Rope Rode - What Type (do you have)? What would you prefer?

[estarzinger]

Uncivilized - for anchor rodes - the vast majority of the bluewater fleet has 'all chain' (with a nylon backer they rarely use), and the vast majority of the coastal fleet has either that or a shorter chain (which usually is still long enough to allow them to frequently be on near on all chain) with a nylon backer. And both usually have secondary rodes with short chain and nylon backer). These solutions work well. Among the 'cruising writers' I would guess there is probably not enough of an issue/debate here to write an article.

There are alternatives, which have some potential pros but they each also pose difficulties which pretty much wipe out the pros. (racers do some crazy things, to meet the rules, but mostly dont really expect to be anchored except to counter current in drifter conditions)

The shore line situation is different - the fleet uses a whole wide range of solutions, and they all work ok, just with somewhat different pros and cons. It really more of a personal choice. There is an article in that. . . . but N Americans dont really use shore lines much.

The drogue rode and para anchor solutions are pretty much 'solved'. Either Dacron or dyneema (depending on affordability) for the drogue. and For the para-anchor, a lot of people are still using nylon, but (IMHO) dacron is by far the better solution.

[thinwater]

Originally Posted by Dockhead

... The prima facie evidence of what I say is that we've all had snubbers break unexpectedly, at much lower loads than the spec of the rope, or at least know people who have, and in this very thread we have an account of what can happen if you don't have the chain belayed in another way.

Actually, this is anecdotal evidence.

Whether it is from heating or not, I don't know...

Niether do I--not in every case--but in every case I have seen, the only evidence was melted fiber, which I have shown--and any lab tester will agree--is not an indicator of heating. I have also done the math--which I posted--which shows that there simply is not enough heat dissipation to cause melting. Unless--and this is important--the rope was cycling way above the fatigue limit, in which case it would fail anyway. Also, remember, from the tables I posted, that nylon will fail far below BS from fatigue within 100 cycles, which is nothing in a storm. So there is nothing surprising if a line breaks at 1/3 BS. We know this. The WLL of nylon is 9% of BS, just as the WLL of chain and most metal hardware is ~ 20-25% BS.

Also remember that I limited my no-heating claim to 3/4-inch, because that is what was relevant to ME. Dashew has a boat that is large far beyond my reality. My article stated that with 1-inch and above heating will begin to become a factor. It is all about the ratio of surface area to load. The larger the line, the easier it is for it to retain heat. This is also why it is important to tug boat folks. Thus, most of the research is for larger lines. But not to most sailors, if the ropes are sized properly. In my opinion (obvious engineering), the parachute ropes that failed were tragically undersized for fatigue. That is why they really failed.

... it is a fact that in real life, nylon ropes in the water break under cyclical loads, at loads far less than their spec....

Yes, that is exactly what I said.

Other factors reducing the strength and reliability of nylon compared to its spec is the well-known -- described even by the rope makers -- loss of strength when wet, and also high vulnerability to CHAFE, a phenomenon which is greatly exacerbated by a stretchy snubber running back and forth over bow rollers or other gear as it stretches.

Obviously. And obviously there are simple solutions.

It is true -- theoretically! -- that you could design a snubber as strong as your chain, even considering all the factors which reduce its strength. But how long would it then have to be, in order to have the desired amount of stretch? Once it has to be longer than the amount of chain you have out, then it ceases to be even theoretically possible.

Actually, this is quite simple, and I showed the math and the testing in a PS article. Cruisers will agree. The snubber needs to be ~ 40-55 feet long, depending whose number's you prefer. This is well proven both in the field and in theory. I don't think it is controversial. Strength will be slightly less than the chain.

Some concrete examples:

I have 12mm chain, G40, with minimum breaking strength of 8400kg/f. According to Dashew, wet and cyclically loaded nylon may have only 45% of its rated strength. Wrong--About 9% per ABYC and well established engnieering practice. So to equal the strength of my chain, I would need nylon with breaking strength of nearly 19 tons. No, you are arguing from a false assumption. If three is a snubber, the load drops by 4-6 times and the nylon is enough. This is well proven. That would be massive, impractical, 32mm nylon cable. OK, so by the time we get that big, it won't be under such cyclical loads, so maybe not 32mm, but how much? And does anyone use even 1" snubbers? And we haven't even started with chafe. Chafe is a matter of careful rigging. Yes, it requires intelligence.

