Flush hatches

[Tom_Groothausen]

Wondering  if anyone can give me some advice on flush hatch instructions. Im building a chesapeake 17 hybrid and ive cut out the hatch. The flush hatch kit/ online directions are much different than the Shearwater hybrid instructions that came along with the Chesapeake kit (there are no Chesapeake hybrid instructuions).  The shearwater hybrid instructions shows a partial doubling of the hatch, one spacer and a sill with a lip while the online instructions say to double the thickness of the hatch with 4mm plywood and go with two spacers along with the sill. Which is better? If I go with the Shearwater instructions is the lip really necessary or does foam gasket seal the hatch sufficiently. If I go with the online instructions whats the best way to attach the 4mm plywood to the hatch without comprising the hatches natural curve. Last question should the foam gasket attach to the hatch or the sill. Project is going great so I dont want to ruin it now with the hatch. Any advise would be appreciated. Unless someone wants to finish the hatch for me- kidding. Ive stressed out about the hatch assembly more than anything else during the process- afraid I was going to ruin the deck.