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  1. #1
    Seaman Apprentice
    Join Date
    Jul 2003
    Posts
    44

    Default Thinking of changing to a smaller prop diameter

    Hi all, I am running a Rapture 14.25 x 25 SS prop on my Yamaha 150 which turns around 5200 WOT (62 MPH GPS) and I'm looking at a Yamaha 13 3/8 x 25. My question is, will the smaller diameter prop get me to a higher RPM range and possibly more speed? I'd like to run my motor at 5500. Any comments would be greatly appreciated. Thanks

  2. #2
    Supreme Mariner
    Join Date
    Feb 2001
    Location
    Port Charlotte FL but never the same since hurricane Charlie
    Posts
    16,978

    Default Re: Thinking of changing to a smaller prop diameter

    We have found that, generally, it really doesnt work out for the best going that direction. The smaller 13 1/4 & 13 1/8 diameters are for the smaller gearcases. Since you have a 14 1/4 we assume you have the larger case. Going to a smaller diameter may cause you to have to lower the motor unless its too low now. We'd rather stick with the larger diameter and play with the set up to gain rpm. Have you tried that yet?

  3. #3
    Supreme Mariner
    Join Date
    Feb 2001
    Location
    Port Charlotte FL but never the same since hurricane Charlie
    Posts
    16,978

    Default Re: Thinking of changing to a smaller prop diameter

    BTW -- you might ask JB or one of the mods to close the other thread. Just so we dont get 2 deals going at the same time. I get confused easy....

  4. #4
    Seaman Apprentice
    Join Date
    Jul 2003
    Posts
    44

    Default Re: Thinking of changing to a smaller prop diameter

    I'm not sure on how to ask the mod to delete the duplicate post..I'll look into it though..I'm running a 10" rite hite jack plate that is almost all the way up (5" travel on the plate). I've got maybe 3/4 of an inch left in the adjustment. I'm pretty sure that I've maxed out the height becasue at one point I was getting spray off of the hull with full trim, so I adjusted the plate back down between 1/4 and 3/8 and she seems to be running on just the pad now. Water pressure is good @ 28 psi and hole shot is also pretty good. My initial post stated that I was running a 25 ballistic, but its a Michigan Wheel 3 blade rapture. I do have a 3 blade ballistic (14.5 x 24) and both perform almost identical on my boat with the exception of the 24 giving me around 5300 WOT. I'm open to any recommendations. Would it make sense to drop to a 23 with the same diameter?Thanks..

  5. #5
    Supreme Mariner
    Join Date
    Feb 2001
    Location
    Port Charlotte FL but never the same since hurricane Charlie
    Posts
    16,978

    Default Re: Thinking of changing to a smaller prop diameter

    That would make sense. Make sure to test the same brand and style prop. That way youre comparing apples to apples.

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