Rope Access: Is the death knot a myth???
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- čas přidán 7. 07. 2024
- Mikey Stevenson and I collaborated to learn more about the scaffold knot which is commonly used in the rope access industrial world. It cinches up against the carabiner to make a knot with a lower profile and it holds the carabiner in place. We also use it in highlining on some leash rings that are designed as thimbles.
We tested it tied normal of course but also the tail strand put in between the loop. It had no effect on how the rope functioned or its strength. We also tied it wrong so you have to pull the tail to cinch it up, which means the tail becomes loose if you weight it, pulling it undone completely which is how it got the clever name - The Death Knot.
What happens is the death knot, if pulled tight before testing, has the tail side trying to get pulled out at the same time the load strand side is cinching up and squeezing the tail. In all three of our tests, the rope broke at almost full strength and did not slip. THE DEATH KNOT IS STILL DANGEROUS but it is interesting how it works. At the very end (after the jingle), we demonstrate how it can fail easily.
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Our break test were done with a new 10mm static climbing rope
Test 1: 8 to 8 - 18.80kN
Test 2: Scaffold knot #1- 20.80kN
Test 3: Scaffold knot #2 - 18.90kN
Test 4: Scaffold knot variation #1 - 18.52kN
Test 5: Scaffold knot variation #2 - 18.42kN
Test 6: Death Knot #1 - no peak hold - strong!
Test 7: Death Knot #2 - 17.70kN
Test 8: Death Knot #3 - 15.56kN
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00:00 Intro by Mikey
00:42 What’s the Scaffold knot
02:10 How to tie it
04:04 Use in Rope Access
05:46 Other uses
07:18 First test 8 to 8
08:28 Scaffold knot tested
11:01 Variation tested
12:37 Death Knot tested
15:24 Conclusions
17:05 Last demonstration
Thank you Mikey for the collab - Go subscribe to him at czcams.com/channels/MRCmuFd696u78hyLkF9X_w.html
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The Scaffold Knot IS a type of noose. It's not a simple noose, and it's not a hangman's noose, but any loop knot which tightens when the standing end is pulled is a form of noose. (The Noose, or simple noose, has only a single overhand, a la the single Fisherman's knot).
Yes and alternatively noose knots are called running knots. Such as a running bowline.
@@russellwalker3830 Running knots are a subset. Specifically, they're knots formed by tying a fixed loop loosely around the standing part. Nooses that aren't running knots can be thought of as sliding hitches tied around the standing part.
@@PeregrineBF That makes perfect sense. I stand corrected.
In my defense though several sites do seem to refer to common noose knots as running knots. Wikipedia even has a category page on running knots which includes these. And Ashley's book of knots doesn't seem to define a running knot other than the instance of the running bowline.
But if there are loops which tighten and loops which are fixed then a noose is indeed is a sliding loop where the rope is hitched around its standing part and a running knot is a fixed loop tied around its standing part.
@@russellwalker3830 Not quite what I meant. Running knots are nooses, but not every noose is a running knot. Just like how all bicycles are vehicles, but not every vehicle is a bycicle.
@@russellwalker3830 yeah i know im late to the party but this is just getting into semantics at this point because a running bowline would definetly work as a noose
the death in death knot for me is not "will the knot kill you", it's more "the lack of awareness and competence will.."
keep up the channel guys, it's great.
I worked in roped access back in the 90s (it was stop and shunt in those days, IRATA) and we only used figure 8 on cowstail (and fig 9 + butterfly hitch, or bunny knots for rigging. Never scaffold) because you couldn't get it wrong and easy to check. A big elastic band keeps the carabineer tight on cowstail. The term "Cow's tail" comes from French (queue de vache) and cavers like Ferdinand Petzl
I love your testing and enjoying your presentation. In this video you demonstrated tying a triple overhand noose knot. A scaffold or double overhand noose knot only has two parallel bands of rope. Yours has three parallel bands. Look at Mikey’s knots that he holds up and you will only see two parallel bands of rope around the main rope.
I'm doing rope access right now and a lot has stayed the same! Although figure 8 is considered just as good as 9 on anchors now.
