/ Clipping directly into an anchor with sling attached to harness

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Chris Sansum - on 07 Jan 2013
A few partners I have climbed with on multi-pitch routes seem to as standard attach themselves directly to the belay anchor with a sling, ie clipping the sling into their harness belay loop with a krab without using the rope in the system. This doesn't seem like best practice to me.

If I rig up an anchor using slings I always attach myself to the slings using the rope, rather than clipping the sling into my harness belay loop. My understanding is that this reduces shock-loading of the system.

Am I being over cautious? I realise that the rope knots (on harness and the one attached to the sling) tightening up reduce some of the force in the event of a fall. Why else would tying into the sling with the rope reduce the force on the anchor compared to clipping into the sling directly?
AdrianC - on 07 Jan 2013
In reply to Chris Sansum: If you search for threads about cow's tails it'll answer your questions pretty much.
drysori - on 07 Jan 2013
In reply to Chris Sansum:

I'd usually favour clove hitching my rope to the anchor, but there are situations where a sling would be useful. E.g. if you're swapping rope ends or multiple abs.

As long as there's no slack then you're fine. A few inches won't matter much, a few feet could kill you.
3 Names - on 07 Jan 2013
In reply to Chris Sansum:

Regardless of the slings on the belay, any fall will still be taken by the rope so shouldn't shock load the belay.
Sebastian Fontleroy - on 07 Jan 2013
In reply to Vince McNally:

He was talking about the rope not being in the system wasn't he?
3 Names - on 07 Jan 2013
In reply to Sebastian Fontleroy:

How would you shock load the system then?
3 Names - on 07 Jan 2013
In reply to Sebastian Fontleroy:

oh I see what you mean, yes he did say that but my point still remains. The only reason for the belay set up to be shock loaded would be caused by a fall, the force of which would be taken by the rope.
Sebastian Fontleroy - on 07 Jan 2013
In reply to Vince McNally:

By falling directly onto the sling that you're attached to that's attached directly to the anchor. I think that's what he's talking about. You could create a factor 2 fall on to a static (non dynamic) piece of gear.
3 Names - on 07 Jan 2013
In reply to Sebastian Fontleroy:


You would only do this by climbing above your anchors whilst still attached to the belay and then falling directly onto your belay, obviously something you would never do.
Sebastian Fontleroy - on 07 Jan 2013
In reply to Vince McNally:
> (In reply to Sebastian Fontleroy)
>
>
> You would only do this by climbing above your anchors whilst still attached to the belay and then falling directly onto your belay.

I know. Some people do walk around a belay looking for other anchors though. I gave the factor 2 as a worst case possibility.

3 Names - on 07 Jan 2013
In reply to Sebastian Fontleroy:

Yes but those people should still be on belay?
Sebastian Fontleroy - on 07 Jan 2013
In reply to Vince McNally:

If so they'll fall to the last placed piece of gear which may be a few metres below. Are you looking for an argument?
ledifer on 07 Jan 2013
In reply to Sebastian Fontleroy:
I don't think it's that far fetched, I have attached myself to the anchor directly with a sling many times.
Say I lead a route make an anchor, belay directly in guide mode and connect myself to the anchor with a 120 sling.
I then bring up my second who obviously strips all my gear. As it's a bit cramped I shimmy up a bit higher, slip and hey presto I've shock loaded the anchor with a factor 1+ fall.

Now like I've said I do this a lot, usually because it's very convenient, although really clove hitching in isn't much more effort, is safer and more versatile (if you bring the hitch back to you you can adjust it and move away from the belay). But whenever I've done it before I've always guessed that if I slipped I'd would be more of a slippy slump rather than a full blown fall, and so wouldn't test the anchors too much.
3 Names - on 07 Jan 2013
In reply to Sebastian Fontleroy:

Well no I thought we were having a chat?

but just to be sure, until the leader has let his belayer know that he is safe, he should always be on belay, therefore any slings being placed for the belay are still just another piece of gear and consequently will not be shock loaded if fallen on, so shouldnt fail.
David Coley - on 07 Jan 2013
In reply to Chris Sansum:
It is common practice to clip in with a sling directly to one or more of the belay bolts. However, there have been several accidents because of people then moving around the belay and falling off. Because a sling is not dynamic, a FF1 will feel like a FF2, which will hurt big time. It might even rip some trad pieces out of the belay.

Like many things in climbing, if used correctly (i.e. don't move around the belay) its fine, if used incorrectly it's not.
3 Names - on 07 Jan 2013
In reply to ledifer:

Why would you knowingly do this when there is no need?
MikeYouCanClimb - on 07 Jan 2013
In reply to Chris Sansum:
As people have pointed out, the problem arises if there is slack in the sling and the type of sling.
A knot can also compound the problem. Have a look at the video, it a very vivid explanation of how huge forces of 20kn quickly arise, a factor 1 or even factor 2 fall can be generated very easily.
http://dmmclimbing.com/knowledge/how-to-break-nylon-dyneema-slings/ .

The thead http://www.ukclimbing.com/forums/t.php?t=533402#x7161125 is discussing a similar topic.
3 Names - on 07 Jan 2013
In reply to David Coley:


This
Sebastian Fontleroy - on 07 Jan 2013
In reply to Vince McNally:
> (In reply to Sebastian Fontleroy)
>
> Well no I thought we were having a chat? OK. Sorry.
>
> but just to be sure, until the leader has let his belayer know that he is safe, he should always be on belay,

Yes


therefore any slings being placed for the belay are still just another piece of gear and consequently will not be shock loaded if fallen on


No. The slings (according to the poster)are attached directly to the leader's harness.

ledifer on 07 Jan 2013
In reply to Vince McNally:
> (In reply to ledifer)
>
> Why would you knowingly do this when there is no need?

