Forums: Climbing Information: Gear Heads: Re: [ian1386] Carabiner and quickdraw FAQ *draft*: Edit Log




qwert


Jul 18, 2010, 3:56 AM

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Registered: Mar 24, 2004
Posts: 2394

Re: [ian1386] Carabiner and quickdraw FAQ *draft*
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ian1386 wrote:
qwert wrote:
One thing to keep in mind when using longer quickdraws is that every centimeter your quickdraw gets longer means 2 centimeters you fall further, should you fall on the quickdraw. When using a 30cm quickdraw instead of an 8cm one, this makes 2*22cm = 44cm of difference. This are nearly 20". This doesn't sound like much, but when falling into the first bolt, or above a ledge, these 44cm can be the difference between a normal harmless sport fall and a broken ankle! As mentioned, long quickdraws have their benefits, but use them with care.

I don't quite understand this part. As far as I can tell, quick draw length can affect your fall distance, but it's not as clear cut as "you'll fall further on a long draw". For example, if you have constant 8ft spaces between draws, as long as you use the same length draws the rope end biners will still always be 8 ft apart from each other. Sure, the rope end biner will be further from the bolt/pro, but it also means you can likely clip it sooner.

Maybe I'm missing something though? I am a noob...
If we are assuming that you are climbing a completely "featureless" wall, then yes, your assumption is somewhat correct. you would get an evenly spaced grid of carabiners, and your fall lengths would always be the same.

However in the "real world" the situation could look something like this crude sketch:
So there is a bolt somewhere over a ledge.
In both situations you are falling at the same point, when trying to top out.
with the short quickdraw you are 118 pixels above your lower carabiner, and thus you are going to fall 236 pixels (not taking rope stretch and rope running through your belay device into account), which leaves you hanging comfortably above the ledge.
with the long quickdraw you are 172 pixels above your lower carabiner, since your longer quickdraw is 54 pixels longer. So (again ignoring rope stretch and rope slippage) this time you will fall 344 pixels, which will cause you to deck on the ledge, without the rope catching you at all.

So how likely is such a situation?
As always: it depends.
If you use a 9cm long quickdraw instead of you normal 8cm ones the difference will most likely be neglible. however if you are going to use a fully extended trad draw you will have a difference of over 1m, so that might affect your "landing" a big way. It might even be so long that you are going to pass the ledge, and hang happily below it.

What i am trying to say is the following: there can be situation where a rather small difference in quickdraw length might make a big difference in the outcome of a fall.

but at the end its down to you to decide if you are in such a situation or not.

qwert


(This post was edited by qwert on Jul 18, 2010, 3:57 AM)
Attachments: shortvslong.jpg (58.4 KB)



Edit Log:
Post edited by qwert () on Jul 18, 2010, 3:57 AM


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