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Thread: proper height

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    Default proper height

    What is the proper height to run a chopper below the pad( center of prop shaft to bottom of pad)?

    I am running now 3.5 inches from bottom of pad to center of prop shaft wit a 10.25 x 18p chopper,turning 5800rpms. If I try to come up to 3 inches below pad it just blows out. Do you think a larger dia prop would be better?

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    Sam Cullis Mark75H's Avatar
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    on what boat?
    Since 1925, about 150 different racing outboards have been made.


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    its a home made 14' semi V aluminium hull with a 14" pad (weight of hull withhydraulic jack plate 450,motor 204 )

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    Last edited by Nason; 04-29-2012 at 06:20 PM. Reason: pics did not upload

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    hi mate i've run a few choppers on my slt boat ,but its a tunnel hull .
    dose your motor ventilate getting on plane?or dose it ventilate at full noise?
    if its struggling to get out of the hole ,you can drill a couple 1 inch hole in your gearbox to relieve the exhaust .it will jump on plane after that,but your motor "will be very loud".
    i have run ron's choppers and the merc small hub old style and chopper 2 to max where my motor stops pumping water and they still bite at that height.
    cupping it will help but if you go to far it kills it.

  9. #9
    BRF Team Europe Member
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    There is no "proper" height as long as there's no water starvation. If you want to go faster try a cleaver. What's your current speed at WOT ?
    Argo Cat 18 - Sold
    Merc 2.4EFI/CLE - Sold

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