Yes Size Counts...Up to a Point
The classic choice of motor for a Mac 25 is a long shaft Honda 10Hp here in Southern CA. Sturdy, reliable, cheap and clean and quiet, the Honda 10 has all the power the hull can use or take. You don't want too much Horsepower or you can rip the motormount right off the transom. Too little and you may have a hard time fighting your way into a headwind against the tide when you are running for port to beat a storm. The Honda 10 also has a nice little charging coil built in to charge your battery. Picking up an old Honda 10 (Check out its sister the 7.5hp) may be difficult as those that have them generally want to keep them. Look around though, they are out there. Mine was given to me by a skipper who didn't know how to fix it. $50 in parts and it works great.Happy Sails to You,Mike