Not sure why you need any motor on a sailing cat...with just over a knot or two of breeze the motor will be dead weight!

But, that size motor is more than enough for pottering around a harbor. We've got a special project craft made out of a SuperCat 19 platform with over 600 lbs of weight on it that we power using a 2 Hp fourstroke Honda. Runs around the harbor very nicely. And we don't have boards/rudders...motor mounted off of one transom...yet the craft still steers quite well just by turning the outboard.