A tied hybrid system for junk rigs -- can it work?

  • 09 Jul 2015 09:04
    Reply # 3427081 on 3426671
    Dave Zeiger wrote:

    Tuned in late, but writing to say this is exactly the method Anke and I have settled on for our new rig (Split Junk Rig approach using flat parallelogram panels lashed to a 'round-only' curve, similar to Roger Taylor's 'hinged rig').

    Well this is exciting -- someone's doing all the work for me. When will you be implementing this? I'll be very interested in seeing details (perhaps on your YouTube channel and blog) and especially in results, of course!
  • 09 Jul 2015 08:13
    Reply # 3427046 on 3399298
    Deleted user

    your tied system is a simplification. No doubt it will work and no doubt you will get more people making a sail because there is less sewing involved. if you have some overlapping material it could even stuff the small gaps you get in between the eys. Reminds me of those military sarasani tents, that are made of modules, also tied together. In order to have it waterproofed, the fabric modules are tied in a certain overlapping way. Now, the question is, can you tie the modules together first and then add the pole in the backside of it with a loop? Since I am a total newbie, please excuse any kind of unpracticality. Also there are various types of tracks which are mainly used to attach fabric onto campers, even double tracks are available that would enable you to slide the fabric onto the poles fairly easy leaving no gap in between. gr John


    Last modified: 09 Jul 2015 08:14 | Deleted user
  • 09 Jul 2015 01:16
    Reply # 3426671 on 3399298

    Hi Richard (and others),

    Tuned in late, but writing to say this is exactly the method Anke and I have settled on for our new rig (Split Junk Rig approach using flat parallelogram panels lashed to a 'round-only' curve, similar to Roger Taylor's 'hinged rig').

    Roger's hinges allow 50% gaps along battens (and total gap in the fwd stretch) , but he reports good results. Lashing will remove the other 50% - likely at some cost - but we're still hoping for a solid gain while retaining the ease of construction from flat panels, and experimental flexibility.

    Set-wise, this should be the equivalent of the round-only method, giving up only area along the battens. Roger's experience seems to indicate that loss to turbulence or other gap effects is moderate to nil.

    One trick we've come up with:

    We'll separately loft rounds (relative to straight-edge baseline) for 2, 4, 6, 8, and 10% camber, marked off at one foot intervals (which is our grommet spacing along top and bottom panel edges). For each camber, we'll mark off the round height at each station along a 'ruler' (likely a paint stir-stick), and then use these to set the lashing length at each grommet for the desired camber for any given panel. This should allow us to set camber with 'quality control'.

    The best lashing we've come up with is several round turns of heavy nylon twine, seized near panel edge with a slipped constrictor knot.

    Our principal interest is obtaining reasonable drive and pointing improvements in our ketch, SJ main, and to see how little camber, if any, we can get away with in the mizzen. We assume that a totally flat mizzen would have trouble setting downstream of an SJ main.

    Chances are, once the dust settles, we'd then sew up a 'final' rig using round-only (barrel) method and closing the gaps.

    Dave Z

  • 07 Jul 2015 18:48
    Reply # 3424777 on 3424737
    Darren Bos wrote:

    ... If I understood your idea correctly, you were talking about being able to adjust the lashing length to create camber.  Unless I've missed something, it seems like this is likely to leave larger gaps between the panels than seen on the Malaysian Junk.

    Exactly so, and that might mean it doesn't work very well. I intend to find out (eventually).
  • 07 Jul 2015 18:10
    Reply # 3424737 on 3399298

    Thanks for the link Richard.  It looks like those sails are lashed pretty tightly to the battens.  If I understood your idea correctly, you were talking about being able to adjust the lashing length to create camber.  Unless I've missed something, it seems like this is likely to leave larger gaps between the panels than seen on the Malaysian Junk.

  • 02 Jul 2015 17:50
    Reply # 3416974 on 3399298

    Here's some evidence for Paul Thompson's earlier statement about Thai junks.  This one at least clearly has the panels lashed to the battens, though tightly, and perhaps not all of them. The panels seem to be flat. Using the URL on the side of the boat http://thejunk.com/ reveals that she was built in Malaysia.

  • 25 Jun 2015 02:18
    Reply # 3403219 on 3402019
    Martin Gronow wrote:

    Hi, 


    I was wondering if anyone had tried making a sail out of individual curved panels,  lashed as tightly as possible to the batten...leaving no gaps but an easily made cambered sail?

    Would this need a bolt rope stitched on perhaps?



    regards

    Martin

    That's exactly what I did for Carl Bostek's Aphrodite, except I used tracks rather than lashings. It worked fine. If I were to do it again, I'd probably use lashings but using a track did eliminate gaps between the panels.
  • 24 Jun 2015 16:03
    Reply # 3402211 on 3399298

    Hello, just noticed this thread. I did just that on one of my trial jibs for my AeroJunk. I made individual panels with the necessary curves, put an eyelet in each corner then tied the eyelets together at each batten end in my case. It worked just fine and allowed me to try different sizes before cutting down my proper jib. Obviously there were horizontal gaps between the panels but that didn't seem to matter.

    Cheers, Paul

  • 24 Jun 2015 13:36
    Reply # 3402061 on 3399298
    Anonymous member (Administrator)

    Martin,

    I am convinced that this will work, as I have made test panels this way. However, it will cost you a lot more work to make and rig, than when making the sail with batten pockets. Even so, if I were to make a really large sail, say over 80sqm, I may produce it as two sections and just tie them together along batten 3 or 4 (from top) the way you describe it. This is simply to split the huge sail and batten bundle into two smaller and lighter ones for easier manhandling when rigging and unrigging the sail.

    Arne

    PS:
    Your sail would mainly need to be reinforced along luff and leech, as these will take most of the load. Along the battens, I don’t know, so I suggest you try and see...
    ..no guarantees...

     

  • 24 Jun 2015 13:21
    Reply # 3402042 on 3402019
    Martin Gronow wrote:I was wondering if anyone had tried making a sail out of individual curved panels,  lashed as tightly as possible to the batten...leaving no gaps but an easily made cambered sail?
    I don't know of anyone, but I think this would obviously work, if by "curved" you mean that each panel is cut with belly, but straight edges. You'd keep the advantage of being able to sew panels separately, but lose some other flexibility.
    Would this need a bolt rope stitched on perhaps?
    My plan is to sew webbing tape into the seam, rather than rope, then punch eyelets through the whole thing. As suggested above it would then be easy to extend the ends of the webbing out a bit to make loops at the corners where there's extra tension, rather than relying on eyelets.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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