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

  • 01 Nov 2019 23:59
    Reply # 8087657 on 3399298
    Anonymous member (Administrator)

    Dave,
    I can see the point in wanting the mizzen flat, in particular if you use (some of) it as a riding sail. One thing I noticed when I hoisted my first cambered panel sail in 1994, was that the luff and leech no longer would flutter, the way they sometimes did on the flat sail. If that is a problem in your flat mizzen, I suggest you stitch on a low-stretch boltrope. If you stitch it on a bit taut, you will introduce a very light camber, and the weights will mostly move out to luff and leech, and keep these quiet.

    Arne


  • 01 Nov 2019 20:11
    Reply # 8087383 on 8086599
    Anonymous wrote:

    So that means that you have tried the mainsail with 8 and 12 % camber in its main section, right? What was your impression about the performance?

    The mainsail you had before, was that an ordinary cambered JR or was it a flat sail? The mizzen, is that the same as before?

    I once got an advice from a sailmaker in West Virginia (Dabbler Sails), to use black or dark blue sail covers. They collect sunshine and the sail under it will dry out faster and thus avoid mildew.



    Hi Arne,

    We're prototyping a rig for our new boat, a 32ft x 8ft x 1ft sailing barge, cat-ketch rigged. The rig is very similar to that of our last boat, which was entirely flat cut. 

    We make a lot of use of the flat cut mizzen as a riding sail, for forcing the bow to windward while drifting, sailing backwards and short room maneuvers. While camber would help some of those, in others it doesn't help and would flog when neither set nor backwinded. Mizzen camber is still under consideration, but we waffle.

    Our limiting sheeting factor into the wind is the flat cut mizzen, whose boom must be strapped in very tight to twist and draw. The SJR main, which points much higher, could be eased, swinging its thrust vector forward. In effect, the main is on a close reach when the mizzen is close hauled. This translated to considerable gain in power.

    We started the main at 8% and tried a limited look at 12%, trying one (middle) panel to see how it drew relative to the 8% and how the 'pop' felt in light wind with a bobble of water (common in our area to get snap rolled in turbulent conditions... all sails get tossed, but a cambered sail 'pops' from full to backwinded and back again and again, with a little way made between).

    The 12% panel began luffing slightly before those at 8% as we pinched up or eased sheet. Presumably, it developed more power, but at a slightly wider angle of incidence.

    [This doesn't surprise me, but was startled that the blunt luff of the jib(let)s don't luff first! I'm guessing there must be some mast turbulence or wind shaping going on ahead of the after sail luff? Or a 'spinnaker effect' in the jibs?] 

    Pop / flogging was considerably greater than the 8%.

    Between the two, we decided on 8%, which we'll hopefully sew into final sails this winter. As mentioned, still waffling re mizzen camber.

    I'll be posting a full write up, this winter, which I'll make available to the JRA. We dumbed the SJR concept down in several ways which appear to have worked our for us, but compromise away from power and windward ability.

    Thanks for that input on sail color! Our final sails will be a dark burgundy, so we may have lucked into the right end of that advice!

    We don't use covers for the same mildew issues as pockets, as UV is low at our latitudes (about 55 to 59degN) and as we often have to get going on a moment's notice at night (no engine to buy time). We may try the pouch style covers at some point.

    But I assume it applies as well to sail cloth in the absence of covers.  8)

    DZ


    Dave Z


    Last modified: 01 Nov 2019 20:20 | Anonymous member
  • 01 Nov 2019 08:13
    Reply # 8086599 on 3399298
    Anonymous member (Administrator)

    Hi Dave.
    I’m sorry if I sounded a bit blunt in my posting below. I may be a bit one-eyed at times.
    Prototype, yes, every method is legal on prototypes (everything is legal on junkrigs, anyway...).

    So that means that you have tried the mainsail with 8 and 12 % camber in its main section, right? What was your impression about the performance?

    The mainsail you had before, was that an ordinary cambered JR or was it a flat sail? The mizzen, is that the same as before?

    Arne

    PS:
    I once got an advice from a sailmaker in West Virginia (Dabbler Sails), to use black or dark blue sail covers. They collect sunshine and the sail under it will dry out faster and thus avoid mildew.



