Snubbers and climbing rope

[Mike OReilly]

Why is climbing rope superior to normal 3-stand rope?

I asked earlier, but didn’t see a response.

[LongRange]

Originally Posted by Mike OReilly

Why is climbing rope superior to normal 3-stand rope?

I asked earlier, but didn’t see a response.

In this context, it is not markedly superior over nylon 3-strand.

Climbing rope is manufactured for a very specific purpose, to much higher standards of consistency, and it is tested to the n-th degree. Single "dynamic" climbing ropes are available in diameters from 9mm to 11mm, in virtually every 0.1mm increment, to cater for the individual buyer's risk appetite. Thicker rope has higher safety reserves, in the sense that it is better able to cope with sharp rock edges, but it is also heavier and that can make a massive difference in high-end climbing.


If the climber is safety-conscious, and follows standard guidelines, they will retire a rope long before most people would think it necessary. Since there is no such thing as a "suspect" climbing rope, unless the individual has a death wish, climbing ropes fall into only two categories:


1) Life-support. UIAA-rated, less than 48 months old, always stored in dark, dry, and cool places, never exposed to chemicals, never absorbed a factor-1 fall or greater, known history (not second-hand).

2) No-longer-life-support, because it does not meet one or more criteria outlined above.

To a climber, ropes in category 2 are useless and even dangerous, because they could potentially get mixed up with cat1. Conscientious climbers will thus get rid of a cat2 rope quickly, even give it away for free, and that's when a yachtie should pounce because most cat2 ropes have plenty of life left in them for boating purposes.


I'd never suggest buying a new or near-new climbing rope to hang a boat off it. That would be a costly misuse of resources.

[LongRange]

Come to think of it, climbing rope may even be worse than bog-standard nylon anchor rope.

The force/stretch profiles of single dynamic climbing ropes are optimized to minimize impulse forces in falls involving 80Kg weights, for obvious reasons. It was somehow determined (probably the hard way!) that the human body cannot take more than 12KN impulse forces over ~1s tops. Any more than that, and the climber gets pureed, or extruded through their harness.

The design and certification goals of climbing ropes thus involve being stretchy at typical human weights and forces. Anchor loads for a 40-footer in a 50 knot storm simply do not figure in the equations of climbing rope manufacturers.

It occurs to me that dynamic climbing rope may thus feel stretchier to a human than 3-strand, at typical human loads, only to run out of stretch and go comparatively stiff closer to its ultimate breaking strain.

I have no data to back that up, but bog-standard nylon mooring 3-strand may deliver a stretch profile which is more linear and more suitable for boat-level loading, especially when those loads are 10KN+ for extended periods of time.

[Gaia]

Originally Posted by LongRange

Come to think of it, climbing rope may even be worse than bog-standard nylon anchor rope.

The force/stretch profiles of single dynamic climbing ropes are optimized to minimize impulse forces in falls involving 80Kg weights, for obvious reasons. It was somehow determined (probably the hard way!) that the human body cannot take more than 12KN impulse forces over ~1s tops. Any more than that, and the climber gets pureed, or extruded through their harness.

The design and certification goals of climbing ropes thus involve being stretchy at typical human weights and forces. Anchor loads for a 40-footer in a 50 knot storm simply do not figure in the equations of climbing rope manufacturers.

It occurs to me that dynamic climbing rope may thus feel stretchier to a human than 3-strand, at typical human loads, only to run out of stretch and go comparatively stiff closer to its ultimate breaking strain.

I have no data to back that up, but bog-standard nylon mooring 3-strand may deliver a stretch profile which is more linear and more suitable for boat-level loading, especially when those loads are 10KN+ for extended periods of time.

This thread is becoming more and more interesting as people with real knowledge contribute. We did substantial damage, since repaired, when we caught our anchor chain under a rock off of Ascension island and a large swell rolled in. We wrapped our anchor roller, a heavy duty affair, against the hull and twisted our solid lifelines until they looked like spaghetti. We were using, as always, a long 3/8" 3 strand nylon snubber which broke. Since then I have wondered if i should use 1/2". I have also looked askance at the frequently seen short, large diameter, braided polyester snubber thinking they are not snubbers at all. But I have also wondered at how much stretch remains in my long rather thin nylon snubber with time since we use it every day. And I worry about chafe since the snubber runs on the loose chain and on the bottom.

Our snubber is attached at the waterline which materially increases our scope hence its frequent use even when there is no swell. Because of its importance, with a modern anchor, I immediately got interested in the OP's question.

Jim

[LoudMusic]

I haven't done a significant storm mooring away from a dock so I'm not certain what it truly entails, but sounds like you guys are looking for some snap energy dampening. Would in-line dock line snubbers not be effective? PBO did a review a few years back of a variety of styles.

https://www.pbo.co.uk/gear/pbo-teste...snubbers-45131

I've seen the metal spring style and the wrap around style in use at marinas before. For storms at anchor you could even double up on each leg of the snubber if you felt it was necessary.

[Pete7]

We tried using climbing ropes in the diving club for a while as shot lines with a big weight to sink to the bottom. They were quite thick so may have been ex abseiling lines.

