Re: 97 17' Maxum with 120hp Force Outboard - Optimal Prop
Well, Anthony, that's like asking: "I have an apple tree in my backyard. How many apples will it grow?" Just too general a question.
A quick answer is that if the engine is running within its rated RPM range of 4500-5500, then the prop is optimal. However, if you change loads and the engine is no longer in that range, then it is not. Additionally, these engines like to run fast, so you would want a prop that lets it rev up to close to 5500 at full speed.
Obviously, you need a tachometer to determine these things. For these engines, props are generally about the same diameter and pitch varies within a relatively narrow range. You can get one anywhere from about 15 pitch to 23 pitch. Pitch would be like gear ratio in a car.
To choose a starting point, you must know approximate weight of the hull, engine horsepower, approximate useage (heavy load, light load, skiing, trolling, etc) current prop size, and current RPM and speed at full throttle.
That said, as a guesstimate, the pitch you would use would be most likely in the 17-19 range, however, until you try a prop, you can not know if it will be the best one.
