The delam shown in your pic is quite uniform along the upper surface. As you noted, this is not usually the case. When I cut my 6 inch deck port holes (to also allow me to repair the hull delam) on my H16, the foam had separated from the upper layer in some areas, and the inner layer in others. The inner glass weave was about 1/2 an inch lower than where it would have been if not damaged. (It looked like a 3D map of mountains and valleys). It would have taken a lot of epoxy to fill in all of the space between the layers!

Mark
1976 H16 sail #19857