the development, fabrication, and testing of a complete submarine hull insulation materials system, based upon an anti-sweat fiberglass insulation panel is described. recommendations for further work are outlined. in the product submitted, one-inch-thick felts of three pounds per cubic foot density, made from five-micron diameter glass fiber are sandwiched between three-ounce, woven fiberglass scrims, sewn in place by a quilting technique which uses teflon-coated fiberglass thread. the core felts are rendered water-repellant by incorporation of a reactive silicone in the phenolic binder systems which are employed in their manufacture. the scrimmed structures are designed to be sufficiently strong in the direction perpendicular to the plane that they can be attached to a painted hull by means of a two-component, solvent-free, high strength, spray-applied polyurethane adhesive. the scrimmed felts are covered (on one face) with tough, woven fiberglass facings which incorporate aluminum-coated mylar films. these are employed to provide durable wear surfaces and protective water-vapor barriers. these facings are attached to the panels by use of a very light loading of specially developed, high-strength polyurethane adhesive. seams are covered with fiberglass tape, and treated with a vapor-barrier coating