Fixed Hand Lines

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Fixed Hand Lines

Postby Extremeophile » Feb 16, 2013 9:17 pm

It seems lately I'm spending a lot of time visiting caves with numerous fixed hand lines. Generally these are installed where a short pitch could be free climbed, but a hand line makes it easier, and nobody would be willing to haul vertical gear for the occasional exposed or awkward 10-15 foot climb. The route between the elevator and camp in Jewel Cave has at least ten hand lines. In Jewel Cave these are all 1" tubular webbing. Webbing is rated for about 4,000 lbs, which is a 10-20x safety factor, it's less expensive than rope or cord, it packs small, and my impression is that it is more static than thinner cord (e.g. 6-8 mm). Many of the fixed hand lines in Colorado are kernmantle rope. I believe many of these are retired rock climbing ropes, so typically they are dynamic. My concerns with these are that they don't have a traceable history, and I dislike climbing dynamic rope. I'm considering replacing these with 1" webbing, but I thought I'd ask for opinions.

1" webbing seems like a good choice because it's widely available with a good strength rating. I'm favoring mil spec over climbing spec because it has more of a ribbed surface that I think probably makes it easier to grip. My general sense is that webbing might be easier to grip than rope. It's certainly easier to wrap a loop around your hand for extra security.

Rope is obviously easier to use with vertical gear. In locations where there is some potential that someone might bring vertical gear, then it seems like rope ought to be used.

If you want to connect webbing to something like a 2-bolt anchor, can you use a double figure-8? I understand that technically this can be tied in webbing, but probably not without a lot of twisting.

I'm not sure if rope or webbing is more durable. Since webbing is flat maybe it's more likely to stay in place, but kernmantle rope has a built in sheath for protection.

In the Guads they try to use white webbing for fixed rigging. I guess they have seen some leaching of dyes. Most cavers aren't too fashion aware, so maybe white is the best option.

In some locations (e.g. a steep slope with extremely slick footing), knots or loops are tied in the hand line. I generally prefer the loops over something like an overhand knot. Most times I don't use the loop itself, but the knots are bigger and easier to grasp. With rope I prefer a butterfly knot for tying a loop, but in webbing I favor an overhand. You can tie a figure-8 or butterfly in webbing, but it tends to twist the webbing, though maybe this doesn't impact its strength or security. Of course once a rope is knotted it's no longer an option to use vertical gear.

Maybe I'm overanalyzing, but that seems to be the point of Cavechat. Let me know if you have any opinions or best practices when it comes to fixed hand lines.
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Re: Fixed Hand Lines

Postby Scott McCrea » Feb 16, 2013 9:34 pm

FWIW, in my search for straps for Swaygo packs, I compared tubular to flat webbing. I found that flat was significantly more durable. It also stayed flat better, where the tubular liked to fold or roll.

The sheath on kernmantle rope does makes it more durable than webbing. But, how durable does it need to be? Minimize rub spots and it may not be a big deal.

Then there's the "rig for rescue" option to think about. In a haul or lowering scenario, rope is more useful as it works with Prusiks and ascenders.

If the footing is slick, the rope/webbing/handline is going to be slick, too. But, a hand wrap with webbing is usually more comfy than with rope.

Also, webbing is cheaper than rope. And, I think webbing stretches more than cord or static rope.
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Re: Fixed Hand Lines

Postby chh » Feb 17, 2013 6:31 pm

I'm all for keeping that rope in place as opposed to replacing it with tubular webbing. It interfaces better with potential rescue scenarios, and I find it actually easier to grab than tube webbing.
FWIW I also don't like handlines with fixed knots. If you need more friction, use a body belay/shoulder wrap or whathave you. Adding knots also takes away from other potential uses of the rope where technique easily compensates.
Also, for a handline, who really cares if it's dynamic or not? It'd have to be one long handline for that to be of any appreciable effect I think. But then, I use dynamic ropes all the time. I don't hate them;)
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Re: Fixed Hand Lines

Postby JSDunham » Feb 17, 2013 7:31 pm

One factor no one has mentioned yet is that webbing is easier to inspect; rope with questionable history may have deterioration of the core that isn't visible from the outside. I would never trust rescue rigging to a rope that just happened to be in the cave myself, unless I knew its history. Webbing, by contrast, I could inspect and be more confident about.

