I have a big johnson problem

[oldgradywhite]

I have a half way restored 1972 grady white. I had a 90 20 in shaft mercury on it but I replaced it with a 150 johnson 25 in shaft. now when I go high speed the motor pushes water in to the boat. what can I do to make this work? I think the shaft it to long

 

[Joe Reeves]

Re: I have a big johnson problem

Yep, too long. That creates what we call a rooster tail.

 

[ebry710]

Re: I have a big johnson problem

Without more detail, I am not 100% sure what is causing water to go into you boat, but on my Johnson 120 I have a planing fin which helps keeps prop water going in the right direction.

 

[mikesea]

Re: I have a big johnson problem

You simpliest fix would be installing a jack plate.If I recall,the Merc.had different mounting holes.Ideally,you would like toinstall the jack plate up higher than the holes the johnson is installed into to help you gain the 5in you need.You really got a situation there because the best fix for strength ,looks and practicality is have the transome raised.OR,find a short shaft eng,and the V6 were a rare eng in 20 in.if you go to the 140 ,pehaps trade someone you will have a direct bolt up and can use the wiring and controls.I bet with a 140,the way you boat performs now,the speed etc.will be about the same.

 

[tashasdaddy]

Re: I have a big johnson problem

install a jackplate. your motor is 5 inches too long.

 

[jonesg]

Re: I have a big johnson problem

I have a half way restored 1972 grady white. I had a 90 20 in shaft mercury on it but I replaced it with a 150 johnson 25 in shaft. now when I go high speed the motor pushes water in to the boat. what can I do to make this work? I think the shaft it to long

theres a few used jackplates on craiglist

http://www.searchtheentirecraigslis...wxemloc&cof=FORID:9&ie=UTF-8&q=jack+plate#945