We did a few pulls in the tensile tester. Note: Due to the way the particular bolt hanger we used was stamped, one edge was slightly rounded, whereas the
other was definitely more sharp (see photo)—therefore we girth hitched the stopper both ways, getting data with the load bearing strands on the
rounded edge AND on the sharper edge. (see photos)
Note: Just for reference—a #4 Stopper is rated to 6 kN (1349 lbf); and a quickdraw typically is rated to 22 kN.
We decided to perform similar tests (i.e. load strands over the rounded edge and load strands over the sharp edge) but in a dynamic (i.e. drop) scenario.
The results were very similar:
|| Value at Failure
|Load strands over rounded edge
||1755 lbf (7.8 kN)
|Load strands over sharp edge
||1424 lbf (6.3 kN)
Observations & Conclusions
- The way the stopper wire was threaded had a significant impact on the ultimate strength of the system (variation of approx. 30%).
- Similar results were found in tensile tests and dynamic tests.
- Significantly weaker than if a proper quickdraw was used (approx 30% of "full strength" (i.e. 22 kN).
- Girth hitching a stopper to a bolt hanger results in a system strength such that the loads at which these set-ups will fail are within the loads
that can be seen in real climbing situations in the field.
- It most definitely is possible that if the climber in question here had whipped onto that bolt, the stopper wire could have cut and he/she would
have plummeted to the next piece.
Sometimes if you're in a situation, you do whatever it takes—because sometimes "something is better than nothing." I've used my gear sling to
girth a shrub, clipped my ice tool and left it there as my last piece as I've topped out, stuffed a knotted sling and even a carabiner into a crack
as a stopper as well as a host of other not-so-smart-but-in-times-of-desperation-perhaps-better-than-nothing things. I've heard of guys rapping
off of boot laces, using tent poles as a dead-man to rap off of and even jamming a camera lens in a crack using it as a chockstone to bail off
a route. The reality is that sometimes you do what you need to—but in most cases this is not necessary, and gear should be used as it is
intended, otherwise the strength, and ultimately your safety, can be compromised.
Use carabiners when clipping to a bolt, or between a cam, piton or stoppers and slings. Clip your rope through a carabiner, never through a runner.
Don't girth hitch stoppers to bolts, slings to bolts, slings to stoppers, or even slings to slings, etc. Understand how to properly use your gear, read the instructions and seek instruction from a qualified
guide if you are unsure.
Climb safe out there,
Kolin Powick (KP) is a Mechanical Engineer hailing from Calgary, Canada. He has nearly 20 years of experience in the engineering field and has been Black Diamond's Director of Global Quality since 2002. Kolin oversees the testing of all of Black Diamond's gear from the prototype phase through continual final production random sample testing. If you have a technical question for KP, please email him at firstname.lastname@example.org and he will TRY to respond.
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