I was told that your motor cavitation plate needs to even with the bottom of your boat and one inch high if your running an stainless prop ? I have an 20 ft roughneck jon with an evinrude 140 and when I installed the motor I put it all the way to the stops on the transom. Right know I have mine about 2.5 inchs below the bottom of the boat. 2 problems I have, one is when running around 25-30 and very little trim, when I hit full trottle the prop will cavitate, secound is I cannot trim very much before I get to porpoising. I now I am probably a little over powered. Do you think by raising the motor will help or is going to be trial and error. Also would the cavitation plate being below the boat cause some drag ?
Hi Todd I think it is suppose to be close to the bottom when rigging your motor. I am sure if you call rough neck they will give you the good poop. On my grizzly 90 h/p Merc, I put on a fin(stabilizer), its the kind you dont or no drill. It slips on the cavitation plate and is held with torq nut for the trim stablizier. It works great! StingRay XPRIII Hydrofoil Stabilizers for Boat Motors I feel you need to place it at the right height, The stailizers work great for top end and control.
Sounds like props not getting a good bite and slipping. Have you tried taking to prop guy to add more cup? My 1872 sea ark had same issues (almost verbatum) when I bought it (used) with a 115 merc and 17 pitch prop. I tried several props and re-pitching but kept getting blowout and cavitation on turns. This was all before me having modify the boat any. What fixed it was putting a new 90 4-stroke (little heavier than 2 stroke was) and distributing the weight better. Put a 20 gal tank and 2nd battery across the front just behind front deck. All anchors go way up front, etc... Think when I installed the motor I set cavitation even as you said (resting on top of transom). My only issue is if other people ride w/me I put them ahead of me for better ballance. Woulnt want two people sitting on rear bench as performance wide open would suffer.
I had the same problems with my boat when I bought it but I put the stingray hydrofoil XPII on it and all the problems went away, those things are awesome, planes out faster, faster top speed, better mileage, and turns better. For $50 they are worth more than they cost. I would stay away from the one you install without drilling holes, I hear a lot of people have problems with them falling off. I've had mine on for almost three years without a single problem.
My 2072 War-Eagle would do the same thing. ITs part of having that heavy motor hanging off the back. But also motor being low. Raised mine up where it was just above the bottom and it cleared up. Pete
Interesting Jason. I have one of those from my old rig and may have to give it a try on the new 90hp next time out. I agree re the non bolt on units..... Thanks.
That anticavation plate needs to be above the keel so it keeps the prop in some what less distrubed water.