Keep expanding towards rope access community, it will grow your audience. Also expand to audiences and snap their shit too.
bro i just sit at home 24/7 and I'm addicted to this channel
In RA we typically only do 2 wraps whereas you tested with 3 wraps. Curious how the death knot would fair with only 2 wraps. Thanks for the interesting content.
@Flying C Land double overhand noose as well
The death knot numbers are among the most surprising test results I've ever seen! I didn't even understand why you were taking it to slack snap. I was sure it wouldn't hold more than 1KN.
I think the problem with the death knot isnt how much it holds but when its loaded only slighty (read human weight). It will keep slipping cause it never will get tight enugh
@@jonas-om3th there have been plenty of knots that have been shown to keep slipping and slipping on the slack snap. The slack snap only increases force when the knot starts binding, if it slipped at 1kn as you claim it would never get past 1kn load. I think there is something to be said for potential dangers for low load cyclic loading which I wish they tested, but for most applications this knot won't be seeing cyclic loading (maybe in a rescue?)
@@sebastianflynn1746 it slips slow enough that the higher load can restrict slippage. Maintaining a 1kN or lower tension, it would continue to slip slowly.
You should try the death knot with only 3" of tail on the end. No one works with 2' of tail hanging out of their knot. There may be a slighy different outcome because it looks like the tail is getting shorter as you pull on it until the is until the wraps cinch down on it. Rope access program manager here.
"Get a guard protection, Ryan!" - Ryan
+100. Eye protection at least. Dust/Fragments can fly at very high speeds.
I'm very excited to see this one redone on the drop tower! It might take a few tries to get one that doesn't cinch up, but I think you might get a pull though.
Seconded^^^
I'm a professional tree climber which is somewhere between rope access and rope soloing. Been a fan of the channel for a while thanks for the content. I use the anchor bend for terminating my lines on carabiners, any chance you can or maybe already have tested this knot. Also requesting anything else from the arborist rope access side you could test would be interesting i.e. sheet bend and double sheet bend, or Yosemite bowline vs bowline vs double fisherman. Thanks
The Anchor Bend is my choice, as well...
The danger of the "death" knot comes from it's use as a positional strop. They don't get loaded up properly so the knot never sinches down especially on tougher/older or static rope. In rope access the equipment shouldn't experience fall forces like rock climbing so it works its way out and when you do load it it's only with body weight.
Would love to see the death knot on the drop tower to see what the shock loading does! Wonderful video as always.
Great tip I use that knot daily in tree climbing, tree work in general super easy to mess up thank you shining light on this
"Caving industry"
Can't help but crack up at that...
Yeah, I wondered too. Maybe they are finding diamonds down there and they don’t tell us about it? 😁
Happy to see my boy Mikey up there!
I can imagine that some knots may be more vulnerable to very quick and high loads (as in a fall). In the test of the death knot it was quite clear that the slow pull made the knot tighten up and squeeze the tail so it couldn't go through, maybe in a fall situation there would be a different outcome, especially if it isn't very tight to start with.
I was thinking the same thing, I'd love to see this tested with different lubricants, or even mud. Is there any static coefficient of friction low enough that this would slip through?
I use the scaff knot both in caving and RA, so it's great to see what they're capable of.
Great video, very informative. Keep up the good work
Found this super interesting! I've been using the scaffold knot for over 10 years, mainly as a cow tail and often been questioned about it's strength and reliability.
I am a big fan of these tests.
The proper scaffold knot is a badass knot. This definitely improves my head game.
I call that a triple fishermans knot. I do a varient called the double fishermans with only 2 raps instead of 3. It's like the reef knot where people call it different things.
The fisherman's wether loop or bend is typically two counter overhand (single-triple) ABOK 1038, 1143, 1414, 1415
Much appreciated video from a long time viewer of both you guys!! -IRATA tech in Ontario
if you add a stoper knot on the other side of the death knot then you efectivly making a double fisherman loop knot. it could be nice to try it vs figure 8 knot
That would represent a Double overhand on a bight…though he is tying a triple overhand so, a Triple overhand on a bight.
At 71, I'm not a climber, but I love to study knots, especially to understand how their internal structure affects their ultimate strength. Hence, I LOVE YOUR VIDEOS.
