Does the "magic x" make a daisy chain safe?

Instead of the loop in the video, I clove-hitch the 'biner to the end of my daisy. Problem solved, regardless of how many loops you clip or don't clip. The only challenge there is making sure it doesn't end up as a muenter instead.

That being said, the daisy is almost never my primary anchor. I like the safety of clove-hitching the rope to my master point. I usually give myself a decently long leash with the rope, and then I use the daisy as a quick-adjust so I can be comfortable and efficient at the belay.

Samuel Stone wrote:Will the "magic x" method from the video always work? or is there some way that it could fail?

In short:

• Without "magic X" those using daisy chain to attach to anchors will kill themselves.
• With "magic X" they will kill themselves and theirs climbing partners - static fall on an anchor is a big no-no.

how many folks here have taken a fall on static material?

how about one that is greater than FF1?

how about on gear?

raise yr hand if yr that stooooopeeed (hides)

theres alot of myths out there about it ... and that includes "official" tests from manufacturers and other such organizations

;)

Personally, I've never fallen off a stance with any kind of anchor fabric.

Here is a link to the lanyard tests BB mentioned: grimper.ca/escalade_montagn….

There is nothing there about the shock-absorbing effect of ripping pockets. The items quoted by BB refer to the reduction in strength of the entire sling after two pockets have been ripped out.

rgold wrote:Personally, I've never fallen off a stance with any kind of anchor fabric. Here is a link to the lanyard tests BB mentioned: grimper.ca/escalade_montagn…. There is nothing there about the shock-absorbing effect of ripping pockets. The items quoted by BB refer to the reduction in strength of the entire sling after two pockets have been ripped out.

note the fairly LOW impact forces on the daisies on FF2 drops on the first pic table i posted, without them breaking

dont believe a poor breeder of bears? ...

Another high force test consisted of fall factor 1 drops onto Spectra daisy chains. All of
these tests were conducted using Black Diamond ½” Dynex (Spectra with a small amount
of nylon) daisy chains. Some of the daisy chains were 55 in (140 cm) with 14 bartack
sets, and some were 45 in (115 cm) with 12 bartack sets; but in none of these drops did
all of the bartacks break (in which case we would expect a spike in the peak force). All
the daisies were manufactured with 2 tacks per bartack set (providing similar energy
absorption per bartack set). Figure 8 (vertical bar chart) shows that the peak forces vary
significantly even for a given type of load. The peak forces generated by the steel plates
are anywhere between 5% and 37% greater than the peak forces generated by the Rescue
Randy. The diamond markers in Figure 8 show the number of bartacks broken for the
five drops. Measured this way, the differences between the steel load and the Rescue
Randy are obvious: much more energy was absorbed by the many bartack failures during
the drops of steel weights (the energy being associated with not only the greater number
of bartacks broken, but also the larger total distance through which the load fell). In other
words, much more energy was absorbed by the Rescue Randy than by the steel plates,
indicating unrealistic results for tests with steel weights simulating drops with humans.



incidentally those kind fellows also say outright that ...

More significantly, for dropping onto highly static systems such as steel cable (Figures
3 and 5), or for dropping onto nonlinear systems such as Dynex (Spectra) daisy chains
(Figure 8) or Purcell prussiks (Figure 10), the use of a steel load can lead to significantly
unrealistic results (much higher peak loads, significantly more bartacks broken, very
different dynamics, etc.). In these tests, the use of steel loads may produce grossly
misleading results rather than just conservative (higher force) results. Although it adds
significant cost, realistic force data combined with adequate analysis (material strengths,
etc.) will lead to better system designs and operating procedures.


as i said many of these drop tests are pretty unrealistic

as to bar-tacks ... its not a question IF they absorb some force ... but rather how much and will it make a difference ... and i dont mean on unrealistic steel weights

i may think i am a "man of steel" (and da hawtays definitely agree) but thats a figurative matter of speech ... were just mostly WATAH

;)

PS ... i should probably be dead or paralyzed after taking a > FF1 fall on a sling ... instead i got a sore back for a week ... disapointing

Like I said - great troll.

Samuel Stone wrote:Will the "magic x" method from the video always work? or is there some way that it could fail?

Topologically the "magic X" equals to 2 clips. Clipping a pocket equals to 1 clip.

2 - 1 = 1.

2 + 1 = 3.

Never zero. So it would never unclip if clipped to one pocket.

BB, as I said, the first document has nothing in it that says ripping pockets reduces peak loads.

Frank, get ready for a real knee-slapper :)

The second document speaks of energy absorbtion but doesn't address how much. In any case, my point (not stated explicitly to spare the audience) is that I thought it unlikely that the net effect of ripping pockets would reduce the net potential energy to be absorbed, because of the extra drop that occurs each time the pocket stitching rips.

