Jack Plate Question

foreman33

Seaman Apprentice
Joined
Jul 25, 2002
Messages
47
I have a 89 Stratos 285 Pro which is 19ft long and a 89 150HP Johnson motor on it. I want to put a jack plate on it but do not know how much of a setback I should use.<br />1. How far back can I go and what are the advantages and disadvantages either forward or back? Can I go back too far? <br />2. Should I get a manual or automatic jack plate and what are the pros and cons of both?<br />3. Is there one manufacture that is better than the others?<br />4. How much of a lift up and down should I try to get?<br />I've been doing some reading but am still confused as to how much of a setback, how much of a lift, and should I get a manual or automatic one. I would greatly appreciate it you guys could give me some suggestions and recommendations to help me solve this problem.<br /> :confused:
 

Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Jack Plate Question

Great question. The lift and set back depend upon your set up and hull design. The prop being a very important factor. The prop type style and design will largely determine your motor height (X dimension) at any given setback. A SS (like an SST for E/J) prop will run higher than an aluminum one. A Raker will run higher. A Stiletto will run higher and a large diameter 3 blade like a Turbo will run higher yet. A 4 blade will run higher than a 3 blade. <br /><br />If I were setting up your boat I would start with a Bob's manual plate. I think we can safely guess you don't have a low water pick up and thats good for now. Bob's standard plate can be transformed into several configurations. It can be a 3" setback or 5". It has 5-6" of travel and can be adjusted in the water easily. He also makes 2" spacers so we now have a set back range of 3", 5" or 7". <br /><br />The setback will depend on your center of gravity. The more nose weight you have the more setback you might need. Hull configuration come into play also. <br /><br />Establish your baseline now. Top speed, rpm and water pressure. Write down everything! Including how the boat feels and handles. How much torque in the wheel is very important. That tells us what the gearcase is doing at any given X dimension. Establish what you are trying to achieve. Strictly top sped or rough water comfort. Always test with the same load. Most important - MAKE 1 CHANGE AT A TIME! Take your time.<br /><br />I would start with a manual plate and see how the hull responds with your existing prop. You may opt for a hydraulic plate later and can always sell the manual plate. If we figure out your setback then you can buy the right hydraulic plate the first time. <br /><br />Sounds like a neat rig. Post your numbers and we can calculate slip % with your existing set up. <br /><br />Good luck!
 
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