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Sheeting system identification quiz

  • 16 Jul 2015 12:42
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    Reply # 3435701 on 3430851
    Anonymous member
    Thank you all for your replies.  Jake has his mast up and is figuring out his sheeting.  He's seen your diagrams.

    I was also in touch with Robin Blain who suggested this kind of arrangement, saying that the reason the middle span has no block is that it's the terminal, giving the sail more curve.

    It's easy to experiment!

    I've advised Jake to keep his sail as it is for a while.  He's just learning to sail.  But it seems likely to me that bendy battens won't work long term.

    One though I had was that he could stick some inserts into the tubes to stiffen up the battens a bit.  I would've thought that you'd want them stiffer at the top, so that you could get a flatter sail when reefed.  Inserting things into the batten tubes is another easy way to experiment.

    I'll get him to report back!
  • 15 Jul 2015 05:55
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    Reply # 3434372 on 3434258
    Deleted user
    Annie Hill wrote:  But I can't see the logic of bendy battens, which, as David Thatcher pointed out, get bendier as the wind increases: just when you need the sail to be flatter.


    There is bendy and there is bendy. When I first purchased 'Footprints' she had a flat sail with battens made from pvc water pipe at about 50mm diameter and 6 meters in length. These were very bendy to the point that when holding a batten in the middle the ends would bend down to almost touch the ground when held at waist height. As sail battens they were a disaster. When sailing on a reach in smooth water when a gust hit the sail the battens would curl around creating a large hook at the leech of the sail and the boat would actually slow down rather than accelerating as it should have done.

    I constructed new battens of 60mm x 38mm cedar with one and sometimes two layers of fiberglass unidirectional cloth on each side of the batten to add stiffness to the cedar which would have otherwise been too soft for use as batten material. These battens were still a little bit bendy and could be deflected in the middle of the batten by about 30cm for the 6m length. They would also bend to a slight curve when in use in the sail but made a radical change to the boats performance. In the same sailing conditions described above 'Footprints' would now accelerate when hit by a gust of wind.
  • 15 Jul 2015 03:56
    Quote
    Reply # 3434258 on 3430851
    Anonymous member
    I have had experience of Sunbird's pultruded fibreglass bendy battens and they were not a success.  I would go either for a cambered sail, or a hinged batten like David Tyler is presently using.  Or a flat sail.  But I can't see the logic of bendy battens, which, as David Thatcher pointed out, get bendier as the wind increases: just when you need the sail to be flatter.
  • 13 Jul 2015 22:33
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    Reply # 3432310 on 3430851
    Deleted user

    I've added another roughly sketched alternative sheeting to the technical illustrations. Basically Arne's Johanna sheeting for a 5-panel rig. I assumed the top "batten" was the yard so not sheeted.


    Last modified: 13 Jul 2015 22:35 | Deleted user
  • 13 Jul 2015 21:49
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    Reply # 3432262 on 3430851
    Deleted user

    No one else has responded to this so I will put in my two cents worth ....... 

    This seems to be the basis of a sheeting system with what are known as anti-twist spans on each pair of battens, that is with that purchase system between each pair of battens. The only thing that you seem to need to figure out is the actual sheet itself. This could be similar to what I have on Footprints. You would need 3 blocks at the stern of the boat for the sheet. Start the bitter end of the sheet at the lower span, (boom & first batten), take the sheet down through the first block at the stern, up to a block at the mid point of the middle span, back down to the second block at the stern and then up to a block at the top span, and then down and through the final block at the stern of the boat and then to the belaying point for the sheet, this is the end you pull on. Does that all make sense? See page 67 of PJR for details about the length of the spans.

    I don't think you need the block and tackle system for each sheet span because they just add complication, greater potential for tangles, and more weight to pull up when hoisting the sail. It would be more simple for the two lower pairs of battens to just have a simple sheet span as per PJR and then keep the anti twist span for the upper pair of battens. If you have the sheet set up as I have described you will then have the least pull on the lower end of the leech and then the strongest pull on the upper portion of the leech therefore minimising twist in the leech. Please note that when sheeting the sail you will be pulling on the upper part of the sail first.

    I have uploaded a simple (rough!) diagram to the Technical Forum Illustrations.

    Not sure how well the bendy battens will work, in fact if they are too bendy they may not work at all. On a flat sail it is OK to have bend in the battens so that when sailing they describe a gentle curve along the length of the battens. If however the battens are too bendy, in stronger winds they will just develop a deep bend and curl around at the leech end of the sail, maybe even to the point of acting as an air brake actually slowing the boat. And then of course if they are very bendy there is a greater potential to break the battens.

    Last modified: 13 Jul 2015 22:22 | Deleted user
  • 13 Jul 2015 00:55
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    Reply # 3431324 on 3430851
    Anonymous member

    Here is a short video looking at the sail, in case that's useful.
  • 12 Jul 2015 15:18
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    Reply # 3430939 on 3430851
    Anonymous member

    As far as I can tell we have something like this diagram.  I can't see how that's the basis for a real sheeting system. Perhaps the question now is: how can Jake rearrange his spans and blocks to make something sensible?
  • 12 Jul 2015 12:14
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    Message # 3430851
    Anonymous member
    Yesterday I visited Jack McLewee's Newbridge Coromandel Sinobee in Brighton Marina to help him figure her out. He's new to sailing. We pulled out the sail from its bag for the first time and discovered that it's a flat-panel fanned bendy-batten sail made by Chris Scanes. We weren't able to lay it out flat, but it looks like it might be a Sunbird 90's rig.

    One of the puzzles is the sheeting arrangement.  Here's a picture of it, as disentangled as possible.  Can anyone figure it out and how it's supposed to be arranged and connected to the block?  I've looked through PJR but can't match it to any of the schemes there.

    And bendy battens — how's that going to play out?  (I'm quite curious to see them in action.)
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