Origami rig comments

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  • 10 Sep 2023 22:25
    Reply # 13252526 on 13252522
    Anonymous wrote:

    The canonical form for batten parrels is to have them span many times the width of the mast and allow the sail to be moved fore and aft with the multiple running parrels, but Paul McKay and Steve Dawes have had good results and simplified running rigging using rigid formers that attach the sail to the mast with limited degrees of freedom. I've doodled a dozen layouts myself, but there is quite a bit of fiddly design, fabrication, and assembly needed for all of these formers.

    The purpose of the formers is not (only) to restrict freedom fore and aft but also to simplify the rig and to allow the mainlets to use the mast as the leading edge of the foil in a manner that makes sense on both tacks.

    So this is one of those places that what is fiddly to one person, is simplified to another. I would put things another way, coming from a programming background. In programming, the programmer does extra work once while creating the program so that thousands of users do less work many times. In the same way, the formers are meant to require more work at build time so that the usage of the rig in daily practice is simplified many times over.

    I don't know how well this actually works in practice  ;)    However, considering that the origami concept was started on the same rig as the airo jib style (I have mangled the name) rather than switching to using parrels does say something about the value of the system.

    I guess I should point out that most Junk rigged sails are designed to be able to be moved fore and aft for balance, it is only the split version that needs to be constrained and is set to hang within this constraint as a design goal. It is also the SJR that that would benefit most from having the mainlets line up with the leeward side of the mast.

    Last modified: 10 Sep 2023 23:20 | Anonymous member
  • 10 Sep 2023 22:03
    Reply # 13252522 on 10239242

    The canonical form for batten parrels is to have them span many times the width of the mast and allow the sail to be moved fore and aft with the multiple running parrels, but Paul McKay and Steve Dawes have had good results and simplified running rigging using rigid formers that attach the sail to the mast with limited degrees of freedom. I've doodled a dozen layouts myself, but there is quite a bit of fiddly design, fabrication, and assembly needed for all of these formers.

    If the batten parrels are made shorter and fastened to the battens just barely on each side of the mast, then the sail can't shift much but the parrel can bind up when hoisting or reefing. Can two parrels per batten constrain the sail balance yet not bind? The fore parrel passes around the aft side of the mast, wraps partway round, and is lashed to the batten 2-3 mast diameters forward of the mast. Like a singular luff or tack hauling parrel, it pulls the sail to the front. Another batten parrel passes in front of the mast and ends 2-3 diameters aft of the mast, and pulls the sail aft. Together they should hold the sail at the desired balance point almost as well as the rigid formers, but be simpler, lighter, and less expensive. Just two pieces of cord for each batten should allow a simple rig with only halyard and sheet as the running rigging.


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    Last modified: 10 Sep 2023 22:05 | Anonymous member
  • 06 Sep 2022 16:52
    Reply # 12908315 on 12906810
    Anonymous wrote:

    Hi all, I live on the west coast of Canada, and I have been following the development of the junk rig for decades, lurking and reading, hopefully benefitting from all your expertise.  I was very excited about the split junk rig, although it looked complicated in its execution, so when I saw the simplicity Paul McKay's Origami rig, I knew I would have to give it a go. I improved my time last winter during the 'covid response insanity'

    I also live on the west coast, though we moved away from Surrey to the Comox Valley years ago. I wanted to reply if for no other reason besides encouraging you to keep going. I too have been following the SJR and the Origami rig (SOJR?) and now that I am in the process of buying a suitable boat (just need insurance so we can transfer the moorage), I am almost ready to try things.

    I also want the sail to be balanced as it is reefed, requiring each jiblet/main pair to have the mast at 33% of the length of the battens framing it, for ease of sheeting and better balance on all points of sail.

