Here's my 17 Hobie with a ''super jib''~(from Murrays).
I don't have a square top, but it goes.. I don't think it's a good idea to put a ''spin'' on it. I've been told the mast wouldn't take the load unless ya have ''diamond wires'' Alotta stress on the hulls to, they are tender <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" />