230 Challenger SE

I have 50 hours on my boat and put it on the beach maybe 5-6 times and the gel coat on the hull is worn through showing fiberglass. I do not leave my boat up on shore but I do pull up to let my Family out. What is really wierd is it is also Dissapearing from the aft end as well, not sure what that is about. The boat is a 2008 with really minimal use on it and really minimal use on the beach. All the video show boats up on the beach but if just after 5 times I would not recommend doing this, very very costly to repair. Anyone else have any issues like this, ??