Flat, hinged or cambered?

  • 28 Jun 2021 12:07
    Reply # 10707084 on 461931

    Interesting Paul.

    It would seem to me that the amount of 'drift' from centre of the anchor point would relate directly to the desired yard angle.
    Do you have the numbers on that relationship if it is indeed the case?

    x 'drift' = y yard angle.

  • 28 Jun 2021 01:30
    Reply # 10705847 on 461931

    Regarding the THP, you can take a lot of the load off it and even eliminate it completely by using a three or five part halyard and taking the standing end to a position about 5 percent of the yard length aft of the central slingpoint. I only use a three part halyard and just add a winch when needed. Drawing attached.

    1 file
    Last modified: 28 Jun 2021 01:31 | Anonymous member
  • 27 Jun 2021 22:53
    Reply # 10705557 on 461931
    Anonymous member (Administrator)

    David, yes, it is fully possible to screw up when making a Johanna-style sail.
    It seems that quite a few just pick elements of my designs and then drop others.
    The results are often ‘interesting’.
    The standard failure is to not fit the parrels correctly, HKP THP and even the YHP. Then they drop fitting the tack-line and make a 6-part sheet to own design with no anti-twist in it.
    Then there are the super-tall sails with almost vertical sheets, some even set on forward-raking masts, and schooners with too little clearance between the sails. I could go on (...yes, omitting the important boltrope   -  and of course the telltales, and, and , and...).

    However, if they just pick one of my master sails, and follow the instruction, they stand a good chance. After rigging the sail by the book, so to speak, without pushing the limits, there is very little tweaking to be done afterwards. I stress; a sail is not completed until it has been correctly rigged.

    There are of course other ways of making good junksails with cambered panels and straight battens. Paul Thompson seems to make very fine sails, and more and more of Slieve McGalliard’s Split Junk Rigs appear to be fully operational and very good, these days. And then there are some successful amateurs spread around the world following their own ideas.

    As for Martin Simmons(?) and his Taiko, I have no idea. I don’t know his boat and have never been contacted by Martin.

    Arne


  • 27 Jun 2021 20:17
    Reply # 10705286 on 461931

    Once again, Arne, you answer points that I'm not making, and fail to answer the point that I am!

    I'm not talking about the all-fanned sails. For our purposes they are an evolutionary dead end. They are quite effective, but even more  labour intensive than yours.

    I'm not saying that setting up and using your sails is rocket science for "experts". I'm saying that it takes more work to set them up initially and then to use them, than other rigs of comparable performance. 

    When we take bermudan sailors out on a JR boat, they say "oh now I get it, it's much easier to use than my rig." Well, when you get someone in a position similarly to compare a high-peaked baggy panel sail with a low-peaked, flattish, hinged sail, I will bet the farm that you will get much the same comment. It's certainly true in the case I mention, Martin having succesfully cruised Tystie (flat hinged main, cambered panel mizzen) from NZ to New Caledonia; and now having cruised Taiko (baggy panels) from Mexico to Nuku Hiva and not having enjoyed the rig one little bit, to the extent of talking of scrapping it (new sails, old yards and battens) and asking me what I would make to replace it, to get away from the problems that he's had. And my answer is lower angled yards, hinges, a little bit of barrel camber forward of the hinges, flat sail aft of the hinges.

    No, hinges are not an evolutionary dead end. But neither are they the only way to go, any more than your rig is the only way to go. Your rig suits rig tweakers better than it suits relaxed cruising sailors. That's the sole point that I would ask you to accept.

  • 27 Jun 2021 17:52
    Reply # 10705008 on 461931
    Anonymous member (Administrator)

    David,
    the high peaking of the yard is not the point; it is how the sail looks like below the yard.

    I understand that Annie had quite some problems with getting Fantail’s sail set well, and that HK parrels used to bend the battens upwards. Fantail’s sail has much in common with the mainsails of the Hong Kong schooners in being very low-AR, very unbalanced (with respect to mast) and in being fanned all the way down to the boom. As can be seen on photos of the HK-junks, they used HK parrels, which clearly saw huge loads. Therefore, the battens were beefed up substantially: One can see they are made up of bundles of bamboo  -  and they still bend quite a bit. On Fantail’s similar sail (not that extreme, though) the battens were clearly undersize, so could not stand up to the needed tension from the HK parrels. Clever use of luff-hauling parrel(s?) sorted it out.

    The Johanna-type sail  -  my take of Hasler and McLeod’s standard sail, is a different animal than a true fan-sail. Only the top three panels are fanned, while the lower 3-5 ones are not much different from those in Weaverbird’s or FanShi’s sails.

    It is true that the loads on the THP and LHP were considerable in the sail of Johanna. However, I learned from this and increased the halyard-to-slingpoint drift on later sails. This both let me move the halyard’s slingpoint about 5% aft of the middle of the yard, and the YHP was moved 2/3 up. These two measures have reduced the forces in both the YHP and THP, maybe with 50%. Below the top section, the parallelogram panels live an easy life. The Hong Kong parrels now only work as lightly loaded (fixed) stabilizers. When sailing up and down my fjords, I never have to touch the THP or YHP underway, except when adjusting the sail area.

