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Re: [asdf] 10.5 and a 9 used as doubles:
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pastprime
Feb 15, 2007, 6:58 PM
Views: 1757
Registered: Jul 7, 2005
Posts: 251
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Most of the ropes sold and UIAA certified for use as double ropes are 9mm. When you are alternating clips you are only on one rope at a time, so it doesn't matter if the dynamic characteristics are different. If both ropes are clipped in parallel, as twin ropes, there are some possible scenes, where one rope is stretching more than the other, that can create rubbing of the sheaths, so different sized ropes shouldn't be used that way. Using two different sized ropes as doubles has been very common in Europe for decades. If you fall on two single rated ropes, the impact force does get higher, but does not go up to dangerous levels. You would think it would double, but it doesn't. The reason is that the impact force of a rope is not a linear curve. The early part of the curve is softer than the later part, and when using two ropes you are doubling the forces from a softer part of the curve. Think about it: If it weren't this way, it would not be safe for a 90 pound climber to use a rope designed to be ok for a 180 pound climber. Don't have time to look for a link now, but I would ask those who want to argue to not just give and opinion, because this is one of those questions that comes up over and over and the answer is always the same.
(This post was edited by pastprime on Feb 15, 2007, 7:20 PM)
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Post edited by pastprime
() on Feb 15, 2007, 7:20 PM
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