Are the old halyards internal?
If they are, just connect the new one to the bitter end of the old one. Then pull the old halyard from the shackle end. As it goes up the mast and over the sheave at the masthead it will pull the new halyard behind.The procedures for connecting the old and new halyards together and securing the old shackle to the new halyard were discussed a couple of weeks ago. Try the forum archives under "new halyards" for more details and feel free to ask additional questions as needed. Good luck.PeterH23 "Raven"