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rgold
Trad climber
Poughkeepsie, NY
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Topic Author's Original Post - Nov 26, 2008 - 02:43pm PT
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I started this thread in an effort to protect Largo's equalette thread from clipping-the-anchor drift. Whether it will succeed in that goal, and whether there is even any interest in the issue I've excised to this location, remains to be seen.
I've included quotes from myself, stzzo, TradIsGood, DR, Peter, and Karl Baba from the equalette thread. I've also taken the opportunity to juxtapose my responses with the quotes.
The result looks a bit egotistical, since I appear to be having a dialogue with everyone else, but there didn't seem to be any way for a lowly participant such as myself to transfer over the discussion to another thread. If the subject is at all interesting to others, then the discussion will go on in the usual fashion and I will rapidly fade from any hint of centrality.
The post that began the discussion in the equalette thread is next.
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rgold: If you fall, statically belayed, directly onto the belayer (and your impact is transmitted by the belayer's tie-in directly to the anchor), then the anchor has to absorb the load of a factor two fall, say 9kN.
If the leader clips the anchor, then the fall factor is, at first, greatly reduced, but because of the pulley effect (mitigated by friction) the load to the anchor is 1.7 times the peak load in the leader's end of the rope. So, low fall factor means lower peak load, but this load is nearly doubled by the pulley effect.
As the leader gets higher above the belay anchor without anything else in, the fall factor increases, the peak rope tension increases, and the clipped anchor has to withstand 1.7 times that increased peak load. At some point, the leader reaches a ``break-even point,'' at which the leader's lower fall-factor fall, with impact 1.7 times the rope tension, equals the anchor impact of a factor-2 fall directly onto the belayer.
Once above the break-even point, a leader fall imposes a higher load on the clipped anchor than a factor-two fall onto the belayer would.
What is not generally appreciated is how close the break-even point is to the anchor. If belays are static in both cases (not a very reasonable assumption but one that allows some comparisons), the rope has a UIAA rating of 9 kN, and the leader is the standard-issue 80 kg flyer, then the break-even point occurs when the leader is half as far above the clipped anchor as the length of the belayer's tie-in. (This easy to visualize statistic assumes that the leader has clipped the power point of the anchor. If the leader clips one of the anchor pieces, then the break-even point is half as far above the clipped piece as the distance from clipped piece to the belayer's waist.)
Let's say the belayer has a 3-foot tie-in. Then the break-even point occurs when the leader's waist is a foot and a half above the power point, roughly when the power point is at the leader's knees. Once the power point is lower than the leader's knees, it will be subjected to a higher load if clipped than it would be if the leader factor-twoed onto the belayer. This is what I meant when I said the break-even point is really very close to the anchor.
If we assume a dynamic belay as a result of the rope slipping through a belay device with, say, a 4 kN slipping threshold for a particular belayer, then there is no break-even point. The peak anchor load for a factor-two fall onto the belayer is 4 kN, and the peak anchor load for the fall with lead rope clipped to the anchor is 9.7kN. (Edited to include tito's correction) This is interesting, because it suggests that a statically belayed factor-2 fall onto the belayer does not load the anchor any more than a dynamically belayed fall in which the leader has clipped the anchor.
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stzzo: rgold, I'm interpreting that the take home points are that
clipping the anchor or one of the anchor pieces can be a risky practice.
at the start of the pitch dynamic belays could be of great use.
Is that accurate?
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rgold: There are a number of issues to consider, and no single recommendation is going to cover them. What is almost certain is that clipping the anchor will expose it to higher loads, perhaps much higher loads, than not clipping the anchor, if there is a leader fall before the first piece is placed. How the party resolves that issue ought to depend on the anchor in question as well as the skills (and even the equipment) of leader and belayer, rather than on any single rule slavishly followed.
Dynamic belays are likely to be be dictated by the severity of the fall, and so will not occur as a matter of choice. Since no one practices dynamic belays any more, whatever skill might be involved in instigating and controlling them is not available. Whatever the case, a dynamic belay is an option for keeping the load low on an anchor. The only other one, proposed a while back on another thread by Karl Baba, would be to put a screamer on every piece of an anchor.
