Props

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dcracn24

Cadet
Joined
Apr 12, 2003
Messages
14
I bought a boat and had to rebuild the motor. The boat shop I bought my parts from said I need to turn 5500rpm @ WOT on my 1996 johnson 112 spl. The boat is a 96 wellcraft CC. I turn 5000rpm @ WOT with a 13-3/8 x 17 ss prop.<br /><br /> From what I have read my best option avaiable is a 13-3/4 x 15 to acheive the exta rpm.<br /><br />Does all this sound right? with the extra rpm will I have more holeshot power or top end speed??<br /><br />I going to buy a alum. prop because of price. Are the any brands you recomend?
 
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Dhadley

Supreme Mariner
Joined
Feb 4, 2001
Messages
16,978
Re: Props

Have you tried working with the set up? You might raise the X dimension to gain rpm. It really doesnt cost anything except time. <br /><br />I bet you broke rings on the starboard side.
 
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trumpetbucks

Petty Officer 2nd Class
Joined
Jun 2, 2003
Messages
140
Re: Props

DCRANN:<br /><br />I would take dhadley's advice first and try moving your motor higher up on the transom. Try one hole up and see what results you get. If you get cavitation while turning, then you need to put it back down.<br /><br />If you buy a new prop, the change to 15 pitch should get you around 5400rpm. Michigan Match is a good brand prop.<br /><br />You can use the iBoats PropFinder tool to see all the props recommended for your motor. Click on the Marine MegaMall tab at the top of the page, then click on Props, then click on PropFinder Tool near the top.<br /><br />Good luck!
 
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dcracn24

Cadet
Joined
Apr 12, 2003
Messages
14
Re: Props

I had broken top rings on three cylinders and a burned piston with a broken ring on the port side only one cylinder was good. your right! WHY??<br /><br />The motor has a plastic fin on it that helps it plane (so Im told). I notice I cant trim the motor up much or I start bouncing. Is this normal and will raising the motor make that worse.
 
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dcracn24

Cadet
Joined
Apr 12, 2003
Messages
14
Re: Props

Now that I think about this, when I bought the boat and didnt know better. (didnt check compression) it was way under powered, maybe the guy lowered the motor just to get it up on on plane. It was very slow getting up before I rebuilt it.
 
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