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The big trad gear destructo challenge 10-Nov-2010 At 9:38:07 PM jam

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On 10/11/2010 Olbert wrote:
>On 10/11/2010 jam wrote:
>> i'll have
>>a much better idea of how good my equipment and placements are (especially
>>with the data you've collected - thanks for that by the way :) )
>
>Your judgement on whether placements will hold a fall or not will hardly
>be effected by the results of these tests, or the maths. There are three
>types of placements (in terms of quality).
>
>-A bomber placement is a bomber placement, it aint going anywhere.
>-A shit placement is a shit placement. Its most likely not going to hold
>a fall, hopefully you only use these when you are aiding but of course...
>-A marginal placement is where your might think the maths will come in
>handy, however, it wont.
>
>The reason the maths wont help you on a marginal placement is because
>the error in marginality is much greater than any guestimates you might
>make using the maths. Some marginal placements are actually quite good
>and some are complete rubbish. All the unknown factors such as unknown
>weakness in the rock, unexpected pull direction, etc etc will trump any
>uncertain maths you may do.
>
>Knowing the maths, although interesting from a physics point of view,
>doesnt do shit for your placement quality and judgement. You will always,
>in any situation that is half dodgy, place the best gear you can - thinking
>about the maths wont help. Most of the time you will probably go on anyway
>or search around for more gear if your doubtful. Logically knowing the
>maths wont make you any less doubtful/more confident.
>
>The only situation where I could see this benifitting is maybe when you
>are high up on a route above marginal gear and you decide to keep going
>because you know that impact forces are less. However for this you only
>need to know that you have heaps of rope out and wont fall too far; you
>really dont need to know any higher level maths than that.
>
>Where Claws and co's testing really come in handy is on the judgement
>of placements. A prime example would be the use of tricams in soft rock
>- I trust these more because I know marginal placements can be good.
>
>

I think you've misunderstood me... I'm not worrying about marginal placements. I don't plan to be making any unless it's that or nothing.

What bothers me is that all these numbers mean effectively nothing unless you have the corresponding numbers to match...

They say the "average leader fall is about 4-7kN" - what is this based on? How much rope? How heavy is the faller? Are they wearing a bag? How far are they falling?

This leads me on to ask - just how "bomber" is a really shit hot placement? For an extreme example, say I have a number 3 wire in the wall, it's real nice and snug and it's going no-where. But it's only rated 6kN... Will I be approaching a breaking load if I fall from 1m above to 1m below with not much rope out? Or is that well within the "average leader fall"... What about if I'm wearing a bag? Is that much much worse? What if it's 1.5m that I fall instead of 1m... Is that worse than having stuff on my back?

It's all well and good having numbers on how good a wire or a cam or a hex really is in relation to its rating, but unless you can really quantify the difference several other factors make then you've not learned very much in that respect.

I know that there's no substitute for experience, and that with time I'll know what different what makes, but until then, I'd much rather have a sound understanding of the maths so that I can make a calculation and say to myself for sure "ok if that's a bomber placement then I'm at about half the rated loading if I take a big old fall" rather than "well if that's a bomber placement then I guess if I fall on it then... it could well be between 4-7kN given an unknown amount of assumption and that would make it x amount of the rated strength.. but i don't really know how close I am to the limits because I haven't done this enough yet"

Surely the more knowledge I can arm myself with the better?