I've often thought that if I could get (2) 1000 ft spools of paracord or something similar I'd like to try rigging a reverse zipline with a suspension line and a haul line.
A zipline needs a cable FAR stronger than the weight being moved, plus the posts at both ends have to be extremely strong. It wouldn't take much weight at all to break a 1000' paracord stretched between 2 trees. I've long since forgotten the math involved but a weight hanging in the middle of a stretched cable will exert far more tension on both sides of the rope than it would if it was just hanging straight down on the cable. The tighter the cable, the greater the stress on each side.
A poor man's winch can be rigged with a cable between a stuck car and an anchor by getting the cable as tight as possible then pulling at a 90 degree angle in the middle of the cable.
