Caving on string

[andrewmcleod]

This has started being discussed in the 'Emergency Climbing Rope' thread (https://ukcaving.com/board/index.php?threads/emergency-climbing-rope.32776/post-418414) because I think it's something that's going to become much more significant and regulated (or at least available) so deserves its own thread?

Ropes are getting thinner and thinner, despite CNCC advice whose website advocates 10-10.5mm ropes with occasional justification of 11mm ropes.
From https://cncc.org.uk/equipment/rope-care/
"More serious considerations apply to small diameter ropes, of less than 10mm diameter. Of course 9mm ropes are lighter, more compact, and initially strong enough, but the weight saved is hardly significant, while the reduction in safety margins is considerable, Heavy shock loading and abrasion damage apart, imagine for example, the prospect of mid-rope rescue of an injured caver on a well used 9mm rope! We might well question the wisdom of using a rope which is only safe in certain circumstances."

I think many cavers these days happily and routinely cave on 9mm ropes without major issues, particularly given that the rock in most well-travelled Dales caves is generally pretty shiny so much less rope-destroying in the case of poor rigging than say a big Alpine cave. You can of course now get 8.5mm class B ropes, of which I have a few.

I also have some 8mm Petzl Segment which I really like - it does squeak like other Petzl rope but I think it holds up better than the 9mm Push (after accounting for the diameter difference - the 8mm will still be more fragile despite the added polyester in the sheath). My Petzl Rig auto-locks happily with it with my weight, which is nice (this won't work if it's 'too' worn, where 'too' may not be very worn of course).

8mm stuff is, however, NOT ROPE. It does not comply with the requirements of the low-stretch rope EN1891 or UIAA 107 standards; it is rated as accessory cord which means it is not rated to do things like have a minimum strength of 22 kN/18 kN (class B/A) in, or 15 kN/12 kN with a figure 8 knot in, or take a FF 0.3 fall with a 100 kg/80 kg with an impact force of less than 6kN (which also requires rope survival of course in this drop test).

That said, it is still 'ropey' i.e. it has a certain amount of stretch, it take take a certain amount of energy absorption (less than a dynamic rope but still important). It is weaker - it has a static strength of 16kN (below the 18kN requirement for class B) and a strength with a Fig 8 of 10kN (below the 12kN requirement for class B), but it isn't fundamentally 'different'? I *suspect* (given that it is actually more bouncy than most 9mm rope) that it would achieve an impact force of less than 6 kN in a FF 0.3 fall with an 80 kg mass, but we can't know that (unless Petzl tell us somewhere). Conveniently I weigh closer to 70 kg than 80 kg so hopefully that gives me an extra edge (although add the weight of all my caving gear and a big heavy bag of rope etc...).

With Petzl Segment we are down to 43 g/m (other 8mm cords are available). Thinner accessory cords are obviously available but after that it starts getting silly.

So that's 'thin not-actually-rope', anyway - I don't think it needs fundamentally different risk assessments to normal rope, just more care. Rub is, as ever, unacceptable.

 

[andrewmcleod]

One of my Christmas presents this year is going to be 50 m of 7 mm 'Petzl Caving Line' which is definitely *not* rope (at least, not as we know it). The obviously advantage is weight (32 g/m) and pack size, but I am expecting to have to be much much more careful with it and consider whether a pitch can even be safely rigged with it at all with the anchors as they are.

Caving Line is one of many '(hyper)static cords'

There is _no_ applicable EN standard for this sort of thing; they get rated as accessory cords but they really aren't. They are always made of some fancy technical fibre rather than nylon (polyamide) and have much lower stretch, with all of the inherent consequences. The UIAA have recognized this and written a UIAA standard that does not match an EN standard: UIAA 110

Introducing UIAA Safety Standard 110 for Static Ropes - UIAA

The publication of the UIAA Standard 110 for Static Ropes heralds the latest achievement of the UIAA Safety Commission. It was approved at the Commission’s 50-year anniversary meeting in Chamonix in April following five years of intense efforts from a dedicated working group, composed of...

www.theuiaa.org

https://www.theuiaa.org/documents/safety-standards/UIAA_110_2025_ExplantoryNote_v1.0.pdf

https://www.theuiaa.org/documents/safety-standards/UIAA_110_StaticRopes_v1.pdf

It's a new standard, and Petzl have not rated Petzl Caving Line against it, but I suspect it behaves similarly, so it's worth thinking about the consequences of using UIAA 110 'Static Ropes' instead of more 'normal' nylon skinny ropes.

