If I lift the engine.....

[matata]

The outboard needs lifting by approx two but maybe three bolt holes to get the anti ventilation plate at the right hight. After I do that, will the effect be to help the boat onto the plane or make it worse. (115 outboard. 5.5 rib) and why? Ta Nik

[neil.mccrirrick]

It will help it onto the plane. The cav plate needs to be just under water. Too deep and you will get engine drag and your rig will feel sluggish. Too high and your prop will suck air on turns

The only solution is trial and error as a lot depends on how your rib sits in the water and rides on the plane. Traditional agreed position is 1" above or below the keel line. But with more powerful outboards some are rigged now 2-3" above the keel. This will give better top end speed but you can run a risk of cavitation and you may not suck enough water at high revs in a lumpy sea

[matata]

Got that... problem is that it already red lines on a 17" prop 6000 and raising the engine will increase its top revs. Therefore I'd need a courser pitch to lower the rev but that takes longer to get on the plane. Is there such thing as an 18" pitch prop to resolve the problem half way....if you know what I mean!

[Roflhat]

You can add or remove 2" of pitch to a prop (generally speaking). Speak to Steel Developments or another prop company, they can do this for you. May be worth adding some cup to your prop if you lift the engine to give you more grip on acceleration and turning.