Install steering pedastal to transom hung rudders

Discussion in 'Multihulls' started by Day Tripper, Sep 9, 2010.

  1. Day Tripper
    Joined: Nov 2008
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    Location: Maui

    Day Tripper Junior Member

    Anyone have the pleasure changing from tiller to pedestal steering utilizing cable and pulleys? I have transom hung rudders. I want to put on a edson chain and cable steering unit.
     

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  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    It's pretty straightforward. You need to route the lines where the crew won't be tripping over them.
     
  3. bax
    Joined: Feb 2007
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    Location: Massachusetts

    bax Junior Member

    pedestal

    I'm building a Woods 9m Skua, which calls for transom hung/underslung rudders with tillers and crossbar. Since the wife wanted a wheel, I purchased a Lewmar cobra from a salvaged Hunter on ebay. It was under water about as week in Chicago. A bit of mud here and there, but cleaned up like new.
    I have yet to finish the project, but I designed and built a kickup rudder desing which integrates into steps on the transom. The rudders are a cross between transom hung and underslung, as they fit into a cassette that makes up the bottom of the transom and the bottom step as well. The second step is the pivot point for the kickup mechanism and the rudderpost as well. The quadrants are located just under this step at the top of the rudderpost. 1/4" diameter contorl lines (vectran for weight savings and lack of flesh hooks!) run from the quadrants to blocks that run to the hull surface on the inboard face of each hull, then out to the pedestal under the bridgedeck.
    I will be fabricating a quadrant to attach to the bottom of the pedestal which is a gear driven drag link. It should be even easier to attach your control lines to the chain/cable assembly.

    Good luck!
    bax
     
  4. Day Tripper
    Joined: Nov 2008
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    Location: Maui

    Day Tripper Junior Member

    Is a quadrant required

    Thanks for your reply, would you know if a pulley system can be achieved without the use of a quadrant? i.e. blocks and cable without quadrant. My main interest is keeping the slack out of the cables / lines.
     
  5. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    The problem with not using a quadrant is the distance between a block and a tiller or rudder changes differently on the two sides as the rudder deflects. So unless you have it set up as a pantograph with the cables running between two parallel arms of the same length, you won't be able to maintain the cable tension on both cables throughout the range of motion.

    A quadrant takes in and gives out the same amount of cable on both sides, so it doesn't have this problem. The point in the boat's reference frame where the cable from the block intersects the quadrant remains fixed. You can come into the quadrant at any angle and it still works. That's why people use quadrants.

    You could take the cable from the pedestal directly to a pair of bellcranks and use pushrods from the bellcranks to the rudders. The bellcranks could be T shaped, with the tops of the Ts connected by parallel cables. The pedestal would be in the middle of one of the cables and a simple cable running between the Ts to maintain tension. The pushrods would be connected to the legs of the Ts. You would want to use decent rod ends and bearings to eliminate slop and friction.
     

  6. catsketcher
    Joined: Mar 2006
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    Location: Australia

    catsketcher Senior Member

    No quadrant on mine

    Gday

    On Kankama (38ft Chamberlin) I went to the wheel about 18 months ago - it was good decision. I always had a crossbar about 700mm up the tillers. The crossbar now has vectran lines taken off it as far from the centrally mounted pulleys as possible. This reduces the amount of offline pull as the crossbar moves either side. The centrally mount of the pulleys increase the distance between the crossbar take off point so that the vectran does not need to be lengthened.

    Although I can feel a very slight increase in tension of the line at hardover it is not a problem. If you can't get a large distance between the take off points and the pulleys you will need the quadrant.

    cheers

    Phil
     
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