Re: 12ft. alu. boat with a 25hp on it...
HP ratings for very small boats are usually based on tiller steering. You dont say what kind of boat you have. With remote steering, you can go higher than whats on the CG plate, within limits. But you have to live with very low transom freeboard from the extra weight at stern. When I was young, I was flipped out of a 12ft bateau (jon boat) with a 15 hp tiller motor by making a sudden turn, its not hard. Its standard practice here in south louisiana to run 35-40hp on 14'-36" bottom bateaus with remote steering, CG plate usually says 20 or so. I had one until recently, with a 35, and it was properly powered, ran about 35 mph, and was very stable. If you plan to add a steering wheel or stick steering at bow, you could probably do it OK. Definitely not if a tiller motor.
