Main Halyard
Rich, I replaced both my Main and Jib Halyards a couple of years ago. All I did was tie a couple of tag lines, or strong twines to the ends of each of the halyards, and pulled the halyard completely out, leaving the tag lines in place. I was able to lay the halyard on the ground and measure them. After I purchased the lines, I made up the eye splices to the head shackles and it was just a matter of tying an end to each tag line, and pulling them through. I had whipped the ends of each halyard, and just above the whipping I ran the tag line through the halyard and tied and taped it to keep it in the center of the bitter end of the halyard so that it wouldn't get hung up at the sheaves in the mast. Any strong twine can be used for this task. If it should get caught, just pull the halyard back a little, and give the tag line a light tug again. I Replaced the three braid lines in my boom the same way. This is the way I did it, but you should do it which ever way you feel comfortable with. Sewing each end together with a strong Nylon whipping twine is doable. I've done that with success. Good Luck!Joe