UKH

I’ve heard conflicting opinions on whether you can use dyneema slings for abseiling anchors. I’ve always thought it to be a perfectly safe practice given you don’t suddenly shock load it, but have recently been told otherwise.

Opinions please?!😬

In reply to Ggilbs:

I can't think of a reason why it wouldn't be safe.

In reply to Ggilbs:

If used in the right context, not introducing any shock loading and keeping away from any sharp edges/protecting from sharp edges, I see no issue. 
 

Every setup is slightly different and I think its important to setup the right one for that situation. Whether that’s a dyneema sling wrapped around a monolithic anchor (huge stable block/solid tree) or a dynemma sling joining several pieces of gear together. 

So, if used correctly in the right context, no issue. 

In reply to Ggilbs:

You are unlikely to be able to create a factor 1 fall when abing on dynamic ropes below the sling, I usually retire old slings by Abbing off them. 
 

would never use an insitue one that has had a rope pulled through it though, 

In reply to Ggilbs:

The problem is using a dynema sling as a lanyard to extend belay plate and/or using to clip into anchors on a multi-pitch abseil. There have been fatalities with abseilers slipping at belays/abseil anchors - shock loading the slings, causing the sling to fail. This occurs when not actually hanging on the anchors, creating unnecessary slack in the system.

The Petzl Connect Adjust is a great piece of kit. Because it's composed of a short length of dynamic rope, keeps the fall factor low, and is easily adjustable, ensuring no slack in system. Worth considering if intending to do lots of planned abseils. I haven't taken mine off my harness, since first buying one 4 years ago.

In reply to Gary Latter:

Petzl connects are great for certain jobs, but for trad I find they get in the way unless I'm primarily rigging. The dynamic properties over that length of rope are close to none. Long story short, don’t shock load anything static and you’re laughing. Used properly and safely, dyneema slings are fine.

In reply to Harrison_Connie:

Yes, 'don't fall onto the sling' is the theory but it's certainly not uncommon to have slack in the system on a multipitch abseil, and the dynamic rope is obviously out of commision since it's being used in the abseil.

Would be interesting to know what the OP's sources' concerns were and their suggested mitigations.

In reply to Michael Gordon:

Aye it would. I’ve never heard of any reason why it’s dangerous other than folk using them dangerously! 

In reply to Harrison_Connie:

I seem to remember that a Larksfoot knot drastically reduced the braking strain of dyneema, or was that nylon slings as well?

In reply to Harrison_Connie:

I suggested a much safer and more convenient option to mitigate the possibility of the catastrophic failure of accidentally shock loading dyneema slings. 

Used properly and safely, dyneema slings are fine. By using a PAS (Personal Anchor System) such as the Petzl Connect, you completely remove the possibility of catastrophic failure of the attachment point. I agree that it has limited dynamic properties, but it isn't static, far from it. The long and the short of it: it wont fail if you mess up and accidentally slip off an abseil anchor, unlike a dyneema sling...

In reply to Baz P:

Larks footing reduces the strength of a sling from 22 to ~14KN. If you manage to generate 14KN in an abseil, you are a genius, or a blue whale.

In reply to Gary Latter:

I agree that using a Petzl connect as a PAS is safer than using a Dyneema sling as a lanyard to attach yourself to an anchor is when there is slack in the system. If used correctly, both are safe to use with the dyneema sling being more appropriate to what is generally carried when trad climbing in the hills. My point was that both are safe in context but the connect is rather unnecessary and cumbersome. 
 

Sport climbing however, I take mine all the time! 

In reply to Harrison_Connie:

I apply the same logic to small RPs. Correct use = don't fall on them! Very safe pieces of kit provided this approach is followed.

In reply to Ggilbs:

Do you mean abseiling off a dyneema sling - i.e. leaving around a spike at the top of the pitch you are abing down? Or do you mean using it as a lanyard on your harness to extend your belay device/clip into anchors with?

Different people on this thread seem to be presuming you mean both.

