While creeking, sometimes boats get lodged on rocks and held there by the force of the water. Two or even three people are often not enough to dislodge the boat. If you know how to set up a z-drag than you know how to double the strength of yourself or your creeking team. A z-drag is basically a mechanical advantage device to pull on the boat. Often times you will hear this idea/device referred to as a "block and tackle" in science/math/engineering classes. If your team members are doing everything during the rescue and you are not sure what to do maybe you should consider grabbing your rope, pulley, binear, & some straps so that things will be ready for a different plan of attack if plan A fails. The picture below provides a basic visual of how a Z-drag is set up. If the kayak requires 300 pounds of force to free it. The man pulling the rope only has to pull with 150 pounds of pressure if everything is rolling smooth and friction is not a major issue. The pressure pulling on the boat is split between the two ropes that are going to it.
Setting Up A Z-Drag