Rpm and propellers

[Abbeysdad]

So 1Fast, is the typical target bottom pad to motor bullet center 3" ?

[1FASTLASER]

Typically speaking you are correct abbey. 3" would be a great starting pointing. In fact that is what I recommend ALL persons start with .........after obtaining a 3" measurement then the "FINE" tuning starts. Now when doing this one needs to keep in mind all the variables involved like how much fuel on board,where and how you have loaded the boat,what prop is on the rig etc ,,etc.. That is why I suggest when fine tuning her you have the boat loaded like you normally run........such as fuel tanks,empty wells, and all the equipment you normally cary and in place. Then you start the runs recording time to get on plane,MAX rpms and MAX topend speed. With a manual jack I recommend bumping it up 1/4" at a time and run her again. ALL the while keepin an eye on the H2O gauge. What you are trying to acheive is a happy medium between Max rpms,Max speed and still have good water presure. Depending on the prop your spinning it will vary......longer rake props can handle taller motor heights and still allow for good water pressure.......there are some props that even though they have a longer rake dont surface well so you loose bite as you go up but yet still have good water pressure.the Raker is notorious for that. A chopper prop you can jack to the moon. You will notice when jacking, sometimes your rpms go up but no speed increase.....AT THAT point or if you loose water pressure below I say 12-15psi .STOP.......drop the motor back down an 1/8 and run again. What happened is the prop lost bite allowing the motor to spinmore rpms without any speed increase. You have reached MAX potential for THAT prop.