Something I've wondered about: does anyone know how fast a rope deteriorates when left in a cave? I know, various conditions--but any ideas?
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Re: Fixed Hand Lines

Postby Stridergdm » Feb 17, 2013 7:43 pm

JSDunham wrote:One factor no one has mentioned yet is that webbing is easier to inspect; rope with questionable history may have deterioration of the core that isn't visible from the outside. I would never trust rescue rigging to a rope that just happened to be in the cave myself, unless I knew its history. Webbing, by contrast, I could inspect and be more confident about.

Something I've wondered about: does anyone know how fast a rope deteriorates when left in a cave? I know, various conditions--but any ideas?


What deterioration of the core are you worried about in a rope in the cave?

In my limited experience, it's the sheath that is the issue and that's fairly easy to inspect.
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Re: Fixed Hand Lines

Postby Extremeophile » Feb 17, 2013 10:02 pm

JSDunham wrote:Something I've wondered about: does anyone know how fast a rope deteriorates when left in a cave? I know, various conditions--but any ideas?

I've seen fixed ropes in caves that have been there for 15-20 years that appear to be in good condition. There's another thread on the lifespan of helmets where it is pointed out that manufacturers, such as Petzl, say to retire any plastic goods after 10 years. I believe PMI recommends the same 10 years for ropes, regardless of how they are used or stored. It's true that polymers in some plastics may hydrolyze, or chemically degrade by other mechanisms, resulting in some loss of strength, but this process is extremely chemistry and environment dependent. My guess on the 10 year recommendation is that this is probably partly influenced by the manufacturer's legal counsel. I'd trust a 20 year old rope rigged in a cave before I'd trust a 5 year old rope rigged in full sun. I'm sure some of the rescue and safety folks could provide some pull test data on old fixed ropes, or even ropes stored unused in a basement for decades. Would a 10 or 20% loss in strength be enough to justify retiring a rope? I use 10mm PMI Talon rope, which is already at a 27% strength disadvantage to Pit Rope when it's brand new. So how much of a loss in initial strength would be justification for retirement ... 30%, 40%? A lot of fixed ropes end up being retired due to wear, but there seem to be very different opinions on whether to replace a rope on the basis of age alone. This is complicated further when the history of the rope is not known. PMI includes a tracer in the core of their ropes, so the approximate age can be determined, but other manufacturers (e.g. Bluewater) do not. PMI ropes have the exact manufacture date included in the lot#, although it's somewhat encrypted, but many ropes end up being cut and the lot# isn't retained. I'd be more inclined to leave fixed hand lines in place if I could both inspect them and verify their age. Without this I'd probably guess the hand lines date back to the original exploration.
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Re: Fixed Hand Lines

Postby Mike Hopley » Feb 18, 2013 6:12 am

I've seen fixed ropes in caves that have been there for 15-20 years that appear to be in good condition.


Appearances can be deceptive. A cautionary tale from Alpine Caving Techniques, about leaving ropes underground for too long:

If a rope stays too long underground (i.e. several years), it can have serious effects on the rope, even resulting in breakage during normal use. We have already seen this with a dynamic climbing rope left in a cave for seven years. While it had only been used twice in those seven years, it broke on the third use under the weight of the second person to climb up that day!


This issue applies to nylon rope and webbing/slings (polyester ropes might not be affected in the same way, because they don't chemically absorb water). On expeditions, we've often left ropes (derigged and coiled) in the cave for the next year. We limit this to about three years total, and then replace the ropes -- but of course it depends on the situation, and we take advice from an expert...

Dynamic rope is really not a good choice for caving, except for belaying climbers. Abrasion resistance in a rope is proportional to its elasticity; that's partly why Dyneema, which is static, is so hard-wearing. Semi-static (caving) ropes stretch a lot less than dynamic (climbing) ropes; therefore semi-static ropes resist abrasion better than dynamic ones.

On top of this, caving ropes tend to have a thicker, stiffer sheath that is more abrasion resistant.
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Re: Fixed Hand Lines

Postby paul » Feb 18, 2013 7:08 am

An interesting and relevant story from an old newsletter from my caving club: The strange story of orpheus rope number 10.
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Re: Fixed Hand Lines

Postby Mike Hopley » Feb 18, 2013 8:31 am

paul wrote:An interesting and relevant story from an old newsletter from my caving club: The strange story of orpheus rope number 10.


Indeed, ropes can last for decades. This is also true of ropes left permanently rigged outside. Kernmantle rope is remarkably strong and durable.

If a rope looks okay, it probably is okay -- even if it's 20 years old and has been left to bleach in the sun! Nevertheless I wouldn't choose to climb such a rope.
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Re: Fixed Hand Lines

Postby Extremeophile » Feb 18, 2013 10:41 am

Mike Hopley wrote:
I've seen fixed ropes in caves that have been there for 15-20 years that appear to be in good condition.


