This forum is so great I can hardly wait to get one question answered so I can ask another :))

I would like to have a 7"-9" cockpit accessible hatch cover which would be just behind the cockpit and low to the right of center. I am putting a bulkhead right behind the seat and another 10" behind that for this hatch. All I seem to find are replacement covers for solid glass boats. I bought what I thought I needed, a rubber cover with a metal installation ring. It opened with extreme difficulty because of a built-in lip on the ring which matched a groove on the rubber cover. I turned off the metal ring and now it is way to loose. The only solutions I can think of are to install a strap over the cover or build my own ring similar to a cockpit coaming with a very small lip to match the cover. Neither idea strikes me as the best.
What I "think" I need is a ring and cover that has a twist or pull lock that can easily be accessed with my arm behind me that will fit on the Guillemot "L" deck.
Please, tell me what I am looking for or change my mind about what I really want.
Thank you,
Randy