It is standard practice to fit FRP decks and superstructres to production line craft . Custom made decks based on a standard moulding have been discussed. The moulding may be single skin or more usually sandwich construction. Ply is the favoured core for working boats where weight is lesscritical while allowing fastenings to be applied to the deck with little fear of crushing the core. Because of its relative inflexibility ply should be sawn to blocks of 150% 200 mm and installed individually to achieve a void-free bond.