Design issues aside,unless you're going to do glued sails it's all about the sewing machine, especially on mainsails. There's nothing like a flywheel machine with a compound walking foot that will do triple pick zig-zags, with the forward-reverse set just right so it needles through the same holes on the lock stitch without dropping stitches or sending broken needle shards flying at your eyes.......uuuuhhhhmmmm....walking foot..uuhmhm....