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toejam
May 1, 2006, 9:41 PM
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Math guys help me out here, please.
Assume for the sake of discussion that one is forced to rely on a questionable anchor for the purposes of:
a. lowering one or more injured victims.
b. belaying a leader.
c. belaying a follower
To minimize the force on the anchor, the ideal belay method for a would be to attach the belay device to the anchor itself. For b and c, it might be to belay off of the harness for a little extra force absorption, though the increase in fall factor would offset this in situation b. In any case a redirected belay through the anchor would increase the forces unnecessarily due to force multiplication/pulley effect. Right?
Assuming the belayer is attached to the anchor but partially supporting his own weight (say 40%), how does this play into the decision. Anyone have some equations to help sort out my muddled thinking on this?
Thanks.
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clmbnski
May 1, 2006, 10:58 PM
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I think I would belay off my harness in all situations where the anchor is questionable. Try to find a good stance where your body is in a position for the most power. Then the anchor is just a backup. I would not redirect the belay through the anchor because as you said "the pulley effect"
With the redirect:
The anchor takes 1.6 times a lower factor fall (not that much lower) compared to a factor two load. According to my calculations, 1.6 times the impact force of any fall factor will be a higher impact force than the factor 2 impact force. So I would never use a redirect through the anchor.
Can someone confirm that?
I used this equation for impact force http://www.bealplanet.com/...age=force_choc〈=us
Chris
edited to clarify
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catbird_seat
May 1, 2006, 11:12 PM
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I agree completely with clmbnski. Belay off your harness, get a good stance, and pray to whichever god you believe in.
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gunkiemike
May 2, 2006, 12:35 AM
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In reply to: I agree completely with clmbnski. Belay off your harness, get a good stance, and pray to whichever god you believe in.
Agreed. I'll also add - tell your partner not to fall. Be honest so they can make an informed decision; it's their life at risk too.
And by all means consider NOT continuing. Downclimb to the last good gear and abandon the attempt or belay from there.
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jimdavis
May 2, 2006, 5:22 AM
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In reply to: I think I would belay off my harness in all situations where the anchor is questionable. Try to find a good stance where your body is in a position for the most power. Then the anchor is just a backup. I would not redirect the belay through the anchor because as you said "the pulley effect" With the redirect: The anchor takes 1.6 times a lower factor fall (not that much lower) compared to a factor two load. According to my calculations, 1.6 times the impact force of any fall factor will be a higher impact force than the factor 2 impact force. So I would never use a redirect through the anchor. Can someone confirm that? I used this equation for impact force http://www.bealplanet.com/...age=force_choc〈=us Chris edited to clarify
I would! I wouldn't want to catch a factor 2 fall that's pulling straight down on my hips! F*ck that!
Hopefully your only talking about having this happen until the climber get a good piece in (hopefully soon!!!) and by redirecting through the anchor, your minimizing the fall factor, and the amount of time the climber is in free-fall...reducing the force felt on both the belayer and the climber.
Taking into account that the belay should slip at around 2kn...the climber won't feel over 4kn (or less, not doing the exact math here to account for friction) so your force felt on the belay anchor is still under 6kn, in the redirect.
Say you belay straight off your harness. Climber takes a factor 2 fall onto you...rope slams down against your leg/ foot or something...pulls you out of your stance...you now have 2 climbers falling onto the anchor, both in relativly high factor falls (depending on the belayers attachment to the anchor: sling, or rope) so I think that'll end up being around 4kn on the anchor, except with both the belayer and climber getting thrown around.
I'd hope you could build an anchor that'd hold at least 6kn...that shouldn't be TOO hard.
Cheers,
Jim
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brutusofwyde
May 2, 2006, 7:47 AM
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Personally, I see far too many folks belaying the leader off a questionable anchor, and they never seem to realize it.
I'm talking about an anchor without at least 1-2 pieces placed specifically to oppose upward pull.
Brutus
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toejam
May 2, 2006, 8:54 AM
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In the situation that got me thinking about this, the belayer was forced to rely on a questionable tree in a cliff face of loose rock. He lowered the rescuer who picked a victim off the face and secured him to the rescuer's harness, then lowered together. The belayer had about 60% percent of his weight on the anchor, and the lowering line redirected through the anchor. Only an ATC was available as a device.
