In reply to jkarran:
> However, I'd argue it's quite conceivable the force required to snap a small wire or strip wires out of soft rock, perhaps 10kN would not cause serious injury when applied through a sit harness, that's 'only' 12g for an 80 kilo climber. People survive enormous 'straight up' accelerations in motoring and aviation accidents, often relatively unscathed.
They do. But 10kN/12g is a *lot*, especially applied to the body through a sit harness as opposed to an ejector seat. If you've not seen it before this (already slightly dated when it was published) paper might interest you:
http://www.hse.gov.uk/research/hsl_pdf/2003/hsl03-09.pdf
The data in there hints at some pretty gnarly post-war experiments. It puts 12g towards the upper end of what's endurable by a military pilot in a parachute harness, and sets out the reasoning behind the decision to set the maximum "safe" load on a human body in a (full body) harness at 6kN in the European standards for industrial fall-arrest lanyards. (In practice the shock absorbers in those lanyards generally start to blow out at about 4kN)
In the post I was replying to you didn't mention any wires though, you were talking about overloading a sling. Unless that's a skinny dyneema sling with a knot in it, that would mean a fair bit more than 10kN.
> I'm not certain this is true under all conditions but it seems likely to me and I've argued similarly in the past, that drop tests with rigid proof weights are unrepresentative of the dynamics of a real fall involving a big floppy climber.
No doubt you're right. I've certainly discussed this on here before and I'm sure you have too.
> Either way, it's a bad idea to fall on a sling, somethings gotta give and I didn't wish to encourage it.
Can't argue with that!
The above is really just a pedantic digression; the point is entirely moot.