QC Lab: Girth Hitching a Stopper

A buddy of mine emailed me the other day—he was out at a crag and saw someone girth hitch a #4 stopper to a bolt hanger, then clip a biner to the end, clip his rope and continue on. Hmmmm?? Maybe short a biner? Not sure. Regardless—he asked if I could do a quick test just out of curiosity to see how strong it would be.

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.

Drop Tests

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:

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.

Bottom Line

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,

KP

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.

Recent Talk (1)

• geoff
  2 Dec 2009, 5:53PM

  thanks for doing these tests, and for sharing them. I understand that knotting the spectra webbing is bad, I had been using them like my old nylon webbing , tying a figure eight for an anchor etc.

• R. Cronk
  3 Dec 2009, 7:51PM

  What if the wire cable were passed through the eye of the bolt hanger and both ends clipped into the lone biner? No girth hitch. RC

• steve p
  4 Dec 2009, 5:35PM

  KP said: ...Don’t girth hitch stoppers to bolts, slings to bolts, slings to stoppers, or even slings to slings, etc....
  
  How much strength is lost when two spectra slings are girth hitched together with the webbing shifted so that the connection looks like a square knot? Occasionally this is useful if I need a double length sling to put around a jammed block or whatever but only have singles.
  And what about if a figure 8 is tied in a spectra sling?

• kelly c
  5 Dec 2009, 11:11PM

  hi kolin, and thanks, as always, for your terrific work. it's fascinating and also real-world useful. reading this brought to mind a couple of other thoughts -- if you have any answers or ideas, i'd love to hear 'em:
  
  1. do you think the reduced strength of the girthed wire (as opposed to the qd) was more due to the sharp bend in the girth hitch (likely, i'd guess) or due to the materials? (i.e. the wire is surely far more static than a qd.)
  1a. would be interesting to see the data in a girthed wire (above data) vs a girthed sling (or even a girthed spectra/dyneema as well as a nylon.)
  1b. speaking of static/stretch...ok, the possibilities are endless, perhaps you should just delete this note...how 'bout a regular qd vs using a wire as a qd? (ya know, with a biner on each end -- thus showing the exact difference between static metal "draws" and regular qds)
  
  2. ever do any testing of knots jammed in cracks? obviously lots of variables (type of knot, etc) so hard to standardize, but i've wondered how strong that is. would be some really cool tests!
  
  thanks again, kelly

• Shoo
  7 Dec 2009, 11:30AM

  I'm curious to see what R. Cronk suggested as well. However, since it's cable and naturally springs a little, I imagine it would position itself such that crossloading is much, much more likely.

• Kolin Powick
  8 Dec 2009, 2:50PM

  Wow… lots of comments and suggestions for all kinds of other tests. Nice to see what people are thinking out there! Obviously there are unlimited questions and possibilities, but unfortunately we just don't have time to perform experiments with every possible scenario. So I apologize I can't respond directly to everyone's particular question with further tests.
  
  However, I can say that in a pinch, as always, something is better than nothing. I've used a gear sling as a runner, and left my ice tool as a piece of pro, topping out the pitch with one tool. You have a higher chance of SOMETHING holding in a fall rather than nothing. All of the other "what if" and " I wonder" scenarios are valid for sure, but chances are in almost all cases some level of strength will be compromised.
  
  You should always use the appropriate gear when possible, but sometimes you do what you gotta do and it’s just a matter of choosing the best option in a worst-case scenario. For example, looping a Stopper through the bolt hanger is probably better than a girth hitch. In theory, you should get twice the strength of the cable, and it will most likely cut over the relatively sharp radiused edge of the bolt hanger. [Note: I just ran in the lab and did another girth with a 10kN Hex. It broke at 1853 lbf (8.24kN), and then did the loop through. I got 4045lbf (18kN), so not quite double. So looping it through is better than the girth hitch, but using a quickdraw or two biners and a runner is best.]
  
  Regarding the other questions posted above:
  * slings knotted or girthed——it's safe bet to say that you lose anywhere between 40-60% of the strength, so avoid knotting if possible.
  * Girth hitching a sling to a bolt hanger—haven't done it, maybe next time.
  * Knots in cracks——that'd be a toughie with LOTS of variables to
  contend with. Can't see us getting to this one in the lab.
  * Regular quickdraw vs wire quickdraw——regular slings are rated to 22kN. Any of the swaged wires in typical climbing gear (Stoppers, Hexes, etc) don't get there, plus… why would you want a wire quickdraw? It would hurt like hell when you’re all sketched out, crying like a baby at the
  runout and need to GRAB it.
  
  Over and out --
  KP

• DS
  4 Jan 2010, 9:00AM

  Something else to throw in there about wire vs fabric quick draws. In addition to the wire sling having a lower strength rating, the additional stiffness over a fabric sling will also result in less total energy absorption before failure.