Firstly, they must have stretch less than 2.5 % under 100 kg load which is less than normal 'low-stretch ropes', and means Petzl Segment would, for example, not pass.
Secondly, they must have a static strength of at least 12 kN without terminations and 8 kN with a Fig. 8 knot. Both Petzl Segment and Caving Line would pass this test.
Thirdly, the rope must survive a FF 0.15 fall with a 80 kg test mass. No requirement for a minimum impact force (with a knotted strength of only 8 kN, I think this is almost redundant), and only one fall needed. I don't know if either Segment or Caving Line would pass this test.

The last element is important - FF 0.15 is not much. Basically falling must be absolutely avoided, but sometimes this is impossible. Single-bolt rebelays become a problem - if you assume there is 2 m of slack at the bottom (e.g. bottom of the loop 1 m below the anchor) then the anchor above needs to be about 13 m above you. Obviously people don't act like 80 kg steel tests masses which gives you a little bit of wiggle room, but you still want to be _really_ careful - there is *very* little safety margin left on a 8kN max knotted strength!

Rub is of course still a major issue. There is a good bit in Alpine Caving Techniques about caving with super-skinny cords (7/8mm) although they weren't thinking about very static cords but just skinny nylon rope/cords. Basically, rub should be treated as if it will result in instant rope cutting and death, and *everything* has to be rigged so that any anchor failure will not result in rub.

That means any deviation whose failure will result in rub (as opposed to just keeping you dry, for example) *must* have decent cord and two bolts or otherwise have no reasonable possibility of failure. Normally on 9mm or above we have a bit of a (dubious?) hidden assumption that the rope will survive one ascent without failing, but this is definitely even more dubious on 7mm or 8mm. Similarly, a nice Y-hang in the roof where the rope won't rub off either bolt is nice; a wide Y-hang across a pitch head where failure of one anchor will result in rub is a problem.
Given these constraints, it may not be possible to rig many UK resin-anchored pitches 'safely' unless you are relying on the extremely low rate of resin anchor failure. On spits, it would be much more daft.

I am looking forward to my Caving Line, but I am going to treat it really quite differently to my 8mm, and I think everyone should...

In fact my advice is not to use 8mm cord or 7mm hyperstatic cord for rigging because 'yer gonna die'

 

[CNCC]

Hi Andrew. It is worth adding that the rope care text on our website is very old and probably pre-dates the involvement of most of our current volunteers. We don't know the exact background of the text but assume it links to old BCA/NCA advice issued around 15-20 years ago when the CNCC website was first created. We're very conscious that many cavers happily and safely use 9mm rope. If there is any more up-to-date BCA guidance we'd certainly be keen to review the information in this section of our website, or simply to link to BCA resources.

 

[andrewmcleod]

Hi Andrew. It is worth adding that the rope care text on our website is very old and probably pre-dates the involvement of most of our current volunteers. We don't know the exact background of the text but assume it links to old BCA/NCA advice issued around 15-20 years ago when the CNCC website was first created. We're very conscious that many cavers happily and safely use 9mm rope. If there is any more up-to-date BCA guidance we'd certainly be keen to review the information in this section of our website, or simply to link to BCA resources.

I suspected this was the case
But it's not actually wrong or dangerous advice, and some people could probably do with encouragement to use thicker rather than 'cool' thinner ropes (massive hypocrisy here )

 

[andrewmcleod]

If you look at the Petzl 'caving on very skinny string' document:

https://www.petzl.com/sfc/servlet.shepherd/version/download/068Tx00000GUbgyIAD

and the Petzl Caving Line thing:

https://www.petzl.com/sfc/servlet.shepherd/version/download/068Tx000006x8PaIAI

(if those links don't work, just look at the two 'Technical notice' links at the bottom of https://www.petzl.com/GB/en/Sport/Ropes/CAVING-LINE-7-mm )
there are a number of specific differences for Caving Line in particular.

1) You *cannot* use a barrel knot for Caving Line (presumably it is too skinny/slippery and could run through a descender/undo). You should use a Capuchin/barrel knot on a bight/'doubled' barrel knot (whatever you want to call it, look at the pictures)

2) For both (officially), the approved devices are:
- Simple >= 2019 with Freino Z
- Stop >= 2019 with Freino Z
- Basic >= 2013
- Nano Traxion
- Micro Traxion
- Pantin
- Croll S but explicitly NOT the Croll L
I suspect in practice older Simples/Stops will 'work' with suitably aggressive braking carabiners (even with a new Stop it is not expected to actually 'stop') but this is what is 'approved' and no caving descender will be rated below 8.5mm in a general sense I think.
The last one is interesting as the Croll L is the only device specifically mentioned as *not* OK? Presumably the rope groove is 'too' large or something (since it is rated for 8-13mm instead of 8-11mm) and possibly the Ascension hand ascender (which I use) may also not be OK? (it is not on the 'approved' list, anyway).

