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  1. #1
    Member
    Join Date
    Jun 2021
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    Church point louisiana
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    7

    Need advise on prop to pad height

    I have a 2004 procraft 185 with a 2012 150 optimax 25”shaft with a 22 solas prop, when I bought the boat the prop to pad height was around 5&5/8 running 51mph at 5,500rpms. So I picked the motor up to 4&1/4 prop to pad and now I’m running about 42mph around 5,000rpms, I tried a tempest 23p and that moved me up to around 46 mph and 5,100rpms. So it has gotten worse picking the motor up towards the Normal 3&1/2 prop to pad height, anybody have any suggestions on what to try out next? Thanks

  2. Pat Goff
    Join Date
    Jun 2004
    Location
    Seadrift TX
    Posts
    10,942
    #2
    I’m going to try to save you some pain and suffering because I’ve had the same pain. That 25” motor will never run right. You think it should if I just put enough height on a plate. I thought that also. I was wrong.

    The closest to almost adequate will be to mount a static plate to the transom and then your adjustable behind it. You need 5” of height to start, just to overcome the shaft difference. It’s going to look really strange, so get ready.

    Or try to trade for a 20” motor and save a lot of headaches.
    Pat Goff

    Two degrees from center
    of nowhere.
    Smithwick TX.

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  3. BBC SPONSOR/ Shallow Water Anchors Moderator
    Join Date
    Apr 2015
    Location
    New York
    Posts
    10,912
    #3
    yes what Pat said ditch the 25 go with a 20. save yourself a headache

  4. Member
    Join Date
    Oct 2019
    Location
    Keswick, Ontario
    Posts
    1,485
    #4
    I don't understand why this didn't work?
    1997 Ranger 692VS
    2014 Mercury 175 Pro XS 2B111166

  5. Pat Goff
    Join Date
    Jun 2004
    Location
    Seadrift TX
    Posts
    10,942
    #5
    Quote Originally Posted by Ranger Rod View Post
    I don't understand why this didn't work?
    I've tried to rig two different boats with 25" motors, a 190 champ with a 200 and a Cat Cougar with a 250. No combination of plates, spacers, props and height could make either one of them run equal to a 20" motor.

    Why? I'm sure there's some math equation you can do to explain, all I have is experience, and it wasn't good.
    Pat Goff

    Two degrees from center
    of nowhere.
    Smithwick TX.

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  6. Member
    Join Date
    Mar 2017
    Location
    Tuscumbia, AL
    Posts
    1,069
    #6
    Makes sense that where the motor bracket attaches to the boat matters. You end up with two levers that translate effectively to a diagonal lever when trying to lift the bow. If you are running 4-8” of setback raising the motor 5” more has an incredible impact on what that effective lever angle is at the back of the boat. Don’t need to work out the actual math to see that torquing a 6” lever at 180 degrees straight of the transom is different than torquing a slightly longer lever at an effective 45 degree angle off the transom. Same effect the go fast guys run into at extreme drive heights, which is why they buy even shorter shafts than 20”!

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