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  1. #1

    Pitch / RPM / Hulls

    If you have two of the same model ski's with a 14/19R turning 8000-8050 shouldn't theoretically they be the same speed. No matter the temperature.

    If they aren't would you think hull drag would be the reason.


  2. #2
    My friend (SpeedJunky on here) just bought 2 2005 GP1300R last year. Left them stock all year. One was his, the other was his dads. They broke them in together, so they were boke in exactly the same. SpeedJunky's was always 1mph to 1.5mph faster than his dad's. Both turned the same RPM.

    So why the hell is one slower?

    This saying may be over used but it's true...every ski is different. That means the hull's probably have some differences in them and the engines have some differences. Its part of the mass production process. Not everything is made perfect or exactly the same when manufactured.

  3. #3
    RustySeaRustyDoo's Avatar
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    Quote Originally Posted by RXPkid
    My friend (SpeedJunky on here) just bought 2 2005 GP1300R last year. Left them stock all year. One was his, the other was his dads. They broke them in together, so they were boke in exactly the same. SpeedJunky's was always 1mph to 1.5mph faster than his dad's. Both turned the same RPM.

    So why the hell is one slower?

    This saying may be over used but it's true...every ski is different. That means the hull's probably have some differences in them and the engines have some differences. Its part of the mass production process. Not everything is made perfect or exactly the same when manufactured.
    So Im guessing they both weigh the exact same?

  4. #4
    Yes. One hull could be slightly heavier than the other, but I highly doubt that would cause a 1~1.5mph difference between the 2 skis.

    Dry, the both weigh 653lbs.

  5. #5
    but if 2 of the same boats have 14/19 and going the same rpms and one is going faster then it has to be something different with the hull.

  6. #6
    RustySeaRustyDoo's Avatar
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    Sounds logical..As imperfect as hulls are..

  7. #7
    Jarrett's Avatar
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    Quote Originally Posted by Kinchyle
    If you have two of the same model ski's with a 14/19R turning 8000-8050 shouldn't theoretically they be the same speed. No matter the temperature.

    If they aren't would you think hull drag would be the reason.
    There are a million things this could be:

    Diff pitch on props yielding same RPM
    Different air
    Different altitude
    Different rider weight
    Currents
    etc
    etc
    etc

    And a better hull is also a possibility.

  8. #8
    Quote Originally Posted by Jarrett
    There are a million things this could be:

    Diff pitch on props yielding same RPM
    Different air
    Different altitude
    Different rider weight
    Currents
    etc
    etc
    etc

    And a better hull is also a possibility.
    Assuming the pitch is the exact same 14/19R and with both boats turning 8050 on the nose which would mean the engine power is the same no matter the difference in mods. If they were side by side in the water then they should be going the same speed.

    If they weren't I would think the ONLY factor would be the hull, true etc.
    Pump couldn't play because it would effect rpms.

    true ?

  9. #9
    Prohibido usuario
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    I think the only way to prove this is to speed run one of the ski's, remove entire pump assembly and put it on the other ski. Have same person speed run that ski. Just because a prop is pitched the same doesn't make it exactly the same.

  10. #10
    Quote Originally Posted by Kinchyle
    but if 2 of the same boats have 14/19 and going the same rpms and one is going faster then it has to be something different with the hull.
    Most likely, but like I said before no two engines are the same either. One could be putting out a couple more horsepower straight from the factory.

    Evan though you may be running the same setup on each engine, one could be putting out a couple more ponies than the other.

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