I will introduce myself. My name is Mike, I live in the San Francisco Bay Area. I have a project I will be embarking on to entertain myself, my two boys ages 12 and 14, their friends and any other adults who might find interest in riding my zip line on my property. Longest run of three should be around 130' with others in the 100' range. This should be a pretty fun ride once completed. Property is a half acre with elevation differentiation of about 20+ feet from the top back of my property to the lowest area in the orchard. Sooo, I would like to get started planning, and engineering a safely built mini theme park.... LOL This multiple zip line and tree fort(s) would be for the purpose of playing "Commando" with Air Soft guns. The boys and I envision teams of 8 kids each on each team, some on the ground forces and some snipers from the forts and zip lines... Would I need to sketch a set of drawings for someone to evaluate what size cable, pole diameter, depth, length of run, etc? I presume so. I would first like to say that it might be cool to have cable strong enough for the zip line so that two kids could ride simultaneously or, one large adult could ride at a time, say a rating to accommodate up to 375 lbs? This would be for the two growing boys at 185lbs each over time, of course. The adults would be no more than 250lbs I would imagine.