Most out of My Merc 25hp

Hi everyone, I have a 1993 tracker 175 with a merc 25hp. I was wonder what prop i could get away with that would perform the best top end speed. The boat is loaded with 2 deep cycle batteries and 6 gal gas tank. I currently have a 13 pitch prop on it but was wondering if i could get away with a 15 or would it dog the motor. Cant remember what the rpm range needs to be. But as of right now i get around 21 mph and thought i use to get around 25 to 27. not sure why i loss speed. maybe cause i gained weight, lol. thanks.

Re: Most out of My Merc 25hp

a tac is critical in helping detirming your correct rpm and proper prop.tiny tac comes to mind .you might even get by with a laser type rpm reader .

Re: Most out of My Merc 25hp

Is a 175 a bare bones boat or is it loaded with floors,live wells,remote steering etc.Do you know the dry weight?
Using the prop calculator ,guessing some numbers, w a 13" prop at 10% slip 21 mph produces about 4200 rpm.At 27 mph rpm would be about 5500.
So it does seem that if a 13 Is correct a lightly loaded speed of 27 might be possible and reasonable.
Is your speed by gps?Speedometers can sometimes be off.Some cells have a gps app.
If the boat has indeed lost speed you need to explore what may be the cause i.e.: a dirty bottom,excess water weight in the flotation foam,an out of tune motor,poorly adjusted throttle cable.Throttle not opening all the way.

Re: Most out of My Merc 25hp

The Tracker 175 dry weight=1100lbs. 500 lbs people/gear and 6 gal of gas=1668lbs.

The Mercury prop selector calculates with a 25 hp, it should use a 13 pitch and do 25.8 mph at 5500 rpm. The boat should look something like this one?

It should be noted that the 25 is the smallest motor available on this model, with most being equipped with a 40 or 50. Tracker estimates the speed with a 25 at 23-25 mph with a new motor and prop.

Since your motor is not new(1993?), you can expect some loss in performance. Depending upon what rpm it can muster now, it may be time to step down in pitch, because it's doubtful that it will pull any more. That's the way it goes as motors age.

The rpm range is 5000-6000, with the hp rated at 5500 rpm.