Appreciate the info, I'll get some pics today.
The bow is a very slight downward bend, not to the curvature of the roof. No space above it, it sits flat against the coachroof, also can't detect any rot, and the wiring comes up on deck beside the mast, not through the beam.

I'm in construction and do a lot of post and beam building and reconstruction, Kept wanting to call it a lintel, but knew that wasn't the nautical term.....

Ken.