Setting up a zip line

[mindrehab]

Howdy. I'm part of a non-profit group that does recreational tree climbing with kids that have disabilities. We've been doing it for a couple of years, and we're trying to expand the experiences that we can offer disabled climbers. To that end, we're working on the details of setting up a zip line between 2 trees. We often use a double pulley system to get the kids out of their wheelchairs.

Our thought was we'd use that to get them in the air, raise them to the level of the zip line, transfer them onto the zip (and use a tag line), then they ride the zip line down toward the other tree - almost to ground level, where they are clipped into another double pulley system, then lowered back into their wheelchair.

I've had some email conversations with TheTreeSpyder after looking through some of his pages about different rigging concepts and examples. There was a discussion about 5 years ago about speedlines that included a bunch of force calculations. ( Speedline forces ) Unfortunately, the accompanying diagrams are lost to cyberspace. Anyway, he suggested I post here for some further help.

One of the things we're trying to do is figure out the forces involved, so that we can determine how best to rig it (especially in regards to angle of the ropes) and even what kind of rope to use. We currently use 1/2" arborist rope(XTC), but we figure we'll have to change that for this application. I've seen the tables that list the amazing increases in force on the rope as the angle of pull gets closer and closer to 180 degrees, but I'm having a hard time visualizing how to figure that out in a zip line setup. Obviously, we don't want to rig it in a way that creates forces that might damage (or break - Yikes!) the rope.

We have a couple of print resources that discuss the setup of a zip line, but it is more geared toward people in the rock climbing industry.

Does anyone have any diagrams or additional thoughts about forces involved in setting up a zipline?

Thanks for any help,
Patrick
www.arborquest.org

Sorry for the long post!

 

[NickfromWI]

For a permanent setup, I would not use rope. I would install a steel cable system. I've spent several years working on a fine ropes course set up by Innerquest (located somewhere in Virginia). You can go to their website at www.innerquestonline.com

They can send someone out to look at your trees and suggest the best way to set up the zipline in accordance with ACCT standards.

love
nick

 

[Tom Dunlap]

I've done a little work with the installations standards committee of ACCT. They are a fine bunch and really want to have good, solid systems built. Contact their office and you can get hold of someone to help you out.

http://www.acctinfo.org/

 

[mindrehab]

Nick: We have thought about using wire cable, if we have to. Our problem is that we go to a bunch of different sites. We don't have a "home base" where we climb exclusively. That was one reason for trying to do it with rope. We thought it might be easier, lighter, and less expensive to rig it with rope. But if cable ends up being best, we'll do that.

Tom: I've had some interaction with ACCT, too. I'll contact them.

Thanks,

Patrick

 

[NickfromWI]

Well, if you're talking about a sytem that you'll constantly be setting up and taking down in different places, seems like rope might be the best choice here.

I'd work on the side of overkill, just for safety sake. I'd use a double braid rope with a high strength core (see yale's crystalyne for a good example). Get a splice in one end. Set your anchor in the tree, then hook the splice to the anchor, then run the other end down to the next tree and here you will either have to tie a knot in the rope, or maybe a prusik could handle the loads, but that'd need some testing and I'm doubtful it'd work.

Indeed your lack of a home base will make this more difficult, but it's just one more challenge for you to overcome, and y'all should be good at that!

What you are seeking to do can be done.

love
nick

 

[TheTreeSpyder]

Good ideas and link to steal; thanx!

Dave Spencer is a good one to drag in on this, and might have missing pix to the ISA Speedline thread; as i believe all of them were his, save 1.

 

[davespencer]

If you are doing this in different sites, rope is the way to go. How is your liability insurance for this? In Canada they would not insure something like this at all (having tried).

Your sites have to be pretty specific for the ideal zipline. You don't want to hit the ground at any sort of speed but you want to be able to get off. A ladder can be helpfull but if you are doing it with disabled kids it may not help much.

Lose the arborist rope and go with a 12 mm static kernmantle. At 11,000 lbs breaking strength it will easily hold 1 person as long as you dont reef it too tight. Be prepared that even static rope stretches and you may have to re tighten it after the first person goes. Leave it for a few hours and the rope will "shrink" again.

Look at my avatar: the blue sky picture has a person in the middle of it on a zipline I did. 250 ft high on one side, 120 on the other and 500 ft across!!!

The attached picture shows how to best anchor a zipline. No splices required. wrap the rope 4 times around a good hunk of tree, 8 inches is great. this is a tensionless anchor and does not reduce the strength of the rope at all unlike knots and splices. You can use this as is as an anchor and I have as a demonstration before.(but I don't reccommend it.) Tie the same anchor low on a tree behind and in line with the first. This will back up the first anchor and even hold if the first tree starts to fail. Nice and redundant! Take the end and tie a fig 8 or a bowline around the line between the two trees. Repeat with the other end of the rope and voila! If you need to tighten the rope at all, a piggy back 2:1 can be put on with a prussik or ascender, then removed after so you have a system with no knots in it and a zipline rated at 11,000 lbs.

Breaking systems can be quite complicated but if you want jusk ask and I will write about them too.

