remember the loads are the tensioning force and the weight of the piece. rule of thumb for me is not to send a piece down that 2 guys cant control with the line. and 1 guy when the zip line is on a limb. we save firewood so I cut it to log size and zip it right into or beside the trailer. til it gets big. I've used all kinds of stuff for the zip line itself. if your just holding the line with a ground guy, any rope will do. theres not enough weight to stretch sag in the line. the angle of your drop determines whether you need a pulley. if its steep, you can send it on oval life rated non locking biners. if its flat, you need a pulley. I keep 1 end of the zip line with me and choke it in place. the ground guy pulls it tight. if its a pine, you can tie one end around the base, run it through a block at the top and out to the ground guys. the plus to this is that once the limb is cut, they can actually raise it. so you can zip the lowest limbs. you'll need to keep a line attached to the zip line to pull it back to you. it'll get stuck at the ends of the limbs if not. i tie off my limbs just a bit tip heavy. so the brush is down. you can take longer pieces over structure this way and if it would contact something, its more of a sweeping impact than a denting one. as far as rigging, i use a 12 strand 1/2". i haven't rigged a tree yet that I've had to take big weights. my ground guys are good at letting pieces run. but things happen and i never rig anything that scares me while i am in that tree. it takes me about 5 minutes to relocate and get a piece down. i'll work later and make less money before i kill myself rigging risky loads.