I think the misunderstanding is that you have not accepted the whole point of using a long snubber--to reduce the load to not much more than the wind load. It is still important to use a strong chain--that insures robust durability, allows for corrosion and sharp rocks, and even for snubber failure (see below). For example, the reason ABYC allows rope rode of about the same strength as the chain is because they recognize that the load on a rope rode is MUCH lower. A snubber can be slightly thinner, because failure, if the chain is also belayed separately, is not tragic.

So I stand by my point -- don't use a snubber to belay your chain!

Without question, there should be a back-up anchor chain belaythat is very strong. I do not believe anyone (not me) argued against that. I think this is what we call a strawman argument (you have successfully assassinated a proposition no one made).

My mind is wide open. Show me math that is different or testing that shows heating (measured) in small lines. I am interested.

Also remember that a line does not absorb, as heat, energy that is released in the next cycle. Only hysteresis causes heating. For example, a spring does not heat. Also note that nylon must reach near boiling before there is more lose in strength. that's not just warm!

[thinwater]

Originally Posted by UNCIVILIZED

1. - Specifically, is/was it 3-strand, 8-plait, 12-plait, doublebraid? Why?
2. - Nylon, Polyester, Polypro, or other? Since Spectra’s been discussed a little bit in this application. Ditto some Polypro blends.
3. - Would you use it again, or switch to something else? And regardless of how you answer this, why would you make said choice?
4. - What size (diameter) & strength are your rodes, & how big is your boat (LOA, & Displacement)?
5. - Did you “discover” any techniques in using a specific rope type that were particularly helpful? That, or the reverse; meaning bad ideas?
6. - In a worst case scenario, like riding out a named storm or Hurricane, what rope would you ideally have? Why?
7. - Do you think that the ABYC rode recommendations are accurate? Too conservative? Or perhaps the reverse? Why?
8. - How much/how many rodes do you keep onboard? And of what length(s)? Where are they stored?
9. - Fiscally what do you consider to be the best choice when it comes to rope rodes? And where do you shop for them?
10. - Chain rodes aside, if cost isn’t part of the equation, what would you have in terms of rope rode?
11. - What rope rodes; types, or brands, & or, suppliers would you avoid?
12. - What kind of lifespan do you get with your rode(s)?
13. - Do you think that UV resistance is a big factor in rode lifespan?
14. - What else significantly lengthens or shortens rode lifespans in your experience?

1. 3-strand because I can use a long splice.
2. Nylon
3. No change
4. 1/4" x 100' G43 chain, balance rope. I VERY seldom anchor deeper than 7', so this is, in effect, all-chain for me. If the water were deeper I would have more chain, I think, consistent with light weight (catamaran). 24 x 16 x 9000 pounds.
5. skip
6. skip
7. Accurate for all chain with no snubber in shallow, exposed water.
8. skip the rest.

I use a 36' bridle as a snubber. Climbing rope with chafe gear. This dramatically reduces peak loads (4-6 times below ABYC). This also helps keep the hook in the bottom.



I would go with G70 chain if I had a larger boat, but for me that would not save weight.

[estarzinger]

Originally Posted by thinwater

testing that shows heating

a spring does not heat.

Really - a spring does not heat?

https://m.youtube.com/watch?v=Z6-CiSyI9oE

. . . . just as the first example test I found that shows (want looks like) heat.

Educate me, I m interested.

are you drawing a technical distinction between "temperature" (average kinetic energy I believe) and "heat" (energy transfer I believe)

Or are you making a point about a perfect theoretical 'cycle' of the spring?

I think you will agree that breaking bonds within a spring during vigorous cycle will generate heat (using any definition) but I guess you exclude that as above the working load? I dont know much about nylon - do molecular bonds not break at all at say 15% elongation?

[nautical62]

Retired climbing rope. Coils or flakes well, does the job and was free. Though I tend to prefer chain.

[mako]

Depends on the situation. In my area we don't have any (live) coral, but there are all these limestone outcroppings. When you dive down all you see are nylon 3-strand anchor lines lying all over the place. I follow them and build up my anchor collection!

So I've used polypropylene because it floats. Heavy anchor and a short very heavy chain leader. For a cruising boat I wouldn't recommend this as the primary, but it does work will and helps prevent damage to the seabed.

Future boat will be all chain but for the 2nd anchor (stern/kedge) I've specified floating polypropylene/polyester blend.

[thinwater]

Originally Posted by estarzinger

Really - a spring does not heat?

. . . . just as the first example test I found that shows (want looks like) heat.

Educate me, I m interested.

are you drawing a technical distinction between "temperature" (average kinetic energy I believe) and "heat" (energy transfer I believe)

Or are you making a point about a perfect theoretical 'cycle' of the spring?

