200 or 100 yards to the target, when the pilot would eject after blocking the rudder. At impact, the hull would be broken amidships by a small explosive charge, sinking the boat and the warhead, which was fitted with a water-pressure fuse set to go off at a depth of one metre. By the end of September 1938 the Navy Department ordered six explosive boats