The problem was after a few dives the rope would dry out and set in a coil like a really think piece of wire and was sod to flake out becoming almost unmanageable. We gave up and went back to cheap 3 strand nylon.

Pete

[Mike OReilly]

Thanks LongRange/Gaia/Thin (and others) for the thoughtful analysis. I’m quite curious about the whole question b/c I’ve seen reference to using climbing ropes in the past for snubbers.

I’m sure they would work, but I’m not clear under what circumstances they may be better than good old 3-strand nylon. This line is already abundantly available, and fairly inexpensive. It is also available in a wide variety of diameters.

I can certainly see that if one has inexpensive access to the stretchy form of climbing rope, then sure, why not use it. Although the chafe and UV weaknesses give me pause. If you’re a cruiser/climber crossover (as some of you are), it seems like a fine idea, but for most of us, I don’t (yet) see an advantage over nylon.

… but I’m here to learn .. Educate away .

[thinwater]

I've done a lot of physical rope testing, including some projects in cooperation with manufactures. The following are facts I can support. I am talking specifically about UIAA single, dynamic climbing ropes.



* Climbing rope is the same strength as other rope constructions. 10-11 mm ropes are about 5000-6500 pounds tensile strength when pulled as other ropes are tested. However, they are rated based on a specific fall test and strength is very rarely published.
* Only dynamic climbing ropes can reliably pass the UIAA tests. Put another way, the 3-strand and double braid ropes will fail, as will polyester and Dyneema ropes, and webbing of any type. I've witnessed the testing.
* You may read of a limited number of drops and an impact force of ~ 1200 pounds. However, this is NOT a normal pull test. The drop is over a sharp edge and the rope is attached with knots, not splices. All other ropes generally fail on the 1ts or 2nd drop. It is a TOUGH test.
* Climbing rope is more abrasion prone, because more of the fiber is in the core than the cover. Double braids are balanced 50/50.
* The core of a climbing rope is twisted but not laid. This gives climbing ropes BETTER fatigue life than any other construction. There is less internal wear. This is why 10-11 mm climbing rope is PROVEN to work on boats up to 40-45 feet. Not theory, proven by world sailors cruising long-term. That said, I'd use something heavier in a hurricane.
* The 1200-pound impact force limit was developed by the US Army Air Corp (early USAF) during parachute testing. If the force is higher than that, too many soldiers were injured. That is NOT to say 1200 pounds on a sailing chest harness is OK; you will break ribs. Additionally, sailing tethers are NOT climbing rope and the impact force can be much greater than that. On the other hand, the impact force will be far less than that, generally no more than a few hundred pounds, if climbing rope is used for tethers; it will stretch 3-6 inches during a hard hit, like hitting thick padding.
* No, double braid and 3-strand rope do NOT absorb as much energy. In fact, only 50-70% as much as climbing rope. This is why they will ALWAYS fail the UIAA drop test. It is not even close. The elongation to break on climbing rope is >80%, vs. 35-45%. Try to break a climbing rope with a slow pull and watch how long it gets!
* Climbing ropes are a bugger to splice. Fixed eyes are formed by sewing using methods a DIY will not likely be able to duplicate. Your sailmaker can't either. I've done a lot of stitched eye testing. It is the extreme elongation that causes the trouble.
* Climbing ropes have superior knot strength because the core is composed of 8-12 free floating strands, not constrained by a braid or lay. This means they behave more like a collection of 1/8-inch ropes and are not weakened as much by tight bends.


If any of these points require clarification... ask.


I'm not saying climbing ropes are superior for snubbers. I've used both climbing rope and 3-strand. I'm just laying out some facts.

[Macblaze]

Originally Posted by thinwater

I've done a lot of physical rope testing, including some projects in cooperation with manufactures. The following are facts I can support. I am talking specifically about UIAA single, dynamic climbing ropes.

I'm not saying climbing ropes are superior for snubbers. I've used both climbing rope and 3-strand. I'm just laying out some facts.

And they come in 60m lengths, so if you have a couple laying around like I do, its a whole lot of potential snubber

Mine are 6 years+ old and I can no longer justify using them even for simple toproping and it hurts to consider tossing them...thank god I started sailing!

[Mike OReilly]

This is great stuff Thin. I was hoping you’d step in here.

I really am interested in understanding this stuff. I spend a lot of time an anchor, and rely on my snubbers to take continual pounding (stretching) over months at a time. They are protected from chafe, but are exposed to UV and continual salt water immersion.

I’d be thrilled to try something better than what I currently use: 1/2” to 3/4” diameter 3-strand nylon (I’m away from the boat right now, and can’t remember exactly what I’ve got in service right now).

Can you help me with this though. You say "Double braid and 3-strand rope do NOT absorb as much energy. In fact, only 50-70% as much as climbing rope. This is why they will ALWAYS fail the UIAA drop test. It is not even close. The elongation to break on climbing rope is >80%, vs. 35-45%.”

This sounds like "dynamic climbing ropes” will be superior to equivalent diameter 3-strand nylon. Great… but then you go and confuse me by saying, "I'm not saying climbing ropes are superior for snubbers.”

