In theory that’s how its suppose to work ….i.e. no water creep
Looks like that theory didn’t apply here !!!
And I think Capt Chuck has something about the delamination ..I too had areas like this .. maybe it "flexed" one to many times or wasn’t lay-up right to begin with and the bond broke between the glass cap and the end grain…
For me all soft spots were recored with ply wood ...although some of the composite materials would have been good to use in this case ....just gets expensive
The end grain balsa has good strength to weight ratio and can be formed to some degree...so that’s probably why it was used here …and you can still buy it .. as far as the squares go ….I know my hatches had squares cut out of PLYWOOD and laminated together to form the core ….. but that was to help keep such a large are “true” and eliminated cupping that can be seen with sheets of plywood …. There is a thread where Hermco informs us of that …. I would presume that the squares were used to laminated the cap as such and made for an easy lay-up