This is a very small catamaran that is already being made. I think it would be interesting to use as a kids intro cat.
http://backbayboatworks.com/rowmaran.html

I love the idea, it's light. However adding rudders, rigging, someway to keep it from going sideways, structure to keep the rigging loads from folding it up, etc, etc. It's a lot easier and probably better to use a Wave

If the oars are sectional, use one for the rudder and one for a dagger board? Add one of those tiny little "fishing rod" masts for kayaks?

If you cold make the oar blades removeable, use them for rudders, use the shafts for a mast and boom, put up a small sail on rings like a Sunfish sail, you could make it sail...downwind.

Carl, that would solve the problem! <img src="http://www.catsailor.com/forums/images/graemlins/shocked.gif" alt="" /> Then what would I do? This is a lot easier than yard work.

It says right one the page, has a sail and mast in each hull

<img src="http://www.catsailor.com/forums/images/graemlins/blush.gif" alt="" />

they obviously didn't think it had enough bouancy for a mast and took one hull from the rowmaran and added a bigger hull for the sailing version.
the other solution is to use a kite with it, and maybe a seatbelt.