OK.

I knew I had some sort of trouble. The white laminate on the forward side was no longer glued down over large areas. I took the cabinets and sink out of the head and everthing off the bulhead and started peeling (carefull, the laminate is sharp along broken edges!). It helps a lot that Foghorn is sitting on her new trailer next to my garage and workshop!

The blukhead is almost entierly blasa cored. There is a thin layer of fiberglass matt over the foreward side, I suppose to hold the balsa together. The chainplates bolt into a triangle of 3/4" marine plywood. The plywood is about 15" wide at the top and 24" long and does not extend over to the hull (there is blasa from the edge of it to the hull. On the aft side of this there is about 1/4" of glass in the painted areas and seems like 1/8" and less under the veneer. There is about 1/2" of 3M 5200 like stuff between the bulkhead and the hull. The tabbing is about 1/4".

After peeling the laminate the extent of water damage was obvious. I could see it right through the glass surfacing and large areas of the matt had cracked. It peels of easily with a cutting tool and a chisel. I had soaking wet, water damaged, or missing balsa over a region from the hull to about 3 feet in from top to bottom. I have almost stripped it all. The plywood that the chainplate bolts to was about the consistency of cooked lasagne noodles and peeled out in big soft flakes.

There was really nothing other than the glass on the aft side holding the chainplate in. I'm not sure what the heavy tabbing on the foreward side was for since it is connected to nothing more than a thin layer of matt that glues together blocks of end-grain balsa.

A warning. The laminate on the foreward side started peeling last spring. Before that all looked well. However, this must have been going on for a long time. There are two places you can inspect the bulkhead core material: the access for wires and waterlines under the cabinets, and under the floor just foreward of the keel. Also, in the cabinet over the head you can tap holes into the plywood that the port chainplate bolts to and the starboard chainplate in accessable in the closet. My starboard chainplate looks fine from tap holes and visually with the laminate removed.