Because I hadn't fully considered it before. Now having learnt something I'll endeavour to use the rope to clip in in the future.

See, these forums can be useful sometimes!
Sebastian Fontleroy - on 07 Jan 2013
In reply to ledifer:
> (In reply to Vince McNally)
> [...]
>
> Because I hadn't fully considered it before. Now having learnt something I'll endeavour to use the rope to clip in in the future.
>
> See, these forums can be useful sometimes!


Lol

3 Names - on 07 Jan 2013
In reply to Sebastian Fontleroy:

Yes of course im being thick
Jon Stewart - on 07 Jan 2013
In reply to Chris Sansum:

Here's my motto: if it's not obviously not fine, it's fine.

Or to put it another way, if something's going to f^ck up and kill you, it'll either be you or your climbing partner, not a one in a million chance of your kit failing because it was shock-loaded, cross-loaded, blah blah. Are you definitely attached to the rock? Check. Is the rock definitely attached to the crag? Check. Is your partner definitely on belay? Check. Robert's your father's nearest male relative.
Hannes on 07 Jan 2013
In reply to Chris Sansum: I do it all the time, you just have to be a little careful and make sure the sling is taut at all times otherwise you are setting yourself up for a slight case of death. Well I actually use a daisy chain but if I end up shortening it with the sewn pockets by more than one or two I usually back myself up with the rope. The reason for me to do it is that is far more practical than tying in with a clove hitch and the rope. Tying in with the rope will almost always be safer from a falling off and not dying point of view but you will set yourself up for more faff and potentially annoying/dangerous rope salad. I see it almost like skipping gear when it would be good to have but falling off while placing it seems inevitable.

Some precautions are good though I think, one is to use a sling of a completely different colour/type, that is why I have a green metolious daisy with a bit of black nylon reinforcement so there is simply no chance of that being mistaken. The krab is a twist lock which is safer than a screw gate for this and the only one unless I have two daisys so again no risk of confusion. Since I almost exclusively use a direct belay I rarely worry that I'll find myself above my belay without thinking about it.

To me this is a more efficient and therefore a safer system with less risk of confusion and faff.
Sebastian Fontleroy - on 07 Jan 2013
In reply to Vince McNally:

Lol no problem mate.

BMrider - on 07 Jan 2013
In reply to Jon Stewart:

Hear hear!
In reply to Jon Stewart:



The key isn't to worry about the type of sling/rope you are attached to the belay with, but not to climb above it, and if you really have to climb above it DON'T FALL OFF.


Chris
obi-wan nick b - on 07 Jan 2013
In reply to Chris Sansum: I may have misunderstood the question but where you are able to attach yourself to the belay using slings you could only use a very short length or rope to substitute for the sling attachment. I believe that the shock absorbing capabilities of such a short length of rope is minimal and therefore won't make much difference. Short lengths of rope used in via ferrata slings rely on friction devices or screamers to give shock absorption capability not the properties of the rope.
David Coley - on 07 Jan 2013
In reply to obi-wan nick b:
>I believe that the shock absorbing capabilities of such a short length of rope is minimal and therefore won't make much difference.

Beal have some measurements on their site of just this. They compare the force generated by falls onto a sling and onto an equivalent length of rope. The rope produced much lower forces.

This isn't surprising. The whole concept of fall factors is about the length of fall or of rope not making any difference, just the ratio. So, a short fall on little rope is the same'ish as a long fall on a lot of rope.

The reason VF kits use shock absorbers is that in a VF fall you might have a fall factor of much greater than 2, possibly 5 or more. Which ropes and your body are not designed to handle.

I hope that helps.
lazzaw - on 07 Jan 2013
In reply to Hannes:
> (In reply to Chris Sansum)you just have to be a little careful and make sure the sling is taut at all times otherwise you are setting yourself up for a slight case of death. Well I actually use a daisy chain but if I end up shortening it with the sewn pockets by more than one or two I usually back myself up with the rope.

Does anyone use a Purcell Prussik for this? Adjustable length, so you can keep it taut if you move around and (supposedly) the prussik knot allows enough slippage if you fall to make the short length of rope dynamic.
Mark / Alps - on 07 Jan 2013
In reply to Chris Sansum:
Best practice will vary according to the circumstances, there are many ways to clip to an anchor on multi pitch routes. Some people will often copy what others do ( including copying guides and instructors ) without having all the relevant information or questionning if the technique suits different circumstances.
For example on UK multipitch trad routes I would usually use the ropes for the same reasons Dave has highlighted above. On a long route in the alps or multipitch sports route I will often use a PAS, as will second / seconds,such as the Grivel or Metolius if clipping to a bolt, bolts. Speed is also important in this situation. PAS should be taut at all times.
Please note that not all daisy chain have all loops rated to a high enough level. The Grivel Daisy Chain has all loops rated to 23KN, a 'normal' daisychain will have the end loops rated around 22KN but the inbetween loops are usually around 2KN.
One experiment demonstrated that a 22KN rated dyneema sling with a single overhand knot failed after a 1.2 metre fall / drop of force factor 1 at 11.5KN. ( Source DMM )
Jonny2vests - on 08 Jan 2013
In reply to Jon Stewart:
> (In reply to Chris Sansum)
>
> Here's my motto: if it's not obviously not fine, it's fine.