What I'm trying to reason out is whether the force multiplication is really an issue in this case. Either way, the weight of the rescuer, victim, and belayer are all on the anchor. I'm not sure that any of this force is multiplied. Naturally the lowering will be a little bumpy, and I suspect that this would be where the force multiplication kicks in, but I'm not sure.
If the belayer did go off of his harness, I'm sure that the ride would have been a little bumpier, resulting in more force on the anchor, and all of his weight would have also been on the anchor. Perhaps the best option would have been a munter on the anchor itself.
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dirtineye
May 2, 2006, 9:42 AM
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Questionable vegetables turn out to be good in my experience, but you are wise to think about the smoothness of the lower or rappel.
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clmbnski
May 2, 2006, 3:42 PM
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In reply to: And by all means consider NOT continuing. Downclimb to the last good gear and abandon the attempt or belay from there.
As far as the rescue situation you described:
In reply to: In the situation that got me thinking about this, the belayer was forced to rely on a questionable tree in a cliff face of loose rock. He lowered the rescuer who picked a victim off the face and secured him to the rescuer's harness, then lowered together. The belayer had about 60% percent of his weight on the anchor, and the lowering line redirected through the anchor. Only an ATC was available as a device.
In reply to: Say you belay straight off your harness. Climber takes a factor 2 fall onto you...rope slams down against your leg/ foot or something...pulls you out of your stance. |
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dirtineye
May 2, 2006, 5:14 PM
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Some of you are seeming to say that the belayer doing a lower off a questionable tree should be attached to the anchor?
IN this particular situation, the belayer should be attached to somethign else besides the ancor, because if the lower pulls the anchor, the belayer is dead as well as the loweree.
Better to have a good stance to one side and then if the anchor goes you can try to hold it or let go god forbid when you have to.
But these days, we don't do no marginal anchors. Can you say, bolt kit?
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krusher4
May 2, 2006, 6:30 PM
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yell down to your second "If you fall we will both die....so ummm....don't"
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adnix
May 4, 2006, 8:20 AM
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In reply to: a. lowering one or more injured victims. b. belaying a leader. c. belaying a follower |
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catbird_seat
May 4, 2006, 9:32 PM
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Dude, you have it ass backwards.
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adnix
May 5, 2006, 1:10 PM
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In reply to: Dude, you have it ass backwards.
I can give you a very thorough explanation if I wish. It's pure physics. Weight, pulleys, friction and counterweights. If you belay directly off the anchor, you'll eliminate the counterweight. It's pretty simple really.
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adnix
May 5, 2006, 1:18 PM
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In reply to: I think I would belay off my harness in all situations where the anchor is questionable. Try to find a good stance where your body is in a position for the most power. |
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csproul
May 5, 2006, 2:20 PM
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In reply to: In reply to: Dude, you have it ass backwards. Me? No, I don't. I can give you a very thorough explanation if I wish. It's pure physics. Weight, pulleys, friction and counterweights. If you belay directly off the anchor, you'll eliminate the counterweight. It's pretty simple really. |
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ontherocks
May 5, 2006, 3:08 PM
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I think the rule of thumb is: if your anchor is questionable, belay of your harness. Your body will act as an screamer to protect the anchor.
In reply to: I wouldn't want to catch a factor 2 fall that's pulling straight down on my hips! F*ck that!
If the anchor take the fall, the anchor, and then you would fly out (and down). Then your only option is start lowering/belaying with your knife ready, close to the rope. I wouldn't like to be belayed with someone with that mindset.
In reply to: Say you belay straight off your harness. Climber takes a factor 2 fall onto you...rope slams down against your leg/ foot or something...pulls you out of your stance...you now have 2 climbers falling onto the anchor, both in relativly high factor falls (depending on the belayers attachment to the anchor: sling, or rope) so I think that'll end up being around 4kn on the anchor, except with both the belayer and climber getting thrown around.
You should be attach in short to the anchor, then when you get the fall, you reduce the shock load over the anchor before the anchor takes the blow. The belayer is not falling on the anchor, she is part of it. That's the base of the whole misunderstanding.
