Just read the entire thread and thought I'd toss in some personal experience. I work in a boat yard and do quite a bit of bottom stripping etc.
Hopefully this won't bring on more lawsuit crap here, but every boat that I have sanded down that had 2000 for a barrier coat had loads of blisters just under the 2000. Like the 2000 was letting water in but not letting it back out. I get in arguments with the other yard guys regularly about it as it's still the only barrier coat we seem to offer here. I get the inproper prep reply often but many of the boats come from many other yards. I couldn't fathom that everyone was doing it wrong so I re-read the directions on the 2000 can numerous times. For some reason, possibly it's just been added, I'd never noticed some small print that says to go to their website for their "full" tech sheat instructions if desired. I advise anyone considering 2000 to go to the site themselves and check it out. First of all, they require an initial coat of their own straight epoxy before the 2000, along with other pretty rigid steps to the point that I doubt any yard has ever followed, even if they'd somehow known the steps existed.
As far as major blister problems, I'd advise going with stripping the gellcoat. Gellcoat is 99% of the time polyester resin which is not as waterproof as epoxy resin. And the problem with blisters is that the water supposedly changes chemically when trapped in with resin to the point that it will almost never really dry out without incredible effort and months to years in a rediculously dry and warm environment. We've just trialed a new electric mechanical stripper and have to say it is the cat's meow. It's actually a paint stripper which is simular to a grinder but has 3 triangular blades which do the stripping. One guy took the entire bottom gellcoat off a 37 foot Pearson in about 6 hours. Damn near a perfect removal to the glass on his first time using the tool. It's called a paint shaver pro and came mounted on what seems to be a Hitachi grinder body. You can check it out at American International Tool Industries, Inc. LLC | Makers of the Paint Shaver Pro paint stripping, paint stripping tools, paint removal, paint removal tools, paint scrapers, lead paint removal, stripping lead paint, infrared paint heater
. I'm not affiliated with em, but highly recomend it. Shaved to the glass quicker than even just sanding off the bottom paint alone. And it came with a vacume attatchment. Be prepared with ALOT of vacume bags but very little mess! Amazing tool.
Back to barrier coat. I will be going with straight West system epoxy on the Wanderer next winter. Just don't trust the whole microplatelet thing. How can millions of mechanic bonds to microplatelets be more impervious than a solid barrier completely chemically bonded to itself? Seems like a marketing gimmick to me. And as far as epoxies, I've seen MAS and can't say anything bad about them, but I absolutely love West System. I have never, ever heard anyone have West System fail. The only reason to me to even think about trying anything else is price, and these days there's just not enough difference in price to consider it. Hell, if all boats were built entirely out of West there wouldn't be a boat yard in business anywhere.