Posts: 3480
Location: Elk River, Minnesota | Hiya,
I assume the hot sticky weather was the issue with the motor in your other thread?
The best way to get the nose out of the water is to get a prop that has more tip cupping, which when placed at the tip will give the motor more ability to raise the bow out of the water. In a nutshell, I would bet your motor has more in it with a good prop change. The black max prop is pretty much a standard aluminum prop which gives good overall performance and handling characteristics at lower engine heights. As soon as you raise the motor off the transom a hole or two, the prop has very little capability to stay hooked up in moderate turns and at higher trim heights.
So...here is what I would suggest... Get to a stainless of some sort, or at a minimum, get a Solas aluminum in a 13-1/4 x 17 (or something to that affect). Out of the three that you mention, I would say you will have a hard time turning any one of those with your motor. Usually when one changes over to steel from aluminum, it is recommended to go about 2 inches in pitch lower than the current aluminum. The reason for this is due to the extra flex that a stock aluminum prop will have. In effect, your black max prop is probably acting more like a 16 pitch than a 17 pitch while under load. Steel will not flex anywhere near as much as a standard cast aluminum, thus a lower pitch is needed in most cases.
In the solas aluminum, what you get there is less flex due to a process called squeeze casting, which instead of the aluminum being poured into a cast, it is put in under pressure, which allows for the prop to be shaved thinner, yet keep flex down. So...it is a good prop when steel is not giving you much, but the aluminum is not good enough. I carry a solas as my spare from a michigan ballistic prop, and both are about the same in peformance and handling.
The ballistic prop when switched in place of a stock aluminum, I have not seen any sort of fall-off in RPM's, but that also was offset by raising my motor up to as high as it can go, and then some with a 4" manual setback plate. If I switched without raising the motor, I saw roughly a 300 rpm decrease over my stock aluminum.
If you can find one, I would suggest finding a ballistic in a 17 pitch, or something like a 15 pitch michigan rapture (no longer in production). I would feel a 17 pitch rapture would be a bit too much for your motor due to how thick it is. The ballistic is a thin bladed, highly cupped prop that does not drop off as much. If you happen to go this route, I would highly suggest moving the motor up to it's highest position on the transom.
Lots of variables here, but going steel will give you more lift, and the right prop will allow you to be at the motor's highest mounting position and still give good handling and top end performance.
Steve |
