Hobie 17 or Inter 20 are not appropriate boats.
If you are looking for a used boat then a Hobie 18 would be a good choice, or a prindle 18 or 18-2, or a nacra 5.5sl, or a mystere 5.5.
In the new boat categort, the f18s (tiger etc) are not a good choice for a beginner. Rather I would suggest a Nacra 570 or 580.
I agree completly. Perfect.
Read this webpage before you buy a used boat to find out what to look for when evaluating the boat.
http://www.sailingproshop.com/catamaran.aspThe pricing suggestions are a little outdated.