FYI source of info on repair WEST SYSTEM Gel Coat Blisters: Diagnosis, Repair and Prevention Book | West... (http://www.westmarine.com/buy/west-system--gel-coat-blisters-diagnosis-repair-and-prevention-book--384420)
A word of caution, epoxy is not compatible with gel coat. That is, you can't put a gel coat finish over epoxy.
West states that you can. I did it on the skylight that I made and so far it is okay. You must wait for it to fully cure and remove the blush. http://www.westsystem.com/ss/assets/Uploads/Ew22Polyester.pdf