Dyneema caving ropes

[Grolin]

I know this is controversial but could be an interesting discussion point and a theoretical concept for the future.

So a 6mm dyneema rope as a core covered by an aramid sheath could be a incredibly light and strong caving rope. I know that it doesn't stretch so in a anchor failure it would probably be deadly same with badly rigged traverse lines. But in the UK where we use resin anchors with double bolt re-belays (mostly) and well rigged traverse lines, is the lack of stretch a concern? I know that in many caves there are still single bolt re-belays where you absolutely do not want to use dyneema rope but on a pitch such as alum pot the direct route where there are y hangs a single bolt failure should not lead to a shock load and the lack of stretch makes prussiking easier. the same could be said for Titan. The reason I am suggesting the aramid sheath is due to dyneema's low melting point and slippiness the aramid sheath would provide heat resistance and friction while descending.

the cost of such a rope would be insane but it would be essentially indestructible.

now feel free to tear me to shreads but I will say that every new idea was once perceived as crazy.

 

[Space Doubt Caver]

I know this is controversial but could be an interesting discussion point and a theoretical concept for the future.

So a 6mm dyneema rope as a core covered by an aramid sheath could be a incredibly light and strong caving rope. I know that it doesn't stretch so in a anchor failure it would probably be deadly same with badly rigged traverse lines. But in the UK where we use resin anchors with double bolt re-belays (mostly) and well rigged traverse lines, is the lack of stretch a concern? I know that in many caves there are still single bolt re-belays where you absolutely do not want to use dyneema rope but on a pitch such as alum pot the direct route where there are y hangs a single bolt failure should not lead to a shock load and the lack of stretch makes prussiking easier. the same could be said for Titan. The reason I am suggesting the aramid sheath is due to dyneema's low melting point and slippiness the aramid sheath would provide heat resistance and friction while descending.

the cost of such a rope would be insane but it would be essentially indestructible.

now feel free to tear me to shreads but I will say that every new idea was once perceived as crazy.

Imagine a fall factor 2 on such a rope that'd be messy,

Theoretically it could be done, with the right research, manufacturing, testing and funding but first you'd have to put a lot of research into it, applying research funding, then you would have to manufacture, more funding, and you'd need a standardised testing rig, more funding like what they use for rope testing, but you would fail some times but you might get it right once, but before using it you would need to rigorously test it then put it through quality assurance, then get approved, probably by the UIAA, and even if it didn't pass as a rope you could use it as a rope it could be used as slings footloops, cowstails, you never know.

You miss 100% of the shots you don't take.
A person who never asks a question is always a fool, the person that does ask becomes smarter for asking

 

[Wolfo]

So it's been done, we use 5 and 5,5mm Beal Dyneema line in some ultra-lightweight applications...but more mine related.
There are no decenders and ascenders available which work properly. You could use a fresh Croll and also a bobbin on those "ropes", but performance is more or less bad. Adjusted bobbins and ascenders working on a lever priciple (like the old Petzl Rescuecender) performance best, but they need to be made specially for these thin lines.
Anchors are 6mm push-ins and Ablakov-type V-anchors.

To be fair, if you are not into manufacturing and a bit mad...it's propably not a way to go.

 

[JoshW]

In order to meet an en standard for a semi static rope (ie to have any sort of market for the rope), it needs to absorb enough force under a factor 1 fall to not tear someone’s spine in two (less than 6kN).

Dyneema is too static to absorb the load and would cause a maximum load of over this amount (I think).

I’m not saying it couldn’t be done to physically make the rope, but in order to get a manufacturer to make it they’d have to know enough people would buy it. As it wouldn’t meet an en standard it’s unlikely to be able to be sold to any professional outfit, severely impacting possible sales.

 

[zzzzzzed]

You could use dyneema rope if your ascenders were attached to your D-ring by something that can absorb shock. They use 11mm steel cable on some via ferratas and that can be made safe.

 

[JoshW]

You could use dyneema rope if your ascenders were attached to your D-ring by something that can absorb shock. They use 11mm steel cable on some via ferratas and that can be made safe.

Via ferrata lanyards are attached by single use shock absorbers.

Tbh I’d be a big fan of certain traverses just having steel cable installed as a traverse line, rigged at a height where you’d always be below it obviously.

