Out of curiosity, what does the cutout on the outside (toward the engine control panel in your photo) fit on the boat? Is it the right shape for the aft corner or swim platform of your transom? I'm thinking that 8" is too small for propane, but what about the top or bottom of a dive tank? Looks like it is made of Starboard. Any wear on the surfaces, or fasteners to secure it to the boat?