Why does my head hurt?

Offwidth - on 08 Jan 2013
In reply to Wil Treasure:

"a few feet could kill you." rubbish. To snap a sling like this you need something approaching a FF1. Moving around on a belay ledge with the harness and/or rope loop end taking a lot of the shock load would not acheive this.
Sir Chasm - on 08 Jan 2013
In reply to Offwidth: Try reading the thread again, of course a few feet could kill you.
jkarran - on 08 Jan 2013
In reply to Chris Sansum:

What's your actual concern, I'm presuming it's the belayer getting clumsy, developing slack in the sling while doing something at the belay then slipping and falling directly onto the sling?

In that case, you're right, using the rope would be better. Best though would be to not get into the risky position at all. To my mind it all boils down to whether your friends are putting themselves at risk and whether they're aware they're doing it.

My personal preference is always for the rope but only because it's always with me at every belay, it's neat and it's infinitely adjustable, slings aren't. That's not to say I wouldn't and don't occasionally clip directly to slings, sometimes it's convenient.

Are you being over cautious? Probably but better a bit over cautious than under cautious if you're not sure.

jk
Postmanpat on 08 Jan 2013
In reply to Offwidth:
> (In reply to Wil Treasure)
>
> "a few feet could kill you." rubbish. To snap a sling like this you need something approaching a FF1. Moving around on a belay ledge with the harness and/or rope loop end taking a lot of the shock load would not acheive this.

http://dmmclimbing.com/knowledge/knotting-dyneema-vid/

Bit of a wake up call for me.

Simon_Sheff - on 08 Jan 2013
In reply to Offwidth:
> (In reply to Wil Treasure)
>
> "a few feet could kill you." rubbish. To snap a sling like this you need something approaching a FF1. Moving around on a belay ledge with the harness and/or rope loop end taking a lot of the shock load would not acheive this.

Who said anything about snapping a sling anyway? He is absolutely right, if he's a foot or too slack on his belay and gets pulled hard, his gear will get a bigger loading than if he was tight. A sling will make that effect slightly worse. That has killed people on marginal placement belays before.
Offwidth - on 08 Jan 2013
In reply to Postmanpat:

I'm very aware of that and even before they produced that film I was always someone who strongly advised care with cowstails on steep rock and never to clip to a sling then vertically climb the full length above it for more gear (sadly I still see this done from time to time).

Although it's obviously good practice to keep the belay tight when someone is standing/sitting on a belay ledge I cannot see anything approaching a FF1 scenario on a slack belay sling from the second falling. If a rope loop and/or the harness is part of the system (standard UK indirect belay) its certainly not possible.
Offwidth - on 08 Jan 2013
In reply to Simon_Sheff:

Anyone with half a brain belaying on marginal placements shouldn't be using a static sling to connect them.
Postmanpat on 08 Jan 2013
In reply to Offwidth:
> (In reply to Postmanpat)
>
> Although it's obviously good practice to keep the belay tight when someone is standing/sitting on a belay ledge I cannot see anything approaching a FF1 scenario on a slack belay sling from the second falling. If a rope loop and/or the harness is part of the system (standard UK indirect belay) its certainly not possible.

I agree it's very unlikely. My concern would be more about slipping or tripping whilst faffing about when the sling may not be tight.

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Simon_Sheff - on 08 Jan 2013
In reply to Offwidth:
> (In reply to Simon_Sheff)
>
> Anyone with half a brain belaying on marginal placements shouldn't be using a static sling to connect them.


What a get out. You tell someone earlier in the thread they are 'stupid' for suggesting standing away from the belay a few feet with a sling 'could kill you'. Your retort is that only someone 'with half a brain' would do that.............
I'm sure your very knowledgeable, but sometimes its okay to man up and admit you made a silly rash comment.
In reply to Simon_Sheff:
>
>
> Who said anything about snapping a sling anyway? He is absolutely right, if he's a foot or too slack on his belay and gets pulled hard, his gear will get a bigger loading than if he was tight. A sling will make that effect slightly worse. That has killed people on marginal placement belays before.

Is this really true, people killed by belaying on marginal placements, having loads of slack in the system and falling off? On the incredibly rare belay failure cases I have been aware of the leader has fallen and taken the whole team.

Chris

Simon_Sheff - on 08 Jan 2013
In reply to Chris Craggs:
> (In reply to Simon_Sheff)
> [...]
>
> Is this really true, people killed by belaying on marginal placements, having loads of slack in the system and falling off? On the incredibly rare belay failure cases I have been aware of the leader has fallen and taken the whole team.
>
> Chris

Hi Chris, I completely agree, wasn't meaning to imply a belayer would pull himself off, but was agreeing with earlier poster that being slack ( a few feet from the belay he said) could result in fatality from a leader fall, and would only be more likely to happen with slings (marginally).
In reply to Chris Craggs: There a case discussed here some years back where, IIRC, the the poor guy built a belay, clipped in with a sling and then climbed up a little abvove the belay to do something - perhaps add another point to the belay? - thinking he was protected by the sling. He slipped and fell on the sling and shock load either broke the sling or his harness, and he fell off and was killed. That's the only case I remember hearing about and I seem to have a good memory for these sorts of things.
needvert on 08 Jan 2013
I'm pretty cautious and don't have a problem with using a sling.

