So I made a fins top cover last night. one of my 1st experiences with non treated ripstop nylon 1.1. I found that while making a rolled hem, the fabric wanted to be folded in straight lines, but my cut was curved. I was trying to make a channel for shock cord in the hem. I found that the channel always wanted to close up with thread due to the curve of the cut and the straight of the fold, and the fact that the thread injector wants to sew in a straight line.

Im thinking that if I go with smaller portions of the hem I can get it to turn the corner. Or maybe, if I gently lift the foot and turn the fabric every 3 inches or so then my folds might sort of make darts around the corner.

Any tricks, or thoughts out there on hemming a curve?
and Is it ok to use a rolled hem as a channel?