These thoughts we based on BD (and others) 3 kN rating for their pockets. But it seems the pockets could perhaps withstand three times that load, which changes the estimation but still doesn’t suggest any benefit. Here is some back-of-the-envelope arithmetic.

Let's say the falling climber is Rescue-Randy weight, 165 lbs, and the pocket size is 3 inches. If stitching fails, the 165 lb weight falls 3 inches and so adds 41.25 ft-lbs to the total potential energy that will have to be absorbed by the system.

Suppose the two-tack stitching breaks at r lbs. The two tacks take up about 1/4 inch of space; it is an over-estimate to assume that over that 1/4 inch the resistance is always r lbs, but let's make that assumption anyway. Then the work done in breaking those tacks is r/48 ft-lbs. This has to be bigger than 41.25, otherwise there is a net increase in potential energy that the system will have to absorb and so a higher peak load. Setting r/48 equal to 41.25 and solving gives r=1897.5 ft-lbs or 8.44 kN.

So those double bar tacks between pockets have to have a breaking strength above 8 kN in order for ripping them to provide any reduction in peak load for a 165 lb faller.

Black Diamond rates its pocket strength at 3 kN which is way below the 8 kN break-even threshold given above. If true, ripping those pockets would certainly increase the peak load in it would surely be misleading to speak of some energy-absorbing benefit. This was the basis for my original comment.

The RMRG paper, with the intervening effect of R-R, is certainly not a way to ascertain whether or not there is a peak load reduction effect from ripping daisy pockets. And unfortunately, they don't indicate how the pockets were clipped. Nonetheless, the numbers there are surprising compared to BD's pocket ratings. One R-R drop test broke no pockets while peaking at 2004 lbf or 8.9 kN. The other broke one pocket while peaking at 2182 lbf or 9.7 kN. So in these tests, the pockets appear to be breaking at something just a bit over 2000 lbf.

There is some other evidence out there that these pocket values might be true; see onrope1.com/GearDaisy.htm, in which single bartacks in nylon daisy's broke during slow-pull testing at around 9 kN. I have no idea how much variation there is in bar tack strength, whether the material being stitched (nylon or dyneema) makes a difference, and what the differences between slow-pull and rapid-loading loads are.

If we take 9 kN or 2023 lbf as the pocket-breaking number, then our 165 pound faller gets a very small benefit from ripping pockets, as the system absorbs 42.15 ft-lbs while losing 41.25, for a net absorbtion of about 0.9 ft-lbs per blown pocket. I think this is still going to be a wash in terms of any significant peak load reduction, and even this small effect will vanish if a nice plump UIAA standard 180 lb climber takes the plunge.

bearbreeder wrote:...PS ... i should probably be dead or paralyzed after taking a > FF1 fall on a sling ... instead i got a sore back for a week ... disapointing

I have nylon daisies because I expect one day I'll accidently ~FF1 onto one.

One wonders, of all the people on aid who have fallen onto their daisies, how many have broke? (I'd be quite curious to know the experiences of people with dyneema daisies)

rgold wrote:BB, as I said, the first document has nothing in it that says ripping pockets reduces peak loads. Frank, get ready for a real knee-slapper :) The second document speaks of energy absorbtion but doesn't address how much. In any case, my point (not stated explicitly to spare the audience) is that I thought it unlikely that the net effect of ripping pockets would reduce the net potential energy to be absorbed, because of the extra drop that occurs each time the pocket stitching rips. These thoughts we based on BD (and others) 3 kN rating for their pockets. But it seems the pockets could perhaps withstand three times that load, which changes the estimation but still doesn’t suggest any benefit. Here is some back-of-the-envelope arithmetic. Let's say the falling climber is Rescue-Randy weight, 165 lbs, and the pocket size is 3 inches. If stitching fails, the 165 lb weight falls 3 inches and so adds 41.25 ft-lbs to the total potential energy that will have to be absorbed by the system. Suppose the two-tack stitching breaks at r lbs. The two tacks take up about 1/4 inch of space; it is an over-estimate to assume that over that 1/4 inch the resistance is always r lbs, but let's make that assumption anyway. Then the work done in breaking those tacks is r/48 ft-lbs. This has to be bigger than 41.25, otherwise there is a net increase in potential energy that the system will have to absorb and so a higher peak load. Setting r/48 equal to 41.25 and solving gives r=1897.5 ft-lbs or 8.44 kN. So those double bar tacks between pockets have to have a breaking strength above 8 kN in order for ripping them to provide any reduction in peak load for a 165 lb faller. Black Diamond rates its pocket strength at 3 kN which is way below the 8 kN break-even threshold given above. If true, ripping those pockets would certainly increase the peak load in it would surely be misleading to speak of some energy-absorbing benefit. This was the basis for my original comment. The RMRG paper, with the intervening effect of R-R, is certainly not a way to ascertain whether or not there is a peak load reduction effect from ripping daisy pockets. And unfortunately, they don't indicate how the pockets were clipped. Nonetheless, the numbers there are surprising compared to BD's pocket ratings. One R-R drop test broke no pockets while peaking at 2004 lbf or 8.9 kN. The other broke one pocket while peaking at 2182 lbf or 9.7 kN. So in these tests, the pockets appear to be breaking at something just a bit over 2000 lbf. There is some other evidence out there that these pocket values might be true; see onrope1.com/GearDaisy.htm, in which single bartacks in nylon daisy's broke during slow-pull testing at around 9 kN. I have no idea how much variation there is in bar tack strength, whether the material being stitched (nylon or dyneema) makes a difference, and what the differences between slow-pull and rapid-loading loads are. If we take 9 kN or 2023 lbf as the pocket-breaking number, then our 165 pound faller gets a very small benefit from ripping pockets, as the system absorbs 42.15 ft-lbs while losing 41.25, for a net absorbtion of about 0.9 ft-lbs per blown pocket. I think this is still going to be a wash in terms of any significant peak load reduction, and even this small effect will vanish if a nice plump UIAA standard 180 lb climber takes the plunge.