In my view the key thing is to understand the shock absorption capacity of your gear and the potential of falls. If you don't understand this, you're going to f*ck up eventually in some manner.
AlanLittle - on 08 Jan 2013
In reply to lazzaw:
> Does anyone use a Purcell Prussik for this?

Yes.
needvert on 08 Jan 2013
Ahh, to add.

Here's a guy who took a fall on a quickdraw and a sling, and broke a biner.

http://theuiaa.org/upload_area/files/1/Beware_of_Quickdraws_for_Self-Belay.pdf

drysori - on 08 Jan 2013
In reply to Offwidth:

Perhaps I was a little alarmist, and you're right that in most situations the shock of a shirt fall could be absorbed by your body, your harness or your rope loop (although I'm not clear on how you're implying this is being used?)

I'm imagining the worst case scenario where you're on a steep exposed belay and you're attached using only a sling I.e. no bleaker and no rope at all in the chain. Fall factors are only tenuously relevant in that situation, the distance you fall is more important when there's no specific shock absorber in the system. Admittedly on a lot of delays you're on a ledge and any slip is likely to be less severe than an in obstructed fall directly onto the belay. But people have been killed doing this, there was an incident on the capucin a few years ago.
David Coley - on 08 Jan 2013
In reply to Wil Treasure:
One place where there can be a lot of slack in a sling and the chance of a reasonable fall is on a bivy.

I was standing up on a portaledge last year and it flipped upside down. We had a screamer in the system, but I still nearly wet myself.
Offwidth - on 08 Jan 2013
In reply to Wil Treasure:

What was the case as I'd be interested in knowing how they knew slack in the belay sling was the cause of the death? It's really hard for me to see how to belay in a semi-hanging situation with slack in the whole system
Offwidth - on 08 Jan 2013
In reply to Simon_Sheff:

I'm sticking with my position. Your scenario is idiotic. You don't use static slings to connect marginal pieces to the central belay point (you use the rope as part of the system, consider using your harness as part of the system, brace as if it's an old school unattached belay and if really bad maybe even use a body belay so you can allow slippage on any shock load).

UKC regularly generates alarmist comments that muddle situations and state stuff that just distracts attention from the real serious scenarios (in this case that a FF1 direct on a sling is seriously bad news; on an old sling that you've knotted it will be even worse: NEVER clip a sling direct into your harness, shout safe and then and climb full length above it to find more gear; NEVER use a sling as an improvised VF kit.... etc). Leaving slack in a sling based belay system is bad practice with unnecesary risk; yet its not a high probability of being fatal like falling full length onto just a sling would be.
Simon_Sheff - on 08 Jan 2013
In reply to Offwidth:
> (In reply to Simon_Sheff)
>
> I'm sticking with my position. Your scenario is idiotic. You don't use static slings to connect marginal pieces to the central belay point (you use the rope as part of the system, consider using your harness as part of the system, brace as if it's an old school unattached belay and if really bad maybe even use a body belay so you can allow slippage on any shock load).
>
> UKC regularly generates alarmist comments that muddle situations and state stuff that just distracts attention from the real serious scenarios (in this case that a FF1 direct on a sling is seriously bad news; on an old sling that you've knotted it will be even worse: NEVER clip a sling direct into your harness, shout safe and then and climb full length above it to find more gear; NEVER use a sling as an improvised VF kit.... etc). Leaving slack in a sling based belay system is bad practice with unnecesary risk; yet its not a high probability of being fatal like falling full length onto just a sling would be.

Thanks you've just agreed with the original poster and contradicted yourself. Slack and slings are potentially dangerous, using the rope is better. I believe that is what the person you called stupid was also saying. Ta rah :-)
Offwidth - on 08 Jan 2013
In reply to Simon_Sheff:

A meteorite could kill you on the same belay. Saying something could kill you in climbing is not very helpful in my view; unless like the FF1.x sling it means nearly always. Weighing different relative risks is the key factor in assessing what to do next and I think sensationalism is unhelpful. I'm sure in an infinite universe a person will suffer one day for the extra risk of not using a locking crab on every belay piece. However, back in the real world, the Yosemite accident stats analysis show that year-after-year experienced climbers kill and seriously injure themselves by worrying about the wrong things. On the positive side of this subject: in the high mountains climbers normally quite sensibly accept some significant risks (that they could easily avoid) to reduce other much bigger ones.
tallsteve - on 08 Jan 2013
In reply to Chris Sansum:

Best practice - pah! Are you safe? Will you die if the leader falls? Job done. Some of the best practice stuff people worry over is just splitting hairs.
Simon_Sheff - on 08 Jan 2013
In reply to Offwidth:

Yawn.....................
Offwidth - on 08 Jan 2013
In reply to Simon_Sheff:

Ditto. Not everyone thinks the same and this is a website. Grow up and get over it.
Simon_Sheff - on 08 Jan 2013
In reply to Offwidth:
> (In reply to Simon_Sheff)
>
> Ditto. Not everyone thinks the same and this is a website. Grow up and get over it.

Oh dear, someone doesn't like being corrected ;-)

drysori - on 09 Jan 2013
In reply to Offwidth:

The case I mentioned was this one (although I seemed incapable of naming the correct location): http://www.rockclimbing.com/forum/Climbing_Information_C2/Injury_Treatment_and_Prevention_F25/Fatal_...

