Just picked up a 1988 fiberglass tuff-weave Sundowner 18 for real cheap because it needs repair to three cracked cross-ribs. Owner said they got high-centered on a mid-stream boulder and the bow paddler did some unwise rocking which caused the damage. The hull material didn't appear to crack and doesn't leak but three of the foam core cross ribs did and there is a compromise in the hull stiffness now. My question (already looked at Wenonah website but no help) is what actual material were there cross ribs made of? Should I carefully cut them out and remove them and fabricate or appropriate new ones to re-fiberglass on the floor? Any advice out there?