As an old wood boat owner,(had A GB42 & Alaskan 46) I dealt with the wood repairs a lot. In my experience, it is important to allow the wood to flex. So in deck seams such as your hatch, I would use a flexible sealant such as polysulfide. Booatlife makes one as do others. The main thing is for the seam to remain intact through the swelling and shrinking that occur seasonally. I have done repairs to both of my boats and found the polysulfide seem materiel still flexible from original boat construction. (One was 71 built, & othjer was 69 built!) So I feel it is important to consider the wood swelling and shrinking when deciding on repair procedure. The only exception I know of is, if a board is sealed on all six sides, there is theoretically now possibility of swelling or shrinkage--but ambient (Sun) heating must be considered! Well enough. Good luck with the project.