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An alpine anchor to analyze
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altelis


Dec 5, 2009, 4:25 AM
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Re: [sittingduck] An alpine anchor to analyze [In reply to]
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sittingduck wrote:
sungam wrote:
Although I am curious about the pully effect/fall factor thing - perhaps that's for a different thread, though.

It is relevant, and now that rgold is here we might get a comment ...

Fwiw, I always clip one of the two ropes to the powerpoint when belaying the leader from the harness. I hope that both ropes will eventually engage in the event of a ff2 fall, and by that neutralize the pully effect to some degree.

If you belay directly from the harness, the redundancy for the leader becomes very far stretched. If the belay loop or the belay carabiner fails, the leader will fall until the rope catches him again, since he still is tied in.

edited to add sungams quote

SD, my personal preference on alpine type anchors is to NOT clip the leader through onto the powerpoint because of the pulley effect. 9 times out of 10 I've been able to integrate some sort of stance into my alpine anchors, and my thinking is i'd rather use that in the case of a FF2 than 2 screws in ice whose quality i'm not always totally stoked on. That is just me, and like I said that 9/10 has been MY experience. Yours may differ and lead to different decisions.


sittingduck


Dec 5, 2009, 11:17 AM
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Re: [altelis] An alpine anchor to analyze [In reply to]
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altelis wrote:
SD, my personal preference on alpine type anchors is to NOT clip the leader through onto the powerpoint because of the pulley effect. 9 times out of 10 I've been able to integrate some sort of stance into my alpine anchors, and my thinking is i'd rather use that in the case of a FF2 than 2 screws in ice whose quality i'm not always totally stoked on. That is just me, and like I said that 9/10 has been MY experience. Yours may differ and lead to different decisions.



A ff2 fall is roughly 12kN. In the picture you see a guy holding 4,5kN. I am no mathematician or phycisist, and that is probably why I think that he would not be able to hold a ff2 fall.
I have taken a long ff2 fall on multipitch trad, nobody could have stopped that fall with a stance in MY experience.
So yes, my experience leads to different solutions.

Belaying a second from a stance is perfect with a marginal anchor. We are normally strong enough to hold that weight.


altelis


Dec 5, 2009, 3:15 PM
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Re: [sittingduck] An alpine anchor to analyze [In reply to]
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I think you misunderstood my intentions for including a stance. I (I think) clearly said that I am not planning on catching a FF2 from the stance alone. But rather by integrating myself into the anchor I will be able to at least take some force away from the anchor...


adnix


Dec 5, 2009, 3:45 PM
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Re: [sittingduck] An alpine anchor to analyze [In reply to]
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sittingduck wrote:
adnix wrote:
1. Use only one rope with a fig 8 power knot for anchor and ditch the backup rope.

1. As long as no one falls, any rig works fine.

If you use dynamic cord for anchoring (like you did) it's better to use knots. The dynamic cord is doing load distribution quite ok already - dynamic rope stretches 40% before it snaps. There is no need for sliding x. And if one piece fails the drop and "shockload" are less if you use static knots.

Plus its faster and more simple to rig.


sittingduck


Dec 5, 2009, 5:50 PM
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Re: [altelis] An alpine anchor to analyze [In reply to]
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altelis wrote:
I think you misunderstood my intentions for including a stance. I (I think) clearly said that I am not planning on catching a FF2 from the stance alone. But rather by integrating myself into the anchor I will be able to at least take some force away from the anchor...
Off course it will be a good thing if you manage to take any weight of the anchor.
On that note: I often stand facing the wall, weighing my extension to the anchor, with my front-points dug into the ice. I am worried that I may hurt my knees and ankles if my hips where suddenly twisted by the pull of a ff2 fall. This might also prevent me from taking any weight of the anchor. With a redirect I will be pulled upwards.

adnix wrote:
If you use dynamic cord for anchoring (like you did) it's better to use knots. The dynamic cord is doing load distribution quite ok already - dynamic rope stretches 40% before it snaps. There is no need for sliding x. And if one piece fails the drop and "shockload" are less if you use static knots.
Plus its faster and more simple to rig.
You might be able to anticipate where the direction of pull will come and have good distribution, or you might not. I have rigged many rap anchors with a knot, and thought I placed the knot perfectly, only to see one arm getting all the weight once we rapped off. I use different methods now because of that.
About the speed and simplicity issue; how many knots do you have in your anchors?

edit to get the names right. sorry guys


(This post was edited by sittingduck on Dec 5, 2009, 7:41 PM)


altelis


Dec 5, 2009, 6:12 PM
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Re: [sittingduck] An alpine anchor to analyze [In reply to]
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Yo, that last quote about the knots wasn't me, it was from adnix. if you don't mind fixing that i would appreciate it, or i'll have to ask for the BANZING@>!>!>!@#>#>#(*$


adnix


Dec 5, 2009, 7:04 PM
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Re: [sittingduck] An alpine anchor to analyze [In reply to]
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sittingduck wrote:
About the speed and simplicity issue; how many knots do you have in your anchors?

