The Knuckleduster's straight-sided hull was of all-metal (Alclad) box-section construction, from the bow as far as the pointed main step at the rear of the planing bottom; aft of the main step the fuselage was of monocoque construction.
The Knuckleduster's hull was constructed with a straight-sided, metal (Alclad) box-section design that extended from the bow to the main step at the rear of the planing bottom; after this point, the fuselage adopted a monocoque configuration.