Could you see how the water got in there to rot the ply? Was there a ventilator or something there? Are you replacing it with more ply? Also, thanks for the great pictures; keep 'em coming...
Wilson and I (mostly Wilson;) spent part of the afternoon replacing the cap on our 23' Mako. Maybe Wilson can snap a few pictures and post them. We had some serious water in the old balsa.
JimCt - take a look at the picture just before this one in the 'cap rebuild' gallery. You can see the cap was cracked from some accident before I got the boat. There was a lifting ring there that I removed to get to the rotten core. What a mess huh?