I think you will agree that breaking bonds within a spring during vigorous cycle will generate heat (using any definition) but I guess you exclude that as above the working load? I dont know much about nylon - do molecular bonds not break at all at say 15% elongation?

Yes, in a perfect cycle, all of the potential energy is returned to mechanical energy and there is no net heating. Only hysteresis results in net heating. This is a consequence of conservation of energy and is not material specific.

Yes, breaking bonds would probably result in heating, but not for long (the rope would fail very soon if the number were significant). Moreover, breaking bonds is not a requirement of hysteresis--internal friction, either between molecules or strands--will do the same thing. A liquid-filled shock absorber does this, heating in the process. They can get quite warm.

There is little doubt that a rope that is worked hard gains heat, but...

• The rope must be>= 1-inch.
• The rope must be worked harder than the WLL. Short docklines and sea anchor rodes are often call upon to work above the WLL, so failure is certain, the result of fatigue. They may heat a little, but unless the core reaches ~ 180F, which is unlikely, the amount of weakening due to heating is small.

On the other hand, I'm willing to bet, based on the math, that for a big tug boat line the effect is important. I just don't think it scales down unless the line is overloaded.

[thinwater]

Originally Posted by nautical62

Retired climbing rope. Coils or flakes well, does the job and was free. Though I tend to prefer chain.

Climbing rope has two shortcomings:

• Not very abrasion resistant.
• Windlass can't grab it.

That said, it works fine on smaller boats. I did that for many years. Very nice to handle.

[estarzinger]

Originally Posted by thinwater

Yes, in a perfect cycle, all of the potential energy is returned to mechanical energy and there is no net heating. Only hysteresis results in net heating. This is a consequence of conservation of energy and is not material specific.

Shock Absorbers do heat up - generate net heat,
not just during the cycle - what is the mechanism causing that?

A liquid-filled shock absorber does this, heating in the process. They can get quite warm.

Ah, minds thinking on the same path so it is internal friction - not the spring effect? Is that right? Learning something here which is always nice

There is little doubt that a rope that is worked hard gains heat, but...
On the other hand, I'm willing to bet, based on the math, that for a big tug boat line the effect is important.

ok, so for the dashew case - he usually deals with pretty big boats and the lines may well have been around 1" (I'd have to go back and double check his blog) . . . and the rope guys he asked to confirm have more experience with big commercial ropes and so probably drew on that experience to say his hypothesis was certainly possible. So, that probably square's the circle.


I just don't think it scales down unless the line is overloaded.yea, and most of the para-anchor lines that failed were probably either overloaded or chafed. I actually think dacron is the solution here not because of the heat issue but because it will make it (somewhat) easier to deal with the chafe potential (and you will have enough length for sufficient shock absorption).

Would be fun to do a cycle test here - The next time I do something with them, I will ask the testing lab I use if they have a rig that could cycle 1" nylon

...............

[thinwater]

Originally Posted by estarzinger

...............

You hinted at an interesting point with drogues which is probably lost on many readers. They do not require shock absorption like ground anchors, because the drogue relieves the shock. In fact, you don't want any time delay between strike and increased drag. I used polyester in all of my testing, including taking a running start at drogues at up to 12 knots. The strain always stayed within calculations, no surprises, just G-force.

Sea anchors I lack sufficient experience to comment. The trick is to absorb shock and maintain constant tension without turning into a rubber band. Sounds complicated, and the only fair testing is dangerous. I pass. But I can see that polyester makes a lot of sense, and we need to remember that polyester is lower stretch, not no-stretch.

[Dockhead]

Originally Posted by thinwater

Originally Posted by Dockhead
... The prima facie evidence of what I say is that we've all had snubbers break unexpectedly, at much lower loads than the spec of the rope, or at least know people who have, and in this very thread we have an account of what can happen if you don't have the chain belayed in another way.

Actually, this is anecdotal evidence.

Whether it is from heating or not, I don't know...

Niether do I--not in every case--but in every case I have seen, the only evidence was melted fiber, which I have shown--and any lab tester will agree--is not an indicator of heating. I have also done the math--which I posted--which shows that there simply is not enough heat dissipation to cause melting. Unless--and this is important--the rope was cycling way above the fatigue limit, in which case it would fail anyway. Also, remember, from the tables I posted, that nylon will fail far below BS from fatigue within 100 cycles, which is nothing in a storm. So there is nothing surprising if a line breaks at 1/3 BS. We know this. The WLL of nylon is 9% of BS, just as the WLL of chain and most metal hardware is ~ 20-25% BS.

