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shu2kill
Jul 2, 2008, 8:59 PM
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hey. i need to rig something like this, and would like your help in the knots i could use.
i was thinking about using a garda hitch or the one shown in this link, to tighten the rope.
http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?post=1918273;sb=post_latest_reply;so=ASC;forum_view=forum_view_collapsed;;page=unread#unread
we will use static rope, with the high anchor point about 8 meters above the lower anchor point. i plan on tying one end to the higher anchor, and then, rig a system on the lower anchor to tighten the rope. i already have some ideas that could work, but im always looking for a better method.
thanx!!
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shu2kill
Jul 3, 2008, 1:41 AM
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BTW i know how to anchor on both ends, as i have already rigged this before. what i need is a system to tighten the rope without having to use a lot of force or people. i would like to be able to set it up with 3 or 4 people.
thanx!!
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uni_jim
Jul 3, 2008, 3:40 AM
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How long are you trying to make it?
I would set up a 3:1 pully and get your three people to give it a good yank. Just tie it off or use a prusik to lock it.
if you have set this up before, why don't you do it however way you did before?
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shu2kill
Jul 3, 2008, 5:55 AM
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i want to make it about 50 to 60 meter long, since i will be using an 80 meter rope.
and, i cant do it the same way as before, because when i have done it, it was for my friends and i to use it. so, we were about 8 people pulling.
but the one i need now, is for a summer camp for blind children ages 5 to 12. so, besides me and 2 other helpers, the rest of the staff will be women. since i dont know if they will be strong enough, and i really doubt it, i want to have an another option.
so how do i rig a 3:1 pulley?? BTW the only pulley i have will be used to travel along the rope, so i will be using biners.
thanx!!
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slacklinejoe
Jul 3, 2008, 11:23 PM
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Two Words: Liability Insurance
No offense intended but this isn't what you do for a living, but your doing it for a commercial company and you don't have the gear to do it right. No amount of waivers will free you from a negligence lawsuit, especially when kids are involved.
It sounds like you need to have a professional set it up for you. The camp's insurance would most likely not fully cover an accident if it wasn't properly rigged by someone trained in it's use. I know a lot of camps have to have theirs inspected periodically just to keep their coverage.
There are people who specialize in rigging ziplines, the costs are not rediculous and it would be far safer for all involved.
Zip Line / Ropes Course Riggers
If however you refuse to have a professional do it correctly and show you how it's done then you'd need to invest in the right equipment included a tandem sheave pulley and whatever tensioning system necessary to get the job done.
Best setup:
Usually for a quality zipline system your looking at 1/2" cable and tensioning it with a heavy duty winch system. You'll also need something like the petzl tandem - cable or speed edition. If you are utilizing a 2nd backup cable you'll have the option of using a standard pulley. You'll also want a momentum block of some sort. Check out the CMI stopper block for ideas. You can make your own out of old tires & etc but if your doing cable you'll want to do it right.
You probably don't have the equipment to swag the cable or experience on what type of angle you can do without having unsafe momentum so it'll be a ton of rigging and unrigging to get optimum curve.
Temporary setup:
New static rope 11mm to 1/2" for the span
Plenty of 2" webbing or chain for anchors
Steel carabiners
A block & tackle capable of creating a 9:1 or higher along with some sort of progression capturing system to remove the tensioning system before use.
What climbers tend to do:
Use our old dynamic rope
Use aluminum carabiners
Accept the fact it isn't as safe and will destroy our rope
Hope no one sues us
(This post was edited by slacklinejoe on Jul 3, 2008, 11:38 PM)
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shu2kill
Jul 4, 2008, 12:11 AM
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thanx for your advice.
as you say, this is not what i do for a living. we are going as volunteers for a blind children camp, and we were asked to set the zipline. the camp has insurance, of course, and we are not new at this.
this is the last zipline i rigged:
we set temporary lines just for us to use. we dont have the equipment to setup a cable, and this is only a temporary setup, so we use a static line. so we qualify between Temporary and Climbers, since we use 11 mm static line, have more than enough webbing, use a pulley, but attach to the pulley using our aluminium biners. and for the tension system, we use biners and basically our own force.
today i was trying some stuff i read here about setting a slackline, and i think i can set the rope tight enough. i anchored 1 end of the rope, and then i tied 2 biners at about 4 meters from the other anchor. to this anchor, i attached 3 biners using webbing. then, i used each biner as a pulley, using 2 of the anchor biners to tie a garda hitch. this way, i could add tension to the rope using the pulley system, and the garda would keep the tension there. of course, once the desired tension is achieved, i would anchor the other end safely.
what do you think??
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slacklinejoe
Jul 4, 2008, 2:37 AM
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shu2kill wrote: thanx for your advice. as you say, this is not what i do for a living. we are going as volunteers for a blind children camp, and we were asked to set the zipline. the camp has insurance, of course, and we are not new at this.
As bad of an answer as it is I'd recommend making the camp check with their insurance company to the coverage requirements. Some will have madatory certification or training classes for any riggers. Internet reading counts for squat.
I'll admit, I'm comfortable with what climbers use for myself for small and medium spans. I'm aware of the trade offs and can evaluate the system myself for safety based on experience.
However, look at it from the parent's perspective. They simply aren't educated enough on the risks involved to make an educated decision regarding their child's safety in this instance. If you gave them a link to this thread they'd probably refuse to allow their kid to participate on anything but the best equipment and rigging.
The responsibility is on the camp to ensure that they make all due dilligence to ensure the system is safely rigged. That includes making the call of doing it right, or not doing it at all, that's what makes running camp activities so hard, it might be safe for casual use but group use is much harder on systems and the issue of liability comes into play.
By the way - the garda hitch has tons of friction and negates some of your mechanical advantage.
If you want a tip from rigging slacklines try this:
Rig a prussik knot on the rope and attach a rope to that prussik. Install your tensioning system on the prussik's rope and tension. Once you're tight enough that leaves the actual main rope line slack so you can tie it off nicely without complexity. Once tied off, remove your prussik and tensioning system for a clean setup. That will allow you to have your slings or chain around the tree - carabiners - and then the main line attached with an 8 on a bight on both ends. That makes for a very clean system to check.
Do not put anyone on the system with just the prussik holding it obviously. You'll need it tied off before testing for your correct flight path.
From my understanding all rope based zip line systems require an overhead backup for camp use. In order to forgo that they usually require > 10:1 strength:load systems such as is present in cable. An example of this is present in your first photo you posted.
(This post was edited by slacklinejoe on Jul 4, 2008, 2:55 AM)
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shu2kill
Jul 5, 2008, 6:04 PM
Post #8 of 8
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ok, thanx, i think i get what you mean. ill post pictures of it when we set it up next week.
btw i forgot to mention, we live in Mexico, where a professional zipline rigger would be very hard to find, and very expensive. we do this as a hobby and now are going as volunteers at the blind children camp. this is the third time my team goes there, but the first time we are going to rig the zipline with only 3 people.
thanx!!
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