3) For a Simple, you *must* use a different rigging with an extra loop _or_ basically always abseil in half-lock. Abseiling normally gets the explanation mark ('Exposure to a potential risk of accident or injury'); abseiling with no braking carabiner normally rigged gets DEATH ('Situation presenting an imminent risk of serious injury or death').

4) For a Stop, you basically use it normally, except that not using a braking carabiner gets an exclamation mark.

5) Locking off: for a Simple you have to do a 'normal' British lock-off; for a Stop you can still do the Freino weirdness (presumably a British 'hard lock' is still OK).

6) Strengths are given for Fig 8, Bowline on a bight, bunny ears, and joining a rope onto a Fig 8 on a bight; all are 8 kN (Caving line) or 10 kN (Segment).

Plenty of things to think about!

 

[Ian Ball]

What is the CIC training advice? it was Type based I believe.

 

[hannahb]

That means any deviation whose failure will result in rub (as opposed to just keeping you dry, for example) *must* have decent cord and two bolts

Please, please let's not go down this route

 

[Samouse1]

Please, please let's not go down this route

I took it to mean that people rigging with string shouldn't use it unless there are two bolts for a deviation, rather than we should be putting in two bolts for deviations. I agree we shouldn't be putting in more bolts so that a very small group of people can use their string on every possible pitch!

 

[Bob Mehew]

UIAA 110 on static ropes might be considered to be a variant on EN 564:2023 "Mountaineering equipment - Accessory cords - Safety requirements and test methods" but there are significant differences in the requirements as the EN has no dynamic test requirement. After rub, the other thing which came immediately to my mind was how small a diameter of rope can an ascender acceptably clamp. EN 567:2013 on clamps requires a clap to hold at least 4kN 'static' pull. And sorry EN standards are copyrighted, the cheapest source to read them that I am aware of is via https://www.evs.ee/en/evs-en-564-2023 . My copies are out of date. I've not even looked at sailing ropes / cords.

 

[Samouse1]

***Copy and pasted from t'other thread***


Firstly, Petzl specify that it is a technical cord for "expert" use, though what counts as an expert is undefined. There are three uses I can see it being used for in UK caving.

1. A short line for setting up hauls/breaking into a loaded line. Five metres is barely noticeable weight wise, and can be used with a few bits of rescue kit to set up a haul.

2. Pull through cord. Used on the pull down side to save weight. Fairly self explanatory, can be used as an emergency rope to get you out of a pinch

3. For use in descent and ascent. Here is where it gets a bit more complicated, and definitely not a bit of kit for everyone. As Josh pointed out, there is a different way to rig your descender, first a standard S rig, then an O rig to add more friction. On descent I think this feels close to 9mm rope handling wise, although great care is still needed. I have only used a Simple, though a friend did use a Stop, I will ask if it actually stopped.
Ascent is the same as normal in terms of gear, but you really do feel like you're going up a shoelace. The rigging needs to be immaculate to avoid any rub at all. I even consider how close it could be with some swinging about due to prussiking. "Breakable" knots (BotB, fusion) are highly recommended if you want to be able to untie it once weighted.

The big benefit is being able to squeeze 60m of the stuff into a 6 litre Daren Drum. I turned up to a trip and a friend was in disbelief that there was enough in the bag to get us down the cave.

My recommendation for anyone seriously considering using it for ascent/descent (not just in a "ooh look at me Billy big balls using the thinnest stuff possible" way), really get some practice in on the surface, and only use it where you really need to. Most places and trips don't justify the increased risks.

***End copied section***

For what it's worth, I think Andrewmcleod and I are barking up the same tree here, just Andrew has got all the nerdy data I trusted him to bring to the table!

TLDR can probably be "If you aren't 100% happy on it, or 100% sure you're using it correctly and safely, don't use it!"

 

[andrewmcleod]

Please, please let's not go down this route

Don't argue with me, argue with Alpine Caving Techniques in the skinny rope section

The advice there is only intended for use with 7/8mm stuff.

My point is that caves are anchored for 'normal' rope and most cavers don't get any choice in where the anchors will be; in some cases it will _not_ be possible to rig a cave using those anchors with very skinny ropes/cord in a 'safe' way (for some definition of 'safe' where 'rub will result in likely death' and 'anchors may fail').

