To me, this longitudinal crack looks rather large; and scary. Is it just the picture or is the crack over 1/4" wide and ~6-8" long at the top? At the least I would think the area should be ground back to good glass and then layers of glass and epoxy filled in to the void; with a few layers of cloth over the top to aid in load distribution. But again, this is pure speculation; I'm not able to look directly at the problem.
Yes, your dimensions are correct, approximately 6" by 1/4 or 3/8".