    This makes sense, though I am guessing that being balanced on all points of sail and in all sailing conditions is less achievable. As the angle of the sail changes so will the centre of effort compared to the boat. When as close to the wind as possible, the centre of effort will be aft of the mast by about 1/6 of the chord of the sail but as one goes through broad reach to a run, the centre of effort will be at the mast. Though, to be honest, I do not yet have enough experience to know how much that changes things. (I did manage to crew on a sailing trip this summer)

     I made a test sail, but my construction set-up needs rethinking, I was not happy with the cut of the jib, the set of the sail, so to speak. I think that 35% of batten length was too much, I will settle out at 33% next time.

    With the Origami rig, it should be possible to make the sail position adjustable, at least while experimenting. The mainlets can probably be in a set position but if the battens are a bit overlong, the attachment point of the luff and leech can be made adjustable by combining a loop around the batten with an out haul for positioning the luff. The luff could even be made with two or three bolt ropes to allow changing it's size by folding it over though I wouldn't want to do that for a permanent setup.

    I like the esthetics of the Chinese junk sail, and although the identical panel sails of Sleive and Paul in their respective styles of split junk are designed for ease of construction, I wanted something that was closer to the esthetics of the traditional Chinese junk sails.

    I would suppose reefing a larger amount from full to first reef and a smaller amount at the last would make sense. However, looking at your pictures, it was hard to tell if the difference in size was differing sail sizes or perspective.

    That is all for now, more this fall...

    I will be interested to see how things go.
  • 05 Sep 2022 02:53
    Reply # 12906810 on 10239242

    Hi all, I live on the west coast of Canada, and I have been following the development of the junk rig for decades, lurking and reading, hopefully benefitting from all your expertise.  I was very excited about the split junk rig, although it looked complicated in its execution, so when I saw the simplicity Paul McKay's Origami rig, I knew I would have to give it a go. I improved my time last winter during the 'covid response insanity'

    by working on the design and construction aspects of the Origami rig for a folding inflatable dinghy that I am also working on, as a test bed for junk rig design (I am going to junk-rig my pointy top trailer sailer Mac 25 this coming winter), and I have settled on the Origami rig, or variation thereof, for the FIB (Folding Inflatable Boat based on the Fliptail 9- but that is for another thread...).  Looking at a dinghy sail, it needs certain compromises in order to be functional (I am lazy, or efficiency expert, you choose!) the sail needs to be easy to reef, easy to set up and strike, stow-able without much fuss, efficient upwind, easy and cheap to build and look cool... At least it must look esthetically pleasing to both my engineering and artistic soul, which requires it to have form follow function...  I also want the sail to be balanced as it is reefed, requiring each jiblet/main pair to have the mast at 33% of the length of the battens framing it, for ease of sheeting and better balance on all points of sail.  I have been pondering the mast-meets-the-batten conundrum at length, as I also wish the sail bundle/mast/sailcatcher to be one when stowed.  I planned on having this possible by having a ring of webbing with a rivet/chicago screw holding the webbing ring and webbing stretcher (I am experimenting with attaching the ring of webbing to the strip of webbing the sail will attach to in order for the mast ring/batten to be able to twist when the mast is folded into the sail catcher). the msat must be able to pivot 90* for each batten, allowing them to stay flat as they settle around the mast in the sail catcher when stowed to keep the whole thing un-stressed at rest (like me!). I am starting again this fall with the onset of the west coast 'pineapple express' that keeps the greater Vancouver area wet and snow free most of the winter.  I made a test sail, but my construction set-up needs rethinking, I was not happy with the cut of the jib, the set of the sail, so to speak. I think that 35% of batten length was too much, I will settle out at 33% next time.  The masts, one for each of the dinghies I am going to build, as I am making two, comprise of 8' + 4' of 1-1/16" aluminum tube with a 12" length of aluminum tube to make an inner sleeve , giving a total length of 12' for the assembled mast.  I riveted the sleeve to the 4' top section, to which I added two webbing loops at 90* to each other secured with two 'jubilee clips' or pipe screw clamps for the running rigging attachment, an idea that I 'borrowed' from another fellow junk aficionado. Sorry, not sure who came up with that one! I bungeed the two sections together so they will stay together when folded.  The top of the mast will stay in the sail catcher beside the top of the bottom section of the mast, (along with the sail bundle) and part of the base portion of the bottom section that sticks through the sail catcherwill be strapped to the bottom of the sail catcher with added strap + buckle for ease of stowing.


