We knew from the beginning that the bulkheads would likely need to be replaced. Like every Tanzer we saw in the used market, there had clearly been some water intrusion through the chainplate seal (or lack thereof). Honestly, the areas around all of the bolts and screws (including around the chainplate bolts themselves) were still solid, and none of the bolt holes in the bulkhead were elongated. Perhaps these bulkheads could have served for a little while longer, however, I am hesitant to take chances on the parts that hold up the mast.
It may be worth noting that this is one of the earlier models, so it has a teak veneered plywood. The veneer was very thin and would have been impossible to refinish. The factory plywood was five plys (not including the veneers).
We purchased Meranti 12mm, 9 ply plywood from Noah's Marine as the replacement material. It may not look as nice as teak plywood, but Noah's assured me that Meranti would be the best structural bet for this purpose (and it was about half the price). They also cut the 4x8 in half for me so that it would be easier to bring home. The remaining half will be used in the portlight recoring project.
In order to cut it, I used a jig saw borrowed from the Toronto Tool Library and a Bosch 101ao blade. I read several places that the 101ao was the best for Meranti (as it splinters very badly) and it worked very well. A bit slow in cutting, but no splinters no matter which way I was cutting across the face veneer.
I didn't take any pictures of the shaping portion of the project, but the only edge of the bulkhead that is square is the one that fits into the teak molding piece at the entryway to the v-berth. The rest all need to be faired to match the curvature of the hull.
It was a mistake to follow the fairing of the factory bulkhead. I copied the angles exactly (without going to the boat to see if they were correct). The angles on the factory bulkhead were far too radical, and I am now going to have to try to build a couple of places back up to provide maximum contact between the bulkhead and the surrounding hull. I was frustrated to find this out when I finally did get the bulkhead into the boat. I won't make the same mistake on the starboard side.
Oh, and fairing the bulkhead was not easy. The end grain of 9 plys of meranti is not cooperative to shaping. I tried a hand plane, file, rasp, block sander, and random orbital sander. The random orbital sander seemed to work the best, along with the block sander. The hand plane did nothing.
There is a "slot" in the bulkhead that I read was for removing the teak trim that covers the deck/hull joint on the inside. The teak trim in this boat is in two pieces fore/aft, so I had considered not including the "slot" when remaking the bulkhead.
However, I decided to stick with the factory design, and on the first dry fit, I am very glad that I had kept it. The assembly became wedged in pretty good on the first try, and I was struggling for a way to get the thing back out (not much to hold on to!). Then I realized that the slot was perfectly sized to stick the paddle through. It worked great, and if that is the only time that slot is useful, it was worth it!
However, I decided to stick with the factory design, and on the first dry fit, I am very glad that I had kept it. The assembly became wedged in pretty good on the first try, and I was struggling for a way to get the thing back out (not much to hold on to!). Then I realized that the slot was perfectly sized to stick the paddle through. It worked great, and if that is the only time that slot is useful, it was worth it!
Update: Now this is what I was worried about, the chainplate bolts in the starboard bulkhead have clearly migrated "north." There was a real chance of this failing in the near future, so I'm glad we are replacing it.