In reply to: I'd hope you could build an anchor that'd hold at least 6kn...that shouldn't be TOO hard.
That's the point of the question. That you can't get a good anchor. Think A6.
In reply to: IN this particular situation, the belayer should be attached to somethign else besides the ancor, because if the lower pulls the anchor, the belayer is dead as well as the loweree.
If there is something else, then you do have a good anchor (the "something else"). If the "something else" is equally questionable, then include it as part of the anchor, to strengthen it. If it's worse, then don't use it and attach yourself to the anchor.
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dirtineye
May 5, 2006, 3:54 PM
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What you do not understand is that you have a responsibility to save yourself.
If you are attached to a crap anchor when you could have had an independent stance, then you have killed yourself and your partner if the anchor goes and you go with it.
YOU need to be able to free yourself from this potential disaster.
The something else might just be a stance.
But by all means, feel free to take the glory ride with your partner, don't let me stop you.
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mcfoley
May 5, 2006, 4:03 PM
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In reply to: I think I would belay off my harness in all situations where the anchor is questionable.
Ditto on this...
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fishbelly
May 5, 2006, 4:25 PM
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Belaying from your harness! Make the whole situation more personnel.
Kind of takes the sport out of it.
As the be layer you are part of the anchor. Not a casual observer.
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jimdavis
May 6, 2006, 2:16 AM
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In reply to: In reply to: I'd hope you could build an anchor that'd hold at least 6kn...that shouldn't be TOO hard. That's the point of the question. That you can't get a good anchor. Think A6.
IF I ever put myself on an A4 and up, route, the bolt kit is coming along with me.
There's no reason to ever want to belay someone off of such an anchor. Downclimb to something suitable, or simul-climb up to something suitable.
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majid_sabet
May 6, 2006, 3:04 AM
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If I had to belay or lower a cargo on a questionable anchor, I would try to minimize direct risks on myself and I would belay directly from anchor incase things go wrong
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horseonwheels
May 6, 2006, 5:05 AM
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I think with any questionable situation, the climbing team should be together. There shouldn't be one person that takes a lot more of the risk than the other. Therefore, if there is a solid stance....belay off the harness. If the belayer is depending on the anchor as well....belay off the anchor.
I don't think you could say that one way is better all of the time. Also involved in this is finding the absolutely best possible anchor spot.
Do whatever has the best chance of protecting your team the best, and forget about the belayer being able to save himself if things go wrong. Any belayer that ties a knot in the slack end of the rope is making a statement that theyre not letting go of their partner.
(as an amendment to the previous idea... if your partner tricks, sandbags, or bullys you into getting on something you shouldn't be on, i might not feel so guilty about belaying off the anchor or not tying that stopper knot)
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kman
May 6, 2006, 5:25 AM
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In reply to: In reply to: I think I would belay off my harness in all situations where the anchor is questionable. Try to find a good stance where your body is in a position for the most power. There's always a better one somewhere nearby.
Must be nice :lol:
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rgold
May 6, 2006, 5:26 AM
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The situation, at least for belaying or lowering a second, depends on how good a stance is available. Modern climbing has emphasized anchors to the point that the basics of braced belaying are no longer common knowledge (except in the canyoneering world), but there are many situations that will allow a perfectly safe harness belay for a second, with the result that falls can be held and lowering accomplished with absolutely no load on the anchor.
If a decent braced position cannot be found (assuming the leader knows how to spot them---they may be located in a place with no anchors), then downclimbing and/or simulclimbing to better anchors are options that have to be weighed along with using the anchor. If the anchor must be used, then an attempt to equalize the pieces as much as possible should be made, and as long a tie-in as feasible should be employed to provide some dynamic cushion for the anchor.
In such a situation, I think putting the device directly on the anchor is a bad idea and redirecting the belay through the anchor is a really terrible idea. Any bracing a climber can accomplish with their feet could potentially take some load off the anchor and so a harness belay is the best option. The second must be alerted to the fact that they must climb as if they are on an unprotected lead and cannot fall. The second and belayer must coordinate to make sure that not even a little slack develops in the rope as the second climbs.
The real stress occurs when the second joins the leader and the next pitch must be lead with the belayer at a poor anchor.
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