Silent Partner backup


Original Post
David Coley · · UK · Joined Oct 2013 · Points: 70

Hi,

When using an SP for aid I regularly come up against the backup knot just when I don't want it. This might be a free move, or just standing up in the ladders.

This is my fault as I don't fancy taking a massive fall when by myself, so tend to leave only a few metres between the device and the knot. I guess I should trust the thing more. But falling 10m+ on non-overhanging rock is likely to end very badly in the middle of nowhere by oneself.

I have taken to placing a rope man on the rope below the SP. This has a locker through it, but is not clipped to anything. I also place a back up knot on a very big loop, as an ultimate back up, and also to support the weight of the rope. I can move the rope man along the rope easily one handed with a quick flick of the wrist.

My logic is that if the SP did not lock, the rope man would smash into the clove and stop the drop.

Anyone else done this, or something similar? And should I be concerned about the rope being mashed/cut.

Thanks.

Mydans · · Unknown Hometown · Joined Apr 2014 · Points: 70

I wouldn't recommend using a device with teeth in a situation that might see a shock load.  Devices with teeth can shred a sheath with minimal force (3-4KN)  With that in mind your back up is more likely to damage your rope than stop a fall.

delly84 · · Golden, Co · Joined Jun 2013 · Points: 154

probably less abrasive on the rope than a traxion but more abrasive than a grigri? 

I remember seeing empirical evidence (and maybe tests) suggesting a toothed device can core the rope under dynamic forces but i don't know that it would apply to the ropeman. Does anyone know?


Firestone · · California · Joined Nov 2015 · Points: 509

I don't have a link but I have heard that toothed devices will sheath the rope but grab the core. Devices without teeth like the Kong Duck will chop your rope in half.

delly84 · · Golden, Co · Joined Jun 2013 · Points: 154
Firestone wrote:

I don't have a link but I have heard that toothed devices will sheath the rope but grab the core. Devices without teeth like the Kong Duck will chop your rope in half.

that's interesting. i didn't know that. 

if you could find a link that talks about what forces at which each will happen at, i think that would be helpful. thanks. 

Firestone · · California · Joined Nov 2015 · Points: 509

I'll do some searching and see if I can find any reliable info. Just to be clear, neither device should damage your rope in practical use. 

For OP when I use my grirgi for aidsolo I have the grigri on a steel quick link and then the rope is fed through a kong duck that I keep clipped to the front gear loop. I keep it rigged so that I can pull rope through the duck with one hand and have a loop between the duck and grigri for autofeeding. 

I believe from a few test falls that with the duck in this orientation if the grigri doesn't catch, like in a slow slab or backward fall, the change of direction caused by the duck created enough friction to engage the grigri (the duck is rigged so that rope can pass freely to the grigri but won't feed back to the rope bag) Alternatively I have used a clove on the belay loop below the grigri because it counterweights the grigri and acts as an independent backup knot.

Guideline #1: Don't be a jerk.

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