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prop question

  1. #1
    IAFF 1014 another72's Avatar
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    Default prop question

    I am currently running a 24pitch 4 blade prop spinning 5800-6000 rpm. Do you think i will be able to go up to a 3 blade 25 pitch prop and still spin 5800-600 rpm to gain top end speed?

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    Senior Member OLD MAN ON THE LAKE's Avatar
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    Yes on the RPM.Maybe on the top speed.
    I have a Mirage Plus with hub kit in perfect condition in the box used twice.25p 250.00 plus ride if you are interested.PM me.

  4. #3
    IAFF 1014 another72's Avatar
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    what is a typical prop slipage?

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    Tell us type of boat ,engine , gear box height if out board ,speed etc.

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    IAFF 1014 another72's Avatar
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    21' advantage, 509 bbc around 600hp, bravo 1 1.5 ratio currently runs 80+ mph with 24p 4 blade at 6000rpm

  8. #6
    "BOUGHT NOT BUILT" 2FORCEFULL's Avatar
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    Quote Originally Posted by another72 View Post
    21' advantage, 509 bbc around 600hp, bravo 1 1.5 ratio currently runs 80+ mph with 24p 4 blade at 6000rpm
    I did the 25 3 blade and picked up a couple top end.... was slower at 3000 rpms

  9. #7
    Floatin dirty Lavey29's Avatar
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    You can use the prop calculator forumla to determine your prop slippage. Just google "prop calculator" and it will come up. 10% is a good figure for V bottom. Cat's usually run a little higher percentage due to surfacing the drive/prop more.

  10. #8
    mud slinger plaster dave's Avatar
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    Don't sweat the "Petty", Pet the Sweaty!

  11. #9
    The Hat
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    Quote Originally Posted by another72 View Post
    I am currently running a 24pitch 4 blade prop spinning 5800-6000 rpm. Do you think I will be able to go up to a 3 blade 25 pitch prop and still spin 5800-600 rpm to gain top end speed?

    changing from a from a 4 blade to a three blade isnt likely to change much, and you are making a 1" change in pitch, I doubt you'll see much major difference, because the gain in pitch will likely be canceled due to the reduction of blades and efficency depends on the engine as much as anything, will the guy let you try it before you buy it ?...most used to.

    I saw little difference In top speed of either. if you run 6k with what you have, and 5800 with the 3 blade, you gain only 1 mph...... and like the other guy posted you'll give up something some where,.....and...the only real way is to try the stuff...it works...or it doesnt, and with so many variables and hi prop slippage it's doubtful you'll feel or see much change at all. IMHO

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