Bill,

Cut the hatch openings before you tape the sheer. It would be real hard to get a good seal on the lip. Just make sure that when you cut out the openings, that the hull and deck is matched up as thay will be when finished. If you don't and the hull has spread out, the hatch cover will not be the same contour as the opening. I didn't have much problem taping the seams as per Nick Schade's book.