Unusual Girth hitch technique -ok?

Hey everyone,

So I was climbing with some people a few weeks ago, and somebody used an unusual approach for girth hitching a boulder while rigging an anchor, which I wanted to run by you guys to see if it's viable. Normally, when I've seen people hitch a tree/Boulder/etc, they would create a loop out of webbing by tying the ends together and then hitching one loop through the other. What he was doing instead was making a loop on one end using an overhand on a bight and hitching a single strand, like how you would attach a PAS or Daisy Chain. The nice thing about this is that you effectively need half the length of webbing to reach your master point. Thoughts?

Legit.

Agreed--no problem.

See this discussion also:
mountainproject.com/v/corde…

It's OK, just realize that it's half the strength of the other method. You're using a single stand instead of two.

Rocknice that was my concern as well, but I figured half of that is still pretty bomber and way stronger than most removable pro, anyways. Thanks for the replies!

The forces of FF2 falls (let alone toprope forces) are nowhere near close to breaking strength of 1" webbing, even with a knot. The max impact force of dynamic rope is 7-9kn.

Imagine a really tight slackline with 1" webbing, and 2 people bouncing up and down on it at the same time. Now, imagine that instead of anchored to a tree, the slackline is anchored to your waist and you're anchored to the tree by your wrists and ankles. It would rip you apart long before the webbing failed.

The 2nd method actually creates a stronger loop than the girth hitch method. The girth hitch drops the webbing's strength around 50% of the original spec.

Girth Hitch Particulars

Using two strands to wrap, but only one strand at the power point. The loss tying an overhand, I believe is around 25% or so. My only improvement would be to use a bowline on a bite, mostly because it's easier to untie than the 8, and no chance in this situation for it to loosen and untie itself.

rabbit runner

I might be leery of using that as my one and only anchor, but if we are talking about a multipoint gear anchor it should be stronger than many smaller pieces of pro.

If you're making a single point anchor far from the master point, I'd be more inclined to use a tensionless hitch on a solid tree with some static line. Although that requires trees, and static rope is a bit more expensive than webbing.

A FF2 can never occur on a top rope setup. One must fall twice the length of the rope in the system to achieve that level of force. FF1 is so unlikely, and would need a near criminal belay technique. Such, that I would trust either method, though I favor the 2nd one described.

doak wrote: The max impact force of dynamic rope is 7-9kn.


No. No.

The max impact force is merely the result of a specific test, specific fall factor, specific mass, on a new piece of rope. This is not a max that could happen in the field with higher fall factors, greater mass, older rope, etc.

But, to the op: whether it is single strand or double strand, the weakest point is where the girth cuts into itself or at the knot. So you have either one strand cutting into one strand or two strands cutting into one strand. Probably not much different.

when you girth hitch a sling in the normal way, the peak of the loop is only 1 strand, thing of any knot on a bite, is the loop of rope twice the strength of the rope? No. If you ignore the knot the week point would be where it is only one rope ie the peak or point wear the rope/runner runs around a carabeiner or another rope. So a sling should only be as strong as 1 strand not 2, so the strength should be equal when run through a loop on a bite or girth hitched.

Also I never understand when people want to say a girth hitch reduces the strength by x percent. You dont know all the variables! the width of the rope/ sling and what you are girth hitching around all effect the end strenth. Black Diamond did a QC lab on girth hitching 2 slings and the reduction in strenght was highly variable. Yes we can all agree any knot/hitch will reduce the strength, but you can't know exact numbers without more info!

although if i was gonna do the setup you mensioned I feel like a bowline would be quicker, he either had to thread the cord through the loop, or tie an overhand and trace it back, either way sounds way more time consuming than a bowline, yay bowlines! - oh and if you say a bowline isn't good enough then niether is an overhand! IMO

Yeah, I usually use a bowline on static lines if I'm tying to a tree, but it's a little awkward to tie in webbing. We were also girth hitching a massive chock stone that was like 4 feet buried in a crack, so bowline wasn't an option. Was probably the weirdest anchor I've ever set, lol.

Zacks wrote: is the loop of rope twice the strength of the rope? No.

Yes a loop of rope or sling is twice the strength of just one strand.

The load at the top of the loop is like a tug-of-war.
Say there are two climbers, each at one end of a rope pulling 100kg. There will only be 100kg of force on the rope. Tie a rope to a bolt and have a climber pull 100kg. The rope will only have 100kg of force exerted into it.

I have girth hitched rocks and trees like this for a lotta years now. Never a problem. Not an unusual way to do it.

rocknice2 wrote: Yes a loop of rope or sling is twice the strength of just one strand. The load at the top of the loop is like a tug-of-war. Say there are two climbers, each at one end of a rope pulling 100kg. There will only be 100kg of force on the rope. Tie a rope to a bolt and have a climber pull 100kg. The rope will only have 100kg of force exerted into it.

Here, maybe this will help with your explanation:



If people cannot see the correct answer, they will probably not understand your description.

Dylan B. wrote: I think the answer is "equal to," but I don't know why.

Correct

Diagram One is essentially 50kg up/ 50kg down
Diagram Two is 50kg up/ 50 kg down, except twice.

Picture it if instead of a pulley at the top, those two strands were tied off in Diagram Two, you'd have the same forces. Both ropes share the same tension. But the anchor in Diagram Two has twice the force.

Now for my 2-cents. I wouldn't want to be top-roping off a single strand of webbing. Too thin, too prone to abrasion. That's just me. Also I don't actually know, I never use webbing, but is an overhand on a bight OK for webbing?

Dylan B. wrote: With an 80 kg weight and a FF of 1.87. A heavier climber and a FF2 can achieve higher forces, in theory anyhow. But yes, it would be extraordinarily difficult to reach the breaking point of 1" tubular webbing.

Greg D wrote: No. No. The max impact force is merely the result of a specific test, specific fall factor, specific mass, on a new piece of rope. This is not a max that could happen in the field with higher fall factors, greater mass, older rope, etc.

Regardless of this niggling over the application of a standard test to a real world scenario, there is a real mistake here. The UIAA fall test impact force relates to the force on the climber, not the top piece. The force on the top piece is expected to approach twice that of the force on the climber. In the case where where this single strand hitch is used on the top piece of pro in a fall approaching a fall factor 2, then the forces would be expected to approach the tensile strength of a single strand of tubular webbing (~18 kN). Of course, high fall factors do not occur in top rope falls.

Let me preface this by saying i'm not sure what the answer is. So i'm not trying to start flame war lol

So in your picture, isn't the force on the rope where i put the red line the combined force of the 2 weights, or 100kg in the example. in a loop that point of the line would force equal to the total weight not half the weight. correct me if i'm wrong

Assuming a frictionless pulley, the tension in the rope will be the same throughout even if there were multiple pulleys and one rope. So, you could put that red line anywhere between the two weights and it will read the same.

Move the red arrows around in your mind or in a drawing. Then, ask yourself the question again.

I've tied webbing with an overhand on a bight for like the last twenty years, so if there's something wrong with this practice I probably should have died. Just need to leave a decent tail.

Also, in the case of girth-hitching a boulder (or tree) with webbing in this manner, of course the anchor is going to have several more points of protection in addition to the single strand of webbing going to the boulder.