I assume this is for the Wren?

Once inside, things can be setup so they're pretty similar functionally - and the OC benefits for rough/rolling aren't going to tip the scale that way for the uses you intend. That leaves entry/exit and aesthetics.

For entry/exit - given the design intent and such - with no major factors to really argue strongly either way - it's really largely a personal thing.

Do you want to be able to drop butt in and then bring legs in/put legs out first and stand up?

Or

Are you OK with the sitting on the rear deck and feet first sliding in and out thing? A low rear deck and fair balance (or handy GP outrigger on deep side) makes this a snap - and for anyone used to it it's a non-issue.

Personally I really like OC - but not for everything - and I still have to do a bit of the feet first style with my commercial keyhole boat after I did a seat move - so it's not always B/W.

Aesthetically, either would be fine on the Wren, but (as much as I like OC) I think I'd do a keyhole. The longer opening will visually balance nicely with an 18'x22" kayak (am I remembering that right?) - making it look a bit slimmer and sleeker than the smaller shorter opening might (this effect already shows up in your lines plan).

Plus, a keyhole will make it a little easier on all the folks wanting to demo it! If you were doing a tippier sub 20" beam design I'd say do an ocean cockpit to give folks some idea what they're in for before they try to get in it. Just seeing an OC can keep some away (usually the one's better off not being in really skinny kayaks anyway).

Kris

: I am still undecided as to which i want to go with. What do you prefer and
: most importantly why?

: This boat will be flat water boat. No surf of big waves to deal with.
: Typically getting in and out is done in shallow water with the bow on
: solid ground. Some places there are rocks so you just pull up side the
: bank in shallow water. You have to straddle the boat and stand up in the
: water. In my last boat I got quite good at just lifting my hips on the
: rear deck and balancing. I could then slide my feet out of it. By the end
: of the first summer I could even get in and out from a dock 2'to maybe 3'
: above the water and not go swimming. I am pretty sure I could learn that
: skill again.

: I like the idea of having he deck closer for maps and perhaps an Orca style
: day hatch. But I am just undecided.