Thanks for that. The tolerance for the transom inner/outer parallel seems to be 1/8" which I'm fine with. It's well within that at the moment and I'll keep checking it as I lay on glass. Which is where I am now! The second transom board is fitted, and tabbed in. It also got the resin and glass sandwich treatment and is tabbed in. Time overtook me and I didn't get any glass on the outside of it, which is a shame as the weather has turned (again) and is damp and misty. It rained a bit last night and the transom board got damp, although it's covered up, so I'll have to wait for things to dry out and warm up again before I continue.
A question for the experts. On the old transom, at each top corner of the keyhole, there was a deep recessed sort of countersink. You can see one of them, coloured white, in the attached picture. What are they for and are they needed? I looked at the back side of the inner transom plate and there are no lumps, bumps or shapes at all that might relate to these recesses. Another thing I noticed is the fact that the same inner transom plate has a sort of curve on it, in that it's not totally flat, so how does it sit flush and snug against the inner transom? Is it supposed to? I didn't notice anything unusual about it when I removed it, so any thoughts appreciated.
As to the engine mounts/stringers that I wanted to run full size all the way to the transom, as opposed to the stepped reduction that they presently have, I began some head scratching as to why they reduced in size at all. I figured it's to facilitate something on the engine, perhaps giving better access. So a closer look at the engine, on it's stand, reveals the bell housing area swells out somewhat and dips below the level of the engine mounts. So it seems that this is why it's built that way. looks like I'll have to replace like with like, but in a tidier, stronger way. Some relevant measurements should help. I don't have the means to drop the engine in for dry fitting/ testing etc. so I'll just work around that. And a picture of the second transom board, in place, tabbed in, with some screws in place to keep it pulled together. When I took my clamps etc. away, everything stayed put with no movement or pulling. Getting there......
Transom board 2.jpg
Transom 2.jpg