Sandwich construction

A form of construction used for hulls,

decks and houses, in which two relatively dense skins are held apart and

stabilised by a thicker core of lightweight material. The core may be of balsa

wood, for example, or of foamed plastic. The idea is to save weight and achieve

stiffness, for although a thick skin of plastic material may be quite strong it

will bend easily. Two such skins held apart and prevented from buckling by an

inner core can be a hundred times stiffer than either alone. But it is

essential to get a good bond between skins and core, and to be sure that there

are no cavities into which water could penetrate.