Forums: Climbing Disciplines: Slacklining: Re: [causticfluids] Webbing used for slackling: Still safe for climbing?: Edit Log




Partner slacklinejoe


Feb 21, 2010, 9:22 AM

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Registered: Nov 5, 2003
Posts: 1423

Re: [causticfluids] Webbing used for slackling: Still safe for climbing?
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causticfluids wrote:
My friends and I had tightened things pretty well, but we couldn't get the tension high enough to actually slackline more than a few feet from the anchors.

If you couldn't get very far from your anchors, you didn't tighten it well.

The physics of the sport have been documented and tested. For a quick and dirty calculator on loads, I wrote one and posted it on the Slackline Express Slackline Force Calculator

Let's take a look at the physics of what you just did:
Say you set up a 20 foot line that sagged like mad of 5 feet in the middle (but you couldn't get it to sag that far because it was too loose/low for the height you rigged). Assuming you weight lets say 170 lbs.

The force applied to both ends your line was only 190 lbs if distributed evenly. Since you weren't in the middle, lets guess that 90% of that load was placed on one end, that yeilds a load of 340 lbs placed solely on the end you stood on (this is unreasonably high, but we'll use it anyway for a large margin of safety).

Presumably, you are probably using 4,000 or 4,500 lb tensile test webbing, you only loaded less than 10% of it's overall rating.

The next question is for you: if you put 340 lbs of load on your webbing, do you trust it to continue climbing on it?




Alternatively, if you and your buddies had set up a 40 foot long line (fairly common length) had two people stand up on it while playing around and pulled it tight with someone's pickup the physics would be: length 40 ft, sag, 2.5 feet, combined ofweight 340 lbs. That calculates to a load of 1370 evenly distributed with realistic peak loads while you and your hypotehtical friend are bouncing around of 2,000 lbs.

You then reached 1/2 the tensile strength of your webbing and produced a load high enough to permanently change the shock absorping capabilities of your webbing. Do you still climb on it?

The cost of 50 feet of webbing is around $15 retail price or $20 if you bought it with a sewn loop.

Hardware is a completely different thing, it doesn't have the same load balancing capabilities that stretchy webbing has. Many carabiners have been broken or permanently warped while slacklining - we strongly discourage reusing recreational climbing hardware (primarly aluminum carabiners).


(This post was edited by slacklinejoe on Feb 21, 2010, 9:27 AM)



Edit Log:
Post edited by slacklinejoe () on Feb 21, 2010, 9:24 AM
Post edited by slacklinejoe () on Feb 21, 2010, 9:27 AM


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