TeriAnn:
I wholeheartedly agree on 4:1 being a much better wll, I was using 2:1 in my example because that's what most manufacturers seem to use on recovery equipment.
Very interesting that you worked at UL. I wonder why the recreational recovery industry products is not regulated.
I work as an arborist. Our minimum wll is 5:1. Generally I try ro rig dynamically 10:1 or better. Our climbing ropes must meet a minimum of 5400lbs and all life support pieces must be rated at at least 5000lbs. At most climbers being under 200lbs equipped, that's like a 25:1 wll.
I have lots of used roped for tow lines, etc. I use 1/2" stable braid alot (because I have alot of it). It's rated at 10,400lbs mbs spliced. I have yet to brake a piece pulling my 1/2 or one ton truck out. Its amazing how strong that stuff is. I also have a few lengths of 7/8" stablebraid that iirc is rated around 30k lbs. I use it for a tow line when a little extra jolt is in order to get unstuck. I would like to know what it would take to break it.