Appearances can be deceptive. A cautionary tale from Alpine Caving Techniques, about leaving ropes underground for too long:

If a rope stays too long underground (i.e. several years), it can have serious effects on the rope, even resulting in breakage during normal use. We have already seen this with a dynamic climbing rope left in a cave for seven years. While it had only been used twice in those seven years, it broke on the third use under the weight of the second person to climb up that day!


This issue applies to nylon rope and webbing/slings (polyester ropes might not be affected in the same way, because they don't chemically absorb water). On expeditions, we've often left ropes (derigged and coiled) in the cave for the next year. We limit this to about three years total, and then replace the ropes -- but of course it depends on the situation, and we take advice from an expert...

Dynamic rope is really not a good choice for caving, except for belaying climbers. Abrasion resistance in a rope is proportional to its elasticity; that's partly why Dyneema, which is static, is so hard-wearing. Semi-static (caving) ropes stretch a lot less than dynamic (climbing) ropes; therefore semi-static ropes resist abrasion better than dynamic ones.

On top of this, caving ropes tend to have a thicker, stiffer sheath that is more abrasion resistant.

While I agree that dynamic kernmantle is not a good choice for caves, I'm not sure I understand the anecdote from ACT. So a rope left in a cave for 7 years lost roughly 95% of its original strength? This story, and your explanation after, suggests that this loss in strength was due to chemical degradation (maybe just from exposure to moisture?). While dynamic and static ropes certainly have different constructions, the chemistry of the Nylon strands is identical. For most uses of Nylon in Europe they seem to favor Nylon 6, whereas in North America we favor Nylon 6,6, but I'm not sure if this translates to ropes. In any case, I'm skeptical that simple storage in cool, moist conditions would have much impact at all on strength. It's true that polyester is less hydrophilic (water loving) than Nylon, but the fact that Nylon absorbs some water does not necessarily mean that there is a significant amount of polymer degradation due to hydrolysis. It seems more likely that the rope mentioned in ACT failed due to abrasion, and in this case the lesson should be don't use dynamic rope as fixed line in caves because of lower abrasion resistance, not that fixed ropes need to be changed every 3-7 years because of chemical degradation.

Again, it seems like someone has probably tested Nylon rope under controlled conditions to determine the loss of strength over time. I'm all in favor of regular inspections of fixed ropes and retiring ropes based on visible attributes (e.g. sheath wear), but I believe a decision to change ropes on age alone should be based on data showing the change in strength over time. I have yet to see this data. I don't think a bunch of random anecdotes should be the basis for determining rope longevity.
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Re: Fixed Hand Lines

Postby Mike Hopley » Feb 18, 2013 12:17 pm

Extremeophile wrote:While I agree that dynamic kernmantle is not a good choice for caves, I'm not sure I understand the anecdote from ACT. So a rope left in a cave for 7 years lost roughly 95% of its original strength? This story, and your explanation after, suggests that this loss in strength was due to chemical degradation (maybe just from exposure to moisture?).


They seem to be blaming it on the loss of strength due to water absorption, yes.

It seems more likely that the rope mentioned in ACT failed due to abrasion, and in this case the lesson should be don't use dynamic rope as fixed line in caves because of lower abrasion resistance, not that fixed ropes need to be changed every 3-7 years because of chemical degradation.


I expect the authors would have thought of that possibility.


Again, it seems like someone has probably tested Nylon rope under controlled conditions to determine the loss of strength over time. I'm all in favor of regular inspections of fixed ropes and retiring ropes based on visible attributes (e.g. sheath wear), but I believe a decision to change ropes on age alone should be based on data showing the change in strength over time.


The trouble is there are too many variables. Caves and caving are not "controlled conditions".

Ropes (and harnesses, etc.) do degrade with age. Manufacturers insist that we change a rope after about 10 years, even if it shows no signs of wear. Some people believe this is a ploy to make more money; I believe it is a way of maintaining sufficient margin for safety. If I'm wrong, I lose a little money; if the cynics are wrong, they could lose their lives.

Of course, for the furtherance of knowledge, it's helpful to have people like you around to test old ropes through real-world use. :wink:
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Re: Fixed Hand Lines

Postby knudeNoggin » Feb 18, 2013 3:17 pm

About the life of ropes, much has been made of anecdotes,
less of rigorous study & testing. Pitt Schubert et al. of the
UIAA did one study in which they found even 30yr-old climbing
rope to survive one severe (UIAA FF 1.7) drop test, and made
the recommendation that climbing ropes could be used FOR
TOP-ROPE BELAYING until their sheaths wore through. Beal's
10-year recommendation I think is for LEAD climbing, where
more severe loading is possible.