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TradIsGood: It [rgold's break-even discussion] does assume that the belayer is "static" i.e. somehow tied in such that he does not get lifted toward the power point. The dynamic case limits the load [at least until the point at which belayer reaches the power point] and is a function of the weight of the belayer and the friction at the power point, which I think is also not widely appreciated, though likely more widely understood than your analysis of the break-even point.
The alternative of belaying directly off the belayer's harness carries its own risk that perhaps is not well understood by those who most commonly set up the pulley. If the factor 2 onto the belayer occurs, the belayer must immediately (before the load) alter the position of his brake hand from below the waist to above the waist at which point he will then be absorbing a downward load.
This is an event that he may never have experienced before (especially if he is a beginner, i.e. a member of Largo's target audience). It won't happen in any toprope situation.
I fear that the belayer is more likely to fail to catch the fall under these circumstances, than the anchor is to fail. Maybe you have data or experience one way or the other?
The very few times I have been in this situation on lead, I took care to advise the belayer of the different requirements and did not depart the belay until I was satisfied that he or she understood exactly that a) the brake hand would have to go up, b) why that was so, and c) that the force of the fall would fall onto their legs and possibly pull them off his or her stance, or onto the ground.
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rgold: It is true that lifting the belayer will reduce the peak load of the fall arrest, but by how much is not clearly understood. Belay tests by the CAI suggest that you don't get as much of an effect as you might think. This is probably related to the fact that in a frictionless world, the belayer, after an initial period of acceleration, could be lifted forever at constant velocity, all of that lift making no contribution to peak load reduction.
As for the hand positions for possible factor-two falls, I have, as you probably know, posted about this a number of times. The primary argument for redirecting through the anchor, given that it will virtually always lead to much higher anchor loads, must ultimately be predicated on what I am tempted to call belayer incompetence, but so many belayers would be included in this characterization that I dare not use that term.
I certainly have no data. I have read of several instances in which a belayer lost control of the belay in a high factor fall. Whether this was due to inattention at a critical moment, improper anchoring and stance, the failure to wear gloves, or the use of an inadequate belay device, I cannot say.
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DR: Rich, could you explain what you mean by "pulley effect"?
rgold: The carabiner at the top piece acts as a pulley when a fall is arrested. Without friction, the load to the anchor would normally be double the peak rope tension. With the biner providing some resisting force in the form of friction, the tension on the belayer side of the biner is less than the tension on the leader side. Conventional wisdom seems to have settled on about 30% less, but this figure has never really been properly tested as far as I know. So rather than experiencing double the leader impact load, the top piece gets about 1.7 times the peak leader's side rope tension.
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Peter: I don't understand what force the PAS increases compared to a cordolette or sling. I belay off my harness either way, and usually clip the rope to a power point an arm's length above my waist when belaying the second and at least until the leader has a couple of good pieces in. The only time the second is clipped directly to the anchor is when we're switching leads and there's no risk of a dynamic fall. If you tie in to the anchor with the rope how much force is absorbed by the short length of rope between the anchor and your harness?
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RG: The PAs doesn't do anything in Peter's system other than act as a tether for the belayer; it will almost never be involved in transmitting anything more than the leader's weight to the anchor, and so there is almost no issue that I can see with using the PAS in this way.
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Karl Baba: I agree Peter, the PAS static issue is a non-issue.
Just like many of these geek threads that don't consider enough practical issues.
The real issue on using a PAS to connect the pieces on your belay is this: You can't escape the belay in an emergency without basically disconnecting your anchor!
Same goes for folks who use the rope to anchor directly to the pieces.
Now for folks who worry about the mechanical advantage effect of clipping the rope through the top piece of the anchor, answer me this, if you are at a hanging belay or are just putting your weight on the belay to get off your aching feet, will the multiplier effect still put twice the force on the belay. I think not. If you are hanging on the belay already, the forces on the anchor remain the same.
Personally, I belay the second off the anchor with a gri-gri. I could escape the belay in 1 second, I can haul with almost no set-up, I can take pictures without risking dropping the partner, and if they fall, it's no effort to hold them.
