Three point anchor - The Saga Continues

Eric, I hope you realize that even if you get all three legs equalized with the knot tied (regardless of the method) if the pieces are not in a line horizontally and you move up or down just slightly from the angle at which you directed the master point in order to tie it, this action will throw the tension of the legs out of "equalization". The likely result being no load on the middle point, or less on one or both outer points.

If you really think the "moss method" is worth something, go try it on some real rock setting and fully weighting the anchor and extending yourself to an imaginary belay position. I think you'll quickly see what others have been trying to explain to you.

After you've done that, go climb a bit, Yeh?

Mathias wrote:Eric, After you've done that, go climb a bit, Yeh?

Thats crazy talk

I can't believe this thread is so long now. The only simple anchor that self equalizes is the quad. It is love, it is life, and highly useful.

I'm still not convinced the Moss Method isn't an improvement over not using it. I did an experiment similar to Jim's and the rope slipped.

I suppose nylon behaves differently than spectra.

Forrest Williams wrote:I can't believe this thread is so long now. The only simple anchor that self equalizes is the quad. It is love, it is life, and highly useful.

Except for the fact that the anchor you have show distributes the load approximately 50/28/22... So one piece takes ~2.25x more load than another.

So no it isn't self equalising as shown.

(Not that I have an issue with that level of equalisation. That is typically what I would expect from a climbing rope anchor or a cordelette anchor that is set up for a downwards pull. As far as I'm concerned that is sufficient. As such I keep it simple and use the climbing rope.)

Eric Moss wrote:I'm still not convinced the Moss Method isn't an improvement over not using it. I did an experiment similar to Jim's and the rope slipped. I suppose nylon behaves differently than spectra.

It doesn´t slip consistently before it strangles the other cords. That is; any effect is random just like tying the knot conventionally.
I tested both 8mm nylon cord and 12mm Dyneema hybrid tape.

Sure it's a random effect. However, to the extent that it does slip, the center leg lengthens twice as much as either outer leg because the center leg has 2 slipping strands vs. 1 slipping strand for each outer leg. Call this a 2:1 leg-lengthening-by-slippage ratio. This is in contrast to the regular version where each leg has 2 slipping strands to produce a 1:1 leg-lengthening-by-slippage ratio.

Considering this vis-à-vis the ratios of outer leg length to inner leg length, and considering potential leg stretch differentials, I think that a 2:1 leg-lengthening-by-slippage ratio will be preferable to a 1:1 ratio, at least when it comes to nylon.

Eric Moss wrote:Sure it's a random effect. However, to the extent that it does slip, the center leg lengthens twice as much as either outer leg because the center leg has 2 slipping strands vs. 1 slipping strand for each outer leg. Call this a 2:1 leg-lengthening-by-slippage ratio. This is in contrast to the regular version where each leg has 2 slipping strands to produce a 1:1 leg-lengthening-by-slippage ratio. Considering this vis-à-vis the ratios of outer leg length to inner leg length, and considering potential leg stretch differentials, I think that a 2:1 leg-lengthening-by-slippage ratio will be preferable to a 1:1 ratio, at least when it comes to nylon.

In the outerloop, rope will slip out below and above the knot. Both sides of the stand are being pulled upon. Climber on one side and gear on the other. So the cord should slip equally up and down.

Now the remaining strand should only slip up. But, and this is a big but. How much into the knot will the remaining strand slip out of the knot? 60%, 75%, 100%?

Have you tried using a simple overhand knot instead of a figure 8? I almost always used an overhand knot and don't have any trouble getting the legs equalized. I've also been doing it for over 25+ years so maybe it's automatic for me.

As others have said, as soon as you lean in a different direction, all that equalizing goes out the window..

rocknice2 wrote: Have you tried using a simple overhand knot instead of a figure 8? I almost always used an overhand knot and don't have any trouble getting the legs equalized. I've also been doing it for over 25+ years so maybe it's automatic for me.

Good idea. I'll have to try it.

I have done more tests on the Inner Loops Droop, and I found no consistent advantage.

However, after reading this article (or at least a cheap translation of it): alpenverein.de/chameleon/pu…

I realize a potential advantage of the shitrope:

This potential advantage is that, like the DAV rig from the article, the shitrope has shock absorption from the cloves.

