Osmosis

Day one of Shamrocks fiberglass peeling went well, starboard side done and 1/3 of the port side as well. Svendsen's Marine deep cut to remove all the mat, some cloth and in one area down to the woven roving, remaing glass has some voids/dry spots which will be ground out, but for the most part the remaining glass looks great, clean, dry and blister free.
Most of the problem with current blistering in the epoxy barrier coat and mat can be traced to inadiquate drying time back when the gelcoat was peeled in 1994, they peeled, epoxied, barrier coated, bottom painted and splased in one week, no drying time. The moisture trapped in the hull, mostly in the mat, caused blisters to form in the mat and under the epoxy. It's sort of like getting a deck leak and sealing it from inside the boat, water has no where to go but into the core material, temperature caused the core and water to expand and contract, delamination occures.
I have been studing osmosis reports and finding for 10 years and will never consider myself and expert in the field, conflicting information and proclaimed cures seem to be the norm. Most proclamed sucessful test reports I read with a grain of salt, some I find suspect. In particular, the product test panels I find interesting, but find it difficult to support as conclusive proof of one product viability over another, or testiment of proof of survivability in a real world environment.
Case in point, to calculate the viability of a material for permability in relation to the displacement of the BCC 14,000 pounds, the entire hull is displacing 14,000 pound of water, 8.345404 pound per gallon, a 1 square foot section of the hull is carring only a fraction of the total displacement, water pressure is greater near the keel than on the surface. I don't know what the actual pressure exerted on the hull is at either section of the hull, but I have to believe it is greater than a test panel  suspended/submerged in a test tank of water. In addition, what chemical polutants are introduced into the test tank to simulate marina invironment, diesel fuel, oil, paint thinner, acetone etc? As I said earler, I find the test panels interesting, but not conclusive.
As stated earlier, I'm a diesel mechanic who has taken a keen interest in boat design and construction, built boats and performed all facets of  boat repair sucessfuly over the last 20 years, by no mean do I consider myself a osmosis expert, every day I learning something new.
Osmosis prevention starts with quality products, mixed carefuly  and applied to avoid excess resin, air, and to esure through wetting of the fiberglass products. Hand lay up of fiberglass products (FRP) provides better product control and distribution through the glass. The best fiberglass applicators I've seen of late, seem to be high-end FRP kayak builders of ultra-light kayaks, turn boat hull builders; not an once of excess resin, all resin and hardners mixed to perfection, every ouce of glass saturated and squeeged to perfection, they make some of the lighest and strongest hulls you will ever see.
Polyester resin is still a good product, popular opinion suggests vylnalester and epoxy are reasonably good at "reducing" formation of blisters, vynalester costs forming a mid point between between polyester and epoxy. Prevailing opinion suggest epoxy is only slightly more effective than vynalester in preventing osmosis, while others contend the additional cost of epoxy may not be justified.
Material costs and labor are significantly higher with epoxy, it is a little more challenging to work with, as many builder find polyester and vynalester more easy to control in a production setting.
Our choice of epoxy for Shamrock new lay up had nothing to do with weather vynalester or epoxy is any better than the other; We chose epoxy as it is a familiar product that we have been using for years with excellent results. Our yard and its applicators have an excellent 10 year track record using epoxy in osmosis repair with the West System products.
I believe both products will work just fine in reducing osmosis. The key to sucess will depend more on adiquate drying of the hull, surface preparation, experienced product applicators and a decent warranty.  We learned a long ago, never ask someone to do something they are not either throughly experienced or comfortable in performing. Our yard has extensive background in epoxy repair, and lay up, a good track record, is very comfortable and confident in backing their work and so are we.
Best wishes to all,
Marty Chin, BCC Shamrock