Then I belay the leader off my harness for better dynamics in absorbing the "real" fall,.
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rgold: Karl has been a dedicated "anti-geek" for as long as I've been a geek. I'm not going to try to defend myself, other than to at least mention that I am every bit as familiar with the practical issues as he is. And I do agree that quite often, the geeks descend, or ascend, depending on your sympathies, to a realm with little or no practical relevance. But I also sense, on the other side, a tendency to react with annoyance at geekly pronouncements as if, by virtue of some connection to science, they represent prescriptions that must be followed. Look, it is information that may be worth thinking about before you go on with your business as usual. That's all.
I'm not going to start another line of dissension on what I think is one of the most overhyped developments in climbing: the belay escape. And the hanging belay question is too poorly posed to respond to meaningfully. In any case, it does not, as far as I can tell, have anything to do with the absolutely unquestionable load-doubling, or not-quite-load-doubling, of a redirected belay.
Karl doesn't say if he keeps the anchor clipped when he belays the leader. But if you don't keep the anchor clipped, then attaching to the anchor with something like a PAS is a really bad idea, because this is the one situation in which fall energy might have to be absorbed by the tie-in. And if the anchor rigging might possibly extend which is the context in which I made a comment, then there is signifcant potential for extreme loads resulting in part from the nature of the tie-in material.
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Clint Cummins
Trad climber
SF Bay area, CA
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Nov 26, 2008 - 02:57pm PT
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DMT,
> How many belay sweeping falls have occured in this sport? I don't remember all that many.
How many would it take? I recall one in 1986 or 1987 on the East Buttress of Middle Cathedral - it resulted in a double fatality which I witnessed. I don't know the exact anchor configuration which led to the failure, but other leaders could take a factor 2 fall onto that belay.
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crøtch
climber
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Nov 26, 2008 - 03:12pm PT
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If pro isn't available to the leader early in the pitch, I'd argue for the leader clipping the powerpoint with a screamer, and making sure that the belayer's tie-in is longer than the length of the extended screamer.
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Karl Baba
Trad climber
Yosemite, Ca
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Nov 26, 2008 - 03:18pm PT
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"In any case, it does not, as far as I can tell, have anything to do with the absolutely unquestionable load-doubling, or not-quite-load-doubling, of a redirected belay.
Karl doesn't say if he keeps the anchor clipped when he belays the leader. But if you don't keep the anchor clipped, then attaching to the anchor with something like a PAS is a really bad idea, because this is the one situation in which fall energy might have to be absorbed by the tie-in. And if the anchor rigging might possibly extend which is the context in which I made a comment, then there is signifcant potential for extreme loads resulting in part from the nature of the tie-in material. "
My big complaint is that the geeks often don't write about, nor weigh the practical disadvantages versus the theoretical, mathematical advantages.
In this case, Taking a factor two fall right on your belay device (body) is the alternative to clipping the anchor (MADNESS unless you have a truly crappy belay)
Escaping the belay would be nightmare in that case and you can't lower the leader to the belay because she is below the belay. If you just clip the top anchor piece, you have so much more control and options. Where I live, that top anchor piece is usually way bomber. If now, the leader should place something asap.
I'd like to see the math on just how dynamic 2 feet of rope would be in a big fall situation. Best case scenario might be to clip in one of the loops on a regular pocketed daisy chain and let them rip out one by one like a screamer.
In any case, I suggest considering that at a hanging belay, you're weight is already on the belay, so whatever weight is already on the directional, can be subtracted from the pulley effect on the same piece
PEace
Karl
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Tomcat
Trad climber
Chatham N.H.
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Nov 26, 2008 - 03:22pm PT
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I follow these discussions carefully,and think I understand the issues.Experience has taught me,if anything 1)lot's of people are certain their anchors are bombproof,and they all are until tested.2)The problem with this type of discussion is that it doesn't really factor in the mayhem of a factor two,the sudden yank around,possible forfeit of brake hand bend back.In theory at least,clipping the anchor would keep the orientations right.
