Arne,

Your test carried out on a 835mm x 50mm strip, folded over and sewn once with zigzag stitch: finished length 823mm, 98.5% of the original length.

Your test carried out on a 835mm x 50mm strip, folded over and sewn once with straight stitch: finished length 817mm, 98% of the original length.

Paul,

That's strange, I have no puckering across the roll, on the short ends of my sail cover, only along the roll. So, if a panel were cut from one horizontal cloth, the tabling at luff and leech would not be puckered, but the seam between panels, in way of the batten, where it hardly matters, would be puckered.

Machine: Bigfoot RZZ9
Thread: Hemingway and Bartlett Dabond V69
Needle: Schmetz 135x5 size 19

Weathermax has a pronounced weave in that it's very orientated and pronounced in one direction and all but disappears in the other direction. My new machine (an Elize professional sailmaking machine) can sew along the weave without puckering but across the weave, nothing helps. You can by using the various techniques that David has mentioned minimise the pucker but you cannot eliminate it. Once you are sewing more than two layers, the problem disappears. My Sailrite LZ1 machine on the other hand, produces pucker no matter which way I sew.

Another peculiarity of the material is that is is highly resistant to penetration by the needle and once the layers start piling up it becomes hard work for the machine. It also means that a heavier than normal needle has to be used, else you get a lot of breakage.

It's not a material that I'd recommend to a beginner or the inexperienced and doubly so if you only have a domestic machine. Topgun 9 is much easier to work with and it's what I now recommend. None the less I've still a few more sails to make in Weathermax including my own as I've already got the material.

Paul wrote:

David wrote:

 I think that I'd choose Weathermax 80 for a mid weight cloth, where Top Gun was too heavy.

Have you sewn with Weathermax yet? If not, I'd hold my horses in recommending it to inexperienced/budding sailmakers. It is not easy material to work with.

----------------------

Agreed, Paul. I should only preach what I practice. So, I bought some Weathermax for the sailcover that I should have made last winter.

I followed the recommendations: stretch the cloth as the basting tape is applied; slack thread, both top and bottom; keep the cloth under tension as it passes under the needle. I still got puckering on a rolled tabling, 40mm wide, but a sailmaker's lapped seam, 20mm wide with two lines of zigzag stitching was acceptable. The puckering varied in amount, but was always there, whatever I did. The strange thing is that when the finished tabling is tensioned, the puckering can be pulled out flat. I guess, therefore, that it's not the stitching that's holding the puckering, as is sometimes the case with a thin soft material, but a feature of the Weathermax material itself.

Then I tried the same rolled tabling on a scrap of the Clipper Canvas that my current sail is made from, on the same machine settings - no problem, very little distortion, although the cloth is quite soft, as is Weathermax.

I tried a needle meant for leather, with an edge rather than a conical point - no improvement. 

I conclude, as others have done, that though Weathermax feels very good, and has the kind of properties in service that we need for a junk sail, some puckering has to be expected, even in the hands of an experienced machinist. There is possibly one way in which this can be turned into an advantage: in sewing the seam between two of Arne's flat, barrel-cut panels, we would like to reduce the length of the seam by sewing tightly, building in some gathering. Otherwise, the puckering is undesirable, cosmetically, even if it won't affect performance too much. It's a shame that you have to pay top dollar for Weathermax, and still can't achieve an absolutely perfect result in all respects.

Thank you for the comments, it helped in the thinking process. I wasn't there in person when she did it, but the resume was something like: "as the fabric has that thick texture it deforms more while the needle goes through it, especially doing the triple zig-zag. Changing the shape of the zig-zag to a bit more gentle and keeping the seam a bit under tension while sewing seemed to do the job.
Not perfect, though, but overall it looks satisfying enough to move on.

When i had problems with the needle gumming up i ran the thread through a swab of alcohol before it went through the tension mechanism (film canister with a cotton ball).  The issue went away with waxed thread.

I like WeatherMax - it has a nice hand, seems to be elastic and not take on a permanent set, gets along well with my hotknife, and i was able to get half if my 500 sq foot sail through the throat of my sewing machine.  But Topgun 9 sewed more easily and did not pucker.  That material does not come in the color we want.