Can you elaborate a bit please Big Swede?
I can see 4 bar tacks on that. Whilst the stitching obviously weakens the cloth, it's doubled. If the cloth is weakened by half, it only needs to equal the strength of the single layer.
I'm struggling to get any links to open on the field manual, I'll try again tomorrow.
Does it deal with canvas, polyester and nylon as seperate methods do you know? They all have different stretches, needing different stitch patterns. For instance, nylon webbing is strongest with a series of staright stitches but with polyester, it makes little difference.
Does it take into account the different needles? The cotton will be weakened with stitching as the hole is cut, the super fine and sharp needles used for the thinner sil will damage the fabric much less as it passes through the weave rather than cut a hole in it.
I have seen all sorts of methods used commercially for attaching these tie-outs, lots similar to the above method. They have held up well for me in use, even exceeded the original strength of the cloth.
You've made some good points, I'm going to do some destruction testing and report back.
It does mainly deal with repairs of clothing, equipment and tents. Mostly canvas. Just google US field manual 10-16 general fabric repair.
Poly or PA taping matters little, it is how the seam is made that matters, when it comes to seam strength.
Look here buddy, I worked with heavy sewing machines stitching custom lifting rigs and in a sail loft and now I'm in tailoring, I didn't make these things up. Look at how heavy duty technical things are sewn, ever saw any zig zag seams with the stitches overlapping in a safety belt or a tie down strap?
Please don't take me wrong Big Swede, I'm not questioning your experience and you obviously know what your talking about. I make a lot of gear myself and this is important to me.
As for seeing overlapping and bad stitches on safety belts and tie downs then yes, I've seen some shocking stuff. What I notice in general is that it's not the stitch length or weakening of the fabric that causes issues, I've had far more failures from too small a seam allowance and not enough threads to hold up to abrasion. Just my observations.
Tie outs on the perimeter with thinner cloth is always going to be trickier to get spot on to because of the large force radiating from a small area.
Got the link mate this morning, I shall peruse.