Propeller Efficiency Formular

Discussion in 'Boat Design' started by Adeyele, Mar 19, 2013.

  1. Adeyele
    Joined: Jun 2012
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    Adeyele Junior Member

    Helo all,
    I have the formular: thrust power = Delivered power * Propeller efficiency.

    Am about to calculate Thrust power and I have Delivered power as 80kw. Can anyone help me on how to get Propeller efficiency?

  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    You can usually get that from the propeller manufacturer. They publish the specifications. Once you have them, you can do the rest of the calculations. Otherwise, if you can measure thrust, you can then solve the equation for propeller efficiency.
  3. cme
    Joined: Mar 2013
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    cme Junior Member

    The propeller efficiency you need is that of the propulsor 'in situ' ie the open water efficiency of the propulsor and the relative rotative efficiency of the hull are involved

    what kind of propulsor are you using? how many are there and how are they configured?
  4. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    You need to decide whether you are referring to open water efficiency of the prop and thrust, or the thrust in wake field of the hull and "behind" efficiency of the prop.

    The 2 are very different.

    Open water efficiency is taken from charts of the prop. Efficiencies "behind" refer to thrust deduction factors for the hull shape and inflow characteristic to the prop disc.
  5. Joakim
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    Joakim Senior Member

    You also need the efficiency at the real operating point, not the maximum efficiency often marketed by the manufacturer.

    You don't give any details about the applications and the propeller, but based on the power I'm guessing this is a leisure yacht with some "standard" marine propeller. Most manufactures for such won't give you any data curves, just the maximum efficiency at best.

    A good starting point for the open water efficiency is the Wageningen B-screw series for which you can find a lot of free data and also programs that calculate efficiency for your particular propeller.

  6. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The website for Michigan Propellers has a lot of basic information. They are also very helpful on extra information once you choose a particular size and model.
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