Rick wrote: 2nd of 2: "Submanaut". Made of 4 in. thick PLYWOOD "donuts", covered with 0.75 in. of epoxied glass fibre. TESTED to 350 ft., operating depth 200 ft. Crush depth calculated at 1,000 ft. 4 hrs. at 1 kt That is fabulous! Where can I read more about that sub? Paul