You are, (or have), a very good camera operator/director/editor! The live close-ups of the tests show all the interesting parts of each, and your comments are always to the point. (By the way, when you said, "I'm just making you dizzy," while fussing with the camera, I had to laugh... because you WERE!)
Anyway, here's my two cents. Since you seem, here, to be getting a lot of rope breaks AT the carabiner, then maybe using TWO-LOOPS around the carabiner would reduce the stress on the rope at that point, (kind of like the double loops in an anchor bend).
Frankly, I think it's instructive that the sharp "nip" that a rope makes, around a carabiner, represents its OWN weak point, regardless of the knot being tested.
Anyway, great video. Please keep 'em coming!
Can you guys test a “home made” Kong Slyde style adjustable PAS? With a recommended 9mm dynamic rope? (Triple rated ideally, which most people try to use)
I just find it funny that since getting back from caving your videos seemed to appear on my recommended
One for the algorithm; cheers Ryan
Holy shit! Mikey taught me my IRATA in AB Canada. That dude is awesome!
Great view of the knots being tied
Great Video guys, I have been watching how not to highline for a long time now and learned a ton from them. I have been watching Mikeys videos from the beginning and learned a ton as well. My brother loved working with Mikey. Would you be open to testing some of the anchors I use for temporary access?
Useful as ever, thanks!
Hey Ryan, fascinating videos, love them. Just wanted to say that a couple of 3-4 foot pieces of plexiglass sections hinged in the back (think top loading washing machine) and you would have a pretty cheap, easy, relatively safe gaurd/shield. Just a thought. Keep the content coming and be safe. .
Awesome info as always
This is an awesome test very interesting was wondering if you could test the double fisherman's version versus the triple fisherman's version that you showed in the video to see which one is stronger
We use them a lot in rope rescue to save room compared to a larger profile knot like a figure 8. A good example is the bridals attached to a stokes basket
It is called a scaffold knot because it it refers to a hangman's scaffold. So, you werent wrong, it is still used as a noose, it is just not the same as a noose knot.
Just comment for the algorithm!! Nice videos
I used to rely on Scaffold Knot + 2or 3 extra wraps around for extra shock absorption, but a rigger pointed out that the bend radius of the 12mm cow's tail I'm using with the carabiner is seriously loading the knot which could lead to failure so I'm now advocating for the use of thimbles at the end of each cow's tail.
Like your channel. Four thoughts:
1. If I understood correctly you used static rope. Wondering how dynamic rope would fair in same tests, especially as climbers would typically use a dynamic rope to reduce forces on the belay and on the individual (not that they use cow's tails much at all, if ever, nor the scaffold knot, at least to-date 2021).
2. It might be worth showing what happens to your 'death' version of the scaffold knot under a drop test. Though a part of me thinks, that while tests like this are interesting they may give some people the wrong idea!
3. It might be worth explaining that 'getting lucky' with the death knot is, in part, do to enthusiastically tightening the knot beforehand and then slowly loading it. An accident is more likely to happen when an individual mis-ties the scaffold knot and not notice, in this scenario they probably won't have hand tightened it to such an extent, thinking it not necessary.
4. It might be worth explaining the difference between your death knot in relation to the scaffold knot and the European death knot (as you know, an overhand knot variant, used by many, to abseil).
Hope useful. Be safe.
When you follow a figure 8 through, the loaded line needs to be towards the centre of the knot, this way when you load it, it stays dressed, and is easier to undo
The way to achieve this is to start following back through on the other side of the followed rope than you usually do (since we know that you are doing it the other way currently).
I'm not sure if this is true for both left and right hand versions or which version I usually tie, but for me, when starting to trace back instead of aiming at the big obvious hole in the first loop, I push the existing line into that space and thread the follow rope in the space created by pushing the other strand, in between it and the loop (this is the last step for the way you are currently tying it).
@@TheQuicksilver115 exactly.
I like how rope access and caving are both _industries,_ but slacklining and highlining are both just _communities._
Neat, thanks! Very cool to watch the knot slipping and the rope tightening around itself. I'd be interested to know more about tail length. You guys generally use huge tails(by my standards) in your testing. In most climbing, I try to minimise stuff hanging and flopping about, specifically tails. Any scenarios anybody can come up with where we can say how short of a tail is too short, in various scenarios?