Also remember that I limited my no-heating claim to 3/4-inch, because that is what was relevant to ME. Dashew has a boat that is large far beyond my reality. My article stated that with 1-inch and above heating will begin to become a factor. It is all about the ratio of surface area to load. The larger the line, the easier it is for it to retain heat. This is also why it is important to tug boat folks. Thus, most of the research is for larger lines. But not to most sailors, if the ropes are sized properly. In my opinion (obvious engineering), the parachute ropes that failed were tragically undersized for fatigue. That is why they really failed.

... it is a fact that in real life, nylon ropes in the water break under cyclical loads, at loads far less than their spec....

Yes, that is exactly what I said.

Other factors reducing the strength and reliability of nylon compared to its spec is the well-known -- described even by the rope makers -- loss of strength when wet, and also high vulnerability to CHAFE, a phenomenon which is greatly exacerbated by a stretchy snubber running back and forth over bow rollers or other gear as it stretches.

Obviously. And obviously there are simple solutions.

It is true -- theoretically! -- that you could design a snubber as strong as your chain, even considering all the factors which reduce its strength. But how long would it then have to be, in order to have the desired amount of stretch? Once it has to be longer than the amount of chain you have out, then it ceases to be even theoretically possible.

Actually, this is quite simple, and I showed the math and the testing in a PS article. Cruisers will agree. The snubber needs to be ~ 40-55 feet long, depending whose number's you prefer. This is well proven both in the field and in theory. I don't think it is controversial. Strength will be slightly less than the chain.

Some concrete examples:

I have 12mm chain, G40, with minimum breaking strength of 8400kg/f. According to Dashew, wet and cyclically loaded nylon may have only 45% of its rated strength. Wrong--About 9% per ABYC and well established engnieering practice. So to equal the strength of my chain, I would need nylon with breaking strength of nearly 19 tons. No, you are arguing from a false assumption. If three is a snubber, the load drops by 4-6 times and the nylon is enough. This is well proven. That would be massive, impractical, 32mm nylon cable. OK, so by the time we get that big, it won't be under such cyclical loads, so maybe not 32mm, but how much? And does anyone use even 1" snubbers? And we haven't even started with chafe. Chafe is a matter of careful rigging. Yes, it requires intelligence.

I think the misunderstanding is that you have not accepted the whole point of using a long snubber--to reduce the load to not much more than the wind load. It is still important to use a strong chain--that insures robust durability, allows for corrosion and sharp rocks, and even for snubber failure (see below). For example, the reason ABYC allows rope rode of about the same strength as the chain is because they recognize that the load on a rope rode is MUCH lower. A snubber can be slightly thinner, because failure, if the chain is also belayed separately, is not tragic.

So I stand by my point -- don't use a snubber to belay your chain!

Without question, there should be a back-up anchor chain belaythat is very strong. I do not believe anyone (not me) argued against that. I think this is what we call a strawman argument (you have successfully assassinated a proposition no one made).


My mind is wide open. Show me math that is different or testing that shows heating (measured) in small lines. I am interested.

Also remember that a line does not absorb, as heat, energy that is released in the next cycle. Only hysteresis causes heating. For example, a spring does not heat. Also note that nylon must reach near boiling before there is more lose in strength. that's not just warm!

I really don't understand what you're trying to say here. I must be missing something, because it seems completely illogical.

What I am trying to say is simple -- don't use a snubber to belay the chain. You say that this is not controversial -- a "straw man argument" which no one is making. So what are we arguing about then? I completely fail to see it. You are wrong about this not being controversial, however, and if it weren't, I wouldn't go on and on about it. Very many cruisers do not attach their chains to the boat with anything but a snubber, practically always a short and thin one, failing to see that this creates a highly vulnerable weak link in their ground tackle. This is what I rail against, and I do it because I hope I will help someone, some day, save his boat.


You say snubbers breaking at less than their rated strength is "anecdotal". Since it has actually happened to me, I take that "anecdote" pretty seriously. It has also happened to Ann, who posted about it in this very thread. My snubber which broke was 15 meters long, and should not have been all that much weaker than the chain, but it broke with a huge bang in conditions which should have been well within its working load limit according to AYBC. I've heard many such "anecdotes". If that doesn't mean anything to you, then of course it's your right to choose what to believe.

As to failure from heating -- I specifically wrote that I don't know if that's the cause, and I don't care. I'll leave it to other to figure out scientifically and will read the science with pleasure.