    Initially, getting the rigging right on a Johanna-type sail is no rocket science: Anyone who can read, can find how it is done in chapter 7 of TCPJR. It’s all there in plain Stavanger-English.

    Conclusion:
    I simply don’t buy that the Johanna-type rig with straight battens and cambered panels is some sort of expert’s rig, best kept inshore. Too many deep sea voyagers have proven that it is seaworthy.

    Arne


    Last modified: 28 Jun 2021 09:34 | Anonymous member (Administrator)
  • 27 Jun 2021 16:19
    Reply # 10704791 on 461931

    But don't you see the point, Arne? So many things have to be got right, and then tweaked to keep them right, with a baggy sail. This is OK for a fun sail of 3 hours, but loses its attraction very soon, during a sail of 3 weeks. In the case I mention, the THP needed a lot of tension, which was down to the yard angle as well as the panel camber. The over arching point is that low yard angle, combined with little panel  camber and hinges, as Annie has, all make for relaxed, lower stress cruising without loss of performance.
    My current wingsail is an extreme case of that: flat cut sail, hinges, no HPs at all. I just hoist and go.

    The SJR also offers high performance with low stress. It gets it in a different way, but there is still this commonality with my rig: low yard angle, no HPs, just downhauls, and panels that are not so extremelbaggy as yours.

    Last modified: 27 Jun 2021 16:41 | Anonymous member
  • 27 Jun 2021 14:58
    Reply # 10704628 on 461931
    Anonymous member (Administrator)

    I move to here from  the «Pottering is...» thread
    There, David Tyler wrote 27.6.2021:

    “Arne,

    I'm corresponding with a JRA member who has just completed a 2800 mile passage and thinks his baggy sails, made to your specs, may be suitable for fjord sailing, but are are more trouble than they are worth for ocean passages, and wants to go back to hinges.

    Horses for courses.”

    David, I might have bought that argument if no other vessels had had success with sailing across the oceans with cambered panels only. However, I haven’t heard any complaints from deep-sea sailors like Alan Martienssen or Roger Taylor. I have seen some cambered panel sails that look bad, but most of their owners have not completed the rigging properly, like fitting THP, HK parrels, or getting the sheets right.

    Arne


  • 28 Aug 2018 14:06
    Reply # 6642315 on 6642298
    Mark wrote:

    David,  going back to your previous comment, why would you not first add the pocket to the end of the sail roll, then sew on the next panel?   Thus only a rolled up panel to pass through the machine and nice flat seams. 

    For a cambered sail, the main panels could be joined by a lens shaped panel to which you first sew the batten pocket.  The lens shaped panel gives the camber, and can be made out of a lightweight nylon to  be more stretchy.  With contrasting colours for main panel and lens panels you would have a pretty funky looking sail!

    (having yet to make a sail, hope this is not a stupid comment!)

    You mean this?

    "Our more recent methods, which have the common factor of adding a panel, adding whatever batten arrangements we prefer, then adding the next panel, makes a lot more sense."

    Generally, the seam to join the panels is sewn first, followed by the pocket. I can't see how the pocket can be sewn on first. Anyway, in either case, there is only the rolled panel to be passed through the throat of the machine. Passing the rolled panel through only becomes a problem when a) the 3D shaping has been sewn in and/or b) the cloth is stiff, and the roll needs a lot of space fore and aft of the machine. Difficulty a) can be reduced considerably by only completing broad seam or tucks on the free edge immediately before it is joined to the next panel. Passing a rolled flat panel through presents little difficulty.

    The lens shaped panel onto which the pocket is first sewn has been used successfully. But it's not the lens shaped panel alone that gives the camber - the horizontal shelf produced this way has been found to add rather too much cloth into the sail. The shelf is better at 30 or 45 degrees to the horizontal. This requires plotting, cutting and sewing two differently curved edges together, so perhaps is not for first timers. 

    Stretchiness is not a virtue. We need stable yet soft cloth for good junk sails. No comment on the contrasting colours.

  • 28 Aug 2018 13:41
    Reply # 6642298 on 461931

    David,  going back to your previous comment, why would you not first add the pocket to the end of the sail roll, then sew on the next panel?   Thus only a rolled up panel to pass through the machine and nice flat seams. 

    For a cambered sail, the main panels could be joined by a lens shaped panel to which you first sew the batten pocket.  The lens shaped panel gives the camber, and can be made out of a lightweight nylon to  be more stretchy.  With contrasting colours for main panel and lens panels you would have a pretty funky looking sail!

    (having yet to make a sail, hope this is not a stupid comment!)

  • 28 Aug 2018 10:37
    Reply # 6642188 on 6642132
    Arne wrote:


    It’s a free world, so do it how you like. I just say that standardizing on one camber between 6 and 10% on the [three or] four lowest panels works well.

    I agree. Because we can only have a fixed amount of camber, we don't put much camber into our sails, when compared to a bermudan headsail. A constant amount of camber is fine in the lower half of the sail. Using the same amount of camber in the upper half of the sail would be fine, in terms of drive, but it's not easy to do, in terms of practical sailmaking. I think we're right to use three or four identical lower parallelogram panels, then add whatever transitional/irregular quadrilateral/triangular panels that we fancy, with reducing camber towards the head.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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