Discussion Topic |
|
This thread has been locked |
Forest
Trad climber
Tucson, AZ
|
|
|
Nov 24, 2008 - 05:15pm PT
|
I gotta admit. I'm with DR here.
I use:
3 solid pieces (more if one is questionable)
one 20' cordalette
equalized to most likely direction of pull, and tied off with figure eight.
I could see call for more exact equalization if you find yourself with questionable anchors. I tend not to climb stuff like that, tho. I'll either back down to the last good set of anchors, or push it a bit further to the next one. Protection is so good these days, that I think there's rarely an excuse for being unable to find good placements for your anchor, at least on the type of stuff I climb.
I like this solution because it's easy to set up and take down quickly and safely, no matter hour tired you might be.
Same answer seems to work really well for the overwhelming majority of anchor situations I find. Every once in a while I need to run a long sling to a third piece further up the climb or something, but that's pretty rare.
|
|
Doug Robinson
Trad climber
Santa Cruz
|
|
|
Nov 24, 2008 - 06:06pm PT
|
I think I accidentaly obscured my point, way back up thread. My error was using the term "Cordelette." Its original meaning was simply a chunk of thin rope, 15-20 feet long. But listening to this discussion, I'm hearing that it has come to mean a 3-point equilization with a knot.
What I'm really advocating is using it as a giant runner. Equalized down to a single power point with two sliding Xs. But then NOT tied.
Let it slide. Let it continually adjust as you move around on the belay. Let it be just a big sling. Movement happens. Even ONE INCH sideways takes all the equalization out of a knotted system and throws it onto one piece.
Functionally, spreading the load of a fall over several anchor pieces is crucial. Equalization trumps the value of no extension. So I toss out the "no extension" part.
This simplifies the "standard" cordelette rig. To my mind it stays more flexible, continuously adapting as the power point inevitably slides around.
And it's easier to make. One less step. Faster. Satisfies the KISS rule.
|
|
GOclimb
Trad climber
Boston, MA
|
|
|
Nov 24, 2008 - 06:37pm PT
|
If you're wanting the belay anchor to save the day (to serve, so to speak, as the top piece of pro), you're going about it all wrong.
I think this misses the point entirely. The only real thing the anchor needs to do is be able to keep both people from falling off the wall if, despite all your best efforts to keep it from happening, the sh#t hits the fan. To just hold the belayer on the ledge - anything will do.
But because the difference between having an anchor that succeeds and one that fails, if the worst case happens, is so huge... well, maybe y'all don't give a damn, but I want the best anchor I can quickly and efficiently fashion.
This is not to say that I don't respect Tar's viewpoint. I certainly do.
GO
|
|
Forest
Trad climber
Tucson, AZ
|
|
|
Nov 24, 2008 - 07:27pm PT
|
Let it slide. Let it continually adjust as you move around on the belay. Let it be just a big sling. Movement happens. Even ONE INCH sideways takes all the equalization out of a knotted system and throws it onto one piece.
If you let it slide, then a single cut anywhere in there (i.e. from rockfall or whatever) undoes the whole thing and you die. This remove the redundancy part, which scares me a lot more than being slightly unequalized.
|
|
the Fet
Knackered climber
A bivy sack in the secret campground
|
|
|
Nov 24, 2008 - 08:19pm PT
|
A tied cordelette doesn't equalize.
A sliding X with limiter knots or the equalette, which is really a variation of a sliding x with limiter knots, equalizes two pieces pretty well, has redundancy, and little extension.
I went from slings and the rope to sliding Xs with limiter knots in the late 90s, but it always took a long time to tie the sliding Xs. then I went to the cordelette until the new research came out. I went back to sliding Xs with limiter knots, but just leave them tied, so it's quicker than even a tied cordelette. No knots to tie.
|
|
Mighty Hiker
Social climber
Vancouver, B.C.
|
|
|
Nov 24, 2008 - 09:14pm PT
|
Clove hitches? The concern I have is with belayers who are tied in solely using clove hitches. There may be times - experienced party, alpinism, avoiding knots freezing up while ice climbing - when it's appropriate, but not as a general rule. Not for those getting started, anyway, given the propensity of clove hitches to loosen themselves.
As for the discussion generally, it may be an illustration of the principle that the perfect can sometimes be the enemy of the good. Encouraging those who are learning to climb to create "perfect" belays obscures the fact that there is no such thing as a perfect belay, or perfect belay chain - the latter being often more the issue, those critical first few pieces of protection off the belay. In turn obscuring that there is always both objective and subjective risk in climbing. Better have that out in the open.
And it's impracticable for anyone, let alone novices, to create a perfect belay. Not in the real world, anyway.
There's no such thing as safe climbing, only safer climbing, with judgment always being critical. If people start to think that climbing is or should be safe, it can easily lead to other expectations, e.g. regarding fixed anchors. After all, if it's an effort to learn how to create an acceptable belay using natural anchors, and they (horror!) sometimes fail, shouldn't there just be bolt belays everywhere? A steep and slippery slope.
|
|
rockermike
Mountain climber
|
|
|
Nov 24, 2008 - 09:47pm PT
|
It took me years to change from jerry rigged rope and sling anchors to a cordelette. I think I for one am too old to learn another new trick. My rule of thumb; just make sure all 3 pieces are bomber, throw on a cordelette and be done with it.
