Find out baseline performance, and (B) test other props against it. But for skiing, it is common to use a prop with 2 inches less pitch so you get a good strong quick acceleration to pull the skier up fast.īut you MUST have a tachometer and a reasonably accurate speedometer to (A). Usually, for tubing, you don't change props. A 7 MPH gain just from changing the prop. I switched him to a 19 pitch stainless (one of my favorites) And the RPM immediately dropped to 5000-5500 (I forget exactly) and speed went up to 47 MPH. With his original prop, the engine turned 6000 RPM and the boat did 40 MPH. Dirty, rough bottom-all these things need to be checked.Īs an example, I rebuilt a Force 125 for a fellow. It is also possible that you have a lot of water inside the hull weighing it down. Or, your prop may be damaged enough to affect performance. It is possible that the engine has something wrong but it is also possible that you really simply have the incorrect prop.
22 is way too low.īefore you run out and get another prop, you really need to find out why the boat is going too slow. You should PROBABLY swing a 17 pitch prop and depending on load, possibly even a 19.
#85 HP FORCE ENGINE WONT CRANK FULL#
With the 21, the engine will turn slower, not develop its full horsepower and the boat will go slower. With the 17, the engine will turn faster but the boat will be slightly slower. FOR EXAMPLE: if you are using a 19 inch pitch prop and turning the recommended 5000 RPM, then changing to either a 17 or 21 pitch prop will drop the speed. That engine on that boat can not swing a big prop.
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