Quote Originally Posted by Youngblood View Post
If you look in some of the sewing books you will see they cut darts around neck lines to relieve the buckling(?) that naturally wants to occur. I wouldn't do that on these curved edges on tarps but you have to deal with it a little differently than when you hem straight edges.
Another technique the sewing books offer is to trim the seam allowances very close which makes it easier to "ease" the fabric around a curve. This is often done on arm holes, collar seams and the like. The smaller the seam allowance the less fabric there is to bunch and wrinkle.