First, you should be filling the voids with THICKENED EPOXY, not regular epoxy. Plain epoxy is a lousy filler material.
Second, 407 microballon fairing additive isn't really a good one for underwater use. It tends to absorb water, especially if you sand it and don't coat it with a skim coat of epoxy. Fumed silica or cabo-sil is a much better choice IMHO. Also, microballoon-thickened epoxy tends to sag and run more than cabosil thickened epoxy of the same viscosity in my experience. That makes it less useful for fairing or filling blisters.
If you're going to add something for durability, I would recommend adding a layer of KEVLAR and then a layer of fiberglass over it. Kevlar is far more puncture resistant than fiberglass and also far more abrasion resistant. It makes a hull far more damage resistant than adding just plain fiberglass. However, you need to add the fiberglass over the kevlar when laminating the kevlar, as it tends to float in the resin otherwise... and you will probably want to add two layers of fiberglass over the kevlar, since if you sand through the fiberglass into the kevlar, you'll really regret it... It doesn't sand at all well and merely abrades a bit...and makes the hull "fuzzy"... DAMHIK.
If you're going to coat with epoxy for "barrier coating", I'd recommend using MAS, System 3 or Progressive Epoxy Polymers resins rather than West Systems, as the former are no-blush epoxies IIRC, unlike West Systems. Some of them have additives to help improve the water impermeability of the epoxy resin which you may or may not want to use.
Don't forget to hot coat the first layer of bottom paint to the epoxy barrier coating. You can do this by applying the paint when the epoxy is cured to the point where it will take a thumbprint, but is no longer tacky or sticky to the touch.
Originally Posted by kjsailingSpring
I'm embarking on my first refit of my Ta Shing Baba 35' and need to know if I'm finishing the hull correctly. It has been stripped down to the fiberglass (picture included) because of blistering. I don't see much evidence of blistering now and the hull looks great to me (am I wrong?). What I am planning on doing is filling the tiny voids with straight epoxy (West System 105 & 205) and fairing the blister spots with West System 105 and 407 fairing compound. Sand smooth, add layer of epoxy and then lay 2 layers of fiberglass for extra strength and durability. Then 5 or 6 coats of epoxy and then antifouling paint. Is this the correct process?