Dialing in jack plate height?

brambo0311 · Post by **brambo0311** » Wed Jul 09, 2008 10:15 am

I bought a used procraft 96 18' 3" with a 175 merc a few months ago 4 blade 25 pitch trophy. I canâ€™t get it dialed in right. When I first got it the jack plate was so high, the rpms were only stopped by a rev limiter at 8600 rpm. I almost lost the boat in the delta, really fast and uncontrollable. I dropped it as far as I could and now it chine walks like crazy and rides really high out of the water. If I move it up at all, I lose almost all water pressure when I trim. There seems to be a sweet spot were I get water pressure really high, or really low, and nothing in between. So I am starting over and brought it up all the way to about 5" center hub to pad down. Canâ€™t go any higher without unbolting the motor and moving the entire thing. But at this point the water pick up holes are above the hull so I donâ€™t know if I will get water pressure on plane. Any advice or help? I am heading to clear lake in the AM to dial it in again. But would rather fish than play with boat. I canâ€™t do a wing with all the weeds up here in the delta and clear lake. Although the previous owner had holes in the lower unit to have one.

Chris B. · Post by **Chris B.** » Wed Jul 09, 2008 11:30 am

If you get no local help I would post this to BassBoat Central's "Set-ups by Todd" forum, link http://bbcboards.zeroforum.com/zeroforum?id=11

I'm pretty sure someone there will be familiar with your boat and have suggestions. FYI I'm in the middle of adding a jackplate and getting it adjusted on my older Nitro--got great advice there.

Good luck!

brambo0311 · Post by **brambo0311** » Wed Jul 09, 2008 11:34 am

Posted there, no help yet.

CW2 Tucker · Post by **CW2 Tucker** » Wed Jul 09, 2008 12:09 pm

A good place to start is 3.5 inches prop to pad.

Just so we are on the same sheet of music. Prop to pad measurement is attained by setting the boat pad level then measure from the floor to the pad. Record that measurement. Now trim your motor level (set a 12" level on your ventilation plate) now measure from the center of your prop shaft to the floor. Record that measurement. Simply subtract your prop measurement from the previous pad measurement and that is your true prop to pad measurement.

Ok make a few runs and record your speed (GPS) and your RPMs and Water Presure (WP)

This is the pain in the rear part. you need to adjust your plate about a 1/4" at a time untill you get her dialed in.

Find out what your motors recommended MAX RPM is. You are looking for a setting that will give you the most speed and handling and WP at about 100-150 RPMs below your motors Max RPM rating.

You ask which way do I move the JP up or down. Well that depends on your RPMs, Speed and WP. RPMs to high lower the motor. RPMs to low raise the motor.

I hope this helps you and others, good luck to ya and let us know how its coming along.

John

brambo0311 · Post by **brambo0311** » Wed Jul 09, 2008 12:23 pm

Thanx chief.

I am a bit off on my elevation. Was trying to use a straight edge piece of stock aluminum, and wasnt leveling the motor, just trimming all the way down. I may have to lift the motor and move it up a bolt hole to get as high as 3.5. Guess I will have to find a sandy beach at clear lake tomorrow to wrench and run.

CW2 Tucker · Post by **CW2 Tucker** » Wed Jul 09, 2008 1:20 pm

Oh you are recording your RPMs, speed, and WP at WOT.

How is your hole shot with the Prop you have now?

FYI my little 115 Opti Nitro is at 4.5" prop to pad so you could be doing allot of adjusting from 3.5"

John

brambo0311 · Post by **brambo0311** » Wed Jul 09, 2008 1:43 pm

Yeah I have been recording my rpms, wp, speed. I just cant find the right spot. Its either no water pressure and to high rpms. Or two low and the boat is to high out of the water and is uncontrolable. I can handle chine walk, but this is really bad and cant recover.