Very nice - you've cleared up a few things. Have you ever tested the Double Bulin for traction?
Thank you for another great video!
When you are doing your tests, can you please say the brand of the rope and what its rated for?
I would like to see a water knot break tested in climbing webbing and an over hand with a second back up over hand break tested. I make top rope anchors on trees with webbing and I would like to know what the best way to create a loop in webbing is.
I wonder if the death knot would come undone under repeated cycles of light loading.
Fascinating
Nice shirt man!
This is the best type of episode. You take a practice (No Death Knots) that seems like common sense which rope access policy is based on and honestly it does not hold up to testing! The test shows the death knot is very safe for human loads. I am still not going to use it and this is great to know!
This is why I wanted to test these. I wanted to be dis-proved. I have been in the industry for 11 years and was always told this and the other thing. However, Always asked why or why not. Sadly Level 3s hate when Level 1s ask those kinds of questions.
Cheers Mikey
Please test a Prucell Prusik, it's a common use of personal anchor, I believe the most common it's using 6mm cordelette.
best Regards!
Interesting! Agree, a good drop tower repeat perhaps
You're not entirely wrong in calling it a noose, it's a kind of noose, just not The Noose. In the noose chapter in The Ashley Book of Knots he says:
"A Noose or snare, sometimes called a Running Knot, is a variety of Loop Knot that is tied in hand, and, when placed around an object, renders and constricts when the rope is pulled on"
And the Scofhold Knot is in that chapter.
I read a paper that said the scaffold hitch had better fall absorbing properties than the figure eight. This has enlightened me that it doesn't mean it's stronger.
These are two different things. ;)
Do this do that. Happy to help your digits
Just a guess, but I'm thinking it has the name cowtail simply from appearance. Cows have skinny tails with hair tufts at the end mimicking the rope and carabiner, that can basically spin around 360° and swat flies.
Would like to see how the knots behave in a shock loaded situation. As in bouncing down when descending.
Let's go! 2 loop-arounds vs 3 loop-arounds?
13
I really don’t think it makes a difference. I’ve done a handful of tests with the leash ring projects. They are all hard to untie either way and all hold.
Oooo more rope access plz
I don't even climb. But somehow love this channel
Ryan
Ryan
Ryan
Just LOVE your videos msn!
Can use the Death knot as a stopper knot with a quick release. Come down on the long tail, if you do hit the stop, it just gets tighter. After you're done, pull the short tail and it comes out. Can throw a biner in the loop just in case, but make sure people know it's not an attachment point.
Could you do a test of the zeppelin bend vs a double fisherman knot for joining two ropes?
We are finishing up a episode that includes those two bends. should be out in the next month or so.
I think the rope thickness and type might change the outcome too. Would be interested to find out.
This got me thinking... could the death knot with a stopper knot on the end of a long tail be used as an energy absorber?
Also I'd love to see the zeppelin bend in th slack snap rig.
Nice notice at the end. U r saving urself haha
We call it a barrel knot in the uk I’ve never had any issues with it or ever heard of any issues with it when used on cows tails. when you tie your new set of cows tails you always weight the knot as part of the tying process so the cows tails don’t change length on the first use
It's a scaffold knot mate. I usese them every day at work with my cowtails and safety for tools. A barrel knot is just a knot in a line, like a stopper knot.
Heya, I'm sure this is somewhere in the comments, but in Rope Access it's unlikely to have such a long tail below the knot. Generally it's taught that one fistlength or 10cm is the appropriate length of tail coming out of a knot when placed at the end of a rope. This may vary between different certifications, but I'm speaking as a level 3 SPRAT certified tech working out of Canada. I think with a shorter tail coming out, it's much more likely that the "Death Knot" may actually not have enough slack to tighten up the knot, and would come undone as a result. Especially if the knots were not dressed as tightly, which of course is extremely bad practice, but definitely a factor!
Regardless, the results here were very interesting, and not at all what I expected to see! Also, big fan of the channel. (:
Please test this in the droptower. What about a deathknot with a stopper on the tail for an adjustable lanyard or extra shockload protection?