Anyway, does anybody know what DAV recommends for a three point anchor?

Also, have you seen that video about how to do a one-handed clove hitch? It's amazing.

Eric Moss wrote:.. advantage of the shitrope:

Lost in translation or another thing Mark found in Clear Creek Canyon?

Whip on it all.

Eric Moss wrote: the shitrope has shock absorption from the cloves.

If shock absorption is your thing the use dynamic rope.

Well, short sections of the climbing rope, say 2 foot sections may not be as dynamic as one thinks. I suspect 7 mm nylon cord will have more absorption than the rope. The knots and hitches will do more to absorb energy whether one uses the rope or cord. So, agreed on the cloves for energy absorption.

Greg D wrote:Well, short sections of the climbing rope, say 2 foot sections may not be as dynamic as one thinks.

They are exactly as dynamic as one would think. All the typical energy absorbing characteristics still apply. The FF is what matters. Even 2 feet of climbing rope still has significant stretch.

Greg D wrote:I suspect 7 mm nylon cord will have more absorption than the rope.

Why would yo say that? The forces of falling on static cord are very high. The forces of falling on dynamic cord are much lower.

Well, any test I've seen where nylon vs dyneema was tested the nylon almost always out performs the dyneema despite a much lower rated strength because of its ability to absorb energy. I've never seen any tests or data on ropes as the anchor. I vaguely remember some info suggesting a short piece of climbing rope won't absorb much energy in a dynamic situation because of the impulse time, just way to brief to allow the rope dynamics to deploy.

7mm nylon cord is not "static". I'd be curious to see side by side comparisons of very short sections of climbing rope compared equal lengths of nylon cord with zero knots or hitches, although there is no practical application to that. One advantage of climbing rope is that the knots and hitches are tied "fresh" whereas corded anchors may have some permanent knots that are cinched tight and less dynamic.

I am a fan of using the climbing rope for anchors, though. I am not arguing against them. Just some thoughts to consider.

Greg D wrote:Well, any test I've seen where nylon vs dyneema was tested the nylon almost always out performs the dyneema despite a much lower rated strength because of its ability to absorb energy.

Yep nylon stretches more than dyneema. No surprises there, no relevance.

Greg D wrote:I've never seen any tests or data on ropes as the anchor. I vaguely remember some info suggesting a short piece of climbing rope won't absorb much energy in a dynamic situation because of the impulse time, just way to brief to allow the rope dynamics to deploy.

Which makes no sense. The more stretchy the cord/rope the better performance.

Greg D wrote:7mm nylon cord is not "static". I'd be curious to see side by side comparisons of very short sections of climbing rope compared equal lengths of nylon cord with zero knots or hitches

The length of the section is irrelevant in the comparison. (Obviously relevant to energy absorption capacity. A stiffness is inversely proportional to length.)

Greg D wrote:I am a fan of using the climbing rope for anchors, though. I am not arguing against them. Just some thoughts to consider.

None of them make sense. So all you are doing is muddying the waters.

In terms of stretch and energy absorption: dynamic nylone rope >>> static nylon rope >> tech cord rope. It isn't new information.

patto wrote: If shock absorption is your thing the use dynamic rope.

Actually, I fear a dynamic rope might stretch too much, throwing the load distribution out of whack.

Eric Moss wrote: Actually, I fear a dynamic rope might stretch too much, throwing the load distribution out of whack.

Consider a two-point, pre-equalized anchor. The two arms of the anchor are identical lengths of rope. The two points are on a horizontal line.

If the pull is vertical, 50-50 distribution is achieved. If the pull is horizontal, one leg goes slack and the other takes the full force... unless it stretches to the point that its length exceeds the length of the unstretched arm by the distance that separates the two anchor points.

This example suggests that in general stretchier rope means better load distribution.

I must have questioned your "authority" by questioning your statement "use the rope". Despite all your fancy quoting, you really said nothing and really missed my points, perhaps intentionally.

Relevant to this discussion: anchors.
Relevant to your comment: stock internet comment "use the rope".

2 feet of 9.5 mm climbing rope (for example) doesn't have as much absorption as you may think. And it may not be much different than 7mm nylon despite how many "greater than" symbols you use. Any questions. Your quoting skills are quite cute BTW.