If the pieces are solid, my anchors have two pieces and no knots. I'll "equalize" the anchor close enough with slings and carabiners. The resulting anchor is resting on one piece (preferably cam) and the second piece is a backup with very short or none slack in case the main piece rips (which it has never done so far). The system is kinda like a modern parachute with a pilot and a backup. The backup is easy to clean once the leader has his main piece in. The main piece is removed the same second the leader yells "belaying!" This saves a great deal time. A cam is easier to clean than anything else.

If the pieces are not too solid I'll add a third and fourth piece the same backup style. If it's really bad I might consider adding cord loop with fig 8 knot for distributing the load. I usually carry one 120cm cord loop knotted with fishermans to be left behind while abseiling. I usually use this cord loop in stead of climbing rope since block leading doesn't allow using climbing rope.

In case I'm climbing with less experienced partner I'll usully rig a main powerpoint which he/she feels comfortable (usually a loop of cord with carabiners clipped in pieces and a fiig 8 knot in the middle). The carabiners can be removed easily even by complete amateurs. I've learnt opening knots causes problems for less experienced people.


sittingduck


Dec 5, 2009, 7:50 PM
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Re: [altelis] An alpine anchor to analyze [In reply to]
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altelis wrote:
Yo, that last quote about the knots wasn't me, it was from adnix. if you don't mind fixing that i would appreciate it, or i'll have to ask for the BANZING@>!>!>!@#>#>#(*$

My apology to you! I have edited it.


altelis


Dec 5, 2009, 7:53 PM
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Re: [sittingduck] An alpine anchor to analyze [In reply to]
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no worries- cheers!


sittingduck


Dec 5, 2009, 8:58 PM
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Re: [adnix] An alpine anchor to analyze [In reply to]
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adnix wrote:
sittingduck wrote:
About the speed and simplicity issue; how many knots do you have in your anchors?

If the pieces are solid, my anchors have two pieces and no knots. I'll "equalize" the anchor close enough with slings and carabiners. The resulting anchor is resting on one piece (preferably cam) and the second piece is a backup with very short or none slack in case the main piece rips (which it has never done so far). The system is kinda like a modern parachute with a pilot and a backup. The backup is easy to clean once the leader has his main piece in. The main piece is removed the same second the leader yells "belaying!" This saves a great deal time. A cam is easier to clean than anything else.

Is it something like this:


You are right, that is faster.
Yeah, taking down parts of the anchor is the right ting to do when it is not needed anymore.

adnix wrote:
If the pieces are not too solid I'll add a third and fourth piece the same backup style. If it's really bad I might consider adding cord loop with fig 8 knot for distributing the load. I usually carry one 120cm cord loop knotted with fishermans to be left behind while abseiling. I usually use this cord loop in stead of climbing rope since block leading doesn't allow using climbing rope.
In case I'm climbing with less experienced partner I'll usully rig a main powerpoint which he/she feels comfortable (usually a loop of cord with carabiners clipped in pieces and a fiig 8 knot in the middle). The carabiners can be removed easily even by complete amateurs. I've learnt opening knots causes problems for less experienced people.
Sounds like you guide, adnix? Judging from your experience with climbing partners.


adnix


Dec 5, 2009, 9:18 PM
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Re: [sittingduck] An alpine anchor to analyze [In reply to]
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The harness is not directly clipped in as in your picture. I use a cow tail with a carabiner for clipping in the anchor (ie. a carabiner clipped into the carabiner of the cam). Otherwise you have it perfect there.

The best belay device is Reverso or Atc xp or similar. The second is belayed directly off the stand in autoblocking mode. The leader is belayed of the harness like in your picture.