As for that anecdote of some 7yr-old dynamic rope breaking,
there really needs to be close inspection of that rope and not
mere wide-eyed alarm. After all, if one believed that just
some 7 years led to such severe damage, how confident are
you of 4yr-old rope? And how do you explain the long-lived
service of so many other ropes as can be found in reports?
It's a shame those involved at the time didn't take some
effort to learn why there was that shocking breach. Maybe
it was abrasion; that should've been at least something to
conjecture based upon examination of the rope and the
environment at the point of rupture. Nylon doesn't like
acids : could there be some acidic drainage affecting it?


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Re: Fixed Hand Lines

Postby Extremeophile » Feb 18, 2013 4:02 pm

Mike Hopley wrote:
Extremeophile wrote:While I agree that dynamic kernmantle is not a good choice for caves, I'm not sure I understand the anecdote from ACT. So a rope left in a cave for 7 years lost roughly 95% of its original strength? This story, and your explanation after, suggests that this loss in strength was due to chemical degradation (maybe just from exposure to moisture?).


They seem to be blaming it on the loss of strength due to water absorption, yes.


That's one possible interpretation of the story, but I don't think there's any scientific basis to expect that much loss in rope strength. While it's true that a wet Nylon rope may have up to 15% lower tensile strength than the same dry Nylon rope when new, this is different than saying wet Nylon rope progressively gets weaker and weaker over time until it won't even support body weight. I doubt carbonic acid is strong enough to have much influence. In the absence of any data maybe your suggestion of being especially conservative in replacement of fixed ropes is wise, but are there really too many variables to collect some basic data? Caves are usually pretty static in temperature, and often humidity. Take the worst-case conditions of temperature, humidity, and moisture saturation and test the tensile strength as a function of time. Seems like a straightforward experiment. Then set an objective tensile value (e.g. 4,000 lbs, 18kN) for retirement. Again, if 10 years is the period of time to allow a sufficient margin of safety then why not share the data showing what that margin is?

I'm also not sure why static ropes are being tested in FF2 scenarios. I believe most brand new static ropes won't survive a FF2 test with an 80kg weight. And even if the rope survived, you probably wouldn't. Seems like static pull tests would be more meaningful.

Of course, for the furtherance of knowledge, it's helpful to have people like you around to test old ropes through real-world use.

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Re: Fixed Hand Lines

Postby knudeNoggin » Feb 18, 2013 5:30 pm

I'm also not sure why static ropes are being tested in FF2 scenarios. I believe most brand new static ropes won't survive a FF2 test with an 80kg weight. And even if the rope survived, you probably wouldn't. Seems like static pull tests would be more meaningful.

Indeed! Recently, on ukcaving.org, there are some threads about
potential slippage of ring-loading one-only of a bowline-on-the-bight's
eyes, and testing done in pursuit of understanding that showed some
drop tests of FF 1.0, and IIRC there were breaks (Fig.8, BotB) after
3-8 drops; though I think that they used 100kg.

As for wetness, water has in immediate weakening effect, but that's
not cumulative. Wet nylon apparently will suffer repeated loading
with internal friction, but this anecdote remarks that the rope was
used only a few times, so I don't see this usage rising to a critical level.


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Re: Fixed Hand Lines

Postby Mike Hopley » Feb 19, 2013 7:34 am

Extremeophile wrote:Again, if 10 years is the period of time to allow a sufficient margin of safety then why not share the data showing what that margin is?


I don't know. And neither do you, for that matter. But I'm prepared to believe that rope manufacturers might know more about their ropes than I do, regardless of whether they're sharing the data.

I would also expect that these lifespans are not determined by one simple set of data, but by careful consideration of the many ways ropes are used and abused. They will naturally set a very conservative lifespan to ensure sufficient margin. In most situations this means we retire our ropes several years (even decades!) before they actually break, which seems like a good idea to me.

I know cavers who had harnesses that were around 10 -- 15 years old, and were able to rip the harness in half with their hands. The harnesses seemed to be fine, judging by outward appearances. But don't worry -- you can ignore that information, because it's anecdotal. Only proper scientific evidence should ever be used to make a judgement about anything. :wink:

I think it's stupid to ignore the manufacturer's maximum recommended lifespan for textile PPE. The cost of rope (and harnesses, slings...) is trivial, and the consequence of failure is usually death. The reward of being "right" doesn't seem that attractive when compared to the consequences of being wrong.
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