The Top 50 Advantages of Junk Rig

Discussion in 'Boat Design' started by David Tyler, Jan 16, 2014.

  1. David Tyler
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    David Tyler J. R. A. Committee Member

  2. Arne Kverneland
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    Arne Kverneland Junior Member

    Stavanger, Monday​

    Hi all
    I can well understand the scepticism against the junk rig, as used by westerners today. When you have seen the lack of performance of a flat-sail version, often rigged with too little area for the hull’s displacement, then you don’t forget it.

    I (born in 1954) have sailed under different rigs since around 1970, but since 1990 I have mainly played with junk rigs. I soon learned that the barndoor-flat sails were no good, even when I gave my first boat (23’ Albin Viggen, Malena) 32sqm sail area. Since 1994 I have made my sails with camber (bagginess) in each panel. This, in combination with a healthy sail area, has just about closed the upwind performance gap to the Bermuda-rigged cruisers with white sails. Reaching and running, my boats are generally faster.

    Here is a little write-up I once made, called “Junk Rig for Beginners” which hopefully makes some sense.

    https://dl.dropboxusercontent.com/u...Rig Files/20091112 Junk rig for beginners.pdf


    .. and here is a photo article from a junk rig rally in Stavanger , in 2010. These boats really move.

    https://dl.dropboxusercontent.com/u...to review of the Stavanger JRA Rally 2010.pdf


    As you can see, these boats all with cambered sail are quite powerful.

    BTW, Richard Woods mention Jester’s lousy performance. I can imagine that. With a flat sail of just 22m2 (237sqft) it cannot perform, except in wind force 4 or more. I certainly would have given her at least 35m2 and with 8% camber in the lower panels, even with offshore cruising in mind.

    Cheers, Arne Kverneland

    PS: The racing boat in Stavanger, Marie G, which David Tyler mention has a 20cm thick carbon mast, weighing 60kg.
     
  3. eyschulman
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    eyschulman Senior Member

    I can see where the junk rig would benefit by adjustments which move toward an airfoil shape. When I sailed and evaluated the 30 ft Willy cat I was thinking this was a very modern adaptation of the junk rig employing modern materials. The pole is un- stayed flexible carbon fiber with a wishbone boom and on some a very large roach with full battens. The net result is a very clean simple rig that probably has all or most of the benefits of a junk rig aside from price. It is my understanding these boats sail very well including up wind and do not have to be reefed in a moderate blow. Like the junk dropping the sail is fast and simple into the wishbone boom rope cradle. Yes I agree if there is to be a wider acceptance for a junk rig it has to deal with modern aerodynamics.
     
  4. Arne Kverneland
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    Arne Kverneland Junior Member

    The battens in junk sails are booms...

    Stavanger Tuesday

    Such a top modern «Bermuda» mainsails with a big roach and full length battens may resemble a junk sail, but they differ greatly in one respect; stress:

    The battens of a junk sail, Chinese, or western style, should rather be regarded as intermediate booms or yards. Even though they are sheeted, they bend very little, not nearly enough to produce any useful camber. This is why I cut each batten panel to an asymmetric barrel shape before assembling them along the battens.

    If you look through my “Johanna’s” sail plan, found here,

    http://www.junkrigassociation.org/arne

    you will see how it is being done. The big reduction in stress in a junk sail, compared to a gaff sail of similar size, must be experienced to be appreciated.

    I don’t claim that the junk rig concept is suitable for racing, but for cruising I cannot find any other rig that is both so easy to make and rig and which also is so easy to handle in all sorts of wind. With camber sewn into each panel, the problem with lousy upwind performance has been sorted out.

    Arne
     
  5. David Tyler
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    David Tyler J. R. A. Committee Member

  6. FAST FRED
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    FAST FRED Senior Member

    I still have quite a few reasons that I am 95% sure that my new cruising boat will be another Marconi rigged sloop.


    I will guess that it has 4 or 5 full battens , and possibly a tiny gaff Dutch style (one halyard) up top.
     
  7. Arne Kverneland
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    Arne Kverneland Junior Member

    Well, it's a free world. If you are happy with your rig, then stick to it. I have no junkrig missionary call, so wish you good luck with your project.

    In my case I found the masthead Marconi rig to be a bit awkward to handle when shorthanded, in particular downwind, where I needed a spinnaker to get a decent speed, so that has been my main reason for converting my boat(s)

    Stavanger, Wed,
    Arne
     

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  8. David Tyler
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    David Tyler J. R. A. Committee Member

    If we all sailed the same rigs on the same boats, it would get very boring, and we'd have nothing to talk about on this forum!

    If you use a very short gaff, it will tend to snag as it goes up past the topping lifts/lazyjacks, and so making sail when head to wind will be a necessity. We can avoid that with junk rig, making and reducing sail on any point of sailing.
     
  9. David Tyler
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    David Tyler J. R. A. Committee Member

    So how about starting another thread where you list those reasons, and justify your choice?
     
  10. ImaginaryNumber
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    ImaginaryNumber Imaginary Member

    How did you insert the doubler inside of the mast? Why did you think you needed it, and why do you doubt its effectiveness?
     
  11. David Tyler
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    David Tyler J. R. A. Committee Member

    Let me admit that I didn't do it, it was done by the sparmaker Atlantic Spars, in Devon, UK. The method is to cut out a longitudinal sliver to reduce the circumference sufficiently, squeeze the tube in with some kind of circumferential clamps, weld on a hoop, hook this to a wire that leads through the mast, grease the doubler, and pull very hard with a Tirfor "come-along". Sounds easy, and it is on a very small tube, but not on this size - they said they don't want to do that job again.

    I calculated that I needed a little more than 3/16" wall thickness. I don't think that a cut tube is the same as an uncut tube, for adding stiffness and strength. Try making a longitudinal cut in a piece of cardboard tube, and you will find that you can twist it, bend it and collapse it much more easily. So I calculated on its only adding the stiffness and strength that a complete tube of half the wall thickness would have added. That is, I based the calculation not on 10mm, or 5mm + 5mm, but on 5mm + 2.5mm wall thickness.
     
  12. Baltic Bandit

    Baltic Bandit Previous Member

    Hmm went through the original list and it really came down to 7 actual distinct plusses for the Junk rig:

    1) easier to reef
    2) easier to gybe a large sailplan singlehanded
    3) you can climb the mast without ladder fittings
    4) better visibility
    5) cheaper cuz you can homebuild them
    6) lower loads in some cases
    7) sail damage is less an issue

    the others are either overstated, repeated variants of one of the above - or not unique to Junk Rigs

    So that's a 7x overstatement. I spent 3 years moored living alongside another liveaboard that had junksails and was a similar advocate.

    We sailed more often and in a broader set of conditions than he did. And I was single handing a 50'er.
     
  13. Avoid Rocks
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    Avoid Rocks Junior Member

    Those are still 7 pretty good plusses. Out of curiosity, what downsides/disadvantages would you list? Windward performance would be one thing. What else?
     
  14. David Tyler
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    David Tyler J. R. A. Committee Member

    Nothing else, really, and even the "poor windward ability" is a left-over from the days when all junk sails were cut without camber.
     

  15. pdwiley
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    pdwiley Senior Member

    Yeah and if you start cutting the panels with camber you lose simplicity & cheapness. TANSTAAFL. Not only that it assumes that your hull shape is capable of sailing higher to windward if only the sail plan cooperated. Not true of all hulls.

    A friend of mine is trying this with his BADGER design at the moment. I'm interested in seeing how it turns out.

    PDW
     
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