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Amateur Method B

  • 08 Sep 2012 21:17
    Quote
    Reply # 1067499 on 1067233
    Anonymous member
    Karlis K wrote:Amateur Method C has an simplicity to it that I like very much.  I've been thinking about the stitch line that takes  the initial load (I think this is more relevant for Amateur Method B). If I sew it zig-zag like the rest of the seams, the extra thread in the zigzag width will pull apart a little under load to show thread on the other side where the two panels meet.  This doesn't happen nearly as much if I sew with straight stitch for that batten-side, but something bothers me about relying on a straight stitch there.  Any comments?  Do you use a zigzag for both stitches on the seam, or a straight stitch on the panel-side?

    I use Arne's "Method B" and use a straight stitch for the inner seam and zig-zag for the outer. I prefer "Method B" over "Method C" because when you put the batten pocket on, the seam gains protection from UV. An important consideration in some parts of the world.

    Yes, it does take two passes but that is still quicker than restitching. Also if you put a cover piece on the "Method C" seam to tidy it up and give UV protection, you've made two passes anyway so I do not see any gain.

    "Method C" (if cover strip is omitted) may get your sail together slightly quicker, but that is not where you will be spending your sail making time. Finishing and detailing is where most of the time goes. At least for me that is the case.
    Last modified: 09 Sep 2012 05:30 | Anonymous member
  • 08 Sep 2012 07:58
    Quote
    Reply # 1067247 on 1067233
    Anonymous member
    Karlis K wrote:Amateur Method C has an simplicity to it that I like very much.  I've been thinking about the stitch line that takes  the initial load (I think this is more relevant for Amateur Method B). If I sew it zig-zag like the rest of the seams, the extra thread in the zigzag width will pull apart a little under load to show thread on the other side where the two panels meet.  This doesn't happen nearly as much if I sew with straight stitch for that batten-side, but something bothers me about relying on a straight stitch there.  Any comments?  Do you use a zigzag for both stitches on the seam, or a straight stitch on the panel-side?
    The short answer is that Arne and I are agreeing that it doesn't seem to matter very much what you do, because the loads are well inside the stitching's ability to carry them.
    A zigzag stitch has two advantages in a sailmaker's lapped seam, where the stitches are loaded in shear - it looks better when the sewing gets a bit wobbly, and it gets more passages of thread through the cloth in a given length of stitching, without having to make the stitches so close together that the cloth is weakened, a "tear along the dotted line" effect. However, when the seam is being peeled apart, and the stitches are loaded in tension, then only one side of a zigzag stitch is working, and the other side is not loaded at all. I think if I were aiming for the maximum strength in this kind of seam, I would use long, straight stitches and thick thread. The second line of stitching is only there as a backup, but if it were to come into play, then straight stitches are again theoretically better.
    Having said that, I used zigzag stitching, and I've given the sail enough of a beating over a tough ocean passage that I don't think it will fail through normal loading, only through chafe or UV degradation over time.
  • 08 Sep 2012 07:08
    Quote
    Reply # 1067233 on 1066415
    Anonymous member
    Amateur Method C has an simplicity to it that I like very much.  I've been thinking about the stitch line that takes  the initial load (I think this is more relevant for Amateur Method B). If I sew it zig-zag like the rest of the seams, the extra thread in the zigzag width will pull apart a little under load to show thread on the other side where the two panels meet.  This doesn't happen nearly as much if I sew with straight stitch for that batten-side, but something bothers me about relying on a straight stitch there.  Any comments?  Do you use a zigzag for both stitches on the seam, or a straight stitch on the panel-side?
  • 07 Sep 2012 10:11
    Quote
    Reply # 1066536 on 1066415
    Anonymous member (Administrator)

                                                                             Stavanger, Friday

    I can see your point about amateur method B on the port tack, David. On the new sail for Edmond Dantes the sail looks a bit so and so along the battens. However, the batten panels seem to take up a just as smooth and effective camber as on the sb tack, so I have decided to stick with the method. What I like with amateur method B is that the panel joining seam gets so well protected from sunshine and chafe. I guess you could get a similar effect  with your suggested upgraded version, or even better by adding a length of tabling: After you have run the first panel joining seam, make a tabling which when folded and sewn on with a second seam over the raw edge, will both cover that edge and protect the first seam on both sides.

    The good news to me is that you have come to the same conclusion as I have - that this "tailor’s method" of joining two batten panels is strong enough for serious use. When using cambered panels the load moves out to the boltropes at luff and leech so these "inferior" seams don’t take that hard loads.

    I guess I would be more reluctant to using any of the amateur methods on a flat sail where the load is spread more along the battens. On the other hand, today’s sail cloth and threads are so strong that they seem to take just about any load, so I could easily be wrong on this.

    Cheers, Arne

    Last modified: 07 Sep 2012 13:41 | Anonymous member (Administrator)
  • 07 Sep 2012 06:38
    Quote
    Reply # 1066456 on 1066437
    Anonymous member
    Gary King wrote:I like the amateur C method David.
    What is the sequence to sewing? Tape/staple all 4 thicknesses together and sew? Or sew pocket first?
    Yes, just tape the four thicknesses together, and sew. For the "improved" version, tape the four thicknesses together, with one panel protruding by the width of the seam, then fold it over the other edges and tape it. Sew all five thicknesses together.

    This remains the quickest way to join two panels and a pocket. One assembly job, then sew along the seam twice, and it's done.
    Last modified: 07 Sep 2012 06:42 | Anonymous member
  • 07 Sep 2012 06:20
    Quote
    Reply # 1066437 on 1066415
    Deleted user
    I like the amateur C method David.
    What is the sequence to sewing? Tape/staple all 4 thicknesses together and sew? Or sew pocket first?
  • 07 Sep 2012 05:50
    Quote
    Message # 1066415
    Anonymous member
    Arne Kverneland wrote:

                                                                      Stavanger, Wednesday

                                    Amateur Method B

    David , if my memory serves me, you joined the batten panels of the new sail for Tystie by using my so-called "Amateur Method B". What is your experience with it; does it appear to hold well? When I used the similar method A on Malena’s sail in 1994, I had no idea that it would hold for decades. Only later did I realise how low the stress was on that panel-joining seam and came to think of it as a useful method for serious junk sails. If that method can be regarded as useful for go-anywhere boats, then it certainly  can save a lot of work.

    Cheers, Arne

    Arne,

    I've inspected the seam at the top batten, and there is no sign of any tendency for it to peel apart. This seam is the 'worst case scenario' because the panels either side of it are almost flat, and because it will see the heaviest loadings. If the panels either side of the seam are well cambered, there can be little peeling force on the seam. 

    I conclude that so long as there are substantial tablings at luff and leech, the sections of which lap over each other where they join at the panel seams, this method is fit for offshore use.

    However, I find that while the sail can be made to set well on starboard tack, when the panels are blowing away from the batten, it can never be made to set well on port tack, where the seam between batten pocket and panels, being stiff, cannot lie down smoothly. This is probably worse with the standard sail cloth that I have used than it would be with a softer cloth.

    Giving the matter some thought, I have sketched "Amateur method C", in which the seam protrudes on the port side and the batten is tucked more snugly in towards the sail. I think this will set better, at the expense of having raw edges of the cloth more exposed than is the case with "Amateur method B". It will be even easier to assemble and sew, only having to match up four edges of cloth. 

    With a little extra work, the raw edges can be hidden.
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