Mike,
I think that your best bet Mike is to find someone who has an O'Day 25 similar to yours and ask if you can take some measurements. I would be more concerned with the measurements of the chainplates on the deck as opposed to the bulkhead. Your side stays have to fit in the same way that they did before the PO removed them. So the height of the turnbuckle toggle holes, as well as the exact location in relation to the gunwale and the side of the cabin need to be taken into consideration. Years ago, I installed two O'Day 25 chainplates on my O'Day 222 and I had no holes to go by. My original chainplates consisted of two "U" type bolts with "L" brackets mounted on my bulkhead. I had to wind up cutting the slots in my deck to accommodate the chainplate bars. The bars are angled at the top where the stays connect. So after talking to Rudy at D&R Marine where I bought the OD 25 chainplates, he said that the holes should be level with the deck and this means that the chainplates will be on an angle toward the center of the cabin. Once you get the deck dimensions right, the bulkhead should come right. I beefed up my bulkhead with solid oak in the V berth section and bolted the chainplates through the oak. The oak is also bolted to the settees in my cabin. This worked out great for my boat with the exception of water eventually getting in around the chainplates and soaking the areas of my bulkhead, which is what caused the demise of the bulkhead on your boat. So I had stainless steel covers made up and welded to my chainplates on the deck with bolts holes for extra strength and to keep the water out. My problems were solved after that. You don't have to go the same route I did with the Oak and welded chainplate covers. Just get the measurements right on the deck and put it back the way they had it set up at the factory. Keep them caulked and check to make sure that it never leaks again. I hope that I was able to offer you a little insight on what is really important to getting the stays to fit right. Check out my pictures under Owner's Photo Album- OD 222- Trinkka. Good Luck!
If you've got the chainplates I can take some measurements and pix off of my boat. You should be able to get it close enough to work. What year is your boat?
My pleasure Mike. I got the idea for the plates from Rudy at D&R Marine, and the plates are a great idea, but careful measurements must be taken before making them up for the bolts. There is plenty of room for the bolts and back up plates in the main cabin whereas the chainplates are bolted on that side, but the thickness of the bulkhead has to be taken into consideration for the plate bolts to come through on the back side or V berth section of the bulkhead. Consequently, the plate may need to be longer toward the bow. This never occurred to me when I brought my boat down to the Marine welder, but it all worked out in the end. He made the plates, fitted them and put a couple of tack welds. Then I removed the chainplates and he finished the job. I later had to do a little chisel work on my oak back up boards to accommodate the back up plates and nuts w/bolts. As I look back now the efforts, time and money were worth it.
Rich,Here's the measurement to the inside hull.
When you fit the bulkheads into place there should be a good sized gap between it and the hull and then fiberglassed to it.
Rich
Rich,Here some measurements and pics to help you position your chain plates.
I measured between the chain plates at the bottom inside corner and at the point inside the cabin where they go up thru the cabin top. And also from the top of the chainplate to the nonskid on the deck. If you have the cover plates and the screw holes still in the deck you shouldn't have any trouble positioning the chainplates from side to side.
The chainplates are angled inward-
Here's a shot of the chainplates mounted on the forward side of the bulkheads. This will give you an idea of the angle (The string is actually straight. Distortion from the camera makes it look like it's sagging). I think you'll be alright as long as you're close. You might try to get the angle from these photos. The critical measurement is the height above the deck. I'm assuming that there wasn't any design changes in the years between our boats. Of course Rudy would probably know if there were.