The gap is at the last 8" of the hatch and increases from 1/2" to 1-1/2" at the bottom.
The curve is very slight so it was quite easy to bend the wood to shape. You just attach it to the hatch itself, let the glue dry, then take it off. This is what it will look like:
I primed and painted the shims with marine-grade paint. Did I mention it was exterior grade???
There were still some gaps, so I ripped a few more pieces and glued them in. This is what it looks like:
I made graduated steps to fill in the remaining gaps, applied exterior caulk, then screwed it down with exterior grade screws. Notice the theme there: exterior grade everything.
Now I need to install the weather stripping on the hatch, and I should have a pretty tight seal.
I need to figure out how to keep the hatch closed now. Currently I'm using a hasp and it's not lining up anymore.
Yeah, what the hell is a hasp, right? I didn't know until 5 minutes ago myself. It's that piece of hardware in the picture on the right. It swings over the other piece (which isn't there) and locks. Hasp. I learn something new and trivial every day.
Anyhow, the male part can't go on the hatch where it used to, so I bought a gate hinge. Let's see if I can MacGvyer something up. I'm betting that I can.
Time for a cocktail!