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Topic Date User

cut(e) twins or double trouble? 29-Jul-2009 At 1:07:44 AM gremlin

Message

On 29/07/2009 anthonyk wrote:
>i've burnt through the sling of a quickdraw that a rope ran over, it ran
>over the bit of the sling on the inside of the carabiner. after seeing
>that any kind of nylon-nylon friction is something i'd say to definitely
>do without. you potentially end up with the same situation with doubles
>when they get tension at different times, if the slack rope is on the bottom
>the tight rope is going to rub against it when it takes the load, and it'll
>move a fair way while its under tension.

I don't disagree that it could damage the rope slightly in the worst case scenario, however i don't believe that either would slice through each other. No i don't mix systems mostly because i'm lazy...

One thing no one has every explained to me very well is how the ropes would travel at significantly different speeds and directions through the same piece of gear during a fall.

The ropes run from belay device through various bits of gear and are tied to the harness. Each rope would be different lengths from device to harness. When the climber falls, both ropes are pulled through the gear at the same speed in the same direction until one rope takes the tension, the momentum begins to slows down. The other rope is not under tension, but would still be travelling along at the same speed as the tensioned rope unless the climber has untied it and attached it to a big bloody rock falling alongside.

I have seen test results of experiments where the climbers are rapelling with the rope through a sling instead of a biner or ring bolt (2m or less movement and it'll burn through), but this doesn't really apply to mixing a twin/double system...

If anyone can point out WHERE the speed/direction difference is, i'd be glad to put this one to bed.