I once had to replace my main halyard, and our crew member actually went up a j-35 mast. We rafted to the other boat, and he went up with our (J-30) jib halyard, which he attached to the other mast. We winched the masts close together (about 2 feet), and he swung over to our mast to make the replacement. It was an experiment, but it did work, and he had two halyards from the j-35, so safety was covered.
