how to use a hydrualic jackplate correctly?

[wrestler20]

Hello, I purchased a fish/ski boat last year with a hydraulic jackplate installed on the motor. The boat is a 20 foot with a 175 hp johnson. i have not been able to figure out how to use the jackplate successfully. Could someone here explain what i am doing wrong. My fastest speed seems to be with the jackplate in the lowest position and the motor trimmed out. I have tried to trim the motor back down and raise the jackplate, but it sounds like the prop starts slipping and the rpm's riase, but the boat is going slower. Don't get me wrong, the jackplate has been great for shallow water trolling, but i seriously doubt that was it's only intended purpose. Thanks for any advice you can give. <br /><br />Steve

 

[Hooty]

Re: how to use a hydrualic jackplate correctly?

Your top speeds may well be attained with engine down and trimed out. Give us some more data like hull type, engine revs, speed and prop design.<br /><br />c/6<br /><br />Hooty

 

[wrestler20]

Re: how to use a hydrualic jackplate correctly?

The boat is an Astro 20 foot fish and ski (very similar to the procraft combo hull) with a step transom. The jackplate adds 10 inches of setback. The motor is turning 5400 rpm with a 21 pitch prop and the speedo says about 48 MPH (dash speedo, no GPS on boat). The prop is a 3 blade omc stainless prop in good condition. It just seems like i should be able to get a little more out of the combination than that. Those speeds are with 1/2 tank of gas and two people in the boat on a pretty calm day. <br />Steve