Snubbers and climbing rope

[LongRange]

Originally Posted by thinwater

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.

Even in the non-SI system, the units of pound-force are quoted in "lbf", not "pounds". Disregarding that, you also mentioned "1200 pounds" as some kind of limit in this context, which is strange since the UIAA standard sets a 12KN limit for single dynamic climbing ropes in its drop test. 12KN is a force approximately 2.2 times greater than 1200lbf.

Originally Posted by thinwater

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

Converting to SI, that's 7.27KN. I don't think I have ever seen a single dynamic climbing rope that managed to stay under that value. A recent gear test shows that none of the ropes they tested managed to get as low as the value you mentioned as a maximum:

https://www.outdoorgearlab.com/topic...field=#compare

This is a random 9.5mm rope, which is near the bottom end for single rope diameters, and therefore about as gentle as they come in a fall:



As the 11mm diameter is approached, forces tend to get higher. Over time, rope wears out, which also increases the impulse forces.

Originally Posted by thinwater

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.

Here is a decent test by a top-tier climbing gear manufacturer into the effects of rest time on force:

https://www.blackdiamondequipment.co...een-falls.html

The point is that the constant loading and constant wave action would very quickly demolish the impact absorption performance of a climbing rope - perhaps within a day or even within an hour in heavy weather - and consign it into its "retirement" phase where nobody in the climbing community even considers it safe to use or worth testing.

Then there's the wet, which has been tested to reduce climbing rope performance by up to 50%, irrespective of special "dry" coatings.

Originally Posted by thinwater

d. I don't see why you think the nylon in climbing ropes is different from other nylon.

Perhaps I misunderstood, but I thought you were advocating "climbing" nylon for snubbers. Why is it better in this context than 3-strand nylon that can be bought off the roll in any chandlery for a fraction of the price of climbing rope?

Originally Posted by thinwater

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.

I guarantee the UIAA, and climbers in general, take the issue of sustained loads very seriously indeed:

Originally Posted by thinwater

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.

Yes, it might well be 5% better than 3-strand... during the first hour or so of a 30kn blow, and then never again.

[Mike OReilly]

OK … confused again .

[LongRange]

Originally Posted by Mike OReilly

OK … confused again .

Mike, my suggestion would be to try it, if you can find some second-hand climbing rope in decent condition, preferably for free. Snubbers are not a life-support context, so the consequences of getting it wrong are not dire.

Unless money is no object, I would not recommend buying new climbing rope for this purpose, especially since it is only typically available in 50m+ lengths, which cost two hundred bucks or more. Whatever small stretch advantages that rope may have over 3-strand, nebulous as they are where boats are involved, are likely to be worn away after just a few hours of abuse by wind and waves.


Personally, I do not understand Thinwater's contention that chafe is the Achilles Heel of climbing ropes. The one clear advantage that climbing rope has over 3-strand is abrasion and chafe resistance. The whole point of "kernmantle" construction is to provide a sacrificial layer on the outside, which protects the core that does most of the ropey work. If there is anyone on this planet that really, really cares about the chafe resistance of their rope, it is a climber accelerating downward at 9.8ms^-2, with lots of sharp rock edges between them and the belayer somewhere far down below

[smith8273]

What about climbing rope in the mainsheet traveler? I’ve heard that stretchy 8mm climbing rope would be good in a cruising sailboat — the stretch saves the boom in a gybe. Anyone have any ideas?

[JC Reefer]

If people are looking for inexpensive climbing rope then you might want to check out Sailing services in Miami. Many moons ago I worked there and the owner purchased (at the time) all the remnants off of New England ropes. These are sections of rope that are to short to make a spool. This was a deal done by the pound and we received several pallets worth of remnants. Hey I was the guy lucky enough to inventory it all. 🥴

Nothing was labeled, These were lengths of rope anywhere from 15’ to 150’ and ran the spectrum of their products, including climbing rope. We definitely had dynamic rope and I’m sure that several boxes still exist there.

If you are flexible in your selection, maybe just to test, then you won’t find a cheaper solution.

[Mike OReilly]

To me, it’s less about the cost and more about using something that is most effective. My understanding of why dynamic climbing ropes might be a good idea has to do with their elasticity. Their tenacity and ability to manage the constant cycling nature of the forces involved are also essential.

Price matters, but I view good snubbers as an essential parts of my anchoring system. I might skimp and economize on a lot of things, but not here. So cost is not a primary driver.

My boat is 15 tons (#30,000). I anchor a lot, and often stay in in one place for long periods. Last season I weathered three serious multi-day gales with sustained winds of around 35 knots, and gusts even higher. My snubbers see a lot of action.

