Capt. Neal® wrote:
No osmosis? Then how on God's green Earth do you think those
little blisters formed?

Easy. Some bonehead (possibly a relative of yours) did not do the
correct surface prep on the hull. Then another person of approximately
the same mental capacity sanded through the barrier coat, allowing water
between the fiberglass and the layers of paint.

Osmotic blisters in fiberglass are a totally different thing from
blistered paint, which can occur on cars or houses...

DSK