Because of the issues associated w/FF2, if I percieve much chance of one,I will sometimes move the belay DOWN a bit,and use the anchor as a first piece.I've done this on the Dike for example.In lieu of that I will take some other measure,which for me is usually to knot off the rope X # feet out with a loose knot I can remove with one hand while belaying.That way if I lose control there is a back-up.In that configuration I am Ok without clipping the anchor.Gri-gri's and munters are a cure too,as I understand it,but I don't own a Gri-Gri,and you rarely see a munter off someone's harness,or I don't.
Another solution at times,is to deal with the hard climbing just off the belay before you bring up your partner.Get it done,get some gear in,move back down to the belay stance,and bring them up through the top piece(s).If they are leading the next pitch you are all set.If you are you will have to pull the rope through.This works for me ice climbing.
My " solutions" are OK for specific climbs and situations,but don't cover just everyday sh#t happens scenarios.
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TradIsGood
Chalkless climber
the Gunks end of the country
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Nov 26, 2008 - 03:27pm PT
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Rgold, thanks.
Of course, there is friction, so even if the belayer ascends at a constant speed, some energy - friction force times distance - is dissipated.
That said, I admit I have no idea whether the peak force occurs when the belayer is accelerated, or when his speed drops to zero (I suspect that it is one or the other, and not in between?), or perhaps just after that when the rope stops stretching. Since this is not linear, I am not willing to trust my intuition here.
I guess the best advice is simply, the leader should not fall - at least not until much later.
Unless I see differently, I probably am still going to worry more about the safety of the belay, than the safety of the anchor - and try to get a piece that is not in the anchor where possible. (It has always been my goal to get several pieces in early.)
Post Tomcat EDIT.
Hey, that knot idea is cool!
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rgold
Trad climber
Poughkeepsie, NY
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Topic Author's Reply - Nov 26, 2008 - 03:27pm PT
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Dingus wrote: "Had a recent dialogue with jt512 on this topic. It is his contention that clipping the anchor as a first piece is dangerous and that an FF2 directly onto the belay is less dangerous than this 1.7 peak load thing.
I don't buy it. I'm gonna need some proof to convince me its safer as a general statement. In a bomber anchor situation - why risk an FF2 and a longer fall?
If you have a bomber anchor, indeed why not? And what if your anchor isn't bomber? Dingus, I know you've been at this game plenty long enough to know that isn't an empty question.
"Now what if that first piece were an anchor-indepentant piece, for example, 6 inches above the highest anchor piece - what's the difference? I don't see any myself - a first piece is a first piece and the top piece always sees the pulley effect?"
The first piece always sees the pulley effect. But the failure of an anchor-independent piece doesn't have an immediate consequence for the anchor, because the anchor-independent piece isn't connected to the other anchor pieces.
How many belay sweeping falls have occured in this sport? I don't remember all that many.
My count has gone up a few in recent years. I think the rate now stands at about one every five years over the past fifty I've been climbing. But I can't document that, I'm relying on memory, and don't start with the cracks...
Lastly I think the leader falling directly onto the belayer and anchor, as in a direct impact, is a worst case scenario.
It certainly is a very bad scenario. If falling on the anchor would extract it and falling on the belayer would not extract the same anchor, then it isn't the worst-case scenario.
At the end of the day It Depends.
Absolutely.
But what do I know?
Plenty.
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Clint Cummins
Trad climber
SF Bay area, CA
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Nov 26, 2008 - 03:53pm PT
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To reiterate what others have said, you can drastically lengthen the belayer's connection to the anchor, when there is hard climbing immediately above the belay, and clip the belay with a screamer/load limiter. This is what Kelly and Bruce did when trying to lead p2 of Exodus on Middle Cathedral this past summer. Bruce connected to the anchor with about 20 feet of rope, so he hung well below the bolts.
Besides increasing the height the leader can fall before increasing the load, it reduces the chance of the belayer being hit by the falling leader, or being slammed up into the rock by a hard leader fall.
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scooter
climber
fist clamp
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Nov 26, 2008 - 04:10pm PT
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Dingus-
A couple from CO. fell ALL THE WAY off of DNB a few years back when the leader either fell on the anchor or pulled a piece then fell on the anchor. I can't remember exactly.