    I like the esthetics of the Chinese junk sail, and although the identical panel sails of Sleive and Paul in their respective styles of split junk are designed for ease of construction, I wanted something that was closer to the esthetics of the traditional Chinese junk sails.  With the Origami rig, this is possible.  I laid out the sail panels on a piece of plywood, the largest one first, and it turned out, that each sail panel as I went up the sail, was the same front edge shape as the one below, only a consistent length shorter each time.   As the sail panels are sewn flat and it is the location of the attachment points that creates the 3D shape, they are extremely simple to build.  I tapered the leading and trailing edges (luff and leach) to both keep the overall shape of the sail tapered from bottom to top, but the proportion of the whole sail before the mast stays the same, only the aspect ration diminishes when reefed.  The whole thing has a 5* rise, and 5* slope in the leach and the luff from the vertical.  As I said, the set of the sail was a lot to be desired, although, to be fair, I didn't test it in a stiff breeze. That is all for now, more this fall...  Anyone else with experience building origami junk sails for a dinghy?  My balcony is about to set sail...  Didn't get as far as sheeting yet...  :-{}


    Dave J

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  • 31 Mar 2021 06:42
    Reply # 10255067 on 10250108
    David Doran wrote:

    Hi Doug.

    I seem to remember a mention of that unconventional sheeting system when browsing the magazine archive.

    As far as I can remember, it was mentioned in Paul Mckay's original article on the Aerojunk rig.

    If it worked it would cut down a lot on the amount of rope in the cockpit and allowed a more Bermudan style sheeting arrangement in the cockpit.

    Maybe someone has more information?

    Thanks, David, with that hint I was able to find this Q&A exchange in Paul's article on the Aerojunk in I64, p48:

    [Q:]On the all-white sail there appears to be a 'bolt rope' at the aft end of the battens, but not the forward end. But the red & white sail may have a bolt rope at each end.

    [A:]What looks like a bolt rope is actually the single line sheet running through bull's eyes fitted to the ends of each batten. So this design has a halyard, a sheet and 3 (optional) downhauls to make the sail pretty. That's it.

    So yes, it seems that balancing the sail and (in one of several possible ways) fixing its fore-aft movement relative to the mast provides a lot of simplification. Cool.

    Graeme Kenyon wrote:

    PS I have wooden battens, not regarded as the best solution, and I broke one the other day. (Not from sailing forces - I hit a marker pole with the sail while fooling around with a camera). The batten did indeed break at the mast - and the improvised splint arrangement which was easy to make on the spot, looks so satisfactory to me that I am considering putting splints on all the other battens too!

    Yes, after looking at my sketch again, the spool on the batten appeared ridiculously large. Adding a more modest reinforcement to the battens where they bear against the mast should help reduce point loads and prevent the initial damage that can lead to buckling. A bit like the way I sometimes put a knee brace on before going hiking...

    I'm glad to learn that the ideas I'm throwing out are mostly redundant and not utterly stupid. I think I'm learning! I've downloaded both Arne's and Slieve's info troves, as well as every issue of the newsletter. Lots to assimilate in there, fun reading.

    Thanks everyone-

  • 30 Mar 2021 00:20
    Reply # 10250615 on 10239242
    Anonymous member (Administrator)

    R D Culler (I've dusted off his book and have been reading it again) - has a suggestion to bring the tail of the halyard back and attach it to where it starts - making an endless loop - that seems a clever way of getting rid of some of the rope where the halyard is 1:1 (a dinghy?) - never tried it.

    There is no doubt the JR does involve quite a lot of rope that all has to be kept tidy.

