Originally Posted by lightning
On the open water the boat planes within seconds of opening the throttle using either prop....so l might have wasted my money! I have not yet tried it on full throttle to see how fast it will actually go. So it's now just a case of which prop to leave on, and which to sell. The 8.5 or 9.5 pitch.
When you say planes well with both props, is it with you alone, or with family too ?
You must test if possible on flat calm waters with the load you will be cruising with, full throttle and check if inside factory working parameters (5K-6k) at wot. That's why a induction tach is needed, you could test each prop with you alone and fully family loaded and check both wot readings.
A 9.5 prop will slow down your rpm compared to the ones achieved with the 8.5 delivered factory standard, but as you don't know yet your wot max rpm, you will be doing a wild guess seems at ear sound which could be counterproductive for your engine.
If you already have invested wisely or not on a new prop, buy a Tiny Tach and check, a TT will be usefull to check runing hours for preventive and corrective maintenances as well, same as with a car.