a drop test from CAMP with a harness and dummy in the system ...

To simulate this configuration the CAMP laboratory used a CAMP Dyneema daisy chain and a CAMP Cream Ale harness with a free fall tower and 80kg dummy (Photo 8). The goal was to test a fall factor two at a height of 70cm above the anchor. The theoretical drop height is 70 + 70 = 140cm. But because all pockets on the daisy chain break, the real drop height is 190cm (Photo 9). The maximum registered strength is 4.73 kN. When clipped to an anchor with a daisy, you must never climb above the anchor.

When your harness attachment point is above the daisy chain anchor, if you fall, you break the pocket with two possible outcomes:
1. The karabiner is clipped as shown in Photo 7; all pockets break and you are terrified but still alive and in one piece.
2. The karabiner is clipped into more than one pocket at a time as shown in Photo 8. The bar-tacks between the pockets fail under load and you go to the ground a bit faster than you envisaged! This scenario could occur when any two pockets are connected to a single karabiner.

web.archive.org/web/2010120…

end of story ... the R&I article by mister duane is not "incorrect" in stating that the ripping of pockets MAY reduce the impact force ...

~5 KN is MUCH below what folks have been screaming about (15-20 KN) you can expect on slings and daisies, this matches up with the tests i posted before where the daisy drops had MUCH less impact force than one would expect from a sling on FF2 ... because the pockets bar tacks rip

remember that humans are NOT steel weights

r m wrote: I have nylon daisies because I expect one day I'll accidently ~FF1 onto one. One wonders, of all the people on aid who have fallen onto their daisies, how many have broke? (I'd be quite curious to know the experiences of people with dyneema daisies)

as the rocky mountain rescue group said ... steel weight testing on some things leads to misleading conclusions

one should try never to fall on sewn static materials of course .... and there have been deaths from knotted dyneema (which is why the dynaconnect was invented) ... but a nylon daisy is not the death sentence or instant paraplegic that da intrawebz make it out to be if you use it properly

in fact in such a stupid fall a nylon daisy may well be "safer" than a PAS

all of this is pretty stupid of course ... if you expect to take a fall above the anchors use a rope, or a dynamic tether ... trust me you dont want a sore back and whiplash for a week

thats all there is to it

;)

To recap on the posted material:

(For the third time) The first paper says nothing about breaking pockets reducing peak impact. Moreover, there is no evidence for it in the table cited by BB, in which the daisy's fail at the same or higher loads than the other slings (all of which have been knotted in the middle, by the way), and no mention is made of the tests in those tables being rigged to break pockets. When the pockets are tested in that paper, the only observation is about the reduction in total sling strength after the pockets have ripped.

The second paper says that breaking pockets absorbs fall energy (true as far as it goes), but they don't coordinate that with the added potential energy that occurs because the fall is lengthened. Their numbers are "interesting" in that they involve very high pocket-breaking thresholds, three times the manufacturer's rating, and the effect of a Rescue Randy dummy on everything makes comparisons unclear. The only conclusion I can see is that R-R reduced the peak load below the pocket-breaking threshold, so no pockets broke. The steel weights imposed loads above the pocket-breaking threshold and broke a lot of pockets. There is no evidence for what would have happened if the pockets hadn't been involved at all and so no way to compare the effect of pockets breaking.

