UKC

Hi everyone
Why would you use a sling (on a bight) to extend your ab belay away from you, when everyone says the slings must not be shock loaded?

You're then going off a cliff with a link in the system thats no good?

In reply to zimpara:

Usually in order to create the space to have a back-up prusik on the dead rope attached to the belay loop of the harness (as opposed to putting it on a legloop).

The sling doesn't get 'shock loaded'.

In reply to zimpara:

unless your doing it wrong the abseiling will not cause any shock loading.
would you throw yourself off a cliff edge with slack in the system ? as thats one of the only ways to shock load an abseil.
depending on your anchors then being as smooth as possible will be the safest way to descend.
having the plate extended can give you more control/friction over the brake side of the rope as the device is higher above it. also allows more room for a prussic loop backup.

In reply to zimpara:

And it doesn't matter if there is shock loading because the rope it's attached to is dynamic.

In reply to zimpara:

It doesn't get shock loaded, and slings are good for 25 kN. Shock loading is what happens if you attach a sling to an anchor and hurl yourself off a cliff - the rapid deceleration of you from some velocity to zero *in very little time* produces a very large force which will likely break the sling (and if not, will probably break you a little).

You're not generating 25 kN in an abseil, even on a static rope. Not unless you tie off the plate, climb/prussic above it, and fall onto it - and that would be stupid.

And if the rope's dynamic, it lowers that force drastically by taking time to stretch. Think about it - if you're leading and fall onto a quickdraw, the sling gets "shock loaded" - apart from it doesn't because the time taken for the rope to stretch makes the force apply over a longer amount of time, so it's lower.

In reply to climbwhenready:

Thanks for the explanation.
What if you're abseiling off static?

In reply to zimpara:
You'd still have to fall onto your belay device to get forces high enough to break a sling.

In reply to zimpara:

It will be semi static

In reply to zimpara:

Not really such a thing as static rope (unless you are using steel cable, and even that will have some stretch). Semi-statics are still rated to take falls, just to a much lower fall factor.

In reply to climbwhenready:

Sling used as a cow's tail is significantly weaker than 25kN. I can't quote the number as I can't find the research, but this gives something useful as well: http://dmmclimbing.com/knowledge/improvisation-larks-foot-or-basket-hitch-v...

In reply to zimpara:

If you shouldn't shock load a sling does this mean that I shouldn't be using them to extend gear placements or as placements (such as threads threads)?

Does the rope stretch do enough to make them good enough for this purpose? Do I have to factor in the fall factor?

In reply to cheeky:


Yes.