I contacted the company, here is their response:
"Thank you for contacting Gold Eagle Company. 303® Aerospace Protectant can be used on Gel Coat fiberglass finish. We recommend applying 303® Aerospace Protectant instead of wax, since they can't be used together as they would repel each other. 303AP would have to be reapplied 3-4 months for very sunny conditions up to 6-8 months (seasonal) for less sunny environments. If applied properly, rain or regular washing will not affect the coating. Hope this helps. Please let us know if you have any further questions."