The aft chain plates on Columbia 10.7 (as well as other boats) is a known problem. The chain plate for that shroud is attached to a short cabinet in the cabin. Over the years, the tabbing breaks and allows the chain plate to pull up on the deck, often cracking it and allowing water into the core.
I solved the problem by changing to a longer chain plate that extended below the cabinet and tying that chain plate to the lower stringer with a short cable. The stringer was also reinforced to resist the upwards pull of the shround. Pictures follow!
The stringer was reinforced with a 2' length of 1-1/2 x1-1/2 SS angle iron underneath. Wood filler blocks were then epoxu=ied in place under the stringer/angle iron. ^ layers of 6" fiberglass tape and epoxy were then laminated down the hull, over the stringer and filler blocks and down the hull. A forged eye bolt was installed in the center opening.