  • 31 Oct 2019 23:57
    Reply # 8086278 on 8085001
    Anonymous wrote:

    Of course the lashed-on panels work, why shouldn’t they? Camber is camber.
    However, why, why, why choose such a slow way of constructing a sail? 

    As for freedom to adjust the camber, well, if you have taken the trouble of tying on a number of panels to produce, say 8% camber , then it is quite unlikely that you one day will wake up in the morning and say. “Today I will re-arrange all the ties to see how 10% camber works”.
    No way.

    Hi Arne,

    Our final methods will draw heavily on your approach, and thank you for all the development and info you've made available!

    But in our case, we were prototyping a whole rig.

    We wanted to see how an SJR main would work with a flat cut mizzen, given that the SJR should (and did) point much higher. Would we need less camber to get them to agree? Could we get away with more (and how does that behave in our gusty winds)? Would we prefer to camber the mizzen to get its performance closer to the main.

    Our range of test cambers was 0, 4, 8 and 12%, with tick boards set up for those in advance. I agree that a 2% difference wouldn't likely be worth the trouble. As it was, we never felt the need to try 4%. 

    All this had to be and was tried far from any sheltered workspace, and most adjustments were made while lying to anchor. Constructing a series of sails was out of the question.

    Lashings seemed a workable means to answer these questions, and they were. With a half hour of work, we could set up to answer questions without recutting or sewing. Or at least see if a direction of inquiry was worthwhile.

    We do prefer marline hitches over robands, and either over pockets in our area. Reason is we use wooden battens and sail in a boreal rainforest. Pockets I've seen up here don't dry well enough between showers and collect all sorts of nutrients... they tend to mildew and set to work on wood. They can be kept up with, but it's a chore. So we lash at batten ends and lace between. 

    So, no great leap forward for JR, but I feel that lashings worked and work for our situation.

    Sooo... no objections to anyone else's approaches, nor even a recommendation to emulate. I consider Thai style lashing - with camber or without - to be one of many in the JR bag of tricks. No more, no less.

    Dave Z


    By the way, our preferred method would have been closer to Roger Taylor's hinges with heavy duty hook and loop for quicker adjustment. But they're essentially pockets, with the same objection for our area.

  • 31 Oct 2019 10:56
    Reply # 8085001 on 3399298
    Anonymous member (Administrator)

    Of course the lashed-on panels work, why shouldn’t they? Camber is camber.
    However, why, why, why choose such a slow way of constructing a sail? Are you still unsure if camber works on junk sails, or are you still afraid that panels will fall apart every now and then?

    As for freedom to adjust the camber, well, if you have taken the trouble of tying on a number of panels to produce, say 8% camber , then it is quite unlikely that you one day will wake up in the morning and say. “Today I will re-arrange all the ties to see how 10% camber works”.
    No way.

    Moreover, batten panels fail very rarely, and if you have given the sail a stout boltrope, you may well carry on sailing with a hole in a panel, and then repair it at leisure. It will not rip the way a genoa rips, because of the much, much lower stress in the cloth of a junksail.

    With sewn on pockets, fitting a batten is not much more work than putting on one’s trousers, and joining two batten panels and adding batten pocket (including the cutting work) takes less than one or two hours per joint and batten pocket. In case one is worried about broken (wooden) battens, one can divide the pockets up in 1-metre lengths, to make it easier to pull out the broken stubs. The best argument for tied-on battens appears to me to be that the battens are made from bamboo, of un-even branches, so will not fit in pockets.

    This year I celebrated 25year jubilee (.. or actually I forgot..) for my first cambered panel sail with barrel-cut panels and batten pockets. Cambered panel sails are no longer a step into the un-known. I have made a few of them now, and I claim that you will have a hard time finding a faster method for constructing and assembling the sail than the one I use. My sails even last quite well.

    Sooo, by all means, make the sails the way you please, but don’t tell me, any-one, that lashed-on panels is a leap ahead in junk rig construction.
    Unless bamboo were the only available  batten material, I would stick with batten pockets.

    Arne

    PS:
    Check this photo album , showing the construction of the sail for my present boat, Ingeborg.