My current snubbers are 2x 30’ of 3-strand, ~1” nylon of nothing-special pedigree. They have performed perfectly well. I forget the cost; perhaps a couple hundred Canadian bucks. I’ve also used stout double-braid docking lines in the past. They too have done well, although I prefer 3-strand.

Here’s a simple question: has anyone used or tested climbing rope on a heavy boat in similar conditions to the above, over periods of weeks? That’s the job I need my snubbers to do well with.

[pdxsailordiver]

Originally Posted by Mike OReilly

To me, it’s less about the cost and more about using something that is most effective. My understanding of why dynamic climbing ropes might be a good idea has to do with their elasticity. Their tenacity and ability to manage the constant cycling nature of the forces involved are also essential.



Price matters, but I view good snubbers as an essential parts of my anchoring system. I might skimp and economize on a lot of things, but not here. So cost is not a primary driver.



My boat is 15 tons (#30,000). I anchor a lot, and often stay in in one place for long periods. Last season I weathered three serious multi-day gales with sustained winds of around 35 knots, and gusts even higher. My snubbers see a lot of action.



My current snubbers are 2x 30’ of 3-strand, ~1” nylon of nothing-special pedigree. They have performed perfectly well. I forget the cost; perhaps a couple hundred Canadian bucks. I’ve also used stout double-braid docking lines in the past. They too have done well, although I prefer 3-strand.



Here’s a simple question: has anyone used or tested climbing rope on a heavy boat in similar conditions to the above, over periods of weeks? That’s the job I need my snubbers to do well with.

Mike
Email me your address.
I will mail you a 30’ or so piece of 11mm
Climbing rope.
You add a lot to this forum.
Tim
PS great snubbers!

[Mike OReilly]

Originally Posted by pdxsailordiver

Mike
Email me your address.
I will mail you a 30’ or so piece of 11mm
Climbing rope.
You add a lot to this forum.
Tim
PS great snubbers!

That’s very kind of you to say Tim. And even kinder on the offer. I will happily do so.

I take it you use them with you Cascade 42? Any thoughts on your experience. I’m very interested to see how they stand up to long-term anchoring in sometimes challenging conditions with a somewhat heavy boat.

I know Thin has done a lot of testing with his, but I think his boat is a lot lighter than mine. Your Cascade is a bit lighter than my old beast, but getting up there.

What I plan to do is test the climbing line in-situ as part of my normal bridle arrangement. I’ll rig one side with my normal 3-ply nylon, and the other with the climbing line. This should give a decent comparison.

[Montanan]

Originally Posted by Gaia

Good thread! Had no idea having always used 3 strand nylon. Problem is though where do I find climbing rope in the Bahamas?? ��

Jim

Good point might be a bit hard to come by in the Bahamas. I would begin looking for climbers / climbing rope at the highest point in the nation, Mount Alvernia (also known as Como Hill). It rises to an towering 206 feet (63 m).

[thinwater]

Regarding the 1200 pound limit, that is the impulse beyond which injuries become common. I believe the USAF first proposed it. Climbing ropes typically max at a little more than that in UIAA drops, but real world falls are far less.


Yes, ropes stiffen over time, but drop test data is hardly relevant to the subject at hand, since the impact is RIDICULOUSLY in excess of the SWL of the rope and applied in a different manner (rapid and over an edge). We are comparing apples with hand grenades. Like testing foot ball pads using the ballistic vest methods. We really should stop with the analysis of drop test data, unless we want to compare it to similar studies of double braid and 3-strand. Even then, the test conditions are obviously false. We're way off topic.



The conclusion that "Yes, it might well be 5% better than 3-strand... during the first hour or so of a 30kn blow, and then never again" is unsupported without matching data. I would LOVE to see sub-SWL data for these 3 rope types. I could be wrong. But I have never seen long term, sub-working load fatigue data for all of these ropes in a comprehensible format. I really would love to find that.


BTW, a 30-knot blow will not stress a snubber past the SWL; I've done a lot of testing at that level and used climbing rope and 3-strand snubbers (alternately on the same boat) for enough years to observe that this is simply not the case and there is no data to suggest that it is. Other users will support this.

[thinwater]

Originally Posted by smith8273

What about climbing rope in the mainsheet traveler? I’ve heard that stretchy 8mm climbing rope would be good in a cruising sailboat — the stretch saves the boom in a gybe. Anyone have any ideas?

Yup, Google it and you will find quite a few. I used it for years. I got the idea from Even Starzinger, and I know of some others. Some riggers are now suggesting nylon for travellers. BTW, it does not need to be climbing rope.