What is the CIC training advice? it was Type based I believe.

I would be surprised if it was anything other than 'cave on proper rope not silly string' which is, by the way, also my advice

UIAA 110 on static ropes might be considered to be a variant on EN 564:2023 "Mountaineering equipment - Accessory cords - Safety requirements and test methods" but [...]

UIAA standard 102 is the equivalent of the accessory cord EN 564:2023 standard.

 

[tim.rose2]

Putting aside what's 'safe' to use and within the abilities of certain pieces of kit, shouldn't we also consider what's nice to use (including for the rest of the group)? I can't say I do a lot of SRT but when I do, I usually end up carrying most of the rope & doing the rigging. Personal experience;

• 11 mm or 10.5 mm feels clunky, pain in the arse to tie knots in, takes up loads of space in a rope bag, doesn't seem to feed very well in descenders/ascenders etc. = cavers moaning about the rope / amount to carry.
• 10 mm seems the perfect compromise and is a pleasure to use - probably due to be being the middle of the tolerances in most kit.
• 9 mm seems to run a bit fast, doesn't feed as well going up (particularly getting going due to it weighing a bit less) and psychologically seems thin / bouncy = cavers moaning about the rope. I appreciate a lot of (in particular) Northerners who have to carry lots of rope up hills have got used to this, but for me it's definitely not as nice to use.
• 'That shitty orange stuff' that was available a decade or so ago, was very cheap, turned to wire after the first use and everyone hates. Yes it was 10 mm, but = cavers moaning about the rope. Like many others, I bought this stuff and soon replaced it with something much nicer to use. I only mentioned this as it's when I learnt my lesson - buy rope that's nice to use, rather than cheap, 'I like the colour', trendy, etc.

You can obviously mitigate against some of the negative I've mentioned by varying kit, using pantins, extra friction crabs etc. but is it worth it for most 'normal' trips which we're doing for enjoyment? Surely we want the kit that's nicest to use and to make the caving trip as pleasurable as possible? The advantage in the UK is at most the difference of a few Kg's over perhaps a 3 mile walk, an 8 to 10 hour caving trip or perhaps a slightly smaller tackle sack through a few awkward bits of passage? Which is worse? The misery of carrying a bit more rope or the rope use related moans / hassles when you get to the pitch? I confess, I've not done the biggest most awkward trips the UK can offer or caved abroad, but have done a reasonable amount of caving in most UK regions and not once have I ever thought, 'if only I'd bought thinner rope' that trip would have been so much better.

Quite a few people I've caved with seem to share my feelings - most seem to prefer using a decent quality supple 10 mm. I have a few short lengths of 9mm I use on what I often refer to as nuisance pitches (5m ish pitches) but all my longer ropes are 10 mm and I can't see a reason at the moment to go thinner for normal use in the UK. 10 mm seems to be a great compromise for everything and what most cavers personal kit works best with. Forgetting SRT and instead thinking about handlines, 10 mm is nice to hold / pull on, 9 mm seems to start to cut into your hand. Even using old rope for drag trays in digs - 10 mm always seems the nicest.

So regardless of the additional dangers / arguments over whether it's safe to use, why would anyone want to use something thinner still (such as 7 or 8 mm) other than in situations like expeditions or pushing extremes where you might need to go to the extremes of kit to make things possible? I do appreciate boundaries are only broken by those prepared to push extremes and so these types of rope / cord clearly have a place, but I cannot see one in 'normal UK caving'.

If there's cavers reading this who actually think really thin rope is nicer to use than 10 mm please speak up. What's your reasons? Or is it simply every gram counts with respects to moving fluidly through a cave / walking to it and you're happy to sacrifice the niceties of rope usage? Or, what other's have eluded too and warned against, it's trendy?

 

[cap n chris]

Firing from the hip, so to speak, without fully scrutinising all the above first (unwise, yes, I know!), my understanding is that cord is 6mm or narrower and 7mm-8mm is Type L territory (L for Lightweight); rigging with Type L does indeed require a different philosophy (e.g. twin-anchors for deviation(s) as the consequences of a deviation failure are very high). FWIW I've used 7mm in Rhino (double braking carabiners obviously) and also been off the top of Cheddar Gorge on 7mm during a bespoke filming event so it was minimally visible. I don't do sketchy stuff like that anymore but am very happy with 9mm. I still have (but wouldn't use it due to age) some of the beautiful Beal Unicore 8mm (had a 200m reel but it was a cardboard reel which got damp and all the rope dropped off the end so it was an impossible tangle so cut it to max 40m lengths and given the elongation that was more than sufficient for my purposes. I believe Unicore does still exist - a fabulous "invention" and one which all manufacturers should blatantly copy, imo.