Pat
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rgold
Trad climber
Poughkeepsie, NY
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Topic Author's Reply - Nov 26, 2008 - 04:24pm PT
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Karl Baba wrote :"My big complaint is that the geeks often don't write about, nor weigh the practical disadvantages versus the theoretical, mathematical advantages."
A fair observation. As the current and really rather unwilling geek defender, I'll say that the geeks were discussing what they were discussing. It is up to the reader to supply an appropriate real-world context. It is possible to do this without rejecting everything the geeks were saying.
"In this case, Taking a factor two fall right on your belay device (body) is the alternative to clipping the anchor (MADNESS unless you have a truly crappy belay)"
Well, I think MADNESS is in the eyes of the beholder, or capitalizer in this case. As someone who has held a factor-two fall, I don't recall much in the way of mental instability either before or after the event, but of course you can't trust the inmates to run the asylum. And so it comes down to what the known capabilities of the belayer are and whether a less-than-perfect anchor is worth subjecting to, say, double the load it absolutely has to be subjected to.
A less-than-perfect anchor is different than a truly crappy anchor. It would be MADNESS for the leader to clip a truly crappy anchor. It is sensible for the leader to clip a bombproof anchor. Now between those extremes is where it makes sense to think about balancing opposing concerns before just doing what you always do.
I'd like to see the math on just how dynamic 2 feet of rope would be in a big fall situation.
A request for geekly services? I am honored...but unfortunately I don't know what you are asking here.
in any case, I suggest considering that at a hanging belay, you're weight is already on the belay, so whatever weight is already on the directional, can be subtracted from the pulley effect on the same piece
According to this logic, if the belayer and leader are just hanging from the top piece (no fall involved) then the belayer's weight can be subtracted from the total load on that piece and presto---there is no such thing as the pulley effect, a conclusion that can be disconfirmed in all sorts of reality-based practical ways.
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hafilax
Trad climber
East Van
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Nov 26, 2008 - 04:28pm PT
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Had a recent dialogue with jt512 on this topic. It is his contention that clipping the anchor as a first piece is dangerous and that an FF2 directly onto the belay is less dangerous than this 1.7 peak load thing.
I don't buy it. I'm gonna need some proof to convince me its safer as a general statement. In a bomber anchor situation - why risk an FF2 and a longer fall?
Now what if that first piece were an anchor-indepentant piece, for example, 6 inches above the highest anchor piece - what's the difference? I don't see any myself - a first piece is a first piece and the top piece always sees the pulley effect?
How many belay sweeping falls have occured in this sport? I don't remember all that many.
Lastly I think the leader falling directly onto the belayer and anchor, as in a direct impact, is a worst case scenario.
But what do I know?
DMT
I would rather place another piece instead of clipping the highest piece. Should that piece pull I would rather fall onto a complete anchor than one that had a piece pull.
As for clipping the highest piece? That depends a lot more on the situation. I wouldn't do it as a matter of practice. If I didn't trust that piece 100% but it best protects the climb then I might try to change the anchor in order to make that piece independent.
From rgold's model I found that the force on the anchor is greatest if it is clipped and that the force on the belayer is greatest if it isn't which really does make sense to me. Pick your poison.
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Karl Baba
Trad climber
Yosemite, Ca
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Nov 26, 2008 - 04:28pm PT
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Great advice clint!
Anchors fail once in awhile but it's dang rare. Dropping the leader happens a lot more and your chances of doing so increase if he falls right on your waist via a factor two. Why? Because it's hard!
There is no evidence BTW that the DNB anchors were clipped as directionals. Thing is, with the forces involved in climbing, a really crap anchor pulls no matter what and a bomber anchor stays no matter what. I'd be surprised if the grey are of anchors that may or may not pull was very large
PEace
Karl
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G_Gnome
Trad climber
In the mountains... somewhere...
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Nov 26, 2008 - 04:30pm PT
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I for one would always rather have directional control when holding a high load fall. Besides, the dynamics of the catch when the rope is pulling the belayer up versus pulling straight off the belay look in a hanging belay does not intuitively argue for the later. You would have to prove to me that in a real world application that it is preferable to catch on the belay loop in a very un-dynamic way.
