Motor??
Before purchasing my 240 I had numerous years of sailing and racing small one designs such as Lasers, Albacores, and Lightnings. I have never sailed a 170, but I don't understand why you would put a motor on this boat. I would think it is plenty responsive enough to dock under sail. I have docked my 240 under sail once when the motor vapor locked. I would not want to do it again, but on a boat such as a 170 I would think this is not a problem. Wouldn't want the extra weight on the transom in regards to performance. Just my thoughts.