Abstract: A light-weight contourable core of high strength for inclusion in boat hulls in which the core is sandwiched between facing sheets of resin-reinforced fiberglass. The core is formed by a planar array of block-like modules made of end-grain balsa wood or other material having acceptable properties whose adjacent edges are held together by flexible adhesive joints that have a short elastic limit, such that when the planar core is pressed against a contoured surface for lamination thereto, the resultant stresses cause the joints to stretch beyond their elastic limit to an extent necessary to permit the modules to conform to this surface. There is no spring back when the pressure is released, and the modules, therefore, maintain their conformed positions.