Ring and piston Failure diagnosis help

I took the head off and one piston had metal debris imbedded in the piston and head. The cylinder wall seems to be just fine, but the piston is missing a piece just above the top ring on the exhaust side about an inch long. The part of the piston missing is just above the ring. The ring in that area is also gone. It looks like the ring got caught and ripped the piston and all was deposited on top of the piston. The spark plug gap was completely closed so it was hit by debris.

What do you think and why would a ring break with about 30 hours on it. I should add that is a rebuilt 1999 GP1200x engine by PMC North America.

One other note, this occurred immediately after landing from a large wave.

Thanks,