In reply to Gary Latter:

If you climb above or level with a single sling then you can generate enough force if you fall to break a sling, However no one seems to actually die this way

use of a sling as a lanyard is not an anchor on its own it is a temporary backup whilst you make yourself properly safe preferably with the rope 

I use a daisy chain still which if used incorrectly can easily kill you. But used correctly is perfectly fine to use 

I have the petal connect as well which is bulky and heavy but if you want a dynamic system makes sense! It connects to the belay loop though so I’m sure there is some possibility very small of that failing 

proper understanding of the limitations of your system and correct usage is most important! Slings are fine if used correctly. E.g don’t climb above the anchor  in the belay and expect a single sling to save you

I will continue to use my daisy chain of death

In reply to Ggilbs:

In reply to Ggilbs:

Agree with others that your meaning is unclear. If you mean as a method of securing yourself to the abseil anchor prior to abseiling, then it’s been well discussed and I’d add to the view that using a dyneema sling as a cows tail or lanyard is safe if you ensure you don’t shock load it.

However if you mean using dyneema sling as tat e.g. sling over a boulder with the climbing rope passed through it to ab, then that’s also safe provided the boulder is bombproof and the sling is in good condition before abseiling, but the subsequent pulling of the rope through the sling to retrieve it can damage the sling by friction/heat as dyneema melting point is low. So if I had to ab off a sling and then pull the rope, I wouldn’t use the sling again if I could get it back - and I wouldn’t ab off another dyneema sling that I found in situ without at least backing it up sufficiently.

I know of someone who died in the Alps due to using a static sling (probably not a dynema one) clipped into an anchor who slipped and shock loaded the anchor, which failed. 

Knowing the limitations of a device is important, but any static sling used to connect to an anchor - particularly as stated above for multi-pitch abseils - is IMHO an accident waiting to happen. Use a dynamic PAS like the Petzl Connect.

In reply to David Barlow:

Or the rope and clove hitch onto a screwgate

or make your own anchor system with a piece of rope 

Any system with one point of failure is risky imo though

In reply to Murcantile:

And how do you do this on a multipitch abseil?

In reply to Murcantile:

In reply to Gary Latter:

I had a look around for any incidents of slings failing due to the load on them but am struggling to find any. From my limited googling, I notice that How Not to Highline tried to create a high FF fall on a static sling and couldn't get any forces higher than 4kn for a factor 1 (sliding X failure). 

Using the following FF calculator, you would expect 5.5kn max for a factor 2. Given knotted dyneema should have 11kn, there seems to be a massive safety factor still (even if my calculations are way, way off). 

Theoretically, I can see how >11kn force can happen with static loads like in the DMM video but in reality, I haven't seen any confirmed cases where slings have failure can be explained away only by the load of a high FF fall.

Possibly a slightly odd question, but in a scenario where you're clipping to an anchor with a dynema sling as a cow's tail and you slip, potentially generating a high ff, how much energy would be dissipated by your squishy human body deforming and your bones breaking? In drop tests, is a rigid mass used, which would be perhaps generate a higher peak force? Though I hasten to add I am not offering to test this myself or suggesting that anyone else should!

In reply to a crap climber:

This is where the testing methods fall apart (not literally). A rigid mass is indeed used, as far as I know, which would give a higher impact force for the exact reasons you said above.

I'm not saying that we should disregard the test results, but they are more of an indication of forces rather than absolutes. I'd imagine absolute figures would be difficult to obtain anyway as we're all made of different ratios of squishy bits 

In reply to Wide_Mouth_Frog:

Buy a short length of 9mm dynamic rope, put a barrel knot in each end, clip a locking krab into each end, job done. The knots absorb some of the energy of a fall, re-tie them every time you use the set up, and if you want to use it to extend your abseil device make it a bit longer and tie an alpine butterfly knot at the required distance to clip your abseil device into. Easy to remove from your harness when not required, just clip the two ends together. A lot less bulky than a Petzl Connect, but I do use one of those when sport climbing.

In reply to Ggilbs:

Thanks everyone. Some insightful information there! 
As there was some confusion, I didn’t mean to use as a PAS. I use an Adjust for that when I’m sport climbing. I meant solely for making an anchor for abseiling from. Thanks again. 🙏🏻

In reply to Ggilbs:

I'm sure this is not what was meant, but just to be certain..... 

Abseiling with your rope looped directly through a loop of dyneema would be very much worse than abseiling from a carabineer/maillon attached to a dyneema anchor. 

