Spinnaker
One halyard for your primary jib (usually roller furled), one generally for an optional spinnaker. I suppose you could use it with a storm jib as well. I have the same on my C320 and often use the spare halyard for a "lifting" rig. I've had problems with my mooring float & pennants getting tangled on the chain, so I have occasionally had to rig a light block/tackle to the spare halyard (used as a fixed lift point) to pull the float out of the water enough to untangle the mess. I've also lifted a dinghy onto the deck that way.--Rons/v Lady Jane