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General Climbing Discussion

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More slackline anchors 26-Mar-2013 At 9:31:08 PM Dr Nick

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On 26/03/2013 Wendy wrote:

>I'm not going to claim any expertise on physics, but, these guys safety
>is a normal climbing harness with a single sling/short bit of rope and
>biner onto the slack line. Surely this is the weak point in the system,
>not a decent multipoint equalised gear anchor? Either that, or the person's
>body - aren't they going to fracture their pelvis/perforate a kidney or
>something else exciting at loads of 12 kn?

Someone's already chimed in, but it comes down to where the load is. The harness has to catch maybe double body weight by the time there's bounce from a relatively small fall onto the sling. The anchors have to take that load as a sideways force that's balanced by the other anchor, with a bit of that being the angle of the slackline pulling the person back up.

It's the same reason it's not good to have a trad anchor too far apart - the angle between the pieces actually sets up an opposing force that increases the load hugely. In this case it's a roughly bodyweight load rather than a falling climber, but rather than having about 30 degrees between the anchors you've got about 170, so the load is bloody huge!