Some crews like to use tag lines when pulling lures to help cut down on the natural drop-back that occurs when a clip lets go of an elevated line at the strike. By adding a tag line to the halyard, and attaching your main via a clip or rubber band, it allows the fish to come tight to the drag at almost the same instant he eats it. Some crews say that this increases your hookup percentage, especially when trolling large, hard-headed lures.
All tag lines should come with a tag line retriever system — usually consisting of a stainless-steel weight that slides over the tag line and the halyard. The pressure of a large lure pulling through the water is enough to lift the tag line up to a position even with your pulling point on the outrigger. When a fish bites, the tag line releases and the weight brings the tag line back down to the cockpit so you can reset it once you catch your fish.
This heavy weight can get up to pretty good speed coming down after a strike, so Capt. Peter Bristow on Kathleen B likes to add a styrofoam float under the weight on the halyard. This slows the weight on the fall and also acts as a cushion to save his rigger hardware at the bottom.