BB's latest reference says nothing about pocket-breaking reducing peak load. But it gives a peak load for a FF2 fall that is indeed quite low for this type of test and could be taken as evidence for effective load absorbtion as BB says. The problem with this is the quoted peak load is below the value they quote for breaking pockets (which at 5.36 kN is itself well below the 9 kN value suggested by the second paper and the link I posted). Since the maximum load reported is below the pocket-breaking threshold, no pockets should have broken in their tests, while they suggest that every pocket broke. This glaring inconsistency suggests some kind of reporting or translating error. The likelihood of the 4.73 kN peak force being an error is compounded by looking at the tests in the second paper, in which a far less severe fall (FF1 not FF2) with a rescue dummy and pocket-breaking enabled produced peak loads over 9 kN, more than double the observed value for a far more severe fall in the third paper. Something does not add up here.

I'm perfectly happy to give up my conclusion that busting pockets won't reduce peak loads and is in fact likely to increase them, but I have yet to see any believable evidence for it in the three references, and no one has pointed out any errors in my analysis. We are left with the extremely simple high-school physics argument I gave that suggests either no effect or a negative effect of pocket-breaking, and three references, two of which do not suggest otherwise and one of which is both internally and externally inconsistent.

A way to argue against what I've said would be to suggest that some energy that I haven't accounted for goes into breaking those tacks, say in the actual pre-break stretching of the threads and the production of heat. Google "tearing energy" and "fracture energy" to get started on that rejoinder. On the other hand, I have overestimated the work done by ripping tacks by assuming the resisting force of the bar tacks remains constant in between the bar tacks. These are engineering considerations beyond my pay grade as a simple (non-applied) mathematician; perhaps Jim Titt would be able to cast some light on this.

And of course maybe someone has done some tests whose explicit purpose is to uncover the energy-absorbing properties of breaking daisy pockets. Given the trouble people have had in demonstrating that screamers have any substantial effect, this doesn't seem likely to me, but I'd be happy to be surprised.

In the meantime, the information BB has posted and the arguments I've advanced are complex enough to demand a retraction from about my remark that "Duane should know better." As far as I can tell, he's still wrong, but the issue does not seem to be as clear-cut as I suggested.

The bottom line is that a nylon daisy used properly wont kill you

Its no worse than a nylon sling

Just clove the end or do as the vid suggested

The fear with daisies is overblown on da intrawebz ... Just know what yr doing

;)

Why not just use the rope, has every one forgot how to tie a clove hitch?

that guy named seb wrote:Why not just use the rope, has every one forgot how to tie a clove hitch?

You set up multiple rappels by cloving the rope???

Sweet !!!

;)

bearbreeder wrote: You set up multiple rappels by cloving the rope??? Sweet !!! ;)

No i just improvise, I only carry alpine draws so i all ways have slings.

that guy named seb wrote: No i just improvise, I only carry alpine draws so i all ways have slings.

Darn stoooopeeed gumbayz ... Using purcells, PASes and daisies

Y kant dey b az kool n hardkore az miii

;)

From ecole national des sport de montagnes ... They just put out a new timely vid

They state specifically that the breaking of pockets in a daisy does reduce the force ... And that certain dedicated PAS style full strength pockets can be LESS safe

youtube.com/watch?v=DpWKrgh…

The best of course is a dynamic tether

;)

Very interesting BB!

The video represents a different test than the type I analyzed. I assumed the climber had clipped into a high pocket and the clipping biner ripped through the pockets one by one until it blew all of them out. This meant that every time the bar tacks blew, the climber dropped the length of the next pocket. This is in addition to any stretching of the daisy chain as a whole.

In the ENSA test, the weight falls on the full length of the daisy chain, i.e. the chain hasn't been clipped short. As the daisy chain stretches, the pockets blow (interesting mechanism for this...), but the destruction of the pockets doesn't lead to any further dropping of the climber. What you have essentially is two different lengths of material, and the longer length (the pocket strand) isn't activated until the shorter length has been stretched to the length of the longer strand and has absorbed some of the fall energy. This is a completely different situation in terms of the energy involved and does indeed appear to have load-absorbing results of the sort you've claimed.

The thing is, most people shorten their daisy chains---that's sorta the whole point of all those pockets, right? We still don't know whether blowing the pockets in this case will lower the peak load!

To be blunt again ... It really doesnt matter except as MP arguments

Perhaps they do, perhaps they dont ... But a nylon daisy wont fail any worse than a nylon sling if clipped properly ...

Whats interesting is that certain PASes can be LESS "safe" than even a nylon daisy

The wonders of marketing !!!

If one is worried about deadly dyneema fallz, just make a tether out of dynamic rope

Hell you could probably belay off that too

;)

Marc801 wrote: This. In 43 yrs of climbing, the only times I've ever used a daisy chain was on aid routes.

Nine times out of ten, when I see a climber with a daisy it's a sport climber who uses it to tie into the anchor after finishing a route. If someone is at a crag and they have a daisy, it's probably not being used for aid climbing.