I'm no guide but I've taken loads of friends for their first multipith. And I've passed plenty of guides with their clients in Chamonix. This gives me perverse pleasure in most cases. Wink


sungam


Dec 5, 2009, 9:24 PM
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Re: [adnix] An alpine anchor to analyze [In reply to]
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adnix wrote:
The best belay device is Reverso or Atc xp or similar. The second is belayed directly off the stand in autoblocking mode. The leader is belayed of the harness like in your picture.
Yeah - I've only had one season with a reverso, and it was mostly ice cragging in ouray, but I was pretty chuffed at how east it was to belay a second, and how much warmer my hands felt.
I was also pleasantly surprised at how easy it is to switch to belaying off the harness. Before using or seeing one I had the idea in my head that stuff would have to get unclipped.


sittingduck


Dec 5, 2009, 9:48 PM
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Re: [adnix] An alpine anchor to analyze [In reply to]
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adnix wrote:
The harness is not directly clipped in as in your picture. I use a cow tail with a carabiner for clipping in the anchor (ie. a carabiner clipped into the carabiner of the cam). Otherwise you have it perfect there.
The best belay device is Reverso or Atc xp or similar. The second is belayed directly off the stand in autoblocking mode. The leader is belayed of the harness like in your picture.
I'm no guide but I've taken loads of friends for their first multipith. And I've passed plenty of guides with their clients in Chamonix. This gives me perverse pleasure in most cases. Wink
Ok, I see. I do not fancy the cow tail myself and use the climbing rope. Especially after some horrible accidents recent years.
I found a picture of one of my anchors where I could have used your method:


I am happy for you that you are not a guide. I most often meet the guides and their clients while ski-mountaineering, it actually is a pleasure watching them!


adnix


Dec 6, 2009, 8:46 AM
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sittingduck wrote:
I do not fancy the cow tail myself and use the climbing rope. Especially after some horrible accidents recent years.

Climbing rope is more elastic and harder to unclip, it has its advantages. In my experience it's slower but on the other hand, everyone has to find his own comfort systems. There's no right or wrong here.

sittingduck wrote:
I found a picture of one of my anchors where I could have used your method:
[image]http://www.home.no/sittingduck/anchor321.jpg[/image]

With those two pieces I would have clipped full weight on the cam and used the hex extended with a quickdraw as backup clipped to the biner of the cam. The biner of the cam would have been "the master point". It basicly has the exact same qualities as your current config. The sling isn't too equalized or is it? Your stand has the full weight on the hex and the cam is the backup. Wink


hafilax


Dec 6, 2009, 10:02 PM
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sittingduck wrote:
altelis wrote:
SD, my personal preference on alpine type anchors is to NOT clip the leader through onto the powerpoint because of the pulley effect. 9 times out of 10 I've been able to integrate some sort of stance into my alpine anchors, and my thinking is i'd rather use that in the case of a FF2 than 2 screws in ice whose quality i'm not always totally stoked on. That is just me, and like I said that 9/10 has been MY experience. Yours may differ and lead to different decisions.

[image]http://redlinegym.com/images/andy-bolton-01.jpg[/image]

A ff2 fall is roughly 12kN. In the picture you see a guy holding 4,5kN. I am no mathematician or phycisist, and that is probably why I think that he would not be able to hold a ff2 fall.
I have taken a long ff2 fall on multipitch trad, nobody could have stopped that fall with a stance in MY experience.
So yes, my experience leads to different solutions.

Belaying a second from a stance is perfect with a marginal anchor. We are normally strong enough to hold that weight.
Falls don't have an intrinsic force, they have a certain amount of energy that must be dissipated through friction, damping in the rope and other mechanisms. The most force one can exert with a tube device is around 4-5 kN. To slow a falling body this means that some rope has to slip through the device until the body comes to rest.

Catching a fall on the anchor directly on the harness minimizes the force on the anchor at the expense of letting rope slip through the device. This could be disastrous with bare hands but should be manageable with gloves. By redirecting through the power point the force on the belayer is minimized by using the friction over the biner to increase the arresting force but his puts a much larger force on the anchor.

Choose wisely.


adnix


Dec 7, 2009, 7:25 PM
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Re: [hafilax] An alpine anchor to analyze [In reply to]
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hafilax wrote:
[Catching a fall on the anchor directly on the harness minimizes the force on the anchor at the expense of letting rope slip through the device. This could be disastrous with bare hands but should be manageable with gloves.

There should be two or three more points here.

1. Belaying the second directly from the anchor is usually the most effective way. Use an autoblocking device.

2. Belaying the leader is to be done off the harness if the achor is on traditional gear. Setting up a truly multidirectional anchor is quite rare. In my experience I could say 90% of my anchors aren't such. Remember to have enough slack between the belayer and the first point of protection.

3. On fixed gear the UIAA advice is on belaying the leader directly off the anchor. If you use munter hitch or similar method the extra slippage is no problem. There isn't such. Zanantoni of UIAA calculates that loosing the grip is more likely on belaying off the harness than belaying off the anchors.
http://theuiaa.org/...aying_Techniques.pdf

In addition, the best belay method depends on the weight of the belayer. If the belayer is much lighter than the leader, you should favor belaying off the anchor.


(This post was edited by adnix on Dec 7, 2009, 8:01 PM)

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