    Doug: I forgot to mention - there are lots of different sheeting systems and some of them are said to be very good at anti-twist. I use a 2-part system myself, and am amazed at how well it keeps the sail, you can eliminate all twist if you want to. Evidently some sails like a little bit of twist, but I quite like to keep my sail with almost none (as far as I can judge by looking up from below.)

    Last modified: 30 Mar 2021 08:56 | Anonymous member (Administrator)
  • 29 Mar 2021 22:06
    Reply # 10250108 on 10239242

    Hi Doug.


    I seem to remember a mention of that unconventional sheeting system when browsing the magazine archive.

    As far as I can remember, it was mentioned in Paul Mckay's original article on the Aerojunk rig.

    If it worked it would cut down a lot on the amount of rope in the cockpit and allowed a more Bermudan style sheeting arrangement in the cockpit.

    Maybe someone has more information?


  • 29 Mar 2021 21:08
    Reply # 10249948 on 10239242
    Anonymous member (Administrator)

    Doug: I can't claim in any way to be an expert on this, having made just one SJR sail and used it enough to have some idea about the type. But I can't help offering an opinion and clarifying a couple of points.

    Without knocking any of Paul's ideas regarding D-formers, I really just wanted to point out that a plain full length batten works perfectly well, in conjunction with Slieve's spanned batten parrel-downhauls, and (opinion) I don't think that perfect symmetry or improved aerodynamics makes enough difference in this instance to warrant the extra complication. Perhaps the D-formers have some advantage that I am unaware of, as I don't have any experience of making or using them. Batten parrels will no longer be needed, but whether the downhauls are eliminated I do not know. Any reduction in running gear would be an advantage, at least for small boats which need to be de-rigged after each use - a little less so for moored boats (whose rig generally stays in place) I would expect.

    Your third paragraph seems to me to be a solution looking for a problem, as the running spanned parrel downhauls do all that is required for a SJR, including holding the luff of the main panels closely to the mast while at the same time, as soon as the halyard is released, they slacken too, allowing the "parrel" to let go from the mast. This is quite a different arrangement from a soft webbing parrel of fixed length - the conventional parrel is a "long" standing parrel but I have never used them so can not comment further. Of course, all parrel types can be made to quick release for removal if you should want to - my rig has to be dismantled each time after use, so I have a quick release arrangement on my spanned running downhauls.

    Your 4th paragraph: If my understanding is correct, all junk rigs have modest sheeting forces. The SJR having a little more balance, I suppose would have even more modest sheeting forces, since the sheeting system used is the same as any other junk rig. (Nothing in the sheeting system is deleted.)

    The last part of this paragraph: I simply don't understand what you mean, so I will just report to you that the halyard arrangement and the sheeting arrangement on a SJR is just the same as for any other junk rig. The difference in running rigging is that with the SJR as designed by Slieve, luff hauling parrels, yard hauling parrles, Hong Kong parrels etc are not needed - the other side of the coin is: the SJR as Slieve designed it has a pair of running spanned batten parrel downhauls - which conventional rigs do not need.

    Your last paragraph: When Slieve designed the first SJR he dummied the entire sail with a strings and dowel model, which he made to hang (drape) to his satisfaction without any hauling lines, and thus chose the shape of the sail. The later SJR he designed (Amiina) is somewhat simpler. I would not alter the shape of the top panel of a Amiina sail form. If someone wanted to make a variation on this simple shape, it might pay to make the identical lower panels first, then dummy the top panel with rope if unsure what its shape should be.

    I suggest reading Slieve's notes on the website: members' area/documents/technical articles - and regarding the D-former and the Origami rig, obviously Paul is the best person to comment.

    PS I have wooden battens, not regarded as the best solution, and I broke one the other day. (Not from sailing forces - I hit a marker pole with the sail while fooling around with a camera). The batten did indeed break at the mast - and the improvised splint arrangement which was easy to make on the spot, looks so satisfactory to me that I am considering putting splints on all the other battens too!