But, just for the sake of discussion, how about cordelette or web-elette, with NO knot. Totally equalized; Then back up each leg with ultralight 8mm dynamic slings. Tied off to roughly right length but with enough slack to allow equalization of main sling, but not long enough to allow shock. Those slings are damn light these days. Just a couple of extra ounces of cord to carry. No shock; redundancy; equalization, you get it all.
|
|
rgold
Trad climber
Poughkeepsie, NY
|
|
|
Nov 24, 2008 - 11:23pm PT
|
Dana,
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.
|
|
Inner City
Trad climber
East Bay
|
|
|
Nov 24, 2008 - 11:41pm PT
|
Wow Mr. Gold, way to put a stamp on it. Your knowledge appears to outweigh the discussion in some way. I'm a 3 points of contact former weekender, but I can tell someone who seems to really know what they're saying.....can't I?
How many K were in that plane that fell in upper Merced Lake?
|
|
Ben Harland
Social climber
Baltimore, MD
|
|
|
Nov 25, 2008 - 02:55am PT
|
By my calculation, we have
a) cordalette
- loop cord around three pieces and tie a knot
- not great equalisation
b) equalette
- loop one end of cord
- tie two clove hitches (only one needs to be carefully placed)
- good equalisation
Extension is the same. I go b. What am I missing?
|
|
tito
climber
|
|
|
Nov 25, 2008 - 04:58am PT
|
> 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 [through] the
> anchor is 6.8 kN.
6.8 kN? Isn't the question: what force on the climber's side of the anchor is necessary to generate 4 kN on the belayer's side of the anchor? When 4 kN is generated on the belayer's side of the anchor, then the belay device will start slipping.
4 kN = (.7)(X)
==> X = 5.7 kN
Therefore to get 4 kN on the belayers side, the climber needs to generate 5.7 kN on his side of the rope. So isn't the peak force on the anchor the sum of those forces:
4 kN + 5.7 kN = 9.7 kN
|
|
Peter
climber
|
|
|
Nov 25, 2008 - 05:03am PT
|
I used to use a cordolette and then a webolette fairly frquently. Now I only use them when climbing easyish routes where I'm going to be hauling up a new climber ie; toprope situation, and sometimes in alpine situations for slinging big features. Otherwise too slow to fold up, too lumpy on my harness. As of a year or two ago I always use the Metolius PAS with fall rated loops for myself and all my regular partners are also converts. Seemed silly expensive at first but it is incredibly versatile and fast. We keep the PAS girth hitched to our belay loops. Bang in a few pieces and clip them to the PAS with sling extensions if necessary, or clip the PAS to a bolted belay - You're done. Your partner can clip to your PAS to swap gear and then they're off.
|
|
TradIsGood
Chalkless climber
the Gunks end of the country
|
|
|
Nov 25, 2008 - 08:13am PT
|
rgold, that was thought-provoking analysis. Thanks.
It 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.
|
|
rgold
Trad climber
Poughkeepsie, NY
|
|
|
Nov 25, 2008 - 09:18am PT
|
Tito, thanks for spotting the error, which was in a paragraph I added as an afterthought late at night. I've edited the number in question and credited you for providing the correction.
|
|
Doug Robinson
Trad climber
Santa Cruz
|
|
|
Nov 25, 2008 - 10:11am PT
|
Rich, could you explain what you mean by "pulley effect"?
Re your break-even point, a good one: when leading off the belay, I always clip the highest piece, not the power point. Two advantages. One, it raises the break-even point, sometimes a lot. Two, it reduces the risk of catastrophic failure of the entire anchor.
So many dynamic slippages in a real-world belay, it would be instructive to plug a dynamometer onto that top piece and measure peak force. I'm guessing even in a max fall factor 1.7 situation, by the time the belayer is lifted off his footholds the peak force gets down around 3 Kn.
|
|
rgold
Trad climber
Poughkeepsie, NY
|
|
|
Nov 25, 2008 - 02:29pm PT
|
I'm concerned about hijacking Largo's thread with my response to Dana, since Largo is interested in hearing about the equalette, not this stuff.
So I'm going to hold any further replies for now. I don't have time today, but in a day or two I'll start a new thread and copy whatever comments are here over to that. If that thread then dies for lack of interest, so be it...
|
|
the Fet
Knackered climber
A bivy sack in the secret campground
|
|
|
Nov 25, 2008 - 03:06pm PT
|
Peter the PAS isn't dynamic like the lead rope. Using it to clip to the anchor increases the force considerably. You should always use the rope to connect the belayer to the anchor.
|
|
Mighty Hiker
Social climber
Vancouver, B.C.
|
|
|
Nov 25, 2008 - 03:10pm PT
|
After Obama is sworn in on January 20th, use of the equalette seems likely to rise. The "elite-ette" will no longer be an acceptable method of anchoring.
|
|
Victor
Trad climber
Sacramento, CA
|
|
|
Nov 26, 2008 - 12:22am PT
|
I've been using the equalette for over a year and I've come up with a variation that allows you to avoid using 2 carabiners at the "power point". I don't think I've seen this variation before so I'll post it here.
Here's a photo of it:
Here's a photo of the power point area:
The only difference is that there are 3 strands in the power point. This is done by making an 'S' with a strand of cordalette, then squishing the 'S' down where you find 3 strands overlap in the middle and 2 elsewhere. Tie a figure 8 at each side where there are 3 strands.
Some tips about tying this:
* make the sliding/power point section about 12in long
* one side should be longer than the other to allow for some versatility
I tie this once and leave the figure-8s in there. Easy to set up with three pieces. On one end (usually the short end) clip one piece in, on the other clove hitch two pieces. When you're done, clip into two of the three strands in the power point. In the worse case two of those pieces will be equalized.
And about tying in, I always tie in with the climbing rope. If you can't trust your rope why bother with anything else.
-Victor
|
|
tito
climber
|
|
|
Nov 26, 2008 - 02:26am PT
|
> Tito, thanks for spotting the error
> ...and credited you for providing the correction.
Totally unnecessary. Thank you for all your great posts on anchors here and elsewhere.
|
|
|
SuperTopo on the Web
|
Let us know!