Carbon Propshaft for electric inboard

Discussion in 'Hydrodynamics and Aerodynamics' started by feunatz, Mar 30, 2017.

  1. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Surface drives can have rudders. Also, the name "surface drive" is a misnomer. Unless you have a propeller designed for surface piercing(i.e. running ventilated), it won't perform properly. On the other hand, a ventilated propeller can be run in an outboard or sterndrive.
     
  2. Irie
    Joined: Jul 2016
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    Irie Junior Member

    I think steering should be around 30° or greater., from what I've read on the net. Mine is about 28° and is acceptable when turning in the direction of prop rotation, however it doesn't turn as well when turning against prop rotation. I'm working on a second version now which will hopefully improve turning ability when turning against prop rotation.
     
  3. feunatz
    Joined: Nov 2016
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    feunatz Junior Member

    I've found some kardans allowing up to 45° angle. But torque transmission will be very uneven at angles that large.

    Irie, do you slide the whole motor+shaft for steering? Or am i overlooking something?

    I'm also thinking of ways to add a rudder, possibly linked to the shaft angle.
     
  4. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    This drive have rudders behind the propeller. You can see the vertical tube where the rudder post goes. They are larger than the boat you are building, but the general design should be very similar.
     

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  5. feunatz
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    feunatz Junior Member

    Thant's pretty much what i had in mind. Then using crossed cable or bungees fixed to the transom and use the rudder to amplify the steering
     
  6. Irie
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    Irie Junior Member

    In my setup the motor and shaft assembly rotate on a base plate. It works well but I don't like the 6" hole covered with rubber boot. I wouldn't recommend it for use on a real waterway, but I boat in a puddle and it was the easier way to experiment with the drive. I'm working on a redesign now to hopefully fix some shortcomings. Were you thinking of using a double cardan joint or a cardan shaft?
     

  7. feunatz
    Joined: Nov 2016
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    Location: Austria

    feunatz Junior Member

    The current plan is to go for a single kardan mounted outside of the transom and use 2 linear actuators 45° each(like a V) for steering and trim. Simple setup but uneven torque on large angles could become a problem.
     
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