You can see the lashing strake in this photo. (We can't see it in real life any more, except in a tidy pile in the boat shop, since Trevor has removed it in preparation for painting.)
|With cabin top nearing completion, things are looking distinctly more boat-like.
|Beam chocks. Note lovely purpleheart hatch combing, too.
On top of the chocks there are additional pieces. I lack the vocabulary to name them, but I can tell you they are the pieces through which the alignment pins pass. Or alignment bolts. My vocabulary seems to be not quite up to this part of the project.
Whatever they are called, the picture below shows them in one beam trough. They are made of ipe, an alarmingly-tropical (since not FSC-certified) hardwood from South America, via Westwind Hardwood. We likely would have used purpleheart for this, but it wasn't available in the appropriate (4x4) dimensions. Ipe is very hard, and this piece needs to be very strong and resistant to wear.
No doubt there are official nautical terms for all these bits and pieces. I welcome instruction!