Hi mate, I am an arborist and I use the scaffold with 4 reps, on my ropes. I'm interesting about does it make it stronger if you tie with more reps on it. It's really hard to tight it into the carabiner with 4 reps.
What about shock load. Will it untie with quick , sharpe loading?
So is there a difference between a shock load test vs slow pull? Nice vid!
We will have to wait and see...
you should own more subs
Would you ever consider using the scaffold knot to setup a single fixed line slung around something? I think it's kind of neat and easy to set up
Dont see the point.. I work in ropeaccess but only use it when i want to orient the biners in a fixed way or need to gett as close to the ancor as posible.
To add to what Niklas said. One the knot tightens down on whatever its going around... It can almost be impossible to untie. So, I cant see it being worth it.
It would be great if you could test it with a shock load test.. every ropes texture is different, some smooth, n some not.. also its size would play a role.. so doubt any of these results shouldn't be taken as a general rule..
The most precarious part of this vid is making sure that no one can refer to it as the reason they used a 'death knot' 😂
That's the same reason why there are no bad experience reports and reviews about skydiving ☠
Is bend radius a factor in death knot not failing? What if the death knot was tied on a leash ring?
As an arborist, I call that knot a doublefishermans knot. I use it to mke my own eye to eye prussik cords on my wirecore strops (workpositioning lanyard)
Also, I tie it with just two wraps around and then through.
At 17:00 I would like too see what would happen if you put a stopper knot on the tail end of the death knot and pulled it in the slack snap.
would become a double fisherman?
I was just thinking I was gonna mention the forces involved here and how dangerous those projectiles could be… but this guy ties himself to mountains and jumps of so 🤷♂️
How about a two wraps scaffolding knot, instead of three? Does it steel hold?
How about a death knot with a stopper knot on the tail? Kinda nice to have a loop on the end that doesn't sinch down for some uses
OK, to us laymen, if a body were to fall far enough to reach max speed which generally wouldn't happen in a fall. How many Kn does it take to break either a proper knot or the rope itself?
Are Palomar knots ever used in rope access or highline stuff?
Have you guys tested the Double Dragon Loop knot? I believe it to be one of the strongest knots.
Why it’s a death knot is there is a way to tie the scaffold by pushing a loop through, you just have to make sure it’s from the load side. Easily mixed up.
Just a thought... if you don’t pull it to max and actually pull the death knot at a consistent 1kn to 1.5kn would it come undone? On a personal anchor that’s all the force that will be on it. 20kn is not a force the death knot will ever see?
Thanks for the wonderful free subscription prize.
climbing/rope access really is all about mastering friction...
It would probably kill you (death knot) in rope access the first time you lean out to do work, please be careful out there. I've been in RA since early 2008 and want to keep doing the job I love safely 👍🏾😎 Pro tip from a friend, for your cow's tails tie them up and clip in on the ground pulling tight (body weight) on the scaf knots to seat them properly 💯
You could use an arborist positioning lanyard for your cow tail or personal anchor probably a little more expensive but you could have two rated sewn or spliced eyes and not have to tie any knots for example Yale blue moon or personally I like the petzl zillion but it’s expensive and I climb trees not rocks but love the vids tho
Try soaking the rope in water, pulling standard tight and using a rope with a finer outer sheath weave. Or just water and standard tight maybe???
Scaffold knot is in the noose chapter of the ABOK, p203. So kinda right? Thanks for testing the scaffold ( ABOK #1120 ). Would enjoy seeing how it compares to the gallows knot variation ( ABOK #1121)
ABOK = Ashley Book Of Knots
So there is more than one "death knot"? I thought this was going to be on the European Death Knot / the over hand bend...
EDK has been done
Interesting
FYI. At 2:24 that is not a fisherman's knot. That is a triple overhand. A fisherman's "bend" is used to tie two ropes together.
So a double/tripper stopper knot- on a bight?
Cows tail may come from bull boats? When the skin of a cow was used to make a coracle, the tail was left attached to the skin to use for tying boats together or to a mooring.
Could be. Maybe not. No googling here! Just a thought.
You should test the death knot as the safety and break something else to see if it passes a "drop test"
10:49 a wise man once told me to always be smart about doing stupid things