I’m not saying you cant make it safe; what I’m saying is there’s no market for rope that doesn’t meet en standards

 

[Wolfo]

It's single rope technique...no triple or quadruple lanyards will save you.
Same with hyperstatic ropes/Dyneema (tm)...also these lines have some stretch, but just as with any static ropes- don't fall on it. If you are experienced in bolting realistically no fall should happen, achor failure in alpine rigging with short pitches is not very common, except maybe on bolt climbs.
To be fair, I took falls directly on lanyards while aid-climbing which should have exceeded the 6kn in theory...still there.
There is no "safe" or "perfect" system...a lot is up to personal experience, fear management and skill.

 

[andrewmcleod]

RAD LINE 6 mm - Ropes | Petzl United Kingdom

Petzl United Kingdom. Ultra-light and compact hyperstatic cord designed for skiers doing crevasse rescue, rappelling, or roping up on a glacier to get out of a crevasse zone

www.petzl.com

Not only has it already been done (by several manufacturers I think), it is even available for sale from UK caving gear sellers.

This also exists (pure HDPE so extremely slippery).

PUR LINE 6 mm - Ropes | Petzl Other

Petzl Other. Ultra-lightweight and ultra-durable hyperstatic cord designed for climbers and mountaineers to haul packs and retrieve single certified ropes during rappels

www.petzl.com

I think the problem is that while it would be very tough for 6mm cord/rope, I suspect it would be a _long_ way from indestructible. Yes, dyneema is pretty indestructible in general use but part of that is because it is hyperstatic and therefore doesn't move much when looped around naturals etc. If you are hanging on 10m+ of it, it is still going to stretch a bit and thus rub a bit.

See also:

6.0 Glacier Cord Dry | Mammut

A rope developed specially for glacier trekking and for skiers and mountaineers - suitable for rappelling, haul maneuvers or crevasse rescues. The Dry treatment also gives the rope maximum safety even in the most adverse conditions, by ensuring that the cord absorbs practically no water and does...

www.mammut.com

 

[Grolin]

Turns out I was just describing already known products. I thought the petzl rad lines were something else the mammut one is pretty much exactly what I was envisioning. The only thing to think about now is whether the community may start using it.

 

[JoshW]

Turns out I was just describing already known products. I thought the petzl rad lines were something else the mammut one is pretty much exactly what I was envisioning. The only thing to think about now is whether the community may start using it.

At 155 quid for 30 metres it seems unlikely I can get nearly a full reel of light enough 9mm type B for 50 odd quid more than that

 

[Wolfo]

Problem with some rap lines is the stealth...it doesn't respond too well to toothed ascenders, pure dyneema lines are better in this regard than anything containing nylon. But as I wrote better use lever or anvil type ascenders than the classic toothed ones - a tibloc also works on 4mm, but shreds it up.
Stuff like this may be useful in situations like cave diving or - in our case - difficult and extremely long transports...

 

[AlexR]

Should’ve known this would bring Wolfo out of the woodwork

Effectively +1 to what he said above, sadly the RAD line isn’t really suitable due to it’s comparatively fragile sheath.
The Petzl PUR is much better, but unless you’re pushing deep caves with small teams I would definitely not cave on it. Certainly not in the UK.

I used to (and sometimes still do) cave on 8mm in the UK, but it’s simply not worth it. The ropes get shagged much quicker, your wallet will feel it, and aside from weird stuff like doing multiple caves in a day solo the weight saving is completely unnecessary. This is doubly true for 6mm Dyneema ropes which require specialist gear to ascend/ descend, plus you need to be really paranoid with your rigging.

The new-ish style ‚cut resistant‘ dynamic ropes we’re seeing use some Dyneema and/ or Aramid, incorporating that into a semi static rope for caving would be nice. Purely for longevity I’d say, at the end of the day any rope with 80kg+ hanging from it will be cut by rock like butter.

 

[Cantclimbtom]

...The Petzl PUR is much better...

Isn't Petzl PUR a tag line (the pull cord for a retrievable abseil) or lightweight haul cord, but not sure it's intended to suspend people? Also it'd be a "challenging" abseil, although on the plus side you wouldn't have trouble going downwards!

