And bow kingplank

just to have the complete picture, this piece of 20 mm plywood was glued and screwed
in the very front of the bow for additional strength

Here is the bow king plank dry-fitted in the notches in the deck beams and front bulkhead (this one is made of 20 mm Mahogany marine-grade plywood and glassed with epoxy).

Below the king plank one can see the block for the mast partner (35 mm solid ash)

Jig for the router to achieve a 100% circular cutout for the mast. The jig is just a piece of spruce that was cut out on the lathe.

the router bit with the bearing on the top to follow the jig

the result is a 100% accurate hole for the mast in the king plank and the mast partner block

King plank and mast partner epoxied and screwed in place.