Although it does seem that the belay may have been old, which might have been the deciding factor in it breaking.
HeMa on 09 Jan 2013
In reply to Chris Sansum:

Yes, using a sling to attach one self directly to a belay might be dangerous... If you have a bad belay and then decide to climb over it and manage to fall.


But until I've seem data that the shockloads on the belay are considerably lower if using a rope instead (say 60cm... which is what is generally used for cows tail).


My rule of thumb is not to worry about am I using a rope or sling... but not to climb past the belay and then fall on it.

After all, 60cm of rope will not absorb much... especially if you're not using a brand new role.
Offwidth - on 09 Jan 2013
In reply to Wil Treasure: Thanks but that is not the scenario you described as the climber is not belaying. This is another example of someone clipped above a belay point direct with a sling then falling below it. There are 3 mistakes described in the post: not clipping into the central anchor point; standing above the anchor making a fall onto an anchor possible (clipped with a sling); trusting in-situ gear (a sling)).
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The Ex-Engineer - on 10 Jan 2013
In reply to HeMa:
> After all, 60cm of rope will not absorb much... especially if you're not using a brand new role.

Unsubstantiated nonsense.

There is loads of data on how effective even short lengths of knotted dynamic rope are at reducing impact forces. It is also well known that it is your tie-in knot and other knots that make a massive contribution to absorbing the energy.

For example chapter 7 of the 2001 HSE investigation of Industrial Rope Access PPE http://www.hse.gov.uk/research/crr_pdf/2001/crr01364.pdf records that 60cm knotted dynamic rope lanyards limit maximum forces to 6.3-7.6kN for 100kg in a factor 2 fall.

There is also an excellent and comprehensive 2006 study by French Cavers on Cow's Tails http://www.caves.org/section/vertical/nh/53/lanyard_tests_v6.pdf Tests on cow's tails only 38-60cm long with fig-8 knots gave average forces of only 5.83kN under their 80kg factor 1 test falls. Most interesting is that over their tests on a wide variety of ropes from 8.1mm-11mm the forces only varied by 4%. The report concludes: It seems, therefore, that the tightening of the knots has a lot more influence on the shock load than the type of rope. There is also additional testing which allows a direct comparison between a single clove hitch with a single fig-8 which shows the clove-hitch performing 0.2kN better (6.87kN vs 7.07kN).

As such there is clear evidence that the standard climbing use with a fig-8 tie-in and then using a clove hitch to connect to an anchor is highly effective at absorbing forces regardless of exact length and regardless of whether you are using a single or half rope.
HeMa on 10 Jan 2013
In reply to The Ex-Engineer:
> (In reply to HeMa)
>
> Unsubstantiated nonsense.

There's also abundance of testing from numerous sources, that clearly state that rope ends loose rather quickly their dynamic properties... And all the comparison test I've seen have always used brand spankin' new ropes.

Guess what, not many people buy a new rope for every lead they take.

So the real world values are not that peachy as the studies you posted state.

Oh, and knotting a nylon sling also lessens the impact (just like with using a rope). As the rope gets more wear, it becomes closer and closer to nylon slings. Yes, it will still be better I'd assume.

But then again, YOU SHOULD NOT CLIMB ABOVE THE BELAY MASTERPOINT WHEN FASTENED TO IT AND FALL.
David Coley - on 10 Jan 2013
In reply to HeMa:
> (In reply to Chris Sansum)

> But until I've seem data that the shockloads on the belay are considerably lower if using a rope instead (say 60cm... which is what is generally used for cows tail).

The data is on the Beal website.


>
> After all, 60cm of rope will not absorb much... especially if you're not using a brand new role.

It doesn't need to absorb much energy. The fall will be short, therefore via E=mgh the energy small. The problem is the peak force, which comes down to the time over which the energy is transferred.

The Beal data is for rope lanyards without a fig 8 knot. Although an older rope will have less bounce, the inclusion of a fig8 when using a rope probably makes up for this (and more) - although I don't have test data to show this.

GrahamD - on 10 Jan 2013
In reply to David Coley:

> It doesn't need to absorb much energy. The fall will be short,

Sounds like a quote from Albert Pierrepoint !
David Coley - on 10 Jan 2013
In reply to GrahamD:
> (In reply to David Coley)
>
> [...]
>
> Sounds like a quote from Albert Pierrepoint !

Nice one.
GridNorth - on 10 Jan 2013
In reply to Chris Sansum: Here is a question for all you engineering types. If it's not ok to fall directly onto a static sling rated in excess of 20kn why is there never any mention of falling onto a karabiner that is rated near as damn it the same?
Neil Williams - on 10 Jan 2013
In reply to GridNorth:

How often do you clip yourself into an anchor using only a krab and no rope or sling? Wouldn't give you a lot of room to move.

If there's a dynamic component in the system that will reduce the force. The whole system needn't be dynamic.

Neil
GridNorth - on 10 Jan 2013
In reply to Neil Williams: I know I'm just trying to put the strength of a static sling into context for all of those people who after seeing the DMM video vowed to bin all their dyneema. I would have thought that in the scenarios presented there would be almost as much chance of the karabiner breaking as the sling but no one ever seems to mention that. Or have I got something wrong?
David Coley - on 10 Jan 2013
In reply to GridNorth:
> (In reply to Chris Sansum) Here is a question for all you engineering types. If it's not ok to fall directly onto a static sling rated in excess of 20kn why is there never any mention of falling onto a karabiner that is rated near as damn it the same?