In reply to Michael Gordon:

Depending on what I have managed to find to sling my 5mm piece of tat round, I mostly rethread it then paper scissors to see who gets to test the dubious flake we have found.

I then mostly sh!t myself for the next 5 mins and try not to bounce or do anything to shock load the anchor until I can find a ledge for the next ab.

Sometimes I pray a little depending how dubious i thought it was. Then when I run out of tat I decide which sling to sacrifice to back it up

In reply to Ron Rees Davies:

But surely not that bad if set up so the rope doesn't slide through under tension and melt the sling (which it normally shouldn't). Years ago people didn't usually sacrifice krabs  when retreating. I find it hard to believe everyone does now. Of course setting up a rope left in place one uses a krab as it won't be left after climbing. Perhaps I'm just out of date or the OP assumes the latter case or I'm misunderstanding the question.

In reply to Ggilbs:

As anchor material, Dyneema is fine, as it is for slings in general, because you aren't counting on it to absorb fall energy.  The only issue is if you have to knot Dyneema webbing or cord as part of your set-up.  Dyneema is notoriously bad at holding knots.  A triple fisherman's, well-dressed and tightened, with good-sized tails is required. In particular, a ring bend or water knot, often recommended for webbing, would be a death trap. (Actually, a ring bend or water knot is a terrible choice for any webbing that might be used over and over again by many parties.)

It was mentioned that threading the rap line directly through a Dyneema sling is a bad idea.  In fact, it is a bad idea to ever thread the rap line through any kind of sling.  This is something best saved for nightmare retreats when you've pretty much run out of gear.

When it comes to tethers, what we can say is that if you actually fall on one, the load to the anchor is going to be higher with a Dyneema sling than with a length of climbing ropes as in the Petzl Connect Adjust.  There was a fatal accident in the alps in which the victim fell while attached with a static tether to in-situ tat and the tat broke.  Whether the result would have been different with a dynamic rope tether is, of course, not known.  The problem, as usual, in looking for "real-world" data is that the type of accident needed to test how things perform is exceptionally rare and is typically laden with confounding variables.

There is a misleading statement in the thread to the effect that a short dynamic rope tether has very little "dynamic property."  In fact, it has the same dynamic property as any length of dynamic rope, which is to say that, in theory, the peak load in arresting a fall is determined by the fall factor, so that a factor-1 fall on a short piece of rope and a factor-1 fall on a long piece of rope result in the same maximum tension.  The danger of the short tether, regardless of material, is that it isn't at all hard to get high fall-factor falls.

In reply to rgold:

What are your reasons for saying that? There is no fabric-on-fabric movement so there is no risk of damage to the rope or the sling.  As far as I'm aware it's normal practice to thread the rope through tat, and I've never seen it suggested that it's unsafe or even just a bad idea. 

The Connect Adjust is a great piece of kit, and I use it for sport when I know I'm going to be hanging off an anchor.  However for trad it's bulky and has only one use, and I prefer take kit which can be used for a number of purposes, which includes standard slings.  I'd only consider taking it if I knew I would be facing a long abseil descent.  I'm aware of the dangers of high factor falls, but I try to avoid those even when using a Connect Adjust.

In reply to Howard J:  There is often some 'sawing' by the ropes.  Anyway at some point you'll pull the ropes thro', and the sling is still there, waiting for a less prepared/educated team to reuse ..

This is why leaving abseil tat at popular crags as opposed to a nice chain is a bad idea, but that's another whole can of eels 

In reply to Howard J:

All I can say is that it isn't even remotely normal practice in the US, at least not for the past 40 years or so, and it is surprising to hear it discussed as still standard practice.  Nowadays people carry and install rappel rings.  There are two substantial issues.  One is that it is significantly harder to retrieve the rope when it is threaded directly, and there is a chance that it may not be pullable at all if there are other sources of friction.  It would certainly be imperative for the first person down to test whether the rope can be pulled, and making sure to pull the end that is "inside," rather than "outside" the sling. 

The second is that pulling the ropes abrades the sling significantly, so that each subsequent party encounters a possibly critically weakened sling.  I'm personally aware, from the times long ago when it was more common to thread the rap line, of several instances in which subsequent parties found the rap sling only held together by a few threads.  The party immediately before them was lucky to survive.