You go on to try to show that snubbers can be as strong as the chain, but then this somehow becomes almost as strong as the chain, or something. But if you have properly belayed the chain, who cares? You are free to take some risks with the snubber's strength in order to tune it properly. With my chain well belayed, I wouldn't hesitate to use a snubber which was somewhat weaker than the chain. But as Estarzinger or someone else above posted -- I would use two of them in storm conditions. That way you have time to change a broken one while still getting some effective snubbing. In storm conditions I would be using very long pieces of thick nylon -- I have two 30 meter lengths of 1" nylon three strand on board for this purpose (and for trailing behind while running off in a storm).


Last thing in your post I can't let go without comment is the statement that chafe is a non-issue, if you have any "intelligence". I must be a lot less intelligent than you, because for me chafe is a fundamental and very difficult problem. Chafe is the cause of probably most anchored boats lost in storms. In my experience, having had countless dock lines and other nylon ropes which chafed through or nearly through in my decades of sailing, nylon is the very devil to protect from chafe, seemingly impossible in hurricane conditions. If you put them in a piece of old fire hose, as some do, they soon self-destruct. Good fairleads help a lot of course. But in a really challenging anchoring situation, with the boat slewing around, I just don't see any way to guaranty that your nylon won't chafe through. I think I wouldn't even try -- I would use Estarzinger's solution with a spliced-on length of Dyneema, or I maybe would just use a length of chain or a heavy wire rope strop, if I were leading over a bow roller.

[Hydra]

Sailing yacht, 9m, about 4 metric tonnes laden.

What I’m wondering is, what kind of rope do you use for your anchor rode, or have you used in the past, would you use it again or something else, why, etcetera? Be it for your primary anchor, secondary, or land lines (shore ties).

Bower anchor: 30m of 8mm chain + 45m of 16mm Nylon octoplait
Storm anchor: 40m of 8mm chain + 45m of 16mm Nylon octoplait (stowed in a cockpit locker, not yet used in anger)

All chain would be great but much too heavy: I often anchor in places with 10 to 12m tide (English Channel). To stay afloat at low tide, I want 14m of water at high tide, requiring some 70m of rode. I will not carry 70m of chain at the bow.
Octoplait because it stows well, is easy to handle and doesn't twist under load.

Kedge: a few meters of 8mm chain + 50m retired mountaineering rope (because I owned it)

Shore lines: one retired 100m rappelling rope (because I owned it), one 100m 14mm polypropylene line (because it is cheap and floats)

Towing and shore line: 100m 16mm Nylon octoplait (because it is easy to stow)

- Would you use it again, or switch to something else? And regardless of how you answer this, why would you make said choice?

If money were no object, I would switch to polyester octoplait for the anchor rodes (to reduce stretch and sailing at anchor) and Dyneema-cored double braid for the kedge (to reduce elastic energy and retain adherence on winches).

Alain

[thinwater]

Originally Posted by Hydra

...If money were no object, I would switch to polyester octoplait for the anchor rodes (to reduce stretch and sailing at anchor) and Dyneema-cored double braid for the kedge (to reduce elastic energy and retain adherence on winches)....

Alain

Interesting.

I tend to feel the same way, and yet others swear they like nylon better because it maintains more even tension. To me, polyester has some stretch (lay out 200-300 feet and tension it up--it will stretch 3-6 feet) and gives me a better feel for what is going on. I'm not sure this is a place where I want the stored energy of nylon. But maybe it is, since when the boats starts moving, the tension will keep it moving.

I don't know.

[Hydra]

When winching the rode of a kedge, there is a risk that something fails. In that case, I don't want to have the rode or a part of it whipping back toward me. Too many seamen have been cut in 2 by a whipping line.

For the same reason, the tripping line on my anchor is polyester, not Nylon.

Alain

[estarzinger]

Originally Posted by thinwater

polyester has some stretch

For me nylon all the way on the main rode, because if any rope goes out at all, it is usually a shortish section and I prefer it to act as a good snubber. Rarely, did I lay out much rope on that rode - I guess really only when I was backing into a shore tie and I wanted to drop my anchor way out because of the harbor configuration.

Yea, I guess I could put a nylon snubber on, but if I'm going to have rope out it seems like an unnecessary step.

For a secondary rode, I can see the argument for polyester, because usually you have enough out to create enough elasticity (similar to my argument for para-anchor rode). But idk, if given a choice I think I would still go nylon, in order to be as soft as possible on the anchor.