Where should the cavitation plate on the motor match up to the keel.....

[Kenny Bush]

On my Fountain CC, it has a notched transom, and the cavitation plate on the motor is<br />approximately 3 inches above the keel line. From the rear, looking down the keel line, my prop<br />has about 80% below the keel line. Is this acceptable????? Does the notched transom allow<br />more water to come up into all of the prop???? I think at high speed, I am losing performance.<br />The boat was settup by fountain and I cannot get a response from the factory on this question.<br />The motor bracket has two more holes(to drop motor down)left if I want to adjust. C'mon <br />experts.....please advise........

 

[JB]

Re: Where should the cavitation plate on the motor match up to the keel.....

Leave it be. If you are not cavitating it will give better performance there than if you drop it down.

 

[Dhadley]

Re: Where should the cavitation plate on the motor match up to the keel.....

Ditto. If anything you might be a little low depending on your prop. <br /><br />Good luck!

 

[Spidybot]

Re: Where should the cavitation plate on the motor match up to the keel.....

Had the very same situation on a Sea Ray 160.<br /><br />The transom design reduces drag but at the same time disturbs the water in front of the prop.<br /><br />My boat suffered from heavy catitation when trimming out, cornering or pulling skiers out. The standard 3-blade aluminum 19" prop simply did not work under these conditions.<br /><br />Changed to a High Five SS which under all circumstances has more blade area in the water and really provides the grip needed for using the trim properly. <br /><br />It's like 4WD compared to 2WD on slippery surface - it keeps 'traction'.<br /><br />But - if you have no problems, why change? To decide which prop is right, you need to do some testing and checking on various loads and notice the rpm's acchieved. It is quite normal to use a prop, that provides good accelleration but allows too high rpm at WOT - and then cruise at somewhat reduced throttle.

 

[mbb]

Re: Where should the cavitation plate on the motor match up to the keel.....

you want the motor as high as possible without having cavitation problems. Every inch you get the lower unit out is more mph and less drag. It also depends on the props. Need to test under actual conditions, flat water is not representative of running in 2-4' seas.