The imprinting is caused by the shelf "working" against the hull. In all likelihood, one or more of the partial bulkheads (to which the shelf is attached) have come loose. The interior of the boat is being pulled against the exterior.

I had this problem on my boat. I had an "innie" imprint on one side and an "outie" imprint on the other. I re-tabbed the loose bulkheads. Pictures of that repair are on the first page of the Deck Joint thread.

http://www.pearsonariel.org/discussi...3&pagenumber=1

Tony is going to solve the problem during his clean sweep and reconstruction. Nice work, by the way. I feel your pain.

As for other boats with this problem, I wouldn't panic. If your boat gets normal usage, I doesn't require immediate repair. It may get worse, albeit slowly. Still, it will have to be addressed. Movement is never a good thing.

On the outside, I faired the hull with microlight and painted the hull. Thats strictly cosmetic.