Nothing will adhere well to cured smooth epoxy, not even epoxy... UNLESS is is so recently applied that there is a chemical bond. (Hours with WEST epoxy) and a bit longer with others like Systems Three.
When you say bare glass... do you mean bare gel coat, or bare glass? If it was sandblasted down to bare glass, that does create a good "tooth" for the next step, but slapping on a couple of coats of epoxy is not going to cut it. I have hydrosanded hulls bare. If that is what you mean, you probably ended up with a surface that was in need of re fairing! If it is major, that means squeegeeing on microlite, sanding
fair with a long board and/or the 8" soft pad disk, and then coat with epoxy! Always remove the blush before sanding
If the unfairness is minor, one could coat on 4 coats in one day, sand off two the next... say, three times. MINIMUM... Then a final sand to a glaze, and you are ready for bottom paint
. It should stick!
This all assumes the hull tested out very dry with a moisture meeter first! BTW, when drying a hull, it is best to hang a plastic skirt around the hull and put one or two dehumidifiers in there for months, as well as wipe it down with acetone DAILY. (just turn off the dehumidifiers and lift
the skirt first, so you don't kill yourself!)
If the hull tested dry before the epoxy, the paint
didn't stick because the epoxy was not sanded.
When it comes to the bond between layers of epoxy or ANY two part paints, the surface must be 100% sanded. This doesn't mean just run a sander over the hull, it means that the hull must be fair enough first, that there are NO concaves that the sander misses, and there are NO shiny spots. (Not even the size of a BB!)
I have seen so many people get this wrong, including pros. It is a lot of work, but the poor bonding between layers of anything on your boat, can be years of work, or tens of thousands of $$$. This is no exaggeration!
With any 100% solids epoxy, or LP type paints... To SAND, means to a totally glazed, no shiny spots appearance!
Once you go to the above trouble and have a dry barrier coated hull, it is WELL worth it to keep a dry bilge
. You may have to go with a dripless shaft seal
, or build small sumps around the shaft / engine
, or even the base of the mast
. Then epoxy coat these small sumps really well, and install separate small bilge
pumps, or have one sump tube drain into the lower sump, and let its pump take care of the small amounts of water
. Then have one or two huge pumps up 6" higher for true emergencies. Do what ever it takes to keep a dry bilge, if you want your dry hull to stay that way! Best of luck...