Paul, I take your point about the layered look of the beams. The components are cut from six different billets. To my eye the outer components match, but the middle piece, which is slightly thicker, seems a shade darker. Perhaps it’s the grain or glue line which draws your eye to it? The alternative - cutting 8 mortises in each of 15 beams - is a little terrifying to consider. Hopefully, there will be enough other things to distract attention to it.
Uwek, thanks for the suggestion to will mark a mid-point on each beam as they will need to line up so the carlings fit neatly. I think Paul has likened model ship building to a game of Jenga and he is right - there’s a lot of things that have to fit together and I feel I need to be thinking a couple of steps ahead most of the time.
Here are deck beams laid out as sit in order in the hull, bow on bottom and stern on top.
View attachment 423359
Beam 3 and 4 touch (but are at different heights).
I have been testing the beams in the hull and, as far as I can tell, everything is OK. Some adjustments will be needed to the beams in the bow and stern because of the frame bevelling, but the midship beams seem to need very little.