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Topic Date User

Shockloading is bullshit 2-May-2020 At 9:10:36 AM Olbert

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On 1-May-2020 IdratherbeclimbingM9 wrote:

>I have taken FF2's on a spectra daisy chain while aid climbing (once twice
>in quick succession!), and I have also accidentally taken greater than
>FF2 on a fifi hook during an aid-climbing fall. Neither the daisy, nor
>the hero loop attaching my fifi broke in those incidents. I did however
>suffer considerable bruising from my harness at the time/s...

Exactly - the gear didn't break - you absorbed the impact! Although I'm surprised you weren't more damaged by the incident.

>I agree with gordoste in that the primary concern is how secure the gear
>or belay is under such loading.
>
>Regarding equalisation of belay components, this too is important in mitigating
>cascade failure of a belay or critical piece of protection... which touches
>on Olbert's query of;
>>I do wonder about holding ability of marginal gear when there is dynamic
>loading dynamic loading (ie loading with a bit of movement). And then add
>to that the change in direction of the loading.
>
>Without good equalisation marginal gear WILL rip, though it can often
>be finessed into acceptable protection by careful attention to equalising
>potential loads and loading direction/s on the individual components.

Yeah - I don't disagree that sharing the load is important. It's just that as the stretchiness of the system descreases (ie the amount of dynamic rope is less or the lanyard is not dynamic), the less the fall factor matters. That is, if you were attached to a bit of pro by a one foot fifi hook whilst leading and fell two feet (FF2) you'd generate almost exactly the same amount of force on the pro as if you you took a took the same two foot fall on a two foot fifi (FF1). In this type of scenario the "stretch" in the system is you, not the lanyard.

The fact that your fall was more than FF2 has very little to do with the force generated. The length you fell does. You'd generate twice the force from a two metre fall as on a one metre fall regardless of the length of your fifi.

>~> Cue for egosan to comment here about how his hide was saved by an equalised
>matrix of a number of very suspect components of protection that were combined
>into a single unit, during his ascent on one of the Aidfest weekends a
>while back...
>
>Edit: I was going to put a link to the relevant post of the fifi arrested
>fall, but my Trip Report (Buffalo Oysters) from it has lost the second
>half of its content during the subsequent Chockstone hack-attack preventative
>measures. Disappointingly my backup USB stick containing the original report
>seems corrupted and won't open...
>There is a slim possibility that I have a paper copy of it somewhere,
>but if that exists I'm unlikely to find it any time soon!
>
>Second Edit:
>Here is egosan's TR from March 2010, that also has been shortened by the
>hack-attack preventative measures, though luckily it still contains his
>version of the matrix event...
>http://www.chockstone.org/Forum/Forum.asp?ForumID=2&Action=Display&MessageID=5851&PagePos0&Sort=
>(Further clarification of that matrix by myself is in a following post
>on that thread).
>

My original contention is that the amount of force generated in a "shock loading" situation, is very much smaller than the amount of force generated in any drop test done by DMM where they recommend never to attach to an anchor with dynema. I think a much more apt test would be doing an FF2 on a recent cadaver...though that might be a bit grizzly/unethical. Maybe someone has invented crash test dummies which mimic the human body?