There is, think of a VF kit. The screamer they include is in part designed to stop the krab being exposed to >20kN.

I'm not sure how you would fall onto a krab without clipping it to some form of webbing - i.e. your harness.

GrahamD - on 10 Jan 2013
In reply to GridNorth:
> (In reply to Chris Sansum) Here is a question for all you engineering types.

The whole point is that its not parts of the rigging system that will likely give way - its either the belay anchors or parts of the soft squidgy climber.
GridNorth - on 10 Jan 2013
In reply to GrahamD: I thought that we were talking about using a "static" sling to attach to the anchor point and people pointing out the danger that it might break with just a short fall onto it, as demonstrated by the DMM video, I was suggesting that in such a scenario the karabiner is not much stonger but nobody is getting into a panic about that. Am I getting confused with another thread?
mike kann - on 10 Jan 2013
In reply to GridNorth: The main point about the video is not that a sling is 20kN, but that if you knot dyneema slings, they are no longer capable of withstanding 20kN and break at something more like 11kN which is easy to generate when you use a sling as a lanyard. Especially when you use the system of abseiling whereby you larksfoot a 120 sling to your harness, tie an overhand halfway down it, then clip your belay device below the knot and use the other half to clip into the anchors when you get to them. If you were to then climb above the belay and fall, it would be entire;y possible to break the only connection you have to the cliff.

Also carabiners CAN break. Especially when cross loaded. The point about this video is that many people are doing something unknowingly which seriously weakens their equipment.
The Ex-Engineer - on 10 Jan 2013
In reply to HeMa:
> There's also abundance of testing from numerous sources, that clearly state that rope ends loose rather quickly their dynamic properties...

Testing which it seems you are too lazy to provide references to, assuming of course it exists.

> And all the comparison test I've seen have always used brand spankin' new ropes.

... apart from the one I just provided links to, which it seems you were too lazy to look at.

The French research I linked to, included both repeated drop testing and testing of a large number of used cow's tails. The later was inconclusive but it provides absolutely no support for your hypothesis and plenty to suggest that it may be fundamentally flawed. From p.28 of http://www.caves.org/section/vertical/nh/53/lanyard_tests_v6.pdf (my emphasis):

These lasts tests seemed inconsistent since those Cow's Tails that had been used for several seasons and appeared quite badly worn gave much better dynamic results than those Cow's Tails that had only been used for a few trips. The opposite results occurred when the Cow's Tails were subject to the static tests. It appears that this can be explained quite simply by the fact that with time and repeated usage the fibres of the rope had broken making the rope more elastic but weaker. A more in-depth study with more precise histories (number of trips, type of trips, weight of the user…) could perhaps answer this question on the ageing of Cow’s Tails.

> So the real world values are not that peachy as the studies you posted state.
> As the rope gets more wear, it becomes closer and closer to nylon slings.

Two completely unsubstantiated claims which you present no evidence for - and which are called into question by the study I just quoted.
Neil Williams - on 10 Jan 2013
In reply to GridNorth:

Not sure I have that impression - I think it's just the case that it'll really hurt (either because a component of the system will fail and you'll end up splatted, or because a fall onto an entirely static system isn't pleasant in its own right even if it didn't fail).

Neil
The Ex-Engineer - on 10 Jan 2013
In reply to GridNorth: There are two separate issues which I think have now been fully explained:

First, if you fall directly on a (unkotted) 22kN rated sling, even if it holds you have a good chance of seriously injuring yourself (or dying when your harness fails). That is because 22kN is well above the 15kN that is considered the threshold for serious injury to the human body and the 15kN minimum strength of climbing harnesses*. As a comparison, the UIAA dynamic rope standard was initially set at 12kN, although most modern ropes come in with much lower impact test forces of around 9kN.

Second, as has already been mentioned, as soon as you tie a knot in a 22kN rated sling, it is no long rated at anything close to 22kN. In the real world it will fail with a dynamic impact force of perhaps 11kN which is very easily achievable as the DMM tests demonstrate.

As regards carabiners, although they may hold 20kN+ along the major axis, the minimum EN standard for open gate and minor axis loading is only 7kN. As such there is a very real risk of cross-loaded krabs failing. This is has led some manufacturers to design carabiners with higher ratings - many DMM krabs now have an opengate strength of 10kN. Additionally there is a greatly enhanced ANSI standard for industrial use carabiners which specifies 16kN in multiple loading geometries (see http://dmmprofessional.com/articles/2012/12/12/ansi-standards-for-carabiners/ ).

Hope that is useful.

[* EN 12277:2007 specifies a strength of 15kN for standard sit harnesses. For an outline of the test method see http://www.hamradio.si/~s51kq/photo_album/Climbing_and_Mountaineering/pdf_climbing/UIAA/PictUIAA105-... ]
BolderLicious - on 11 Jan 2013
In reply to Chris Sansum:
I'm betting the rope stretch when the belayer holds a falling climber
allows the force on the belayer's harness to build up more slowly
reducing the chances of anything failing (karabiners, harness material ) or of gear being pulled out of a crack.
Robert Durran - on 11 Jan 2013
In reply to BolderLicious:
> (In reply to Chris Sansum)
> I'm betting the rope stretch when the belayer holds a falling climber
> allows the force on the belayer's harness to build up more slowly
> reducing the chances of anything failing (karabiners, harness material ) or of gear being pulled out of a crack.

