Got my fourth tarp project started and am going to use catenary curves, material is SilPoly, starting with 1.6oz, then got another project with 1.1oz. Tried doing curves once before and found it easiest to a roll the hem by hand around a 10mm piece of grosgrain. The resulting hem had very little stretch. That tarp project was a bust for other reasons.

I am now better at using my 1/4 inch double rolled hem foot and just did a test curved hem, 1.6oz, 67" long, bias, about 3.5" cut in. Hem doesn't look bad, BUT it stretches like rubber, 5 to 6 inches over that length.

It seems to me that two hex tarps of identical design, one with rolled hems all around, and one with grosgrain reinforced hems, cannot possibly behave the same way for pitching. If the purpose of the cat-cut is to straighten out and put more tension on the middle of the panel, which is better, high stretch or low stretch hems? My gut is going with the latter, but advice here is split. All the threads I have read only talk about the difference in difficulty of sewing rolled hems on curves, nothing about whether the stretch of the finished hem is more or less desirable.

I have read at least one thread where a guy had found that his silpoly tarp became flappier over time, with the edges stretching. His hems were just double rolled.

Has anyone used both and noticed a difference?

Thanks

Chris