Use a cleaner like McGuires first. That should protect it but provide some protection for the fiberglass. On the smooth topsides, I'd use a normal marine wax -- assuming your topsides are gelcoat. In any event, don't use a normal wax on non-skid unless you plan to have an early Viking funeral.

Ultimately, if plastic stays in the sun, the sun will win. You want to keep it 40 years from when the boat was made :^)

In any event, don't use a normal wax on non-skid unless you plan to have an early Viking funeral.