It isn't likely that rope motions caused by stretching could do enough damage to endanger the party that installed the sling.  The problem is that you are leaving something for others that is guaranteed to deteriorate dangerously.

In reply to rgold:

I would have thought that normal pratice was to use a krab or maillon on a standard abseil descent which others will be using, but if retreating from a climb or making an unusual descent to just go off the sling unless there are particular concerns about pulling the rope.

I am always surprised at the number of people who routinely abandon screwgates when retreating (most of my collection from recovering them!).

In reply to rgold:

Just looked, my most recent climbing handbook, approved by the British Mountaineering Council implies a no krab set up was still normal in  1997, 25 years ago, UK . The useful web manual multipitchclimbing.com has pics of spike ab points with the rope through the sling.

I do wonder if most people nowadays really leave a krab at each ab point when retreating, even if its not a nightmare? In fact the time I can remember leaving a krab for the ab it was on a nightmare descent!

The concern for following climbers is a very valid point. Though I think anyone abseiling should be aware of the "all eggs in one basket" thing or be with someone experienced as there are many other possible lethal mistakes lying in wait. Occasionally  I just have an ab rope, tat, tiny amount of gear plus a couple of krabs....I wouldn't discard one of these unnecessarily.

Having said that I believe a lot of UK climbers now say one should always use a krab (I think my club emailed a circular to that effect). And  probably the majority of slings regularly used for abbing now do have a screwgate in situ (in my experience). 

In reply to rgold:

I often place 2 or 3 bits of gear in a belay, then clip a long dyneema sling through them all before drawing together and equalising with a figure of 8 knot, which I clip into my tie in loops.  Should I not be doing this?

In reply to Ggilbs:

I don't know if I have any dyneema slings and I wouldn't recognise one if I saw one. Am I going to die?

In reply to Robert Durran:

Yes, eventually.

In reply to Robert Durran:

Wow, I got a lot of downvotes!  Yes, a rap ring or a maillon if the sling is likely to be used by subsequent parties, but of course, you have to be carrying some of that stuff. For emergency kit, five rolled aluminum rap rings weigh as much as a single Petzl Attache screwgate---and you still have your screwgate when you get down.  The rolled rings wear rather quickly and so are not right for high-traffic areas; in such cases, a better rap ring or a steel maillon or at least two rolled rings are called for.  Almost never leave a carabiner, and if so it is perhaps better to tape a regular one closed rather than leaving a screwgate.  If you have tape with you... 

Emergency descents are in a different category, but, as I said, if you are threading the rope direct through the sling make sure you are pulling the correct strand and beware of stuck ropes---especially if the weather is bad and the ropes are wet.

In reply to rgold:

I hadn't realised you were in the US, where I guess you are facing different situations.  Here in the UK it is nearly always possible to walk off a climb, and abseils are usually only used in retreat.  Where abbing is the normal means of descent there are usually fixed ab stations which would normally have a ring or a chain.  The other common scenario is abbing into sea cliffs, where I would usually take a separate rope and fix a line using karabiners and as much gear as it takes, since it is all recoverable when you've finished climbing.  

Despite what wbo2 said, there is not usually very much movement and it is very unlikely to weaken the sling, unless you are using different-sized ropes which can cause sawing.  If this is a concern, you could use a stone knot, or leave a maillon or krab.  I also take the point about it being easier to pull the ropes through a ring, and I would consider leaving a maillon or krab if this could be a problem but I wouldn't do so routinely. 

However you do it you will be leaving a sling behind which will deteriorate due to weather, apart from any damage caused by pulling the rope.  Any party following will have to make their own decision about that sling, and they won't know whether it has been there for hours or months.  

I am not tightfisted when it comes to protecting my life, and if necessary I will abandon whatever it takes in order to safeguard a descent.  However I wouldn't routinely leave a krab or maillon and it would be a specific decision based on the particular situation I was facing. So far as I know, it is not normal practice here to carry rap rings, and I hadn't heard of them until this discussion.  However perhaps I am not up to date with latest practice.

In reply to Howard J:

Just a few comments

1) Quite early in my climbing career a friend was killed trying to escape from Noah's Warning in the pass. It is conjectured that he placed a sling and was pulling the rope through the sling to arrange the abseil; the friction of nylon against nylon combined with the weight of the rope was enough to fatally weaken the sling. Obviously once you're  aware of that possibility then you can mitigate against it (by looping the rope through a shorter, temporary sling and karabiner until you've pulled enough  rope through); I wouldn't have been aware at the time, and sadly Phil wasn't either.