Dave

 

[davespencer]

more pics

 

[Kevin]

I wonder if you can lift the entire chair, have them clip in and then bail out of the chair?
You can then lower the chair and pick them up at the other end in the same chair.

 

[pantheraba]

Those are very cool pictures...here is one we did for a few years ago. And, I know, no PFD...we had good swimmers and canoe on standby...and a lotta fun on a hot day. /forum/images/graemlins/applaudit.gif

 

[NickfromWI]

Dave, those are some remarkable pictures! You are the zip-king!!!!

love
nick

 

[okietreedude1]

Dave,

That avatar pic I had no idea had a man in the middle until you said so. I thought all along it was just a pretty pic.

Since you seem to be the 'zip king' (which should be your new screen name), Have you seen the 'bogachiel spruce climb' video sherrill gives away? If so, How'd they do that? Set up their zipline that is.

This is something too Ive wanted to do, but not knowing the specs, am afraid to try due to the liability thing.

Great pics!

 

[TreeCo]

[ QUOTE ]
Our thought was we'd use that to get them in the air, raise them to the level of the zip line, transfer them onto the zip (and use a tag line), then they ride the zip line down toward the other tree - almost to ground level, where they are clipped into another double pulley system, then lowered back into their wheelchair.


[/ QUOTE ]

Hey Patrick,

Just a couple of thoughts on your zip line. You could use the same rope to raise the climber and then use it as the tag line. This would mean the climber would not have to un-clip and change over.......they would only have to clip into the zip line. This would be safer IMO. I would have the kids in their chairs with their saddles on......and then raise them up out of their chair nice and slow. The tag line then pulls the pulley back to start after each ride.

I don't know how many kids you will have but if a system could be set up where 5 or more of them could 'pull' the climber up to the begining of the speed line it would add to the experience. Of course an expert to belay this climber is good back up. If all of the kids are in chairs they may each need their own pull rope. You've got more logistics to work out on this point but it would thrill the kids and put them in the action even when it wasn't their turn on the speed line. An alternate way to raise the rider would be some type of elevator system. It could be set up and one of the adults could climb a ladder to be the weight to operate the elevator.

On the bottom end of the zip line....

I suggest bringing the climber in at ground level. A chair could be set up on the ground and the climber could be 'tag lined' and then rotated backwards to the direction of travel and right into their chair.

Dan Nelson

 

[Tom Dunlap]

The gang at the Bchl. Spruce shot the throwline out from close to the top of the spruce over to the trail. Once they had one throwline set it was a matter of hauling lines back and forth.

 

[davespencer]

for us to set lines on the big ones, we sent one person up one side with the mainline and another up the other side with a rope long enough to make it to the ground. mainline guy ties the anchor and rappels down, walks the end of the line over and ties it to the bottom of the other rope, which is hauled up and anchored. the smaller rope is left for rappelling down after crossing.

we used a bow and arrow once with a thing called hunting trace to cross a raging river. This was a looong time ago and we only did it once as it was very unnerving to stand behind a tree and yell "ok, shoot it at me".

I have done tree transfers by getting a rope anchored to the base of the tree you are in, up to where you are, putting a throwline in the adjacent tree over a beefy branch, having a ground guy pull it through with the rope and anchoring it to the base of that tree. there is a lot of sway and sag doing it this way so start high, aim low and expect to still do some hand over hand to get to the next tree. We always left our climbing lines attached until we made it across.

Dave

 

[davespencer]

here is a picture of a friend and myself over a decade ago. The rickety deck chairs are tied in with webbing but take heart that we are wearing harnesses and are tied into the zipline rope as well.

This was neat because it was a hot summer day and people come a long way to cool off by walking down the river 50 ft below us. we just pulled ourselves out to the middle, kicked back with some gatorade and relaxed. We mulled over ideas on how to get a hibachi out there with us safely but decided against it in the end. (probably for the best since open flame and nylon don't mix well)

Dave

 

[davespencer]

here is another system in the same area. The bridge was the anchor on one side (figured it would hold) and it went 250 ft to a tree 50 ft lower. This was a fast ride but it was tied high enough in the tree so you would be going uphill at the end and gravity would slow you down. you would then slide backwards until you were over a large boulder were the weight of one other person would touch you down so you could unclip. In this picture I am doing what we called a superman were the tether was rigged to a back tie in and you held a biner in one hand clipped through the zip line rope. This allowed some control over your orientation and if you twisted it it would allow some breaking action. It was a very unique feeling running and diving off of a cliff only to fly away (like superman)

Dave

 

[davespencer]

this is a picture of the zipline on a 10 element ropes course I used to help run. Cable line, telephone poles for anchors. This was put up by an ACCT member company called challenges Inc.

Dave

 

[davespencer]

just another zip shot

 

[davespencer]

last one. This is the start of the picture in my avatar. Funny / scary story goes with this one depending how you look at it.

The location was just outside of Bragg Creek Alberta, kind of an out of the way spot on the way to some ice caves. We had set up and doen this here about 5 different days when a park ranger screamed up and was losing his mind telling my friend to get it down. In Alberta people always do stuff like this (maybe not this big) in the mountains with no problems.

Apparently this valley was a major helicopter route!! We got the rope down fast and never went back.

Its only funny cause nobody died.

Dave