Since the boat hasn't been hauled for so long, it's going to be a horror show of marine
growth unless it's been moored in severely polluted water
. You'll have to get the hull
cleaned which will probably take a diver most of a day to do. The diver should be able to identify any blistering while he's cleaning
the boat. The blisters
don't stick out very far. If it's minor, he might miss it but should feel blistering that's enough to be a problem while scrubbing the bottom.
are caused by water
either dissolving or reacting with the resin. Essentially, the resin is washed away leaving unresined fiberglass
roving, matt and cloth. Gel coat is pretty much water impermable so protects the underlying FRP layup
to an extent. The problem with gel coat is it's more brittle than the FRP laminate so develops a bunch of microscopic cracks that let water into the FRP laminate. The thicker the gel coat, the more prone it is to cracking. Water is going to get to the laminate but isn't a significant problem if the resin doesn't react with the water.
The cure for blistering is to grind any blisters down to good resined laminate and let the boat dry out. Fill any deep areas with cloth, matt and epoxy
resin. Shallower blisters can either be filled with matt and epoxy
or just epoxy with a filler. If blistering is significant, the gel coat should be ground off to a bare laminate. Then coat the hull
with multiple layers of epoxy 'Barrier Coat.' All the bottom paint
manufacturers sell specially formulated resin for this purpose. Epoxy will slow the penetration of water since epoxy is pretty much a water barrier and more flexible than gel coat. Unfortunately, some water will still get in through minute cracks in the epoxy and the barrier redone regularly in a hull prone to blistering.
Just out of curiosity, if the boat has been on a mooring
, how have they kept the boat from flooding. I find it hard to believe there are no leaks
, however minor. The boat would have to have the bilge
pumped regularly. If it had an electric bilge pump
, they would have had to have some way to recharge the batteries. Ideally the boat would have not had a battery
on board but that seems unlikely.