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skymeat
Apr 13, 2005, 10:47 PM
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I've been trying to set up a line in my yard...The problem is the only anchor poins I have are about 50ft apart. I have to place the anchor points about 5 feet off the ground so as not to bottom out in the middle. I want to be able to set it up lower to the ground, because my boys are taking a serious beating. I'm wondering if it's possible to set it up closer to the ground (2-3 feet), over that distance, and I weigh about 200lbs...am I heading for a biner in the head?
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isaacct
Apr 13, 2005, 11:05 PM
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I think it will be hard to set a 50 ft line with the anchor points lower than 4ft. At least using tensioning systems that only involve biners. How are you tensioning the line, by the way?
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skymeat
Apr 13, 2005, 11:12 PM
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I'm using a ratchet tie-down. It's rated to 3000lbs, I can tighten and tighten...yesterday when I looked at the anchored end the biner there was weighted enough to seat the pin in the catch...It was past it's open gate limit which is 6kn/1300lbs. That was when I got worried, I realized how hard that oval would hit me if it failed, it made me cringe. FOTH says that the force on each of two equalized anchors at 170 degrees is 573%. That would mean I would be applying and additional 1100 lbs at the anchors, right?
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phillygoat
Apr 13, 2005, 11:24 PM
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I'm sorry, but I don't have an answer too your question.
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isaacct
Apr 13, 2005, 11:33 PM
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I did a 14 ft long setup a couple of weeks ago and when I tighten the system I couldn't open the gate of the biners either (BD ovals)... But I don't know if that means that the biners went past the open gate limit. This line was about 3' 6'' from the ground in the anchor points. I was only inches from the ground in the middle of the line (I weight 175 lb). I used the first system described in this article:
http://www.rockclimbing.com/articles/index.php?id=189
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fear
Apr 13, 2005, 11:34 PM
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Why not use some cheap Omega steel lockers? You won't break those. 65kn on the big boys.
http://www.nrsweb.com/shop/product.asp?pfid=1413&src=froogle&refer=1413
-Fear
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slacklinejoe
Apr 14, 2005, 12:15 AM
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Just a heads up, your working under a wrong assumption about how much tension is put on a biner before it stretches to lock the pin in the gate.
The exact measurement varies from maker and biner but the only real regulation on it is that the pin's should not lock the gates while under body weight. I wish I could remember what source I had on that but I'm thinking it was just a personal conversation with one of the biner company engineers, maybe Omega Pac, dunno.
At any rate, a 50 foot line CAN be set at the height your shooting for, but your real problem isn't the line height, it's the fact you need to work on your dismount, by the time your walking 50's you should have stepping far to 1 side down and beat down the impulse to step straight down or otherwise let your nads get whapped by the line.
As far as overall strength of your system, you'd have to have it hella tight to meet 3,000 lb test - somehow without filling the ratchet's capacity. At 3,000 lb test, if you have knots in the line I'd be worrying.
As for an idea of how to calculate how much force is on a line while your just standing, here's a good link:
Technical Analysis of a slackline
According to that, a 50 foot line with 3 feet of sag with a 180 lb person standing still in the middle will only have about 800 lbs of tension.
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billypilgrim
Apr 14, 2005, 5:21 AM
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use an Aframe at one end to make a shorter line for learning on, 50 feet is a hard starting length, start at 30 feet and get used to falling off, then lengthen it out.
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petsfed
Apr 14, 2005, 6:11 AM
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Having had a carabiner hit me in the knee when something broke, let me assure you that chances are you'll never get close enough to failure strengths of your equipment, so long as you take good care of it. All you need is a better tensioning system than what you've got. Work in some mechanical advantage and you might be able to succeed.
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skymeat
Apr 15, 2005, 1:23 AM
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I finally got the rocks out of my head and figured out a way to shorten the line. I just had to be a little creative. It seem to be working very nicely.
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healyje
Apr 19, 2005, 7:03 PM
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Everyone is pretty stuck on webbing, but I much prefer 11mm static line cranked down a bit. Bouncier with more lateral stability and way less stretch...
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jt512
Apr 19, 2005, 7:34 PM
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In reply to: Everyone is pretty stuck on webbing, but I much prefer 11mm static line cranked down a bit. Bouncier with more lateral stability and way less stretch...
What!? A grown-up who slacklines? :shock:
-Jay
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g-funk
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Apr 19, 2005, 7:34 PM
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I was totally expecting this thread to be about shoes. :oops:
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areyoumydude
Apr 19, 2005, 11:25 PM
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In reply to: In reply to: Everyone is pretty stuck on webbing, but I much prefer 11mm static line cranked down a bit. Bouncier with more lateral stability and way less stretch... What!? A grown-up who slacklines? :shock: -Jay
What!? a nerd on the inter-net? :roll:
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viacontinuum
Apr 19, 2005, 11:52 PM
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In reply to: I'm sorry, but I don't have an answer too your question.
i was just wondering what a 'ratchet tie-down' is. i'm looking to pick up some of the gear required to setup my own slackline this summer, so if anyone has any recommended tightening methods that don't cost too much in gear it'd be a great help.
peace.
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slacklinejoe
Apr 20, 2005, 2:17 AM
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In reply to: i was just wondering what a 'ratchet tie-down' is. peace.
It's a tensioning system used for industrial use such as tensioning safety straps on loads on the backs of semis or trucks. They don't have to be huge and heavy, they come in all sizes and such.
Check out this site to get an idea A commercial slackline that uses a ratchet for tension
If your looking for a way of not sacrificing your carabiners for a tensioning system, you might give one a shot. If you know what your looking for a decent unit will cost you less than $15 and it will provide far more mechanical advantage than pulling for tension using carabiners. It of course does have it's trade offs and such.
To see some of the debate on pro vs con on tensioning systems you might find something useful here: Tensioning system debates - ratchet vs pulleys
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skymeat
May 7, 2005, 9:20 PM
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By the way, I stopped using the ratchet, I got scared at the thought of it hitting me. So I went back to using biners to tighten it. It was definitly harder, and needed two people to get it tight enough. But I found a way that I haven't seen mentioned. I fastened both ends near or on the ground and tightened them. Then I slid two a-frames I made under it and pushed them up, they worked like giant levers, I found that it was very easy for one person to tension it, I had to be careful not to get it too tight. Hope this helps.
The a-frames I made were just equilateral tiangles with a little overlap at the top and a bolt with a teflon bushing for the webbing to seat on.
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fender13
May 7, 2005, 10:21 PM
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In reply to: I'm sorry, but I don't have an answer too your question. |
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