The background: I hang an eleven foot DIY channel end gathered hammock. Also, the vast majority of my hangs will be of the car camping variety so a few ounces heaver is not a deal breaker.
Good coverage that can be pitched tight are my goals.
I settled on this design
and 1.1 oz sil nylon for the material
I usually see this type of tarp cut into a hex pattern but I would like to keep the length 144 inches. According to the catsplat calculator, for a 62 inch width with a 1 inch per foot sag, would need a 5 inch cut in. For the length (144in) I would need a 12 in cut in. Does that sound about right?
The main question is this. Once I have my two sides cut out, should I join them with flat felled seam then hem the sides or hem the sides first and then join the two pieces? In my head, I see problems each way. If I FF seam first then roll hem the permiter, I think I will have a problem when I get to the ridge line, like there won't be any material to roll. If I go the opposite route it seems the rolled hem will cause problems with the FF seam. I do not plan to add gross grain to the perimeter, just the rolled hem.
I thought I would try to do this right so I made a template out of foam poster board for my cat cuts
Materials for the template
Long curve generated.
I plan to update this post as I go along. Hope someone can benefit from it in some way and I look forward to any help on the rolled hem/FF seam question. Thanks everybody!