The ribs on my Baidarkas did that too. I was using willow ribs so I couldn't peg them in place.
What I did was ran a few loops of twine completely around the hull in about four spots, these pressed the stringers tightly against the ribs and held them up snug to the gunwales. I then skinned the boat around these loops, and then later cut them off from the inside once the skin was in place.
Since then, the skin holds the whole thing nice and snugly together and I have had no problems.

: My SOF if just about ready to be skinned but if i sit in it the
: ribs pop out?! The ribs are rounded (not squared). If I lash the
: ribs to the gunales I am worried that the rib stock will just
: spit where I drill the hole. My brother thinks that the skin
: will hold it all together in the end. Is that a safe assumption
: or should I get this figured out before I skin it? Any
: suggestions would be greatly appreciated.