Wind vane steering

Discussion in 'Multihulls' started by cat nap2, Mar 23, 2017.

  1. cat nap2
    Joined: Nov 2015
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    cat nap2 Junior Member

    I am interested in adding wind vane steering to my 37ft catamaran.
    What are the different methods/designs to accomplish this.
    Generally do wind vane systems work on a cat.
    Any suggestions would be appreciated.
    Thanks. Cat Nap2
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Are you looking to buy a windvane or build your own?
     
  3. catsketcher
    Joined: Mar 2006
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    catsketcher Senior Member

    Most people don't use windvanes on multis. However they have been used before.

    Probably the most common windvane is the Searunner type used on the Jim Brown designed tris. They use a trim tab and need a vertical stern mounted rudder to mount the trim tab on.

    I have thought about a windvane for my 38ft cat. I run into problems with my underhung rudders. David Lewis used two wind vanes on Rehu Moana which was the first multi to sail around the world - one on each side.

    The usual reason people don't use vanes is because the servo pendulum models (which are the strongest type) don't fit well on the back of cats. Tris are a little simpler. Then there is the very real problem of using the apparent wind to steer the boat - on multis the apparent can change very quickly and make self steering much more problematic. The Searunners did manage it for the most part.

    In the end the hassle of making a system will be higher for most people than going out and buying one. My Raymarine ST 4000 is a pretty good system for coastal sailing.

    cheers

    Phil
     
  4. cat nap2
    Joined: Nov 2015
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    cat nap2 Junior Member

    I was mostly interested in mounting locations and options at this point.
    Catsketcher's reply seems to indicate that wind vanes don't work that well on cats.
    However still interested in the idea.
    Cat nap2
     
  5. Tom.151
    Joined: Jul 2009
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    Tom.151 Senior Member

    My thoughts only...

    * The Jim Brown Sea Runner style is reported to work very well - and it's original weakness, insufficient downwind sensitivity, was cured by Jim Brown's later refinement of adding small tabs on the trailing edge of the wind vane.

    * If it works on a trimaran it will work on a catamaran.

    * Although designed for a vertical transom it seems that using push-pull cable for connecting wind vane to trim tab would (a) greatly reduce complexity of the linkage from wind vane to trim tab, and (b) enable you to run one trim tab on one rudder for further simplification

    * Locate the wind vane portion on the centerline

    Hope that helps,
    TomH
     
  6. ImaginaryNumber
    Joined: May 2009
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    ImaginaryNumber Imaginary Member

    Pete Hill has successfully used wind vanes on the two or three catamarans that he's built, the most recent being ORYX, a 10m stretched version of a Kohler KD860. On ORYX he uses two self-built Belcher wind vanes, one mounted on each hull. His sail configuration is unusual, consisting of dual masts, one in each hull, each with a modified junk rig.

    http://junkoryx.blogspot.fr

    [​IMG]

    [​IMG]

    [​IMG]
     
  7. hump101
    Joined: Oct 2004
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    hump101 Senior Member

    If your boat is fast enough to bring the apparent wind forward of the beam when off the wind then, if set for the max speed condition, as speed changes it will be steering you upwind and then downwind in cycles, as the wind speed changes, and will cause the boat to pass through the beam reaching direction which is the most dangerous for a powered up multihull.

    All the multihulls I've seen them being used regularly on have been too slow for this to be an issue, so if yours is similarly slow it may work OK..
     
  8. cavalier mk2
    Joined: Mar 2010
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    cavalier mk2 Senior Member

    Wharram sells vane plans for the horizontal style which are more powerful than the vertical style.

    The Searunners had a linkage update that takes out some of the yaw when waves hit. Marples would sell a plan sheet I'm sure.

    The apparent wind dilemma can be solved by slowing down, of course who wants to?

    For a underslung rudder the easy solution is a stern mounted auxiliary rudder for the vane, maybe a central rear beam mount with a surface piercing blade? Because of the tall cabins on most cats having a vane on each side is probably easier though with a cable system having one high in the air would be possible.
     

  9. aabella
    Joined: Oct 2009
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    Location: Uruguay

    aabella Junior Member

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