Euro Death Knot, Flat Overhand, Barrel Knot evolution

20 kN wrote: Do you have a link to the testing?

unfortunately no. it was done at the petzl facility during the annual AMGA meeting---so several tests done, but not in a structured way. Dylan Taylor conducted them---they tested the flat overhand connecting cords of similar diameter, differing diameters, etc (among other stuff like an equivocation hitch, purcell prussiks, etc)....and it was all communicated via the AmGA members forum on FB...so not exactly rigorous science!

that said, the flat overhand rolled at forces much, much higher (12kn if memory serves) than climbers can generate rappelling...and it rolled slightly higher when tied with cords of different diameters...notably the flat 8 also rolled/failed at forces pretty high...

as long as the flat overhand had long tails, cinched tied, dressed properly (as in the strands ran parallel in the knot, not all wonky and criss-crossed), the thing was more than adequate for rappelling....

Rigging for Rescue has also tested a bunch of this stuff and i know some of their testing is on their site....worth a look?

i'll try and dig later--i'm going skiing! RC

JaredG wrote: "much less likely to get hung up in cracks and on edges." Has there ever been any data to support this claim?

Yes, see bwrs.org.au/sites/default/i…. One of the conclusions that is rarely cited but deserves mention is that the EDK's ability to run over features makes it easier to pull rappels tied with the EDK vs. say, a double fishermans.

Given its usage around the world, the EDK might be the most tested rappelling knot ever. But when it comes to lab testing the situation is a bit murky. Different testers have obtained different results, although the preponderance of evidence favors the EDK over the flat-8. But some recent French tests suggest the much-maligned flat figure-eight might be better, in spite of other tests (like Moyers) and field incidents like the Zion tragedy a few years ago that suggest the flat figure eight can roll dangerously. Meanwhile, tests by the DAV prefer the classical EDK.

A possible problem with pull tests is that they but may or may not model different rope types and realistic rappelling loads well, especially when the loading rate imposed by the testing apparatus is relatively high, as it is in the French tests.

In France at least, the flat figure-eight is not viewed with the suspicion we've acquired over here, and the knot appears in some publications alongside the classic EDK with no indication of preference or contraindications.

Since flat-8 use in Europe seems to be more prevalent than over here, we don't know when we hear about a failure in Europe, like the one cited by Donahue, whether it was an EDK failure or a flat-eight failure, so we don't know whether the failure constitutes evidence for or against the EDK as an alternative.

As for tying under stress, nothing is simpler than a single flat overhand, and the idea that the stressed climber will be unable to pull on four strands to tighten up the knot seems like a stretch to me.

The thing we all should have learned from the flat-8 issues is that just because a knot seems as if it ought to be better doesn't mean it is better or even acceptable---failure modes might occur that are unanticipated. So recommending a new knot without accompanying pull tests, done at least to the Moyers standard, is verging on irresponsible.

But sadly, variations in the pull tests themselves leaves us with a certain irreducible amount of uncertainty. Moreover, the fact that this or that organization is recommending a knot cannot be taken as the last word. Remember that the AMGA had the flat-8 in one of its manuals for a while, and the Ecole Nationale de Ski et d'Alpinism either recommends the flat-8 or at least considers it fully acceptable and has pull tests to back up their position.

This leave the poor climber rather in the dark, but as I said at the outset, the classical EDK is probably the most practically tested knot ever.

Personally, I've been using the EDK with a single overhand backup tied with just one of the two tails, chosen to be the tail that will choke off the rolling failure mode, as this option is much less bulky than doubling up on the overhand.

Speaking of ropes of unequal diameter, there is a right and wrong way to tie the EDK for such situations, so reports of the EDK doing better or worse with unequal diameter ropes that don't reference the tying orientation of the knot are worthless, and one has to wonder if the testers are even aware of the fact that there are two distinct ways to tie the knot.

rgold wrote: ...there is a right and wrong way to tie the EDK for such situations, so reports of the EDK doing better or worse with unequal diameter ropes that don't reference the tying orientation of the knot are worthless, and one has to wonder if the testers are even aware of the fact that there are two distinct ways to tie the knot.

Care to elaborate? I don't use the EDK for rappels, so I've never dug into the details of it. This is the first I've heard of there being different ways to tie it for ropes of different diameter. I'd be interested to learn more if you can point me to some info on this.

Pnelson wrote:Does anyone know the details of the Austrian guide death involving the flat overhand knot? What the circumstances, rope types, etc. were?

Topher, it seems you must know the details of the accident you cited, as it had a powerful enough impact on you to cause you to not only reevaluate your own rappel knot practice, but to feel strongly that no climber should ever use a flat overhand again.

It seems many here (myself included) are unconvinced, perhaps it would help if you share with us the details of the situation that so strongly convinced you?

Sounds like user error more than something inherently wrong with an EDK. If they didn't tie a flat overhand and set it properly, then they didn't have any kind of a knot to argue about.

Rich -- This is what he's talking about (go about half-way down the page to see the pics):

mountainproject.com/v/joini…

It's still a stretch to say "bad" on a rap that you'd roll out the knot, maybe a rescue load that takes a hit, but on a rap you're just not going to have enough to roll it out in either orientation. I would offer "adequate" and "better" -- similar to comparing a v-thread and a-thread, they both work for the intended application, but the a-thread is a better orientation.

Buff Johnson wrote:Rich -- This is what he's talking about ...

Interesting. Thanks Mark/Buff! Hope you're doing well!

Two EDK's with a foot of tail....

Always used the EDK. Always with a foot or more of tail. And sometimes with a second EDK. Never had an EDK fail. Never known anyone personally to have an EDK fail. All the people and organizations I respect encourage the EDK.