Also, in all the cases that I remember where a leader fall cleaned both the leader and the belayer off the wall the belay was quite questionable and/or the facts of the failure were very unclear - perhaps to protect the guilty.
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Peter Haan
Trad climber
San Francisco, CA
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Nov 26, 2008 - 04:58pm PT
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For those who still don’t comprehend how the top piece in a protection system or anchor sustains a load greater than the load that is hanging from it (say a climber or haul bag), consider this.
If you tie yourself off to an anchor, the anchor experiences only your total weight. Similarly, if you are standing on a ledge and want to haul a heavy bag up from the ground with a line directly connected to it, say a 100 lb weight, you have to pull hand-over-hand 100 lbs (plus a bit for friction if there is any with the bag dragging on surfaces or whatever) to start to move that weight upwards.
But say instead you put a pulley at the ledge and run the haul line through it and then you go back to the ground where the haul bag is and haul on that line from there hoping to make the bag go upward, consider this: The bag weighs 100 lbs and you have to pull a bit more than 100 lbs to move it up, but the pulley experiences nearly 200 lbs because of the loads on BOTH ends of the haul rope that it supports have added up for the poor pulley.
Again, if you just tie the bag off to the pulley or a fallen leader off to his high piece, the pulley or highest piece only sustains a load of just what hangs on it of course.
This basic principle also applies when a climber takes tension FROM the belayer through the rope while leading.
And in very hard direct aid it is not smart to take tension from the belayer via the rope but to daisy off of your piece to rest, be supported for the next placement, etc. as tension from the belayer unnecessarily develops quite a bit more load on bad placements than might be understood and may blow them.
The simple mechanics here are not so intuitive and often lie hidden in situations where the participants would be better off being aware of the forces that “magically develop.
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Peter Haan
Trad climber
San Francisco, CA
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Nov 26, 2008 - 05:07pm PT
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I like this cogent discussion.
We always need to vet abstract discussions in at the reality counter; I think this is happening here fortunately.
For at least 4 decades in practice any experienced climber nearly always has been getting pieces in asap right above a belay even on easier climbs. We have historically clipped to the anchors separately (so to not saw through slings) but immediately established a separate new nearby piece (whenever possible) for to get two points at this belay redirect and with this discussion about the near doubling of forces on the highest piece in a fall situation, this practice of a separate redirect piece becomes extremely sensible where it is obtainable. And having clipped both anchor and redirect, you have built friction you really need if a fall happens early. At any rate it should “never” be possible for the leader to directly fall on the belayer’s device.
And I would add that anchors nowadays are incredibly much better than they were even just three decades ago, so mostly they are correctly perceived as bombproof. Even people who don’t understand the basic physics here (and that is most people as it turns out) still “like to put a piece in right away”, because they intuit it is somehow “better” in practice. Good.
The frequent discussion of fall potential evaluation via the “Category” model is really good for everyone and should continue to be in the forefront.
Along with the group here, I can only think of one or two accidents where a belay was swept away, both climbers going to their maker in all these years, so given how very very rare the event is, perhaps the bigger point is the damage done to the belayer successfully holding a Cat 2 fall.
I agree with the group that difficult belay escape is also very rarely required even though it has to be kept in mind.
I think Crotch is right with his modern suggestion of using a Screamer at the first point or if the anchor is clipped for redirect as a matter of course in leading. The things are cheap, small, light, common and produce a remarkable reduction in Kn. Most modern belay devices can easily produce static belays in spite of the need for a dynamic one so screamers help out belayer error there as well. So as protocol it would be a great standard.
Anchoring in an exaggerated elongated fashion as Clint relates here, is an example of a clever and special case of developing belays that are the best in uncommon situations, and which cases we all should be considering and hearing about etc. rather than thinking as most do, that there is basically only one form to safeguard a leader. I like some of those “grounder” climbs where the belayer is unanchored and hopes to run down the hill to eliminate slack if the leader falls, too!
Anyway great thread, and Richie is as clear as ever! Thanks.