    Last modified: 31 Oct 2019 19:40 | Anonymous member (Administrator)
  • 30 Oct 2019 16:26
    Reply # 8083948 on 3399298

    It strikes me as it it did when I first saw it, that Paul's Aerojunk solves a lot of these sorts of problems.   It allows a single flat piece of sailcloth to be a cambered sail on either tack, creates a light weight and strong batten structure, and allows you to do whatever you want with camber, tying in only a few places instead of continuous lacing.    It also eliminates any of the leakage some have expressed legitimate (IMHO) concerns about.  It also makes it at least theoretically possible to change camber easily at sea.... presumably one batten at a time as you raise the sail.

         I don't buy the windage concerns people have expressed about the batten cage, but the loss of the "rip stop" effect of batten pockets is a bit of a concern, as is chafe where the fabric contacts the battens.


                                                                                  H.W.

  • 30 Oct 2019 05:04
    Reply # 8083345 on 3399298

    Okay, it works!

    We went ahead with the lashed prototype and have sailed over a year with it, blow high, blow low (winds to 55kts) in SE AK, for a total of about 750nm as the boobie flies.

    We made three round turns at each grommet forming a roband of sorts, then choked it of with clove hitches set against one another just below the cloth. This allowed the turns to rotate. We've had to replace two which chafed (before full failure), and none have untied.

    The main is cambered split junk rig, with the after parallelogram panels lashed for 8% camber. The mizzen is lashed with marline hitches for 0% camber (flat).

    Both depend from lashed 'crab claw' upper panels, which are flat cut. This acts like a 'headboard... stress is evenly distributed and we've observed no topping up problems. They take their shape from conic section, and are our heavy weather 'last sail standing'.

    Our performance was much improved on our previous flat cut sails. We could point higher or sail with more power into the wind, with improved ghosting.

    This despite not tweaking out some minor set issues (e.g., our roping should have crossed the battens at an angle, rather than perpendicular... as is, there is a zig zag introduced which interferes with a good set.

    We're planning on sewing final sails (SJR main with no gaps and cambered mizzen) this winter.


    PS. I also heard lashing separate panels called 'Thai style lashing', though without reference to camber. It may well have been featured in The Last Sailors, narrated by Orson Welles. From way early on, anyway, before I myself had come around!


    The attached photo isn't showing it at its best, but its the only one we have in profile.

    1 file
  • 02 Jun 2016 13:37
    Reply # 4053429 on 3399298
    Deleted user

    I'm interested to see if "Gap-Cambered, Split Junk Sails" are the next step.  Purposefully creating a gap between battens could increase the airflow over each panel's 'lifting' surface . . . as well as contribute to the 'turbulent air flow' I hear referenced with mystical reverence.  Seriously, though . . . has anybody purposefully created space between panels by individuating each panel to its own batten pair and separating adjoining battens by a small space?  Thanks for any replies.  Steve

  • 13 Jul 2015 02:44
    Reply # 3431363 on 3427081
    Richard Brooksby wrote:
    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...

    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!

    Ah, well, I'm sure we'll leave plenty to be improved upon! And yes, we hope to document the broad outlines of our approach.

    We just cut out the 10 (identical) panels for the mizzen and main. The miz will be the standard Chinese lug planform, and the main will be an SJR variant. We coordinated their panel height and batten length to yield like area with uniform panels. The main will be extended by its jib(let)s, then each will be surmounted with a crab-claw like headsail.

    We have to be across water to our next job sometime in October of this year... plan A is to sail across (possibly under partially completed sails); plan B is to get towed across; plan C is to winterize at our current location and come back to it after our job is complete in spring (that's an ugly plan C!).

    So, hopefully, come October we'll have some sailing results to report. But we're a long way from done with the hull, much less the rig.  8\

    Dave Z


  • 09 Jul 2015 09:10
    Reply # 3427098 on 3427046
    John Dunn wrote:

    ... 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? 

    The key thing here is that when you tack you want the panels to swap sides, so that they pop inside out and form an aerofoil shape on the other side. The idea here is that the lashings can swivel around the battens and allow the flat sailcloth to belly out on either side, in a limited way.

    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

    I believe that was mentioned earlier in the thread. Yes, you can do that, but then you won't get a curve out of a flat panel, and you'd be back to having a flat sail. You could of course have a shaped panel (and many people do) but the idea here is to make panel construction very simple and provide a curve with the lashings.

       " ...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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