Help with design of T rudders for a 50' catamaran

Discussion in 'Hydrodynamics and Aerodynamics' started by Dave_S, Nov 24, 2020.

  1. Dave_S
    Joined: Sep 2018
    Posts: 18
    Likes: 0, Points: 1
    Location: Brisbane Australia

    Dave_S Junior Member

    I'm keen on trying T Rudders on my cat. It's a Schionning Waterline 1480 that measures 15m and 7.2t to 7.8t depending on use.

    I am hoping to achieve a reduction in hobby horseing at 0┬░AOA. I hope this will translate into improved pointing in swell and improved speed in all points of sail when it's a bit rough.

    I have a CNC router to machine the profile or multiple profiles I have been a mechanical design engineer for 30 years working in 3D Autodesk inventor. BUT, no clue what profile or plan view silhouette or surface area to use. Have read a fair amount recently and have figured out there is a lot more to it than some internet trawling might teach me.

    Is this something one of you kind people can give me a ball park spec for, or is it more complex to give a rough spec for. I'm not looking for the last little bit just a conservative ball park specification.
     
    Last edited: Nov 24, 2020
  2. Dave_S
    Joined: Sep 2018
    Posts: 18
    Likes: 0, Points: 1
    Location: Brisbane Australia

    Dave_S Junior Member

    I just saw the post on Typhoon software, I'll give it a try.
     
  3. DCockey
    Joined: Oct 2009
    Posts: 4,886
    Likes: 426, Points: 83, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    I would be more concerned about the forces generated when resisting pitching in waves than the exact details of the shape. Both the bending moment at the base of the T plates and the vertical force on the rudder bearings, etc need to be considered.
     
  4. Carl Henrikson
    Joined: Dec 2020
    Posts: 2
    Likes: 1, Points: 3
    Location: Sweden

    Carl Henrikson New Member

    Hi Dave! I suggest you get a copy of "Hydrofoils Design, build,fly" by Ray Vellinga. A common profile to use is NACA 63412 for the lift foils and NACA 66012 for struts. Also there is a Facebook forum "Frankenfoil Sverige" which is about adding foils to existing boats. It started in Sweden but is now international and in English. I am slo interested in adding foils to my Trimaran - a Weta.
     
    Dave_S likes this.

  5. Dave_S
    Joined: Sep 2018
    Posts: 18
    Likes: 0, Points: 1
    Location: Brisbane Australia

    Dave_S Junior Member

    Thanks Carl
     
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