Check out Diane Gaudynski. She does feathers with a double line for the spine and a small even space in between each part then she echo quilts around the outside with the same distance. I find it easier to do feathers this way as I don't have to travel over any previous stitching and I don't get thread build ups on the spine.
http://dianegaudynski.blogspot.com.a...ether.html?m=1
If you go through some of her older blog posts she explains her feathers very well.