/Removed the old polycarbonate FCS cracked fin plug out of EPS board. All was bone dry ( I thought ). Installed p/u some ( with epoxy ) foam to fill old space prior to installing new FCS anchor and notice water oozing out. Tastes salty. Fear a bad bond if water is in there. What to do?
EPS foam is like a sponge. Water is like kryptonite to epoxy. You’re going to have to dry that blank out before any epoxy will adhere to the foam. Unless you’re using a vacuum rig to suck the water out it may take a couple weeks for the water to evaporate sufficiently to work with the foam.
when the board is cool. take it outside and lay it in the sun. Fin hole down so gravity helps. You’ve read how EPS outgasses when heated? Sometimes expanding gas and gravity can be your friend. Do it for several cycles over several mornings. Until you can put a tissue paper in the hole, and it comes out dry.
For the pro repair, use a vacuum pump at the fin hole , with another hole drilled top side to let air in. Patch both holes.