Propeller design

Discussion in 'Props' started by Jfraz, Jun 6, 2017.

  1. Jfraz
    Joined: Nov 2016
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    Jfraz New Member

    Hello, my name is João and I am a member of team Tecnico Solar boat, our goal is to create a solar powered boat. Right now I was assigned the task of building a propeller, however this is not my area of experties and I need help.
    Does anyone know a free software for propeller designing? My propeller will be very light loaded because the boat will have hydrofoils and it will be a small and light vessel.

    Thanks in advance!
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    The propeller is one of the last things calculated for a design. For example, your claim that it will be lightly loaded can't be verified until the hull and hydrofoils are finalized being designed. The load on the propeller will be a function of the power necessary to move the boat at the target speed. Also, hydrofoils require a large amount of power to lift the hull out of the water before they become efficient. That means a highly loaded propeller at low speeds.
     
  3. Jfraz
    Joined: Nov 2016
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    Jfraz New Member

    Hello, I'm aware of that. I already have the boat and hydrofoils. Inclusive I also have a speed/drag curve for the boat with and without hydrofoils. So I believe I have all conditions to design a propeller, except the software and knowledge, do you know any software?
    Ps: sorry that I was not clear enough.

    Thanks for your aswer!
     
  4. Mermaid Co
    Joined: Oct 2012
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    Location: Singapore

    Mermaid Co Junior Member

    You can design by yourself.
    First step will be to calculate resistance on design speed.Then choose maximum poosible diameter of propeller with proper clearences. Spacing from hull,skeg,rudder and,waterline shall be optimal.Decide thrust deduction and wake factors based on hull geometry and propeller arrangement. Choose pitch/diameter ratio and frequency of RPM for that load.Higher the diameter you choose,lesser frequecy of revolutions will be required.Ae/Ao can be chosen to 0.55 to o.60. Make sure designed propeller is able to take that resistance and absorb the given power. You can take help of PNA for all these calculations. Once diameter,pitch ratio and area ratio is decided, use below link to get the coordinates of autocad 3d design. There are many you tube videos in which you will get details of how to sketch with these coordinates. link is applicable for B Series propellers.

    https://www.boatdesign.net/threads/online-b-series-propeller-design.57976/
     
  5. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi Jfraz,
    The English have a nice free software, but it works not on windows 10 and 8 and 7, only on windows Vista and WindowsXP. It is quite informative and you can play around with different configurations. Castle Marine - Pitch Calculations http://www.castlemarine.co.uk/pitch-calculator.php Bert
     
  6. BertKu
    Joined: May 2009
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Hi Joao, You will not find an answer for your Hydrofoil boat. But what the program will be able to give you is some ideas what could work. First at all, you need to know up front what your brushless motor can produce of power. I assume you use brush-less motor. The second thing you have to know up front is the speed you need to get the hydrofoils to work for your boat. If you have been able to figure that information out, you could enter this information under, high speed runabout and also under race boat type and also under Ski boat type. If you know the power your electric motors can produce, you will then know, after entering length of boat, weight of boat, etc. this will give you the maximum speed the boat can do. If the speed is faster than what you have been able to find out what you need to lift the boat out of water, you have then some good idea from the program, what your propellers should look like in diameter and propeller pitch. If all there are similar, I would as a first try to copy that. If all three are vastly varies, you may have to approach castle marine. I made a couple of propellers myself, maybe not optimum, but very impressive in getting my solar boat moving. Good luck Bert
     

  7. vinotinto
    Joined: Jun 2017
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    Location: Earth

    vinotinto New Member

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