Dog, I think we agree on the practicality of the cure to the blister problem. But skinning a boat is not drying out.
Skinning a boat is often part of the drying out process... you can't dry out a boat that has gelcoat still on the laminate in any reasonable amount of time. In several cases I've seen, the gelcoat was peeled, but the laminate underneath was left intact. The repair on these boats didn't require additional re-glassing. Instead of being re-gelcoated, the boats were coated with an epoxy-based barrier coat.
That is completely replacing the crappy resin/lay up from the factory, provided the roving mesh underneath is good. On my boat I skinned much larger sections than necessary to try and replace as much as I could of the failed resin around the blisters. I believe that a complete skin out will solve the problem. But with good epoxy or resin you wouldn't have to worry about water disintegrating any components of the new skin. And I think barrier coating is a great idea provided the hull is dry, being new skin or just dried out well and not mechanically falling apart.
If the hull is mechanically falling apart... there's not much you can do except scrap the boat.
Permeable is one thing, but chemecally changing because water is present is another. A substance can be 'waterproof' and semi-permeable I guess. But it is not supposed to chemically change and turn from solid to liquid just because it's wet.
Unlike what you're suggesting, the GRP itself isn't changing state—
the GRP isn't changing from a solid into a liquid.
What is happening is pockets of fluid are collecting and forming and forcing apart the layers of GRP.
This is why bad osmotic blistering is considered a structural problem rather than just a cosmetic one. The water that has permeated the fiberglass collects in certain locations due to osmotic pressure created by water soluble chemical deposits being located there and forcing the layers of laminate apart—resulting in the blisters.
This is also why the fluid in most blisters is under a fair amount of pressure—because the fluid has forced the surrounding laminate out of shape and the laminate wants to return to its former shape...applying pressure to the fluid inside the blister.
In many cases, the blistering occurs between the gelcoat and the underlying fiberglass—this is mostly a cosmetic problem since it isn't affecting the strength of the laminate to any real degree, and often due to contaminants in or on the gelcoat during the layup process. In the more unusual case, where the blisters occur between layers of laminate, it becomes a structural problem.
Everyone seems to think that if water gets in the hull it WILL blister. That is just not the case.
Some resins were worse than others... there was a run of Valiants in the 1970's that used a "fire-retardant" resin... and almost all the boats built using that resin have blistered at some point. The resin manufacturers are going to say it is waterproof... but in reality, even if it is mixed and laid up perfectly, it will allow some water through over time. The main difference is whether the water causes damage or not.
Some companies had more problems than others for some reason. It may have had to do with the specific resins they were using, or the techniques of layup they were using, but not all fiberglass hulls will have osmotic blistering problems.
I think that there are a large number of variables that all contribute to whether a specific boat will have osmotic blistering issues. One may be whether the interior was gelcoated or not. One may be whether the boat has a wet bilge or not. One is probably be the exact mix and composition of the resin used in the layup. Another is how well the temperature and humidity were controlled when the hull was being laid up. Another may be how much excess resin is in a specific hull.
A lot of these things were not understood at the time they started building fiberglass boats. Some are only being fully realized today. Back in the early days of fiberglass boat building, they built the hulls very thick and often used more resin that was optimal. Today, they often use less resin and build the hulls thinner, but engineer the hulls to be just as stiff and rigid as the older hulls by incorporating core materials and such.
I don't know as a fact but I am going to guess that my boat didn't come from the factory with a barrier coat. Because Frank Butler didn't expect it to fall apart when it got wet. Probably becasue he looked on the front of the can of resin he was using and it said 'waterproof'.
Yes, polyester resin is "waterproof" in that you can make things with it and expect the water to stay on one side of it or the other. However, individual water molecules do enter the resin and can possibly cause damage to it. If you made a bucket of polyester resin and fiberglass cloth, I'm sure you could use it to carry water... since, in the broader sense, it is waterproof, but don't mistake waterproof in the broader sense for water impermeable.
