A great video from Boreal looking at Advantage Systems and Z-Drag for whitewater, swiftwater & technical rope rescue.

Advantage Systems And Z-Drag

Mechanical advantage rope and pulley systems to help students prepare for their Whitewater (Swiftwater) Rescue Technician Bridge or Recertification course with Boreal River Rescue. Covers simple 3:1 (z-drag) and 5:1 and compound 9:1 mechanical advantage systems with rope to unpin boats and for use in transportation systems. See more information at http://www.borealriver.com