A good comparison of RAD versus PUR

Petzl - RADline vs PURline comparison — Alpinesavvy

Petzl makes two highly specialized ropes suitable for alpine climbers, the RADline and the PURline. Both have a static Dyneema core, both are 6 mm, and both are designed for different applications. Here's just about everything you need to know about these ropes.

www.alpinesavvy.com

 

[Wolfo]

None of these lines are intended for SRT, it's all off-limitations use, don't do that

The Petzl Pur has a sufficient strength rating for this special application - to be fair, if you are into ultra-light rigging your anchors are likely also more in the 10-15kN range, so scaled. 5 and 5,5mm Beal Dyneema accessory cord is also fine for this use.
If somebody ever intends to get into stuff like this I hardly recommend doing own testing, which will include owning a fast enough load cell and a good understanding of material science...
There is actually a trend to lightweight and ultra-lightweight gear in the outdoor industry and specially with users - but a cave is a bad place for any real world testing.

 

[Space Doubt Caver]

on the plus side you wouldn't have trouble going downwards!

 

[zzzzzzed]

Via ferrata lanyards are attached by single use shock absorbers.

Tbh I’d be a big fan of certain traverses just having steel cable installed as a traverse line, rigged at a height where you’d always be below it obviously.

I’m not saying you cant make it safe; what I’m saying is there’s no market for rope that doesn’t meet en standards

Via ferrata lanyards used to be attached by a metal device that allowed slippage once forces exceeded a certain amount.

As you know, many mines already have steel cables to protect traverses.

I realise that dyneema won't be used now, but equipment evolves over time. It's perfectly possible that ascenders could be designed that slipped and braked when forces exceed a safe limit. We could then use super skinny, super abrasion resistant and super static rope that would comply with some future standard.

 

[andrewmcleod]

I would argue the current limit on rope thinness is primarily abrasion resistance, not how static it is (even with the new hyperstatic cords). At least until someone proves otherwise.

 

[JAshley73]

There seems to be a decent selection of "canyoning rope" that uses aramid/aramid-mix materials in the sheath, from 6-9mm.

One could use a fancy-8, or super-munter hitch for descending. I'm not sure what one would use for ascending something smaller than 8mm, as far as I can tell, our typical caving-use toothed ascenders aren't rated for ropes below 8mm. Perhaps they would still work?

 

[Mark Wright]

The 6mm Petzl Rad rope is compatible with a Tibloc ascender and the Micro and Nano Traxion pulley's.

The main issue is the RRP of £5.40 Inc. Vat. / m.

 

[AlexR]

I think the main issue is that the RAD's sheath gets shagged from a single ascent. I love the RAD for glacier travel, mountaineering routes that might need the odd abseil etc. but it will definitely not tolerate continued ascender use.

I guess there are two seperate discussions here, as in what is possible now, and what may be possible in the future.

In the interest of avoiding any room for misunderstanding, this is the current situation:
The Petzl RAD, PUR as well as the Beal 5 & 5.5 Dyneema cordages are not designed, intended, or certified for SRT. There are people like Wolfo and me who have used it for this purpose, but it is an application pretty far beyond what they're intended for. You should be very experienced and comfortable with the use of "Type L" rope to even consider this use.
Also bear in mind that something which seems a good idea from the safety of your living room may rapidly lose its appeal when you're looking down 50m hanging from a very thin thread indeed.

If anyone is contemplating this takes Wolfos words to heart and consider that knot strength reduction does not scale linearly with different materials. Polyamides are much, much more amenable to stretching (read: spreading the load) than polyethylenes (like Dyneema).


For future potential:
Current CE certification does not allow for a completely static SRT rope, though as zzzzzzed points out there could always be a future standard. Also, our friends from over the pond don't suffer from this problem, as their much more static polyester ropes lay testament to.


Caving is an extremely niche market, the development comes from industrial rope access and yachting. The latter already has a plethora of Dyneema-incorporating lines at eye-watering price points. Because they are not life-supporting CE certification is less important.
I'm only aware of aramid being used in some specialty rope access ropes (for heat resistantance). But if you want to use a rope commercially to dangle a person from it'll need CE certification. Well, unless you enjoy spending time at your majesty's pleasure when that specialty ropes breaks and your employee plummets to the ground.

PS:
Counterpoint to the original poster's point of "you'd never use fully static cordage on a single anchor": Well, maybe. What is the likelyhood of a resin bolt failing? How many people have done pull-throughs on single anchors? Not that I'd avise it, but I think there are certainly more risky things we accept as fine.