In the process of planning and designing a new tarp (first diy tarp) and a couple of questions have come up which I'll be happy to get your input on.

Reinforcing corners, pull outs, etc. When using ripstop fabrics that don't stretch in two directions (x/y) but do on the diagonal, do you align any reinforcement panels/patches so they are aligned the same way as the main tarp panels? My thought is that if they are not aligned it could create a stress point where the tarp is being pulled by the guy line on the diagonal of the main tarp panel but the reinforcement patch is aligned so it won't stretch. I hope you can understand what I mean. In my head it just feels more right to have the reinforcement panel be able to also have a bit of stretch to follow the main fabric.

Second question, related to the first. I've never seen a tarp where zigzag has been used on reinforcement panels on corners etc. To me that would be the obvious choice due to it allowing some stretch to the seam where the fabric is a bit stretchy. It also distributes stress over a wider area in the warp. In sailmaking zigzag stitching is basically all you see in those areas of the sail. A straight stitch that doesn't stretch with the fabric can create stress points/lines.

Maybe it's a bit unfair to compare a tarp to a sail where the forces are so much bigger but in tarps where you want to be able to use thinner and lighter materials to save weight it feels important to not create any unnecessary potential failure points.

I'm probably going to go with my gut feeling but were curious about your thoughts on this.