[thinwater]

Originally Posted by LongRange

Personally, I do not understand Thinwater's contention that chafe is the Achilles Heel of climbing ropes. The one clear advantage that climbing rope has over 3-strand is abrasion and chafe resistance. The whole point of "kernmantle" construction is to provide a sacrificial layer on the outside, which protects the core that does most of the ropey work. If there is anyone on this planet that really, really cares about the chafe resistance of their rope, it is a climber accelerating downward at 9.8ms^-2, with lots of sharp rock edges between them and the belayer somewhere far down below

Just experience, which has been mirrored by others that actually use climbing rope full time. They have to be more careful about chafe.



The mantel is relatively thin. I've torn through a few both climbing and sailing. 3-strand wears longer. Double braid can go either way; the cover is thicker, but it is often loose (for easier splicing) and prone to snagging.

[thinwater]

Originally Posted by Mike OReilly

... I know Thin has done a lot of testing with his, but I think his boat is a lot lighter than mine. Your Cascade is a bit lighter than my old beast, but getting up there....

10,000 pounds, but more windage. Additionally, I was using and 8mm bridle. I know Starzinger used it for years on a 45' mono. A friend of mine uses it on a 40' cat.


My position is that all of these materials can work well. 3-strand will last the longest. Climbing rope can be a little shorter for the same energy absorption. You can also get more absorption by going longer, or the same absorption with a fatter line that is longer. Finally, the ideal spring rate varies with the substrate; I like a very soft snubber, because the local mud can be very poor holding ground, but another sailor with good sand and more wind might be better served with a stiffer, more durable snubber. Many variables.



The basic rules are that it must be no larger than the ABYC recommended rode and at least 20 feet long (by the same logic, NEVER deploy less than 30 feet of rope with a mixed rode--the rope will be over strained). The rest "depends."



Which ever material you use, watch for chafe and replace it when the snubbing becomes more harsh, probably 100-200 nights of strong breeze or storm. This is obviously, extremely variable.

[LongRange]

Originally Posted by thinwater

Regarding the 1200 pound limit, that is the impulse beyond which injuries become common. I believe the USAF first proposed it. Climbing ropes typically max at a little more than that in UIAA drops, but real world falls are far less.


Yes, ropes stiffen over time, but drop test data is hardly relevant to the subject at hand, since the impact is RIDICULOUSLY in excess of the SWL of the rope and applied in a different manner (rapid and over an edge). We are comparing apples with hand grenades. Like testing foot ball pads using the ballistic vest methods. We really should stop with the analysis of drop test data, unless we want to compare it to similar studies of double braid and 3-strand. Even then, the test conditions are obviously false. We're way off topic.



The conclusion that "Yes, it might well be 5% better than 3-strand... during the first hour or so of a 30kn blow, and then never again" is unsupported without matching data. I would LOVE to see sub-SWL data for these 3 rope types. I could be wrong. But I have never seen long term, sub-working load fatigue data for all of these ropes in a comprehensible format. I really would love to find that.


BTW, a 30-knot blow will not stress a snubber past the SWL; I've done a lot of testing at that level and used climbing rope and 3-strand snubbers (alternately on the same boat) for enough years to observe that this is simply not the case and there is no data to suggest that it is. Other users will support this.

Climbing ropes do not have a "SWL". That apparent oversight actually contains the crux of this issue. (Just a little lame climbing humour, for anybody still reading )

This is a bit like purchasing a Ferrari and hitching up that 3 ton caravan, for a trip of a lifetime around the continent, because it posts such great times around the Nurburgring.

[thinwater]

Originally Posted by LongRange

Climbing ropes do not have a "SWL". That apparent oversight actually contains the crux of this issue. (Just a little lame climbing humour, for anybody still reading )

This is a bit like purchasing a Ferrari and hitching up that 3 ton caravan, for a trip of a lifetime around the continent, because it posts such great times around the Nurburgring.

Regarding chafe, yes, we all agree. Do you have any data that suggests climbing rope behaves differently than, say, 3-strand rope under sustained load? Remember, that snubbers are designed to primarily operate below 12% BS, the normal SWL of nylon. I have load cell data to confirm that, up to about 50 knots is semi-protected waters, this is true (if properly sized). ANY rope load beyond that will eventually fail due to fatigue. The 12% figure is from ABYC table AP-1 for double braid and 3-strand.



I don't understand where you are coming from. It sounds like you are suggesting that climbing rope construction is, in some way, sacrificial. If this is the case, explain exactly how the construction differences would make it weaker under sustained load, why, and point us to some data. So far, the available data do not point that direction... other than chafe.