Guy's when I open my Tank area it was sealed off also with no drains etc. I insert a new polymer tank and marine foamed (close cell foam) it back in.
The top of my tank is curved in naturally so if any water penetrates in or condensation I would have see the accumulation on top of the tank, Just out of curiosity I opened one of the inspection hatch cover and have never seen any traces of water, I however saw 2 stroke oil this was because I did not tighten the fuel sender screws correctly which I have since corrected. I finished a tube of 5200 sealing the seam around the deck.
My thought process was I wanted to isolate this area in case the Tank pops a hole and leaks fuel, at lease it will be contained to this area only and will not hit the bilge pump and I go Kabul :)
Foam
Gel
PITA 5200 applied
