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Flat, hinged or cambered?

  • 27 Aug 2018 08:40
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    Reply # 6640057 on 6640054
    Anonymous member
    Jami wrote:And there is also the option of separate panels and webbing or sailcloth hinges/loops/tabs (pick a term of your liking) as brought up by Roger Taylor. I also used this method on two sails already. 
    Yes,I'd forgotten this one. Sound, strong, functional and a good way of making a sail in a limited space, but probably one of the more labour-intensive methods.
  • 27 Aug 2018 08:34
    Quote
    Reply # 6640056 on 6639667
    Anonymous member
    Annie wrote:
    David Tyler wrote:Webbing loops, with or without a cloth cover to match in with the sail
    Would be my favourite, although I'd refer to them as 'tabs' or strips.  It's like a very short section of batten pocket, sewn top and bottom.  They are much easier to fit on sails with vertical seams, but much more to the point, they are ideal for offshore work where you may end up wanting to remove a batten at sea.

    Short pockets can claim the same slight advantage when replacing a batten, and I think they're a little quicker to add than webbing tabs (but slower than full length pockets). Also, they can use up more of the scraps and short ends left after cutting out the panels.
    Much easier to fit webbing tabs than pockets? I can't see why. 
  • 27 Aug 2018 08:34
    Quote
    Reply # 6640054 on 461931
    Anonymous member
    And there is also the option of separate panels and webbing or sailcloth hinges/loops/tabs (pick a term of your liking) as brought up by Roger Taylor. I also used this method on two sails already. 
  • 27 Aug 2018 08:21
    Quote
    Reply # 6640040 on 6639557
    Anonymous member
    Arne wrote:

    Jim,

    frankly, I would only use wood (spruce ?) if I had to, for battens. I have read about too many breakages, and they appear to happen during gybes.

    My hunch about this is that a fairly heavy and compact wooden batten, combined with its stiff and not too strong material (compared to aluminium, grp or bamboo) makes it vulnerable to the jerks at the end of half-long gybes.

    Arne

    These (aluminium, GRP, bamboo) being in the form of a round tube, putting all the material precisely where it's needed, is the main point. A wooden batten could be quite strong if it were laminated from two or more layers cut from different pieces of stock, thus eliminating continuous non-longitudinal grain, but it will always be at the disadvantage of worse strength/weight ratio when compared with a tube. Unless, of course, you make a tube out of wood. Not impossible, but a pointless exercise if you can buy good tubes off the shelf.
  • 27 Aug 2018 08:07
    Quote
    Reply # 6640026 on 6639714
    Anonymous member
    Jim wrote:
     But don't underestimate the amount of cloth it takes to make them, it's surprising how much extra, on top of the sail area; make a full calculation before ordering.
    All things considered, what would be the difference in cost be, between a pocketed sail and a non-pocketed sail?
    There are way too many variables even to attempt a calculation, but if cost is important, then I'd offer the guess that pockets would cost less, as using grommets means buying them and their setting tool (not cheap) plus enough extra cloth for the batten-length strip of patching that they need underneath them, plus cordage. A double layer of patching equates with the amount of cloth needed for a pocket.
  • 26 Aug 2018 23:33
    Quote
    Reply # 6639714 on 6639264
    Anonymous member
     But don't underestimate the amount of cloth it takes to make them, it's surprising how much extra, on top of the sail area; make a full calculation before ordering.


    All things considered, what would be the difference in cost be, between a pocketed sail and a non-pocketed sail?
  • 26 Aug 2018 21:58
    Quote
    Reply # 6639667 on 6639264
    Anonymous member
    David Tyler wrote:Webbing loops, with or without a cloth cover to match in with the sail
    Would be my favourite, although I'd refer to them as 'tabs' or strips.  It's like a very short section of batten pocket, sewn top and bottom.  They are much easier to fit on sails with vertical seams, but much more to the point, they are ideal for offshore work where you may end up wanting to remove a batten at sea.  With full-length pockets, you need to get the batten out from either luff or leach, which can be more than a little precarious. With tabs you just push the batten forward or aft until the end is at a convenient point in the sail and then slide it the other direction outside all the tabs.  Easier to put back in, too, because you don't actually have to have the sail stretched flat to do so (and it's not the end of the world if you miss one of them).

    And you can see the battens clearly, which might be useful with wooden battens.


    Last modified: 26 Aug 2018 21:59 | Anonymous member
  • 26 Aug 2018 21:31
    Quote
    Reply # 6639623 on 6639557
    Anonymous member

    Jim,

    frankly, I would only use wood (spruce ?) if I had to, for battens. I have read about too many breakages, and they appear to happen during gybes.

    My hunch about this is that a fairly heavy and compact wooden batten, combined with its stiff and not too strong material (compared to aluminium, grp or bamboo) makes it vulnerable to the jerks at the end of half-long gybes.

    Now, I think I read somewhere that someone had successfully beefed up their wooden battens by adding a layer of glass roving in epoxy. I am not sure if I remember correctly.

    On Marco Polo/Teleport.I used local ash according to the scantlings in the plans. I made each one from two pieces, glued together. I never broke a batten and I don't think Chris and Jess broke any in the Arctic. Ash or similar is recommended for battens in the PJR, pg.157. They report they heard of good resulted from glassing the battens on each side. ((Not top and bottom. )I would use unidirectional glass only. Or carbon fibre tape?
  • 26 Aug 2018 20:39
    Quote
    Reply # 6639557 on 461931
    Anonymous member (Administrator)

    Jim,

    frankly, I would only use wood (spruce ?) if I had to, for battens. I have read about too many breakages, and they appear to happen during gybes.

    My hunch about this is that a fairly heavy and compact wooden batten, combined with its stiff and not too strong material (compared to aluminium, grp or bamboo) makes it vulnerable to the jerks at the end of half-long gybes.

    Now, I think I read somewhere that someone had successfully beefed up their wooden battens by adding a layer of glass roving in epoxy. I am not sure if I remember correctly.

    These days I aim for big-section, thin-walled aluminium tubes for battens (easy to get at here) with a diameter/wall thickness ratio somewhere between 15 and 35. I once managed to bend a 50 x 1.5mm batten (batten 2 on Johanna, replaced by one of 50 x 3.2mm). I had feared that such a thin-walled tube would collapse, but it just bent.

    Arne


    Last modified: 26 Aug 2018 20:48 | Anonymous member (Administrator)
  • 26 Aug 2018 18:27
    Quote
    Reply # 6639479 on 461931
    Anonymous member

    I guess we don't need a new thread. You guys didn't waste any time!

    When Tam Flemming launched Elsie N in 1999, his junk schooner sails had no batten pockets. They were lashed to the battens (PJR style wooden battens) through paired grommets every 12". I had suggested this and Tam boldly went ahead. The leech ends were bolted through the sail. See the album pictures in my profile. Very simple. You can see some water ingress under the epoxy. That just needs better installation detail. I would make a hole drilling jig to ensure standard size and location so battens could be interchanged. Some battens had a slot cut vertically into them at the leech end and a piece of 1/16” aluminum sheet metal glued in the slot. This would ensure the sheetlet strap did not pull out.
    The luff ends were as per Practical Junk Rig.
    Tam reports he had no problems. When he broke a batten in the foresail, gybing, he had easy access to splint and repair it. The boat has made trips from Nova Scotia to Bermuda, Caribbean (twice) Newfoundland and Magdalen Islands. Lots of service. The bolt holes in the sail did not elongate under stress. 

    But David, you have a broader experience to make a comparison. Interesting.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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