Since the fixings don't seem to be removable, I'm thinking of sealing them
from above, using some sort of mastic or highly-flexible sealant, perhaps


Wally, you're going to get plenty of real advise on this one, so I don't feel
there's anything wrong with me pointing out that you're a royal putz who
shouldn't be allowed to own a boat.
Non removable fixings????

Bwahahahahahahaha!

RB