Thanks everyone for your responses. Gave me alot to think about. Some metioned about having the boat taper to quickly forward and aft the seat. I am sure that is it as this is probably the real difference between my ribbed boat and my Yost boats. With my last boat (very stable) I cut three plywood forms to mold the gunwales, keelson and stringers around allowing me to wrap and test without bending ribs. The other advantage was leaving the forms and setting the ribs to fit the stringer ect. position rather than vice versa.
Wish it was easier to post pics here. But ya, now that I think about it foot position in these boats was pretty much heels together, toes against the top corners. Sounds to tight.