So, I'd like to see the lab and field tests results on this first before I'd consider making a switch.

calebmmallory wrote:Two EDK's with a foot of tail....

Why two? it seems this would make it a higher profile knot more likely to snag on features? All the testing data shows that an EDK won't roll under forces generated from a rappel. Hell, I doubt most lead falls could generate enough force to roll an EDK.

Regarding tag lines:

That quote from Dale Remsberg, AMGA Technical Director, was from a Facebook post and subsequent thread. During that thread, the new tag lines on the market are referenced elsewhere. Those lines would be options like the new Petzl RAD Line. Specifically, with the RAD line, Petzl states that the flat overhand is adequate, but with that particular line, the flat 8 is actually stronger. See:

petzl.com/NL/en/Sport/RAD-L…

Also this, just recently from Dale, who is currently at the IFMGA annual meeting (the International Federation of Mountain Guides' Associations, of which the AMGA and ACMG are a part) where he spoke with the ACMG Technical Director, Marc Piché:

"I talked with the ACMG and they are fine with the flat overhand and feel like things were taken out of context. They are recommending that Topher take out the picture with a line through the Flat Overhand in the next addition [sic] [of the book]. They recommended that the Double Over Hand (what is being referred to as Barrel) be used in high load situations like rescue."

This topic does seem to be something of a dead horse, though I find it interesting to hear what people's preferences are and their reasons for them. Personally, I've always used a double fisherman's. I'm curious as to some of the earlier posters comments about the note being untested though. Anyone who used perlon threaded stoppers and hexes used a double fisherman's/barrel knots for years without failure. Perhaps I'm not understanding the issue, but how would using them to tie ropes together for a rap be any different?

Fat Dad wrote:This topic does seem to be something of a dead horse, though I find it interesting to hear what people's preferences are and their reasons for them. Personally, I've always used a double fisherman's. I'm curious as to some of the earlier posters comments about the note being untested though. Anyone who used perlon threaded stoppers and hexes used a double fisherman's/barrel knots for years without failure. Perhaps I'm not understanding the issue, but how would using them to tie ropes together for a rap be any different?

because the double fishy is a symmetrical knot, it is more likely to catch on a some feature than an EDK, whose asymmetrical profile allows it to roll over such features. Also, I hate untying a weighted double fishy

Eli, no, I get that argument, though in 30+ years of climbing, I can think of only one occasion had an issue with it, and even there any knot would have gotten stuck. To me the difficulty of untying isn't much of one at all, certainly not enough to make me abandon something that seems like a solid knot.

Rich Farnham wrote: Care to elaborate? I don't use the EDK for rappels, so I've never dug into the details of it. This is the first I've heard of there being different ways to tie it for ropes of different diameter. I'd be interested to learn more if you can point me to some info on this.

With different diameter ropes, the larger rope can roll over the smaller rope easier than vice versa. Think of a monster truck driving over a car and vice versa.

So, the smaller diameter rope should be towards the flat side of the knot, not the tail side.

Fat Dad wrote:This topic does seem to be something of a dead horse, though I find it interesting to hear what people's preferences are and their reasons for them. Personally, I've always used a double fisherman's. I'm curious as to some of the earlier posters comments about the note being untested though. Anyone who used perlon threaded stoppers and hexes used a double fisherman's/barrel knots for years without failure. Perhaps I'm not understanding the issue, but how would using them to tie ropes together for a rap be any different?

I think you're not understanding the issue (but who knows, maybe I'm not understanding your understanding).
I think from your post that you regard the double fisherman and barrel knot to be the same. They're not at all the same, any more so than the "flat figure-8" (i.e., the knot like the EDK, but tied with an eight instead of an overhand) and the "retraced figure-8" (i.e., the knot that is equivalent to the standard harness tie in). This is all a bit complicated because different people use different names for the same knot, and perhaps, even worse, may use the same name for different knots.

I don't think anyone has suggested that a double fisherman is unsuitable because it's untested. I think the suggestion was that the barrel knot may be unsafe because it's untested.

To my knowledge, people didn't tie threaded stoppers or hexes with a barrel knot, but maybe you do or did.

OK, so let me clarify, because it may be an issue of semantics. My 'understanding' (rightly or wrongly) of a double fisherman's knot is that it is a double barrel knot tied on two separate ends of rope that are tied with the end of the separate rope threaded through the knot. In other words, one half of a double fisherman's is the same as a double barrel. I guess double fisherman's would be a more accurate description of what I'm thinking of. However, that's the only know I can see Topher referring to, and it appears to be what's in his photo.

Fat Dad,
While there is some similarities the double fisherman's is a very different knot then the Barrel Knot.
The double fisherman's is tied one side at a time and is "in-line" and the Barrel Knot is tied both strands together and is "flat". These will behave very differently under load.

OK, now I got it. You're right, that's a very different knot.

eli poss wrote: Why two? it seems this would make it a higher profile knot more likely to snag on features? All the testing data shows that an EDK won't roll under forces generated from a rappel. Hell, I doubt most lead falls could generate enough force to roll an EDK.

From all the IFMG guides and professionals I've climbed with and been mentored by, they've all recommended two. I normally just use one, but for the sake of being extremely safe (which I'm guessing is the purpose of this thread?) I just thought I'd give my take on what is the fastest, simplest, safest, method.

Rich Farnham wrote: Hope you're doing well!

All good, and you too! Off topic, but the ICAR this year had a great rundown of litter rigging comparison in video. Obviously, we knew what we were doing all along, good to see other science backing it up.