BTW, properly laminated glass does not absorb water.
Blisters result from moisture in the laminate but that happens when
the builder uses ultra cheap resin or has a bad mix like a chop gun
set for too little catalyst.
Better resin like vinlyester and especially epoxy have such low
moisture absorption rates that they are used as blister barriers.
Epoxy is also used to protect steel.
Therefore, if you want your boat last, use epoxy.
(Did I mention that we sell epoxy?).

Jacques
http://bateau2.com