Gordon,
understood - I didn't realize that you had fully glassed both parts separately. If you have any left over lengths of the cloth you used to cover the hull and deck, and have enough to run the length of the boat, I would cut a four inch strip and run it down the boat.

If you cut neatly and then wet it out without pulling too hard on it, you shouldn't get too much in the way of frayed edges. I had to deal with a fair amount of frayed edges in putting the multiple layers on the bottom of my Shearwater 17 build, but found that after the first fill coat, these sanded out nicely with 80 grit and in the subsequent fill coats, you couldn't see any of the frays.

This will provide it with additional strength and also serve to seal the seam from water penetration.

Regards,
Gero