I have a Johnson 150GT on an 18' bass boat. I'm looking for the max speed I can get out of it. My RMP at WOT is 5000. Current speed at WOT is 57mph (GPS). The prop on the boat is 14 1/2 x 24.
Re: What would be the best prop for top end speed?
Those numbers are achieved lightly loaded and you alone or with other boaters or family ? Which is the max wot rpm factory stated for that engine ? Around 5500 ?
Re: What would be the best prop for top end speed?
Those numbers are lightly loaded with equipment with myself and my buddy. Both of us weighing aroung 200lbs. The engine numbers I believe are somewhere around 5500
Re: What would be the best prop for top end speed?
If you're positively sure 5500 are max rpm numbers for that engine, going one pitch less, engine should rev at least 200-300 + rpm if that happens to be the standard gained rpm. Some states 200-300 rpm per pitch, others more.
Re: What would be the best prop for top end speed?
My info indicates 4500-5500 rpm range, 1.86 gear ratio calculates to excellent 6% slip at 57mph.
Assuming a 200 rpm change it appears a 1" up or down same model prop still nets about 57. up likely nets slower hole shot
down nets better hole shot.Of course there are props that may net improvements with or without a pitch change.
Re: What would be the best prop for top end speed?
i thinking you wont gain top speed with 22 - i think it will be about the same or maybe 1-2 mph slower. That's assuming you stay with same style prop. 57 is nothing to be sad about with a 150
Re: What would be the best prop for top end speed?
Try remounting to outboard one notch higher and see if that does not give you 1-3 mph more...... be careful you don't mount it to high or you could lose water pressure and burn up the impeller and motor.
Re: What would be the best prop for top end speed?
Bob has good thought there at 57 mph a little increase in height could net some rpm with a little more speed.
Is the present prop Stainless? Do you know the brand or model?
Lowering pitch 2" should net some rpm, maybe 400.Improved hole shot but speed would probably be a wash.
None of these numbers are carved in stone.
Re: What would be the best prop for top end speed?
Thanks for all your input guys. I'm just going to stay with the 14 1/2 x 24. Need a new one due to log vs. blade.
What I am going to do is raise the jack plate a 1/4 inch and see what that gives me.
