Sails that are not directly connected to a spar at some point are illegal for racing
..but for cruising, who cares?!
I have no idea where to find them other than those inflatable
ones that kite boarders fly, but those are probably way too small. I guess it would depend on the size of your boat and being able to manage them from the deck
. I would imagine one of those kites could give you some pretty wild oscillations if not kept under control. Like one hell of a broach that you could not recover from unless you cut the line only to let it blow off into the distance. Hmmmm...maybe that is why they are illegal for racing