We decided to add a stormsail. In bad weather, the big genoa jib is furled and the stormsail is hoisted OVER the furled jib. This requires a separate halyard, and we pressed into service the halyard sheave often used for a spinnaker. (light-wind, down-wind, giant parachute sail. Which I don’t have)
The holes in the mast are all in use, so both arms of the halyard run freely down the outside of the mast.
A halyard is a line on a sailboat used to hoist things, like sails. A halyard often extends to the top of the mast and back down. A tall pulley setup.