Hi - chipping in to this thread again in case the op is still looking. Here is a link to my post #27 on this thread from 2016:
This details the osmosis repair on my boat. 2 key points from that:
Turns out that epoxy resin should not be used with CSM because it doesnt dissolve the powders they use in CSM to bind the mat together.
Vinylester resin is very much superior to polyester, doesnt give the problems you get with epoxy & costs less than epoxy.
Actually I think things have moved on a bit from my understanding then - I believe you can now get 2 different types of chopped strand mat - one for use with polyester/vinylester, & a special one for use with epoxy.
Replacing peeled laminate with CSM does add strength and it is much easier to get layers of CSM to reliably bond together rather than using cloth - all according to my surveyor
in UK who literally wrote the book on these sort of repairs
So to repeat what I said earlier - depending on how bad the hull is - in other words, how DEEP the blisters are - IMHO you either make do & mend (& keep mending) so you can go sailing, or you go the whole hog & do the job right first time. Just be aware you are unlikely to get your repair costs back. I dont see much point in trying for some happy medium which doesnt exist.
I agree with earlier posts - I wouldnt worry about what the underwater hull looks like as long as it is reasonably smooth.
In this context. blisters in the gelcoat
only are not much worse than just cosmetic