I like a tiller...

Discussion in 'Boat Design' started by robwilk37, Jan 28, 2012.

  1. robwilk37
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    robwilk37 Senior Member

    so this project boat ( 40' OA, 33'WL, 20,000 DISP ) came with wheel steering and i would rather have a tiller. i like the feel, forward sitting, simplicity, open cockpit at anchor etc benefits of a tiller. my questions are these :

    1) what percentage of the total area needs to be ahead of the rudder shaft in order to balance the load and not exhaust the helmsman ?

    2) with the helm well balanced, is it not possible to fit a relatively small tiller pilot since the loads are effectively reduced ?

    3) since im building a new rudder, wouldnt it be smart to have a carbon shaft to eliminate corrosion / maintenance issues ?

    4) how best to employ a steering vane with a tiller ?

    pics attached. we can have the whole " yorktowns are POS's " discussion in another thread.

    thanks for any ideas...
     

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  2. Perm Stress
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    Perm Stress Senior Member

    1) what percentage of the total area needs to be ahead of the rudder shaft in order to balance the load and not exhaust the helmsman ?
    The rudder is already well balanced as it is. If hull shape is good, sails trimmed right, this rudder should not tire the helmsman.

    2) with the helm well balanced, is it not possible to fit a relatively small tiller pilot since the loads are effectively reduced ?
    How long it is? ~40ft?
    Only experience will tell. I did see a 30 footer (Carter 30) who used to break tiller pilots on regular basis, because the hull shape peculiarities create extremely large loads on unbalanced skeg-hung rudder. The owner finally resorted for servo-pendulum vane pilot, leaving the electric for motoring in calm. Your rudder is balanced, so again, experience will tell.

    3) since im building a new rudder, wouldnt it be smart to have a carbon shaft to eliminate corrosion / maintenance issues ?
    It all depends. Stainless shafts are used for decades without corrosion issues. Carbon could be corrosively aggressive to any neighbouring metal (on masts, I do have direct info about rudders in this respect)

    4) how best to employ a steering vane with a tiller ?
    The way that suits you best :). Search the vane steering, many of them are designed primarily for tillers.
     
  3. bntii
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    bntii Senior Member

    "2) with the helm well balanced, is it not possible to fit a relatively small tiller pilot since the loads are effectively reduced ?"

    Well balanced in a relative term.
    What kind of sailing are you setting up for?

    The helm will have cyclical loads in any kind of offshore sailing. These can be quite high in following conditions & the autopilot must be robust & designed to meet them.
     
  4. FAST FRED
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    FAST FRED Senior Member

    I would use a trim tab on the back of the rudder , to steer with fingertip loads and also for the electric autopilot.

    There MUST be a good tab locking mechanism if you ever plan on going astern.

    I would fit a pendulum style self steering (Aires?) for ocean work.

    The reason is with an Aries as the boat slews off course going down wind (the hard part of self steering) the paddle in the water is pushed into the proper recovery direction , instantly operating the tiller..

    The wind vane does not need to notice the heading change , because the proper input is being applied to the tiller.

    FF
     
  5. gonzo
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    gonzo Senior Member

    I have sailed and raced boats in that size with tillers. They didn't have a balanced rudder and did fine. Many boats have balanced rudders to compensate for a bad design. Also, if you trim the sails right, there will be less effort on the steering gear.
     
  6. robwilk37
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    robwilk37 Senior Member

    thanks all...

    yes, the idea of trim tab steering is elegant. ive yet to find a working example or drawings that could be adapted. if you have a link id very much appreciate it.

    the boat will cruise, and i will give sheet to tiller every opportunity, and i do like the idea of a small tiller pilot actuating a trim tab, DDW is not a comfortable point of sail and could be avoided.

    i guess since the boat is in my back yard and will be for some time, how best to optimize the below the water line bits now as best i can...

    thanks again
     
  7. philSweet
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    philSweet Senior Member

    sailing a 20000 pounder with a tiller is no fun at all. It will exhaust anyone in short order off shore in more than a few knots of wind. You will want a BIG tiller- seven or eight feet long (can carry a smaller one for fair weather, but you will need the big'un). Autopilots are generally rated by displacement, so you need one good for 20000 pounds. An Aries sets up well as mentioned above. I was part of a four man crew who sailed a 16000 pounder from St Criox to Montauk by tiller when the Aries crapped out. Four very tired fellows arrived at Montauk, and we were blessed with good weather.
    The boat was a bit fussier than yours is likely to be, but still....
     
  8. philSweet
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    philSweet Senior Member

    looking at the boat again, an eight foot tiller would apear to put it about two feet into the salon. That could be a problem.
     
  9. robwilk37
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    robwilk37 Senior Member

    no no...from the rudder head to bridge deck is 9', but still an 8' tiller is quite the cockpit sweeper if it gets away from you, with attendant bone crushing and general mayhem... this is my concern, and my original question : couldnt the area ahead of the rudder shaft be such that it would balance the loads at the tiller head? and how to know the ratio?
     
  10. gonzo
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    gonzo Senior Member

    It depends on the design. Many boats on that size without a balanced rudder are very easy to steer.
     
  11. robwilk37
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    robwilk37 Senior Member

    so gonzo, what are the primary design factors that would affect the rudders performance?
     
  12. philSweet
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    philSweet Senior Member

    Balancing the rudder requires that the center of effort stays in the same place all the time, and it doesn't. For a spade with a foil shape, the CE is about 25% from the leading edge when not stalled and about 50% when stalled. With a skeg in front, I don't know where the CE would work out. But you already have the boat. Don't change anything until you sail it and learn its habits. Then you will be able to do exactly what is needed. If you spread the project out over a few years, I promise you will be much more satisfied with the results of you mods; and sailing tends to rearrange your priorities list and budget rather drastically compared with what it was in the boatyard. At least it does with me.

    What is it you plan to change with the rudder? Why not fix what's broke and keep the designer's original mechanicals?
     
  13. robwilk37
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    robwilk37 Senior Member

    well like i said i prefer the tiller for sailing feel and simplicity. all of these boats ive seen came with pedestal steering so feedback from owners hasnt been helpful. if conversion is something i can address while the boat is out, that saves me from re-hauling in the future. im not opposed to a wheel, just exploring my options.

    and on the subject of wheels...ive seen these boats with what i consider a pathetically small 24" wheel pulling cables connected to a 18"r quadrant. that doesnt seem like near enough leverage to handle the rudder yet owners say they find the boat easy to control and occasionally surf. so i start thinking... man, a 6' tiller and im golden ! what am i missing in the geometry that gives the wheel such mechanical advantage ?
     
  14. philSweet
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    philSweet Senior Member

    What you're missing is the number of turns from +35 degrees rudder to -35 degrees. Could be four. Could be eight.
     

  15. philSweet
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    philSweet Senior Member

    Sorry, my boat is a bit odd.
    My rudder goes +-90 degrees. 2 to 4 turns would be more the norm for +-35 degrees.
     
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