If sand-blasting, make sure a bare minimum of 2 , preferably at least 3 build-up layers of barrier coat are applied after the necessary filler is applied and faired, and obviously before the antifouling is applied.
Our boat was sand-blasted , and while it was terrific to get rid of the 10 + yr/layers of chipping hard epoxy A/F under the ablative, the sight of the former gel-coat before the filling and fairing was a major pause. Sand was the only type my storage yard would sub-contract.I would have much preferred the somewhat more forgiving shells or soda blasting, but they all have risks if performed by the inexpert.
Even with no blisters , any voids just below the thin surface gelcoat will be revealed, ready to be filled. All in all, I'm glad these(several up to quarter-sized & loads of much smaller) voids were found and filled but in some ways I wish I had not blasted and seen them. Ignorance is bliss.
The blasting was done by a very experienced expert-hand at this. Someone not seriously used to blasting fiberglass hulls could really cause big problems. Beautifully smooth hull & ablative A/F now & I like that.
If possible, get an all-inclusive total price with particular regard to any filling & fairing necessary and specified coats of barrier (i.e., InterProtect 2000/2001?).
