Hemming question on DIY Tarp

Hey all, Brandon here. I've spent a few weeks lurking and researching and finally took the plunge and made a couple hammocks. Now I'm in the middle of my tarp project and have a question. I'm following the Hex Cut Tarp pattern from DIY Gear but haven't read anywhere if I'm supposed to do a single line hem or a double? I've got some 200d material to add to the corners and I kinda feel like that I'll do a double line on, but what about between the corners? Single or double?

Thanks!

For extra strength, I fold the hem once then sew. Then fold it a second time and sew again. Maybe not necessary but it makes me feel good and simplifies the sewing.

Here's another tip: keep the hem as small as you can. Since you are hemming on a curve, the fabric tends to bunch up. The bigger the hem, the more this problem is magnified.