Abstract: A marine structure submersible in seawater, such as a hull, which when electrically activated is then resistant to fouling by marine organisms. The hull is formed by a structural laminate having a core sandwiched between inner and outer skins. The outer skin which forms the exposed surface of the hull is coated with a metallic paint defining a cathodic electrode. The core is constituted by balsa wood or foam plastic modules attached to an open-mesh scrim that includes conductive fibers to create an electrical grid defining an anodic electrode that is embedded in the laminate. Impressed across the electrodes is a direct voltage to establish an electric field causing marine organisms which seek to foul the hull surface to migrate away from this surface. Alternatively, the cathodic electrode may be formed by an open-mesh scrim defining an electrical grid interposed between the core and the outer skin.

Abstract: A foam-plastic core for a structural laminate produced by converting standard, rectangular slabs of closed-cell, rigid foam plastic stock in which the density of each slab varies from the inner to the outer regions thereof into relatively thin panels useable as the core of a structural laminate in which the core is sandwiched between facing sheets. To produce these cores, several standard slabs are stacked and bonded together by parallel lines of adhesive compatible with the foam plastic material to create a large multi-slab block. The block is then sliced transversely in parallel planes normal to the lines of adhesive to yield a plurality of panels. Each panel is composed of a series of interconnected foam-plastic sections derived from respective slabs of the block whereby the density of the sections is evenly distributed throughout the panel and the mechanical properites of the panel are therefore predictable and satisfy structural laminate criteria.

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.