It is the maximum force that matters, not the rate of chamge of force.

mike kann - on 11 Jan 2013
In reply to Robert Durran: Thats not strictly true though. Energy absorption has everything to do with time over which the energy is absorbed. Elongate the time over which the fall is absorbed and you will reduce the max impact force. If the rope/knot is more stretchy the fall takes longer to arrest and the peak force is reduced. For example that is why screamers work.
valjean - on 11 Jan 2013
In reply to lazzaw:
Does anyone use a Purcell Prussik for this? Adjustable length, so you can keep it taut if you move around and (supposedly) the prussik knot allows enough slippage if you fall to make the short length of rope dynamic.

You bet! I started using a purcell maybe 3 seasons ago and i doubt ill ever look back. I usually climb with bolted belays -- as soon as i reach the anchor i clip into 1 bolt. I then clove hitch the rope to a draw on the other bolt. Put a "proper anchor" in.... and bring up the second on a reverso/atcguide on that anchor.

Only thing annoying is when the shortest length my purcell can go is still too long for the stance i want
DanielJ - on 11 Jan 2013
In reply to Chris Sansum: Yer gonna die!

No. Seriously. I think the DMM test was good in showing how slings can break but a lot of people have gotten unnecassary scared by it. I´ve been faffing around with some droptests from droptower at my workplace, but without loadcell. (We tried to make screamers release, eg generate more force than 6kn, we used 80 kg dummy or 4*20kg weightplates tied together)

The difference in forces generated between using a solid mass like they do in DMM test compared to a human dummy is substantial. My guess would be that in real life its very unlikely to happen in any other terrain but a hanging belay and fall factor over 1.

So, in short, dont stop, just be little more catious on steep terrain.
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jimtitt - on 11 Jan 2013
In reply to Robert Durran:
> (In reply to BolderLicious)
> [...]
>
> It is the maximum force that matters, not the rate of chamge of force.

Both matter. The human bodies ability to survive accelerations varies with the speed at which they occur. Climbing falls are relatively slow in the rate of change of force but have a fairly long duration and 12g or so is where damage starts to occur. Even slower and the level is much lower, you won´t survive for weeks at 3g for example. On the other hand you can survive 40g for fairly brief periods (46g is the record)or much higher for even shorter periods (179g is though to be the highest).

BolderLicious - on 11 Jan 2013
In reply to mike kann:
Yes. A rope stretches because it is in tension and is slowing a climber down as they fall.So the force on karabiners wires etc. is lessened.
needvert on 11 Jan 2013
In reply to DanielJ:

What is the difference between a 80kg human and a 80 kg chunk of iron, in drop tests?

Being a human of around 64kg, I'm not sure how many slings I'd be breaking in the same drop test.
GrahamD - on 11 Jan 2013
In reply to needvert:

For blokes thats because their bollocks absorb some of the energy.
Robert Durran - on 11 Jan 2013
In reply to jimtitt:
> (In reply to Robert Durran)
> [...]
>
> Both matter. The human bodies ability to survive accelerations varies with the speed at which they occur.

So a rapid change in force should do less damage than a slow change in force, because less time will be spent near the (same) maxcimum force?
Would this in prcatice be relevant in climbing situations though? ie might a short factor 2 fall do less damage than a long factor 2 fall?
jimtitt - on 11 Jan 2013
In reply to needvert:
> (In reply to DanielJ)
>
> What is the difference between a 80kg human and a 80 kg chunk of iron, in drop tests?
>
> Being a human of around 64kg, I'm not sure how many slings I'd be breaking in the same drop test.

For rope drop testing it is 8:10 since this is the rigid body correction factor which is used. Nobody has (as far as I know) a correction factor for a short fall on a Dyneema sling but there is plenty of information for the lanyards used in industrial fall arrest, a good start into the subject of surrogate testing is http://www.hse.gov.uk/research/crr_pdf/2002/crr02411.pdf
jimtitt - on 11 Jan 2013
In reply to Robert Durran:
> (In reply to jimtitt)
> [...]
>
> So a rapid change in force should do less damage than a slow change in force, because less time will be spent near the (same) maxcimum force?
> Would this in prcatice be relevant in climbing situations though? ie might a short factor 2 fall do less damage than a long factor 2 fall?

Theoretically yes but in practice hard to know since nobody is doing the tests since live volunteers are hard to come by!

cuppatea on 11 Jan 2013
In reply to Chris Sansum:

Some interesting points above.

Maybe I should be thinking about a speed zip lock buckle instead of a Luddite buckle for my next harness..I've read that they can be slippery and the tape can pull through them which would slow down the rate of change of falling speed.
mike kann - on 11 Jan 2013
In reply to Robert Durran: No, the opposite way around. Think of it in terms of energy. The energy in the fall is constant and energy is a combination of force and time. The longer the time the energy is disappated over, the lower the maximum force. Rope stretch elongates the time over which the fall is stopped and therefore reduces the maximum force. You can also think of a rope as a spring - the twisted cores are exactly that - a spring. As you fall and the rope takes the slack, the "spring" starts to pull out straight. As soon as it starts to stretch it's absorbing energy, and because very millisecond its doing this takes more energy out of the fall until you come to rest. Hence why a beal rope which has tightly wound core material has a lower impact force than a mammut for example.
mike kann - on 11 Jan 2013
In reply to cuppatea: The rope is just fine, you don't need a harness that comes undone.
Neil Williams - on 11 Jan 2013
In reply to mike kann:

While they can loosen a bit over time, mine has never "come undone". And I'm hardly the lightest person in the world.