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jstan
climber
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Nov 26, 2008 - 05:17pm PT
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"rgold: It is true that lifting the belayer will reduce the peak load of the fall arrest, but by how much is not clearly understood. Belay tests by the CAI suggest that you don't get as much of an effect as you might think. This is probably related to the fact that in a frictionless world, the belayer, after an initial period of acceleration, could be lifted forever at constant velocity, all of that lift making no contribution to peak load reduction."
One piece of data.
Many years ago I ran some 8mm perlon through an 18" length of plastic pipe which had a cross-wise window cut in both sides with an end mill. Then I pushed a finishing nail cross-wise through the rope in the window and also put in a finishing nail so the rope was fixed at one end of the pipe. Then I put a spring bronze clip on the pipe so that under load the nail in the window would push the slip to a new position. By measuring the final location of the clip I could determine the peak instantaneous load. i calibrated this unit in a tensile machine so the rope had had a few cycles on it. It did not show a lot of stress aging in its stress strain relation. By measuring the final position of the clip I could measure the peak instantaneous load.
Just right of Something Interesting there is a small ceiling maybe, what, forty of fifty feet off the ground. Slightly below that ceiling there was fixed pin to which I clipped the unit describer above so that when i dropped a 165# pound duffle bag filled with shale (tied in at the middle with a swami of 1" tubular) from a position above the ceiling it would travel perhaps forty feet before the rope came tight.
When I was anchored to the big tree at the base and acted to belay the "fall" my unit indicated a peak force at the top piece of about 500#.
When I tied the rope off at the tree we got a peak force of about 1000#.
I have not seen the CAI data but my experience convinced me having the belayer whipped about does all kinds of good things for the system. Personally I would never consider clipping a belay device directly to a fixed anchor.
As to the main question, I would never clip a top anchor as a directional if I had any doubts about it. If the top anchor is good and if there was any chance of a fall, I would clip it as long as it was far enough away from me so that when I got catapulted it would not interfere with my belaying. Most of the calculations one makes in assessing how to give the belay get wiped out when you are suddenly going head first down the hill. Had I no directional I would belay directly to catch a FF=2 and reverse my position as soon as a good piece was in.
As an aside, climbing with Richard was a special case. Directionals were not needed.
EDIT:
Perhaps an addendum to my "having any doubts as to an anchor" is in order. This is about the only point where I differ with some of the contributors to this very useful thread.
This thread is about numbers but when we come to discussing the strength of an anchor in rock on a climb we don't have any numbers. There is a very real disconnect between the two parts of the discussion. Well when I was dropping bags of shale I was also engaged in testing actual placements up to 3000# using a portable hydraulic rig I had built. I was able to take real situations and put numbers on a lower bound for the yield point. So when throwing simulated climbers into forty foot falls produced forces on the top anchor well under my lower bounds, I began to feel as though questions were being answered.
Frankly it also made a difference in my climbing. That time I had a single stopper for protection I felt pretty confident. Based on my hydraulic tests and the relatively small amount of shear I saw in all those tests led me to believe the critical nut in this case was easily good for 1000#. As a backup my belayer weighed only 110# and I had specifically not tied her down. Into the bargain I had her stand out from the base of the rock so the initial motion would be lateral. The belay would start out soft and naturally become stiffer. I expected the belay to be quite dynamic. The nut was not going to have to withstand anywhere near 1000#. I have since seen cases where similar strategies are employed for poorly protected grit stone problems.
When Helmut Microys came back from Mammut with these fall factor calculations I thought they were good for qualifying rope and possibly for worst case situations such as coming off a belay. But do we really think 10kN would not break us in half? To test a nut once I foolishly did a FF1 drop of 18" onto a sling of 1" webbing. Nearly killed me. A ten foot drop onto five feet of rope tied to an eyebolt in structural steel? You'd be history. Without a doubt. The very next day I started building my hydraulic rig.
Whatever you do I think you really need to avoid having serious unscheduled changes in direction.
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pyro
Big Wall climber
Calabasas
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Nov 26, 2008 - 07:02pm PT
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I always clip a directional.
