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Thread: Looking for info on how different props designs affect different types of hulls

  1. #1
    Join Date
    Oct 2022
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    Default Looking for info on how different props designs affect different types of hulls

    I'm new to RC boating, and want to learn more specifically about how different types of props and their various characteristics relate to different types of hulls. Can someone point me to some information resources about this subject? I'm a speedrunner for the most part and want to try to learn how to choose the right prop for whatever I want to do, just bashing around or speedruns. So far this is the most fascinating thing for me about boats

  2. #2
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    Jul 2016
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    I learned a lot using props other people had success with on similar hulls/setups and experimented with larger/smaller diameters and pitch. That method saves money on buying new props you won't necessarily need. That got me close and then I could see what small changes did to the performance as I went larger or smaller. I have a huge collection of props now in all diameters and pitch ranges for my personal boats to match the performance I need on a particular day. It's an expensive collection, but really lets me get each boat dialed in.
    Vac-U-Tug Jr (13mph)

  3. #3
    Join Date
    Jun 2010
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    Mi
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    In general, there is a lot of Black Art in props.
    To use a car as an analogy:
    In a fast car, its it not just the engine, but the transmission, differential, wheels and tires that all play a part.
    In a boat, the prop takes the place of the Trans, Diff, Wheels and Tires.
    With the many roles, there is a lot that goes into it.

    In general, the Aluminum CNC props are a cheap place to start, but a ABC prop of the same dimeter and pich will take a boat faster, Its probally some combination of magterial fles and prop design.

    Something that confused me at first: Prop lift. What makes a prop a Lifting Prop?
    The primary design attribute is Rake, or the trailing edge angle of a surface piercing prop. Increasing rake angle tightens the thrust cone.
    Since 1/2 of the prop is out of the water at any given time, a tighter thrust cone will lift less, and and also be more efficient.
    Some hull designs, like Riggers without ski's need prop lift to raise the read out of the water.

    user SweetAcord had a great album of props
    https://forums.offshoreelectrics.com...hp?albumid=991
    Cheetah, Super Rio, (Mod) Starship (Mod and sold),

  4. #4
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    Great analogy about cars, many more variables that affect the outcome. I've seen the chart by SweetAccord, some good info in there with the photos. As they say a picture is worth a thousand words.
    As I become a little more familiar with prop shapes and terminology I can see how a steeper rake equals a tighter thrust cone, more pitch/rake equals more speed in general, (like a higher gear in a car) and less rake gives better acceleration at the expense of top speed (like a bigger low gear in a car)
    As far as lifting props that lift the stern, is this used as a tuning aid to help keep the bow down for high speed runs? Seems logical to me

  5. #5
    Join Date
    Mar 2011
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    BC
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    I found this blog spot while searching ’mercruiser prop tutorial’

    https://community.brunswick.com/area...gy/article/550

    There is a series of parts here, they relate to full size props but the same forces apply. The Mercruiser teachings is how I leaned my basics

    Shawn

  6. #6
    Join Date
    Jun 2011
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    OR
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    I wrote a series on props. Unfortunately, this forum doesn't allow very large files. All my tech articles are scheduled to be posted on the NAMBA web site in the near future.

    Lohring Miller
    Attached Files Attached Files

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