The bulkhead on my boat #25 is two layers of glass on the aft side with 3/4" plywood on the forward side. The plywood on my bulkhead was rotted at the chainplates on the starboard side. I had my yard remove the plywood and replace it with new plywood and lots of West system epoxy. They did an excellent job.
The key to the status of your bulkhead is the tabbing at the hull and the moisture content in the plywood. Check the the tabbing closely with a flashlight and a small rubber mallet. Check for delamination and or cracking. Check the plywood with a moisture meter and an awl. If there is moisture, then you have the potential for a problem. Stab the plywood with the awl. This will tell you if you have significant rot.
I assume that this problem is quite common. The old J30 forum had a lot of entries regarding this problem.
