I need help in choosing a kayak design to build. I am 5'8", 150 lbs and unfortunately extremely stiff (despite regular training and stretching). I have been kayaking for many years, intermediate I guess, with a fairly good balance brace and basic roll. I own a Current Design Slipstream (British design), 16' x 22", rather low volume. I love its low primary stability, its maneuverability when leaned, and speed. My woodworking experience is limited to carving Greenland paddles but that has given me a taste for more...

I am looking for a hard-chined boat for better secondary stability (my boat has no discernible secondary) to feel safer in waves and chop; I wouldn't mind a boat a bit narrower for better control, a lower rear deck for happier rolling (although I can't complain about the Slipstream). This would be a day tripper to use in sea / Great Lakes conditions. In other words the challenge is to find a design that would keep the liveliness of the Slipstream for a light paddler on day trips, combined with the other characteristics I just mentioned, and enough space (height + width) for a comfortable knee position. In the Slipstream when bracing my knees are 18" apart and 12" from the kayak floor.

I have looked at Yost skin-on-frames which seem relatively easy to build and to modify if needed. The Sea Rider is interesting but seems extremely tight-fitting: is it realistic to expand the front deck enough to meet my knee space requirements (I have looked at E. Ogata's modifications but doubt if that would be enough for me)? At the same time its target displacement seems very high -- the Sea Rider is targetted at 240 lbs, definitely too much for me, which I find very puzzling for such a low-volume boat. Has anyone modified a Yost design to the extent I would need to?

I have also looked at some stitch-and-glue kits, but I am bit leery at committing to a more expensive model without the option to customize it and without having tried any of them.

I would appreciate any advice!