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Climbing Disciplines:
Alpine & Ice:
Re: [wmfork] Another rope thread...:
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ja1484
Dec 10, 2007, 8:44 PM
Views: 2313
Registered: Aug 11, 2006
Posts: 1935
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wmfork wrote: unless, of course, if you get sketched 1/2 up a 2000 ft route cause your rope has a core shot.
I'm gonna get sketched on *any* route above 20 ft. if my rope has a core shot.
In reply to: Twins have higher UIAA fall rating (than the same rope tested as double, and the only reason the number of falls isn't close to more than twice is doubles are tested with lighter mass), that much is indisputable. If you don't whip on them, then there probably won't be much difference.
Exactly - most ropes are retired due to sheath wear and tear or loss of elasticity, not strength loss. UIAA falls are a very poor metric for durability - Sterling's Marathon ropes, for example, are "only" rated to 6 UIAA falls, yet due to the thicker sheath, seem to hold up to abuse longer.
In reply to: Which is why twins are used as identical pair with the same stretch property. Please demonstrate my "stupidity" by provide any actual testing or even manufacturer recommendation that each strand of twins needs to clip to a separate biner to be safe.
As per Beal here:
http://www.bealplanet.com/...pe_corde&lang=us
It varies by situation, the primary concern being IMPACT FORCE (and, as already stated, in ice climbing, this is key).
The use of seperate carabiners is mainly espoused by the Long/Luebben school of rope use, and it's purpose is to distribute the increased impact force across more than one 'biner, but not over additional gear, so the nut (ice screw, etc.) better be bomber.
Also, as mentioned, it much reduces the chances of funky loading, friction, and tangles.
So again - you *could* clip em both through the same biner, but if you're going to bother, why not run a single line?
In reply to: Speaking purely of math, you are an idiot. It neither in lab testing nor practically double the impact force, not even close.
You must have trouble reading. Go back and read that section again - worst case scenario mathematically, you're looking at double. This never happens in practice, just like lab-test factor two falls, because the lab is not the field and there are more factors than can be replicated in a test environment. Please don't get huffy if you can't multiply by 2 properly.
Beal states usually a ~25% increase above, which is still 25% more than necessary, and this is of course an average standard. It varies *every fall* due to differences in the position of the rope.
The point is, you can be more severe in terms of impact force than using a single line or halfs.
Let's recap:
Single Lines:
- Fine
Twin Lines:
- Every thing the single does with an insignificant increase in safety and a significant increase in impact force.
Half Lines:
- Same risks as twins if run together, but when run along seperate paths, allow for significant benefit re: rope drag without impact force worries.
Twin. Lines. Are. Pointless. Use a single line instead, halfs if the pro wanders.
(This post was edited by ja1484 on Dec 10, 2007, 8:51 PM)
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Edit Log:
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Post edited by ja1484
() on Dec 10, 2007, 8:51 PM
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Post edited by ja1484
() on Dec 10, 2007, 8:51 PM
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