I've written a little about good rolling kayak design on my blog (see link below). I recommend:

Definitely low back deck. As low as possible.

Maybe a high fore deck? (for forward recovery rolls).

Good fit but comfortable beam (20-22 in)

Good stability. A kayak that is too narrow and tender will just fall over again on less than perfect recovery.

Highly rockered. Helps with stability.

Extra volume and buoyancy at the ends. Upturned ends might help. This tends to keep the kayak on its side after a capsize.

Andrew

: Hi
: What are the desired qualities for designing an easy / learning to roll a
: kayak
: I can see a low aft deck would be good - -