pvc battens

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  • 23 Oct 2019 18:36
    Reply # 8073698 on 7985090

    Bonjour

    My answer was limited to my experience about flexible battens on the forward part of a junk sail. In fact, they were not PVC tubes but GRP rods.

    To confirm that PVC tubes may be an option for JR battens ; MingMing had some PVC tube battens, for 30 years, reenforced with hard wood in the forward part. They worked as the wooden battens described in PJR.

    The flat sail remains very flat on the first forward part of the sail, to prevent S-bending.

    Eric

    PS : You may find in the "télégram" article a nice view of a S-bending on Mingming in a scall... during the Semaine du Golfe.  MingMing - www.letelegramme.fr 

    Last modified: 23 Oct 2019 18:39 | Anonymous member
  • 20 Oct 2019 14:57
    Reply # 8066993 on 7985090

    I attached the Parker article as a FYI that PVC battens work in terms of strength and longevity. I was not saying that the article was how to do junk rig battens but a good resource for some lateral thinking.

    That said, Parker has designed several junk rigs that do use PVC battens  which, I suspect, work just fine and might be of interest.

  • 20 Oct 2019 10:58
    Reply # 8066890 on 8062692
    Anonymous wrote: The Ruel Parker type battens could work in a conventional flat junk sail, allowing a bit of curvature in the fore part of the sail, but keeping the sail flat towards the leech providing a camber like shape to the sail. It would be interesting to see how this worked on a junk sail.

    Bonjour

    It doesn't work !

    As it is explained in PJR, the forward part of a junk rig batten must be very stiff, otherwise you will suffer S-bending : a hell.

    I experienced that, by mistake, on Mingming and it is really not plaesant, the flow becomes turbulent at the luff and the center of effort moves forward. It becomes almost impossible to tac.

    There is no way, I think, to provide camber in the forward part of a flat junk sail.

    Eric

    Last modified: 20 Oct 2019 11:00 | Anonymous member
  • 18 Oct 2019 05:32
    Reply # 8062692 on 7986893
    Anonymous wrote:

    Reuel Parker has been using PVC battens in his various designs (including junk rig) for decades with very good r results.  His basic approach is to fill the aft 60% of the batten with wood.


    I've been using the same idea but with an added piece of PVC pipe one size down replacing the wood insert. This seems to work finestkind.

    Those battens would be good for a bermudan rig where there is camber in the sail, with the battens being a bit bendy in the forward portion of the sail, but with the stiffening timber more rigid in the aft part of the sail where some flatness of the sail is needed. 

    On a junk rig sail where the battens are sheeted the battens need to be very rigid. The Ruel Parker type battens could work in a conventional flat junk sail, allowing a bit of curvature in the fore part of the sail, but keeping the sail flat towards the leech providing a camber like shape to the sail. It would be interesting to see how this worked on a junk sail.

  • 17 Oct 2019 22:35
    Reply # 8062301 on 7985090
    Anonymous member (Administrator)

    Bob,

    That doesn't appear to be a Junk rig. The luff is at the mast. Are the battens sheeted?

    Arne

  • 16 Oct 2019 14:49
    Reply # 7986893 on 7985090

    Reuel Parker has been using PVC battens in his various designs (including junk rig) for decades with very good r results.  His basic approach is to fill the aft 60% of the batten with wood.


    I've been using the same idea but with an added piece of PVC pipe one size down replacing the wood insert. This seems to work finestkind.

  • 16 Oct 2019 14:20
    Reply # 7986834 on 7985090

    Thank you all, for the discussion.

  • 16 Oct 2019 08:22
    Reply # 7986602 on 7986522

    While I have never tried this personally, I gather that PVC pipe filled to expanding foam is substantially stiffer than when it is empty. Master of an old square rigger told me he had done this will 100mm PVC pipe to replace a yard that broke at sea. Might just be an old sailors tale of course. Might be worth a small experiment. 

    I think this is mostly an 'old sailors tale'. The foam will just bend with the battens when we are talking about smaller diameter battens as required for most junk sails, and expanding foam in sufficient quantity to fill a tube is actually quite heavy, and probably quite expensive when a sail full of battens is required. 

    There has been a lot of discussion of battens in these forums. Aluminium T6 tube provides stiff battens for smaller diameter, T5 tube can provide stiff battens for larger diameter with thinner wall thickness and potentially lighter weight, and lower cost. Bendy timber such as cedar with a layer of unidirectional fiberglass each side can also produce reasonably stiff battens at light weight and lower cost. Carbon fiber tube can also be good for those who have access to a gold mine, or other similar funding sources! 

    Last modified: 16 Oct 2019 08:33 | Anonymous member
  • 16 Oct 2019 06:33
    Reply # 7986522 on 7985985
    Anonymous wrote:
    Anonymous wrote:

    Has anyone used pvc tube for battens? What was your experience.

    I had them originally on my junk rig yacht. They were hopelessly bendy. You need something a lot stiffer such as suitably sized aluminium or timber battens.
    While I have never tried this personally, I gather that PVC pipe filled to expanding foam is substantially stiffer than when it is empty. Master of an old square rigger told me he had done this will 100mm PVC pipe to replace a yard that broke at sea. Might just be an old sailors tale of course. Might be worth a small experiment. 
  • 16 Oct 2019 00:25
    Reply # 7986089 on 7985090
    Anonymous wrote:

    Has anyone used pvc tube for battens? What was your experience.


    PVC tube is not suitable for battens as in diameters & wall thicknesses stiff enough to do the job, it's much too heavy.
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