The one situation you have to really watch for is if you're clipping a prussik onto the leg loop when abbing. But even so that would loosen one leg loop out of two, hardly a situation that's likely to kill you, though it might be uncomfortable.

But I agree that that is not a reason to choose one of those harnesses over a double-back - I would just choose one because they are less fiddly to put on and you can't forget to double them back.

The one place where I would actively choose double-backs is for any form of instruction, where a novice needs to know that they exist otherwise they might be trained in using the other type, and so not double back a double-back type harness when they first encounter it, and thus end up dead. (Alpine harnesses vs. the normal type do cause confusion of that type, but no-one's going to get themselves killed by tying into the belay loop by mistake, if they were it wouldn't be suitable for belaying from either).

Neil
mike kann - on 11 Jan 2013
In reply to Neil Williams: Coming undone was a reaction to cuppatea's question. I know they don't come undone and cuppatea is being overly optimistic that it would have any effect at all. I think he just wants an excuse to buy a new harness ;)
cuppatea on 11 Jan 2013
In reply to mike kann and Neil Williams:

I agree with you both, I'm researching at the moment but leaning toward the traditional buckle. Favourite so far is the DMM Regegade Pro, the internet tells me that DMM made it in response to calls from instructors who wanted a version with proper buckles (I assume for themselves to wear - the punters getting cheaper harnesses).

The October High mag says of the 2013 versions of WC's harnesses: "new ziplock buckles are extremely effective and have eliminated any slippage".

I love a good tangent.

Neil Williams - on 11 Jan 2013
In reply to cuppatea:

Quite possibly so that they can use their own harnesses (which they then wear) to demonstrate how to put the centre harnesses on. You can't do that if yours is of the ziplock type and your centre harnesses are of the traditional type.

Neil
Robert Durran - on 11 Jan 2013
In reply to mike kann:
> (In reply to Robert Durran) No, the opposite way around.

No. I was comparing two factor 2 falls on same rope (therefore same maximum force using the usual analysis) of different lengths (say 2m directly onto the belay and 20m directly onto the belay). In the longer fall more energy is dissipated over a longer distance giving same maximum force. However, the longer fall takes more time, so, apart from being more frightening, more time is spent close to the maximum force (and therefore acceleration) which can theoretically result in more damage. Realistically, however,I suspect the sort of maximum forces experienced in climbing falls with modern ropes and harnesses are unlikely to do any damage however prolonged.

> Think of it in terms of energy. The energy in the fall is constant and energy is a combination of force and time.

Energy dissipated is force x distance (momentum is force x time).

> The longer the time the energy is disappated over, the lower the maximum force.

Yes (if you mean distance, not time) for the same energy, but the two factor 2 falls I was comparing have very different energies to disippate.


The Ex-Engineer - on 11 Jan 2013
In reply to cuppatea: Re Harnesses:

Not sure if you looked at the link to harness test methods that I posted http://www.hamradio.si/~s51kq/photo_album/Climbing_and_Mountaineering/pdf_climbing/UIAA/PictUIAA105-... but the testing of waist belts specifies a maximum of 20mm slippage at buckles when loaded at 10kN.

That may allow you to have a better appreciation of Wild Country's marketing claims of 'zero slippage', which seem to me to perhaps be rather irrelevant.
The Ex-Engineer - on 11 Jan 2013
In reply to jimtitt:
> For rope drop testing it is 8:10 since this is the rigid body correction factor which is used.

Thanks for posting that. My recollection was that it was only a 20% de-rating but I wasn't certain.

Either way it is not the 'substantial' difference that DanielJ claimed - in yet another case of a contributor putting forward an unsubstantiated hypothesis without any hard evidence.
cuppatea on 11 Jan 2013
In reply to The Ex-Engineer:

Thanks for the link :)
Turdus torquatus on 11 Jan 2013
In reply to cuppatea:
> (In reply to Chris Sansum)
>
> Some interesting points above.
>
> Maybe I should be thinking about a speed zip lock buckle instead of a Luddite buckle for my next harness..I've read that they can be slippery and the tape can pull through them which would slow down the rate of change of falling speed.

Isn't this what happened at the start of the Cliffhanger documentary?

cuppatea on 11 Jan 2013
In reply to Turdus torquatus:
> (In reply to cuppatea)
> [...]
>
> Isn't this what happened at the start of the Cliffhanger documentary?

http://www.youtube.com/watch?v=wZlfj-VcwK4

"Yer not gonna dieeeeeee!" *splat*

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leeoftroy - on 13 Jan 2013
In reply to Chris Sansum: I like using my cows tail. When I reach an anchor I clip in quickly and am immediately safe...particularly handy when totally pumped. Once I have got myself positioned I then attach myself via my rope and clove hitch but leave my cows tail attached loosely...if leading off this is the last thing I remove. It's my system and it works efficiently for me and I believe it to be the safest way. Having a cows tail girth hitched to your harness is very handy for fast connection to some gear or to a clip when sport climbing. When pumped or when a situation arises it can be a lovely thing to have prepared. I always have it ready before I climb.
deanstonmassif on 14 Jan 2013
In reply to The Ex-Engineer:

Thank you

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