2) I would have thought most climbers have accumulated enough krabs so they wouldn't mind sacrificing their oldest and least valuable (and I've got some that only cost £4 new anyway); I'm happy to sacrifice one of those if it means that the rope will run more freely and the tat will not be damaged for the next user. Assuming you apply some care in setting up the belay, and/or the krab has a reasonable 'gate open' breaking strain, does it really need to be a screwgate?

In reply to Rob Exile Ward:

Awful. I remember reading about that in a climbing magazine. I'm sure it was reported, maybe incorrectly, that he was  actually being lowered from his high point with the rope running directly through a sling which obviously melted through. It's stuck in my memory ever since.

In reply to Rob Exile Ward:

Yes, you would have to watch out for friction while passing the rope through the sling, and that itself might be a reason to use a krab.  I would probably choose to make a sling from a length of tat, and that can be tied round the rope without needing to thread it through.  It's also much easier to pull the rope through a sling made from round shiny cord rather than flat webbing

Just to be clear, I agree there are many situations where it makes sense to leave a krab or a maillon, and I won't hesitate to do so when necessary.  I had simply asked rgold (and it was a question, not a challenge) his reasons for saying it was always a bad idea to have the rope through a sling, since it is a common practice.

In reply to Howard J:

A situation I forgot to mention (but which I think someone else did) is when rapping on two ropes of different diameters.  The differential stretch in that case will produce sawing action.  Webbing is more susceptible to being sawed through than cord, but both are vulnerable.  Whatever you think of my other claims, this is a good time to use a rap ring or maillon.

In reply to rgold:

Agreed, that is definitely a situation which could result in sawing and where fabric-on-fabric contact should be avoided.

Mine was a genuine question, since as I have explained it is common practice here where the situation allows, and it is not considered dangerous if no movement can be expected. I agree that the requirements may be quite different on established descent routes compared with ad hoc retreats.

In reply to rgold:

In the UK rap rings are very expensive for what they are, probably too much to use them as "consumables". The typical price is more than the cheaper screwgates! Unless I've missed a cheap way to buy them, that is. Maillons are cheaper, but not if you want stainless - which is presumably why we have so many non-stainless ones rusting away on in situ abseil points.

In reply to Ggilbs:

Hi. Speaking from experience rather than specialised knowledge, but I can't see why this would be a problem.

For dyneema to be a danger vs say, nylon slings, the difference in elasticity between a short length of dyneema and nylon would have to be critical. That seems pretty unlikely.

As you are abseiling, shock absorption is provided by the elasticity of the rope. The farther down the ab, the greater the rope length absorbing shock, but even if just starting the abseil, it seems unlikely that a nylon sling would provide so much more elasticity such that anchors were significantly more likely to fail with dyneema.

Throughout the thread there has been a debate about the wisdom of threading the ab rope directly onto nylon slings. In extremis you'll do whatever you have to, but personally, I would be keen to avoid this where possible. I think rgold's advice is sound.

I met a girl in her 20s on a club trip once. She no longer climbed as she used a wheelchair following a fall, where she had been lowered with the rope running directly over a nylon sling. Obviously abseiling with the rope theoretically static over the sling will stress the sling much less, but I'd happily sacrifice a biner or 2 for the sake of a few £; you won't get a second chance if the anchor fails.

In reply to mrjonathanr:

An alarming anecdote, but not really relevant to the current discussion, which is about abseiling. I don't think anyone is suggesting a moving and weighted rope directly through a sling!

In reply to bpmclimb:

Agreed, so long as they ensure there is no movement of rope over the sling whilst abseiling and they do no intend to pull their rope after getting down.

It's an extreme example, but it does illustrate the frailty of nylon over nylon. That might be worth balancing against the cost of leaving a biner, especially since the thread suggests abseilers before you on fixed slings may well have compromised the strength of the anchor by pulling their rope directly over the sling.

Up to each to balance the risks and costs. Best to be realistic about what the risks may lead to.

