I put bulkheads into my Tred Avon, with storage in the hull. The idea was to get watertight flotation compartments, with no hatches on deck. I put 4" deck plates into the bulkheads to allow them to breathe and dry. But, I put the access hatched about 1-1/2" above the keel, and water got in there. It either leaked around the access hatches, or condensed. Leaked I think, we were doing wet reentries. The water is difficult to remove, it will not run out because the access is too high. I can get most of it by tilting the hull as far as I can and shaking it, but still there is more left than will evaporate in a reasonable time. I can make an attachment for the shopvac to suck it out, but that wont work in the field. I'm happy with the arrangement, but if you are considering it, put the access ports as low as they will go...