Boat design with movable (up/down) prop shaft??

Discussion in 'Boat Design' started by Rollbar, Sep 23, 2018.

  1. Rollbar
    Joined: Jul 2018
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    Rollbar Junior Member

    Do any of you know of a boat design that used a shaft connection (inboard) to a drive shaft to prop, that could be raised and lowered as needed and could be launched off a beach?

    Thanks,
     
  2. KJL38
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    KJL38 Junior Member

  3. Rollbar
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    Rollbar Junior Member

  4. rwatson
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    rwatson Senior Member

    Heres is a slightly improved version
    " Retracting Drive Unit

    The retracting drive unit in the 35 MKII is a little different from others that have been built. Where others have employed single or multiple constant-velocity joints to keep the angular velocity constant, we can use a simple universal or Cardan type joint. This works because the tail shaft is in alignment with the stub shaft coming from the gear when the unit is deployed. The universal joint also functions as the hinge point for the strut." Bieker Boats: Retracting Drive Unit http://biekerboats.blogspot.com/2012/11/retracting-drive-unit.html


    Retractable Drive 9.JPG
     
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  5. rwatson
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    rwatson Senior Member

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  6. goodwilltoall
    Joined: Jul 2010
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    goodwilltoall Senior Member

    With all the complications of a lifting prop, my conclusion is that a tunnel hull prop is a much better idea. The rnli and other north european SAR organizations use it. Dave Gerr is a modern day advocate for it although I would like to see others using/designing it for low power displacement efficiency.
     
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  7. Rollbar
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    Rollbar Junior Member

    Thank you, awesome design
     
  8. Rollbar
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    Rollbar Junior Member

    Yes agreed, but ,,, :)
     
  9. alan craig
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    alan craig Senior Member

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  10. OCB
    Joined: Dec 2015
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    OCB Junior Member

    I only see sail boats with retractable drives. What size boat, motor and shaft are are you thinking of using? I'm working on inboard boat drive that has the pivot at the transom. I design it for small inboard boats with tiller steering.

    OCB
     
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  11. Rollbar
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    Rollbar Junior Member

  12. JSL
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    JSL Senior Member

    And, what about the rudder?
    Another reason why Mr. Evinrude invented the outboard motor.
     
    Last edited: Sep 24, 2018
  13. Waterwitch
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    Waterwitch Junior Member

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  14. OCB
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    OCB Junior Member

    ESA propulsion

     
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  15. JSL
    Joined: Nov 2012
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    JSL Senior Member

    If you can manage without a shaft, How about a
    (a) sterndrive (inboard outboard)
    (b)a surface drive (Arneson).
    Efficient, Proven, & 'off the shelf''. Can be direct or remote mount with a jack-shaft.
     
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