In reply to mrjonathanr:

Why not? I have a couple of times melted through my abseil tat while pulling the rope. It happened because there was a lot of friction increasing the tension in the rope. It was quite convenient having it just fall down given how hard it was to pull the rope.

In reply to mrjonathanr:

It's actually extremely simple, any abseil anchor is to be treated with some suspicion, ones made with soft goods with a great amount of suspicion. Whether there is a ring, carabiner, maillon or whatever doesn't make them any safer.

In reply to Robert Durran:

Absolutely.... all my slings are nylon....

Always have been...

Barbeg

In reply to mrjonathanr:

Who on earth would abseil but not pull the rope? It would surely only be if you were (a) sacrificing the rope in a nasty retreat, or (b) going back up to retrieve the anchor, in which case you'd leave a krab anyway.

In reply to Ggilbs:

Lowering off a sling is undoubtedly a very bad idea and likely to end very badly, but this discussion is about abseiling.  We are also discussing two very different scenarios.

One is where abseiling is the normal means of descent off a route.  I suspect this is a common scenario in the US and explains what rgold describes is the usual practice there.  There is then undoubtedly a responsibility to protect the sling for any parties following behind, possibly only by minutes.  This scenario is not common in the UK, and where it us there are often fixed ab points.  

The more usual situation in the UK is when retreating from a route.  Here I would suggest the primary responsibility is to get the team down safely.  There need be less concern for anyone following, since it might be years before someone descends the same way, and they would be very unwise to rely on an old sling whether or not it had a krab or maillon.  You could even argue that it is safer to leave a sling which shows visible signs of damage than one which looks OK but has been weakened by weathering.  There is also a culture of not leaving rubbish in the mountains, and whilst leaving a sling is probably unavoidable the same cannot be said for rusting metalwork.  However this is secondary to safety and should not override a decision to leave a krab where this is necessary.

I questioned rgold about his statement that threading a sling is always a bad idea. In the first scenario this makes more sense.  In the second scenario, whilst it will often be desirable or necessary to abandon a krab, there are other situations where threading the sling will be fine. 

In reply to barbeg:

Is it even common to buy non dyneema slings nowadays?  Or even see them for sale?

Unlike what is stated above, and having seen enough abseiling, long abseils will set up a short sawing motion as the ropes are weighted/unweighted.  It doesn't need much movement to damage slings, and I'm not very comfortable with this.  But I guess we should agree to disagree.

In reply to bpmclimb:

Some years ago I looked up prices of stainless steel rings eg from GS products, theropepeople.com, and S3i. These were in the order of £1 to £2 each (not inc delivery). I looked at 4mm (IIRC breaking load 800kg) and stronger 5 and 6mm ones. Didn't find out the weight and imagine the thinner rings might be harder for rope retrieval. Never followed it up. I think some climbers do use them and they'd certainly be cheaper.

In reply to oldie:

Thanks for the tip, that's cheaper by far. Obviously, not sold as climbing gear, so not "rated" for that use, but materials and strength look good. I'd probably go for 6mm for the 2.5x extra strength margin. Or even the 8mm x 40mm for something very strong and chunky, still only £1.43.

In reply to wbo2:

They still seem to be common, possibly the majority of slings on some websites are dyneema.

Unless soloing there will always be someone to observe any problems with the anchor as the first abseils (I can't remember noticing sawing action in setups I've abbed on). IMHO its often a good idea to back up the first abseiler with a second anchor ready to take the strain if anchor one fails, and to remove the backup if safe for the last abseiler. I used to abseil using 5mm cord or thin (3/8"?) nylon tape without problems, though obviously I wasn't able to see if there was damage after pulling down the entire rope. However I've seen similar previously used ab anchors which seemed OK. I would have placed new material for myself anyway. Nowadays I prefer to use more substantial slings.

In reply to wbo2:

So far as I know all thin (6mm) slings will be dyneema. The round Edelrid ones not and are highly heat resistant. 

In reply to wbo2:

Do you mean the sawing action of dynamic ropes over rock edges when they are weighted/unweighted? This is no doubt something to be aware of (and minimised by keeping ropes weighted and abseiling smoothly as far as possible), but it shouldn't result in a side-to-side sawing action of the rope through the sling (unless, perhaps, where the two ropes have very different properties). That's a different issue, surely?