 

[cap n chris]

The "shitty orange stuff" was Mammut (10mm) and more recently Teufelberger (again, 10mm), IIRC. Teufelberger is still available whereas I believe Mammut sold the idea forward and ceased manufacturing it. Their red 9mm was way better for rigging in terms of suppleness etc., but still tended to rigidity earlier than other manufacturers.

 

[Samouse1]

If there's cavers reading this who actually think really thin rope is nicer to use than 10 mm please speak up. What's your reasons? Or is it simply every gram counts with respects to moving fluidly through a cave / walking to it and you're happy to sacrifice the niceties of rope usage? Or, what other's have eluded too and warned against, it's trendy?

So I do a very good chunk of my caving on string, or thin ropes, almost exclusively 9mm or under. This should not be taken as advice or endorsement of using thinner ropes.

I find it easier to handle when tying knots, and less wiry, even after a fair bit of use (although that may be brand rather than diameter).

The weight is certainly a factor too, as a lot of my trips tend to be on the harder/longer end of the spectrum currently. For example, a recent trip into Penyghent, with three of us it was a small bag each, one of which contained quite the feast to keep us going! If we hadn't been using the thinner ropes, someone would have had to carry two bags, or we wouldn't have been as well fed (and probably not enjoyed it as much as we did). The fast and light approach is very much my preferred style these days, minimal waiting around, and keep moving to stay warm.

For bigger pitches most of my friends who I regularly cave with agree that 8.5mm is the preferred, 8mm at a push, 7mm probably not (haven't used it on a big pitch yet, I'm sure it would be fine but psychologically a bit nervy). 9mm for sturdier rigging eg. I recently had Meregill rigged on 9mm for a short while on an ongoing project.

Club trips certainly never go less than 9mm, I would only use 8.5 or less with people I know well enough to judge if they can safely use it.

 

[andrewmcleod]

Knots are easier to put into thin rope, but harder to take out! (easily mitigated by appropriate knot choices). I really like the way Petzl Segment handles for rigging, but it is only 8mm so I don't use it for 'normal' trips.

There's terrible rope at all diameters - all my first rope was Edelrid Superstatic 9mm and some Mammut 9mm because it was cheap, but it was stiff and horrible and nasty and I replaced it all fairly quickly (most of it is still in Thundergasm in the Dachstein for fixed rigging and is only slightly out of date now )

A factor to consider is that a full bag of 9mm rope is heavier than a full bag of 10mm rope, and a full bag of 8mm rope even heavier again (for the same size bag)...

 

[mikem]

I wonder if that's still true for a wet rope?

 

[Badlad]

The essence of this thread depends on the user's experience and knowledge. The pure sporting caver does not have to use equipment that conforms to particular standards - if they don't want to. What is important is that you evaluate and understand the risks involved with various equipment especially non-standard and/or lightweight equipment. That's just common sense.

Lightweight ropes, 8mm essentially, were mostly used in my experience amongst small experienced teams particularly if they were pushing deep potholes. Usually, for speed, this involved other rigging shortcuts and resulted in a greater risk generally.

I don't use sub 9mm these days but when I did it was mostly during the era of a Beal and Edelrid 8mm. The Edelrid was a tighter weave, stiffer and harder wearing. Because it kept its shape, less surface of the rope was in contact with the descender and consequently an abseil was hard to control. Think breaking krab, wrapped round the leg twice and still a scary descent sometimes. The Beal was a softer weave, more surface pressed against the descender or ascending device and there was more noticeable control. However, we considered them more prone to wear and generally weaker.

With rope it is always a compromise between strength, diameter, weave, softness, etc and all the other facets that go into it.

 

[topcat]

I wonder if that's still true for a wet rope?

Depends on the make.
I did a non too rigorous [I did make an effort to be 'scientific' ] comparison of ropes wet and dry.

Basically, as you might expect, softer ropes that were super nice for rigging absorbed the most water.
If memory serves Craven record 143 has the details.

 

[Cantclimbtom]

Mentioning for completeness that rope can also be too thick.

In the summer, a member of the party I was in declined the last pitch of James Hall O.E. because she'd not liked my (very clean and fairly new condition) 10.5mm rope. It was pretty sturdy stuff with a very robust sheath so handled more like an 11mm (Southern ropes LSK 10.5 semi static). She had a new style stop (8.5-11) and the rest of us were still using old style ones (9-12) and she couldn't stand fighting the rope.

You can have too much of a good thing.. as well as not enough!