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Acceptable course wander for a windvane?

  • 07 Mar 2014 07:31
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    Reply # 1512639 on 1511070
    Deleted user
    thanks David--- quite a bit clearer!!  TONY
  • 07 Mar 2014 01:14
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    Reply # 1512520 on 1511070
    Anonymous member
    Tony,
    I think you're referring to the setting for the balance of the blade. There is a screw that can be adjusted so that the blade is well balanced, but not overbalanced, relative to its vertical pivot axis. That's a different thing from what I'm referring to. With a Hasler gear (or any other pendulum gear), you mustn't let the aft end of the whole gear droop down lower than the forward end, or the blade toes forward into the water flow and is unstable. If the aft end of the whole gear is higher than the forward end, the blade is trailing a little. I would say that you should put a spirit level on the horizontal tubes of the framework, and aim for an angle of between 0 and 5 degrees. It is actually beneficial* to tilt the vane forwards at up to 5 degrees as well, so this ties in well. 

    My gear is built with its "horizontal axis" at 30 degrees to horizontal - that's where the trailing action comes from.

    * It's a difficult thing to explain, and involves a 3D visualisation. John Letcher's book on self steering tells it better than I can.
  • 06 Mar 2014 15:26
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    Reply # 1511865 on 1511070
    Deleted user
    Ron Glas steers pretty well with her original Hasler vane gear ,in open water say 10+ miles from the coast Iwould estimate 10-15 degrees of wander. closer to the land its a bit tricky as the wind is rarely constant and flukes about a surprising amount.
    I`ve read with great interest David`s comments on tilting up the servo paddle---  the original Hasler instructions state that the leading edge of the paddle should be 1/4" away from vertical at the tip ---maybe 3-5 degrees of rake. Trouble is the frame work that is used to rest a straight edge against to achieve this 1/4" number has been bent in a previous accident. I  lost the original settings when I rewelded the frame. Should I keep tilting the paddle-- an easy screw adjustment on the Hasler-- to achieve ever more self centering effect ?
    The original manual cautions that increasing the rake will improve self centering but at the expense of power developed to steer the boat. Does this sound right?? TONY
  • 06 Mar 2014 11:15
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    Reply # 1511769 on 1511070
    Anonymous member
    Arion has a trim tab that is well aft of the trailing edge of the rudder, driven by an offset vertical windvane through a differential linkage.  When I am running I usually disengage the windvane and link my Navico 1100 tillerpilot into the trim tab unless the wind is very fresh.  I have just sailed 40 miles dead downwind in 15 - 20 knots, with 3 metre swells on the stbd quarter (from some disturbance in the Coral Sea).  We had 2 panels reefed down, averaged 4.5 knots and wandered less than 10 degrees either side of the course.  Last year, when I really pushed the rig, I had full sail or just one reef in similar conditions and we yawed a bit more, maybe 10 - 15 degrees  We were sailing at close to hull speed - 6.5 knots - but it felt squirrelly and made me nervous of a broach.  If I keep my hull speed when running below 5.5 knots, 10 degrees seems the maximum amount of yaw.  With the wind forward of the beam Arion basically self-steers, like many junk rigged yachts.
    Last modified: 06 Mar 2014 11:19 | Anonymous member
  • 06 Mar 2014 01:53
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    Reply # 1511600 on 1511070
    Anonymous member
    When Badger had her Aries, I would say she generally wandered +/- 15 degrees either side of the course, once the wind was abaft the beam.  With the trim tab and vertically pivoted wind vane, she sailed closer to the course, although that is the opposite of the theoretical result. 

    Fantail wanders all over the place down wind if she's going over 6 knots, but David has suggested that if I tighten up all the lines, this will help.  I'm presently stuck in harbour while I have commitments to various people I foolishly offered to help.  I'm doing a bit of tweaking on the sail, too - if the wind ever stops blowing for long enough.  If things improve, I'll post on it.
    Last modified: 06 Mar 2014 01:55 | Anonymous member
  • 05 Mar 2014 23:26
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    Reply # 1511509 on 1511070
    Anonymous member
    With Tystie, it depends a lot on boat speed. Under 6 knots in a moderate sea, +/- 10. Over 7 knots running, +/- 20 at least, but that's because the apparent wind is getting very light and very variable. 
    But these figures are only achievable because I have pendulum servos that trail aft by 30 degrees, which makes them tend to self-centre. With a vertical pendulum, I couldn't press on so hard as I can with my angled pendulums.
  • 05 Mar 2014 19:17
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    Reply # 1511292 on 1511070
    Anonymous member
    LC under her old rig (gaff ketch) and Monitor windvane could stay within 10 deg of the desired course (that is averaging 5 deg each side). I have rudder issues at the moment which prevents the current windvane (Cap Horn) from steering at all (far to much helm (> 10 deg) is needed before the boat begins to respond) so cannot comment on the junk rig but I expect it to be about the same once I have the rudder issues sorted.
  • 05 Mar 2014 14:42
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    Message # 1511070
    Deleted user
    Yep, still working on it. When not close hauled* our self steering is not too straight. I know +/-60˚ is not acceptable, that is the boat wanders from 30 to 150˚.. is better than that now.
    What is acceptable in the open sea?  +/-20˚ or +/- 10˚ (I don't think our vane could do the latter).

    *Close hauled is kind of cheating, since Ashiki doesn't need a windvane for that.
    Last modified: 05 Mar 2014 14:44 | Deleted user
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