Thanks for answering Rob. My post was unclear what I meant to ask was:

I wrote "deck" to coaming, but I MEANT "hull" to coaming. because I thought the depth of the boat at the front of the cockpit there would have an effect on ease or difficulty of entry. I am making my coaming from a build up of ash veneers (5 layers maybe 4, at the ring, I'll see at the time and enough to make it at least 5/8" at the lip).

People here have been so helpful with my question, I thought I would post just a little of what I got out of it. I think I know now that the size is up to the paddler. He/she can make it what they want. I want a smaller "tighter" cockpit for reasons of my own. I think the factor for me is: I still would like to have the room to raise my knees up all the way from a fully seated position. I am making a little model today to determine just that point. It looks that the cockpit will still (and just) cover my knees when they are extended, which is also one of the factors I want to obtain. I think that if I can lift my knees from a sitting position then I will be able to get in ok because the depth "beyond" the cockpit will enable me to step into this space and that will make for more room at my entry.

Thank you all for letting me find out more of this.

Joe