need more rpm less speed

[frank625]

I have twin 150 4 strokes on a dive boat so I push a lot of weight. I can run on plane about 3200 rpm before I start going to fast for conditions. My props are 15.25 X 15 P now and I also have some 15.5X19P and 14X21P props from my old motors.I would like to increase rpm without increasing speed. Would either of these other props help or do I need to go down in pitch to help my cause ?I dont fully understand the pich explanation as some web sites say go up and others say go down, please help, Frank

 

[usskydvr]

Re: need more rpm less speed

In smooth conditions and typical load, what is your wide open throttle
(WOT) RPM with the current prop?
Increasing pitch ie going from a 19 to a 21 will decrease RPM by 300-400
Decreasing pitch ie going from a 19 to a 17 will increase RPM by 300-400
We use typical conditions WOT current prop as a starting point and then
ask what is your goal, reduce RPM, increase RPM, better hole shot, more speed, etc. to determine which prop to use.