Why? If I understand you, it sounds like the stretch and reliance is superior. Is it the chafe issue? UV? Cost?

[groundtackle]

thinwater, thanks from all of us for this clarity.
Chris

[LongRange]

1200lb is a measurement of mass (or weight), not force. UIAA standards stipulate that the impulse must never exceed 12KN (kilo newtons) during a drop test. That's 2.2 times the force exerted by a hanging 1200lb weight.

The UIAA test is also conducted with several minutes of rest time (I forget the exact details) between drops, to give the molecular bonds time to recover. Climbers are also advised to rest their ropes after hard (high fall factor) falls, and turn them end-over-end if "working" a route over a longer period, involving repeated falls. I hate to think what the UIAA would say about static loads of around a tonne, coupled with periodic extra loading from waves

Horses for courses. If anticipating potential falls while lead climbing on rocks, with a few sharp ledges, dynamic climbing rope is the only way to go. It is designed to behave like a big rubber band during the occasional hair-raising drop of a 80Kg object, with time to rest and change underwear before the next short, sharp impact.

Those qualities may not automatically mean climbing rope is also the best snubber for a ~10000Kg object in wind and tide creating a static force approaching or exceeding 10KN for hours or days on end, with a superimposed additional tug from a passing wave every few seconds.

If somebody has published test data, I would be very interested to see it.

[thinwater]

Originally Posted by Mike OReilly

This is great stuff Thin. I was hoping you’d step in here.

I really am interested in understanding this stuff. I spend a lot of time an anchor, and rely on my snubbers to take continual pounding (stretching) over months at a time. They are protected from chafe, but are exposed to UV and continual salt water immersion.

I’d be thrilled to try something better than what I currently use: 1/2” to 3/4” diameter 3-strand nylon (I’m away from the boat right now, and can’t remember exactly what I’ve got in service right now).

Can you help me with this though. You say "Double braid and 3-strand rope do NOT absorb as much energy. In fact, only 50-70% as much as climbing rope. This is why they will ALWAYS fail the UIAA drop test. It is not even close. The elongation to break on climbing rope is >80%, vs. 35-45%.”

This sounds like "dynamic climbing ropes” will be superior to equivalent diameter 3-strand nylon. Great… but then you go and confuse me by saying, "I'm not saying climbing ropes are superior for snubbers.”

Why? If I understand you, it sounds like the stretch and reliance is superior. Is it the chafe issue? UV? Cost?

In my opinion, the Achilles heel of climbing rope is chafe. If you can deal with that, it's great stuff. If chafe is unavoidable--and it is on some boats--then 3-strand looks very good. That's my opinion, and I have used both for considerable periods.

[thinwater]

Originally Posted by LongRange

1200lb is a measurement of mass (or weight), not force. UIAA standards stipulate that the impulse must never exceed 12KN (kilo newtons) during a drop test. That's 2.2 times the force exerted by a hanging 1200lb weight.

The UIAA test is also conducted with several minutes of rest time (I forget the exact details) between drops, to give the molecular bonds time to recover. Climbers are also advised to rest their ropes after hard (high fall factor) falls, and turn them end-over-end if "working" a route over a longer period, involving repeated falls. I hate to think what the UIAA would say about static loads of around a tonne, coupled with periodic extra loading from waves

Horses for courses. If anticipating potential falls while lead climbing on rocks, with a few sharp ledges, dynamic climbing rope is the only way to go. It is designed to behave like a big rubber band during the occasional hair-raising drop of a 80Kg object, with time to rest and change underwear before the next short, sharp impact.

Those qualities may not automatically mean climbing rope is also the best snubber for a ~10000Kg object in wind and tide creating a static force approaching or exceeding 10KN for hours or days on end, with a superimposed additional tug from a passing wave every few seconds.

If somebody has published test data, I would be very interested to see it.

a. In the US, pounds is a unit of force. Engineers also use pounds-mass and slugs in calculations, but an engineer will understand the context and easily convert between them.


b. I think you will be hard pressed to find a climbing rope that actually excedes ~ 1600 pounds in the drop test.


c. The rest time relates to certain viscous effects within fibers and perhaps some weak hydrogen bonding, but not molecular bonds. Moreover, the time constant in a drop test and the slow surging of a yacht are hardly related. Off topic.


d. I don't see why you think the nylon in climbing ropes is different from other nylon. Although nylon is subject to fatigue, holding force for time has been well researched and is not a major factor (US Coast Guard and US Navy research on tow lines--you can Google it). You are reaching in this case, with no support that I am aware of. I believe the UIAA subcommittee would shrug at sustained loading.


---


Although climbing rope has some interesting characteristics, you can get the same stretch out of 3-strand if you just make the snubber 5-10 feet longer. Obvious, really. Make a choice.

[Mike OReilly]

Originally Posted by thinwater

In my opinion, the Achilles heel of climbing rope is chafe. If you can deal with that, it's great stuff. If chafe is unavoidable--and it is on some boats--then 3-strand looks very good. That's my opinion, and I have used both for considerable periods.

Many thanks. I understand now. You’ve convinced me to give it a try. I need to replace my current snubbers anyway, so this will be a good test.