able to actually climb inside through the access hole and use scrapers, saws and hammers to clean up the inside of the box. It was tight! I then used vacuum panels and blue board to build it back from the inside with a combination of vacuum panels and blue board to a 3 inch thickness. I used some sort of space age plastic that a friend provided. for the inside walls and bottom. He made industrial tanks and had the material left over. He then came in and welded up the seams with his plastic welder. You could do the same thing with fiberglass and epoxy. The one thing I would do again is make the bottom of the box flat and the walls vertical. The old box followed the shape of the hull and everything ended up at the bottom. This way, it all sits up right and is easy to reach. You loose a bit of space but gain in convenience.