Good point and I found the shock cord was too thick, it seemed to hanging up on the mesh on mine too, will try thinner shock cord or go to regular line. I think I will also sew the channel smaller, it seems to be trying to gather a lot of fabric and causing it to bunch rather than close.
I also have a new hammock that I can't seem to get the gather correct so I am trying all this at the same time at home before I take it out. The blackbird is always ready and waiting to go out.
Cheers