mikeschn wrote:I thought about that, but only briefly... swoosh laminations do not make a good hatch structure...
You might want to keep quiet about these laminations not making good ribs - there are a large number of boats right now crossing oceans with laminated ribs holding them together. So it would be a courtesy to those sailing on these boats not to let the ribs know that they aren't strong enough, as up till now they've been happily believing that they're plenty strong enough.....
Or, maybe, there's nothing wrong with laminations? Except that you've made an interior jig - and you'd want the hatch ribs to be thicker than the edge framing, so you'd need another jig.
Which reminds me, I was having lunch watching Norm The Wood God making an elliptical table top using a fixed-length batten with a pencil in the end. I'm guessing many people might prefer this to using string. Norm said he got the idea off the internet so here are a couple of links to sites with this technique.
Carpenter's Ellipse
Drawing an Ellipse
Andrew (the occasionally sarcastic)