I am restoring a 1985 Sea Nymph Fish And Ski 195. I have removed the fuel tank. It is a polyethylene 24 gal tank made by Kracor. The tank sits on a riveted in alum cradle about 2 inches above the inside if the hull. Under the tank and lining the cradle is a thin liner that has the consistency of brown kraft paper with reinforcement string throughout. It resembles the brown reinforced shipping tape used on packages. Of course it is disintegrating and in very poor shape. I pulled up about 8 inches and decided to stop until I determined its purpose. It is too thin to provide any cushioning. My thought is leaning toward some kind of anti- static membrane. Any thoughts on its purpose???