That sounds very similar to what I have on my CC18. A 3/4" lip on the deck, around the hatch opening, about 9mm above the deck. Then hatch covers that extend beyond it about 1", and foam seal on the cover that fits over the lip, and seals to the deck. Mine leak a little, I think because it's hard to keep the curve going that extra 1-3/4" over the opening where the beam is under it. Also, they squirt water up in my face when I stick the nose into a wave. Angling the lead edge helped that a little. I fasten with bungees underneath, no straps showing. Works nice and looks good. Strip hatched contrast the deck nicely, too. I think if I do it again I'll try the flush trick.

> I built a Cape Charles 17 a few years ago and came up with a modification
> to the hatches and hatch covers that has totally eliminated leaks. What I
> did was to take some 4mm ply and cut a piece into a ring that matched the
> dimensions of my hatch opening. The width of the ring was about 1/2".
> I then glued (epoxied) it onto the deck so that the hatch opening then had
> a raised lip around it's perimeter. Sabe? A little sanding and shaping
> will make it come out nice and pretty.

> For the hatch cover I made a jig that matched the radius of the deck and
> glued two pieces of 3mm ply together over it. When this cured I had a very
> solid piece of ply that exactly (or atleast fairly closely) matched the
> radius of the deck. This is where it get a little trickey. I then cut out
> the hatch cover so that it extends past the hatch opening ring and the
> ring that I will glue to the underside of the new hatch cover. Next cut
> out a ring about 1/2" wide to fit under the perimeter of the hatch
> and glue in place. Once again sand and shape so that everything comes out
> looking good.

> To make everything waterproof, put one layer of weatherstripping on the
> ring on the bottom of the hatch and put another layer of weatherstripping
> on the ring around the perimeter of the hatch opening. Any water will have
> to get down under the hatch cover and then up and over the hatch opening
> lip. Mine doesn't leak a drop. I did this setup as I was building my
> kayak, but it shouldn't be too hard to do to an existing kayak. I hope
> this made sense.

> JC john@gearaid.com www.gearaid.com