    Last modified: 30 Mar 2021 09:00 | Anonymous member (Administrator)
  • 29 Mar 2021 19:50
    Reply # 10249775 on 10239242

    Greame and Len, thanks for indulging my ignorant curiosity. I'm going to fearlessly lean back in my admiral's armchair and speculate wildly here, so take it with a grain of salt the size of a Buick.

    Paul McKay has shown several, a few, er, a plenitude of D-former configurations. Some assemble fore-and-aft onto the mast, others slide sideways, some have wishbones, others just single battens. The fwd and aft battens on the non-wishbone shapes would be about 1/3 and 2/3 the length of a simple one-piece batten, so as Len points out any spare parts could be shorter than a full batten. The bending load on the batten is maximum where it crosses the mast, and the round-on-round contact is a point load, so some sort of stiffener/load spreader there seems like a good idea.

    So here's a mishmash idea- a built-up batten assembly made from one or two tubes, with a hefty splice that stiffens the joint and serves as a bead to prevent chafing as the sail and batten shift relative to the mast. The batten tube could be a single continuous length if materials are available in that length. The batten parrel is made of webbing with a half-twist to sewn-in loops that go over the batten, and lashings around the batten tube(s) might prevent the parrel from moving relative to the batten if needed. A buckle on the parrel allows the batten to be installed on and removed from the mast. The entire sail can be removed from the mast by releasing the buckles and disengaging the halyard, sheet, and any other hauls, which the SJR reduces nicely. This soft parrel ends up with a D shape rather naturally, and allows some skew while preventing fore-aft shifting. The halyard should, I think, be outside the parrels rather than trying to thread it through the D gap. The buckles would allow trying it both ways.

    An aside- is it true that the balanced SJR has such modest sheeting forces that the multiple sheetlets and their blocks and euphroes can be deleted? Damned if I can find the reference now (I've been binge reading on all things JR), but someone referred to running a single sheet through some sort of loops on the aft ends of the battens and connecting it to the halyard just above the standing end, without the usual JR multi-sheetlet arrangement. If any version of SJR allows this without excessive sail twist, that would be a big win all by itself.

    I love the method of dummying the top panel with ropes, then building a sail panel to match it. This seems to be another strength of the origami method, separating the various optimization tasks into independent, smaller jobs. Imagine the hassle of sewing in a triangular panel, testing it, then unstitching it to sew in another. The modular construction should allow a lot more experimentation with rapid turnaround.

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  • 29 Mar 2021 00:43
    Reply # 10246065 on 10239242
    Anonymous member (Administrator)

    All very good points, Len.

    I think you are right, the top panel with its yard angle and yard length is, I think, part of the key to the way the sail drapes, I had just set that aside. Actually, I believe it is possible to leave the top panel out for a start, and just dummy it with ropes, then adjusting the ropes to get the right shape. As a way of designing the Amiina-type sail, similar to what Slieve did when he made his first rope model for the more complex Poppy sail. In fact I think it was Slieve who suggested it.

    Regarding the D-former, it just seems a bit of a structural monstrosity to me, albeit a minor one. Leaving aside the question of symmetry, it seems to me much simpler (and stronger) just not having to make them at all. Wouldn't a short standing parrel be pretty much the equivalent of the D-former?  If parrels can be unclipped or made with some form of easy release, they'll do everything a D-former will do, and snug down better too, I would think.

    In any case, I think both would have to fit to the thickest part of the mast, and a "tapered" hybrid mast should have a smooth transition from one diameter to the next. Short parrels could perhaps be eased over the transition by having parrel beads, D-formers might be more likely to hang. Just surmising.


    Your really interesting point is regarding swinging the entire rig up and brailing it to the mast. You have anticipated Arne's current thinking for a dinghy rig. It has great possibilities and - regrettably - does not fit well with either the D-former or the short standing batten parrel. 

    Last modified: 29 Mar 2021 10:17 | Anonymous member (Administrator)
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