Are you planning to include hatches? If so, waiting to do the inside deck seam until AFTER you've cut out the hatches makes it easier. (Do all of the exterior stuff, including fiberglass & fill coats on the deck, first. Then cut hatches. Then do the inside sheer seam.)

I've done it both ways... when I built boat #1 (a Tern), I did the inside sheer seam before the hatches, and was mucking around with a long stick to reach the ends. Not enough to make this preacher swear, but close. On boat #2 (a Coho), I cut the hatches, then did the inside sheer seam. It made the job much simpler and nicer.

Julie Kanarr