Snapping Fins

my friend and I recently bought some new Al Merick's which came outfitted with (presumably) some high end FCS style fins. Well, I'll be the first to admit that neither of us are terribly experienced with about 6 months of surfing under our belts, but we were very surprised to see that all the fins busted off leaving the teeth in the boards during our first outing. We believe it had to do with riding whitewash into the sand and the pressure as such, but it just seems a bit fishy.
Anyway, we replaced the old fins with these new Protech rubberized fins that work VERY VERY well but we were bummed to spend so much money on new boards and have the fins bust on the first day!
Anyway, we replaced the old fins with these new Protech rubberized fins that work VERY VERY well but we were bummed to spend so much money on new boards and have the fins bust on the first day!