[stangtjk]

Between the inner and outer walls there is a center support running front to back and three supports on each side running left to right. My top was sagging between each of these supports creating 6 distinct rectangular areas. I cut out each rectangle leaving the parts of the top over the supports and being careful not to cut into the interior wall Then I glued some 1/2" thick rigid foam insulation in the opening and sanded it down with a long sanding block using the top that remained over the supports as a guide. After it was all shaped fiberglassed the entire top surface with a continuous piece of woven fiberglass cloth and epoxy resin.