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Patrick Oliver
Boulder climber
Fruita, Colorado
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Nov 26, 2008 - 08:16pm PT
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I have about a hundred things I could say, after reading through this thread, but I'm not sure I have the energy to do more than add a few tidbits from the peanut gallery. I don't know how many people have had the kind of experience I've had at holding serious falls. The first major one was Kor leading above me, in a lieback, when he pulled off a block and went sailing past me, as I stood on a small stance on a near vertical wall... Soon after he took an even larger fall from higher above and went far past me and below... Then I caught Dalke in a nasty freak fall off a climb in Eldorado he never normally would have fallen off. I then caught Dalke on a route on Castle Rock... Then with Rearick, as he went liebacking up a 5.10+ overhanging crack, his feet on lichen, strung out with a marginal bong half way between him and me, and he slipped... I could go on and on, but I began to feel somewhat of an expert at the realities of such falls and such forces. I developed a mindset to be always prepared, no matter the skill level of my partner.
Of course Peter hit it on the head, if I understand his term "power point," in saying a belayer needs a point to run the rope through independent of the belay and independent of the leader's protection, presumably in most cases just above the belay, or possibly to the side if the next pitch is a traverse... Such a point, if one can get it, could make all the difference.
If I've learned anything through the years, no situation is like any other. You can't exactly make rules that apply in all cases. One has to examine every situation separately and set things up appropriately. A bad mistake is to get into that habitual mentality, where you simply do the same thing at every belay that you always do, a kind of mindless routine approach. Staying awake is vital and to look and think and not follow any rule if it doesn't apply.
I have always felt (or through an evolution of experience came to believe) if any sort of mastery at the belay is to be achieved it might be to imagine at each belay point that there is no anchor at all. To envision such a thing, which may seem a bit absurb (and of course doesn't work in all cases), makes you find the position where your body is in the best place and you face the right way and so forth and so on, and have the best chance of holding a fall. Then, the anchor set-up is added, in relationship to that idea. Too often, I think, people rely solely on the anchors or their belay device, or some or other form of mechanical appartus, as the strength of their belay. They don't even think about body position or of catching a fall and instead leave it to the gear to do the job. I have found the belay is much stronger by relying on oneself first, and secondarily the gear -- as a general rule.
No matter what the forces are, or what they measure in terms of numbers, assume it will be significant, and don't take anything for granted.
The leader too plays an important role, in a strong belay, by being especially careful to get the right gear in, to think about the belayer, in the classical mountaineering fashion of considering one's partner above oneself. Sometimes when I lead I am positive I'm not going to fall, but I always think about my belayer and what would happen should the farthest thing from my imagination happen. I've known very good climbers who have more or less felt the belay was the belayer's job and the belayer's responsibility, and took no interest in any "possible contingencies" but rather focused solely on the rock ahead. It is always a joy to be with one who has that special integrity to exercise whatever necessary restraint to make things safe, no matter how difficult the climibng is.
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jstan
climber
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Nov 26, 2008 - 08:23pm PT
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Hump? What hump?
Name the movie?
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Karl Baba
Trad climber
Yosemite, Ca
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Nov 26, 2008 - 08:31pm PT
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Rgold wrote
" And so it comes down to what the known capabilities of the belayer are and whether a less-than-perfect anchor is worth subjecting to, say, double the load it absolutely has to be subjected to. "
I dispute that it would be double the load, merely the load plus the weight of the belayer, after all, the leader is the only one flying at 32 feet per second squared.
Rgold writes
"in any case, I suggest considering that at a hanging belay, you're weight is already on the belay, so whatever weight is already on the directional, can be subtracted from the pulley effect on the same piece
According to this logic, if the belayer and leader are just hanging from the top piece (no fall involved) then the belayer's weight can be subtracted from the total load on that piece and presto---there is no such thing as the pulley effect, a conclusion that can be disconfirmed in all sorts of reality-based practical ways. "
No, According to this logic, if the belayer and leader are just hanging from the top piece (no fall involved) then there is the weight of two people on the top piece. It doesn't matter if they are hanging on the piece with separate daisy chains or connected to each other by a rope.
peace
Karl
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