On my 2006 Sea Breeze, the floor construction from top to bottom is:
Plywood (I can clearly see it is plywood) attached to steel support frame
Block insulation between steel supports
Thin gauge steel (painted black) attached to bottom of steel support frame and visible from storage bays.
I was able to see this by removing the 12v breaker panel and following the wiring thru the flooring. Hope this helps and let us know how your repairs go, with pics of possible.
Steve & Cheryl Walsh
2006 National Sea Breeze 1350
Orange Park, FL