rudder post and shaft size 11 metre cat

Discussion in 'Sailboats' started by Racman, Feb 25, 2018.

  1. Racman
    Joined: Feb 2018
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    Location: Perth W.A.

    Racman Junior Member

    HI GUYS
    would love to draw on your skills here .What would be a standard aprox size for a yacht of this size.
    are there any drawings or books that adress this area please.
     
  2. jorgepease
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    jorgepease Senior Member

  3. Bruce Woods
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    Bruce Woods Senior Member


    60mm DIAMETER 5mm wall 316 ss
     
  4. Racman
    Joined: Feb 2018
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    Location: Perth W.A.

    Racman Junior Member

    Thank you both for your speedy and helpful input amazing.
     
  5. Richard Woods
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    Richard Woods Woods Designs

    We don't know what catamaran you have, but one problem is that a catamaran rudder is small, thus thin, yet goes at high speed. So a too thick stock means a too thick foil. That's why I like a small shallow skeg as the stock can be fitted further back in the rudder where its thicker. I'd go for 45-50mm and a bit thicker wall rather than Bruce's suggestion (no relation BTW)

    Assuming st steel of course and assuming you mean rudder post and not the prop shaft as Tansl thinks

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  6. TANSL
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    TANSL Senior Member

    My mistake, sorry, I've deleted my post for having nothing to do with this thread.
    In relation to this thread, it would be necessary to know the shape of the rudder, its surface and the speed of the boat.
     
  7. Bruce Woods
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    Bruce Woods Senior Member

    We can make a list of rudder shaft sizes for balanced spades we know have been used on catamarans.
    Snell Easy 48 mm OD SCHEDULE 80 SS Tube , pretty small rudder blades, .
    Simpson 10 50 mm OD solid, largish blade size for boat length.
    Schionning 12 60 mm ss tube with solid inserts, Smallish blade size, eventually broke from sailing loads.
    42 ft Be Good 2, 38 mm ss, failed on first outing.


    Feel free to add to the list, anyone?
     

  8. Richard Woods
    Joined: Jun 2006
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    Richard Woods Woods Designs

    well as Tansl says we don't know the boat, performance nor rudder size/shape/AR and until then we cannot discuss it any more

    RW
     
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