Hi Heinrich. I hadn't been in for a while. Get low email alerts!?!
I am so sorry for you that this happend with your build. But glad that fellow builders have the courage to notice point.
When I came across those 1st two posts, I thought of 2 optical illusions, which I hoped were the cause.
I want to share them anyway, because the method of planks and the wood grain of the oak shown, can play tricks:
For the upper part of the transom:
View attachment 316285
The two big lines run parallel and are compleet right next to each other.
For the lower part:
View attachment 316290
It is a perfect rectangle. (For the best view, I rotated it 90dgr).
For both: scroll a line to the top of your screen to check.
So, respect for your decision, but necessary for this build.
Check, check and double check........ we know all ....... but don't let your eyes confuse you.
Regards, Peter