In the second semi-final, three policemen from Hampshire (Cops and Bodgers) and a team from the Royal Navy (Destroyers) built curling machines that can skim full size, wheel-less cars across an ice rink. The winning team would be the one that has its car closest to the centre. Destroyers built a chain driven, motorized pushing arm; Cops and Bodgers built a gravity-driven hammer. In challenge day, the machine from Destroyers was broken, but eventually fixed. Destroyers won.