Flat, hinged or cambered?

  • 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.
  • 28 Aug 2018 10:14
    Reply # 6642182 on 6642110
    Annie wrote:
    David Tyler wrote: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. 
    Personally, I'd claim it as a huge advantage.  I said they were easier in sails with vertical seams, where you have to send the whole sail through the throat of the machine, when sewing the battens pockets on.
    A flat sail that is made by sewing all the cloths together, and then adding the pockets, certainly does require half of the sail, to be passed through the throat of the machine, rolled up, (working from the middle towards the top and then from the middle towards the bottom). But I can't understand how adding your webbing tabs is any different? How did you do it?

    Personally, I'm glad that we've moved on from that scenario, which was hard work with a big sail. 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.

  • 28 Aug 2018 09:30
    Reply # 6642132 on 461931
    Anonymous member (Administrator)

    Over the years, I have noticed that many who have made camber in their sails, this way or the other, have taken great care of progressively reducing the camber from the lowest one and upwards. Frankly, I think that is waste of time. Only my three top panels have been made flatter. This lets me use the same pattern on all the 3-5 lowest panels, and thus save time during production. This goes whether the sail is constructed with the barrel-only, the barrel plus broadseam, or with any kind of shelf-foot method. Re-using the same pattern(s) 3-4 times saves time.

    Mind you, although I only sail inshore these days, I certainly reef quite often, partly since I generally rig my boats generously, and partly because the west coast of Norway can be a windy place. Still, I have never felt ” oh, dear, I wish I had cut panel four and five flatter”  -  not for a single time. The 8% camber that I have standardized on in panels 4-7 on my small boats, is just about right for my use. It gives a good compromise between brute force and pointing angle.

    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 four lowest panels works well.

    Construction time.
    The sail of my Ingeborg was started 29.12.2014 and was finished 11.1.2015. Malena’s blue, cambered sail was made in exactly 40 hours (May 1994). There I used the super-quick-and-dirty amateur method A. Even the roping of it; hand-stitching on a rope-type boltrope (including a lot of splicing), took only eight hours. When that sail fell apart after 16 seasons, it was the cloth that gave up. Both the machine seams and the hand-stitching had held well.

    Arne

    PS:
    The lovely thing is that any of the known methods of building camber in the panels can be combines with Jami’s improved hinges for joining the panels at the battens. Jim C is sooo right about the internet  -  back in the nineties this info would have taken years to spread.


    Last modified: 28 Aug 2018 09:58 | Anonymous member (Administrator)
  • 28 Aug 2018 08:45
    Reply # 6642110 on 6640056
    David Tyler wrote: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. 
    Personally, I'd claim it as a huge advantage.  I said they were easier in sails with vertical seams, where you have to send the whole sail through the throat of the machine, when sewing the battens pockets on.
  • 28 Aug 2018 08:05
    Reply # 6642095 on 461931

    Credit to Roger for being the first to think of this system (unless anyone knows differently?), and to use it in a sail that is fit for purpose and satisfies his requirement.

    And then credit to Jami for taking it on a step, and reducing some of the air leakage paths, particularly in way of the mast. Whether the air leakage matters very much is an unanswerable question, without a test programme, but for offshore cruising usage, Roger has shown that it can be lived with.

    A bit of armchair sailmaking: I think I'd try making shelf foot panels, then working the straight edges of those shelves into the alternate hinge/gap format. That way, the hinges don't have to be made as separate pieces. Still time consuming, though. 

  • 28 Aug 2018 06:49
    Reply # 6642020 on 6641513
    Arne wrote:

    Howevere, here the panels have not been cut with round in them. Instead, Roger has  created the camber by making hinges of raising size towards the middle (or max camber) point of the battens. This must have been quite time-consuming, as one cannot just mass-produce hinges of one size.

    I guess I would prefer the way Jami solved it  -  quicker to do and with the same benefits as the sail on Ming-Ming 2.

    I wouldn't say quicker - one just uses the time differently. In my system the hinges can be mass-produced, but the camber must be done with a barrel-shape and/or broadseaming, whereas Roger's panels are simple and straight.


  • 27 Aug 2018 22:51
    Reply # 6641581 on 461931

    I was just reflecting on how wonderful it is to have the Internet, so we can discuss what we love, in real time, as apposed to letters and magazines which toke months to do what we can do now in a day or two.

    I attach a screenshot of Jami's new sail.

    1 file
  • 27 Aug 2018 21:40
    Reply # 6641513 on 461931
    Anonymous member (Administrator)

    Now I have been struggling my way through six YouTube clips about the reconstruction of Roger Taylor's Ming-Ming 2

    There, in Part 6, I learned to know how Roger constructed his sail. The upper three panels are quite conventional, lightly cambered panels with batten pockets. Only the lower panels are made as independent panels with these 'hinges'. However, here the panels have not been cut with round in them. Instead, Roger has  created the camber by making hinges of raising size towards the middle (or max camber) point of the battens. This must have been quite time-consuming, as one cannot just mass-produce hinges of one size.

    I guess I would prefer the way Jami solved it  -  quicker to do and with the same benefits as the sail on Ming-Ming 2.

    Arne

    PS: One can only speculate if the much bigger gaps around MM2's hinges do any good or harm to the airflow around the sail...

    Last modified: 27 Jun 2021 10:08 | Anonymous member (Administrator)
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