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

[Dockhead]

Originally Posted by thinwater

I'm sorry, but I'm going to call this out as a myth if the nylon is properly sized. The long version is in the post below, this is only a summary:

• If the rope is properly sized, it will be operating at <10BS and will not heat unless very, very large. Period.
• If the rope is operating over 10% BS it is going to fail from fatigue. Nylon is bad that way.
• ALL nylon ropes melt when they snap due to energy release and low melting point. I have pics of brand new ropes that were pulled once, slowly during testing, and the ends melted. Many people mistake this for heating.

The bottom line is that if you take the actual energy dissipation and do the calculation, it simply is not enough heat to warm the rope. Sorry, but this is a myth, unless the rope was working so hard it had no chance anyway. It has also been suggested that chafing gear adds to the problem, but first, the chafe gear was on an edge and there was friction, and be, the line was over worked.


The solution is to size the lines properly and to make them long enough. The challenge is to find proper guidance. I have published several articles that included measuring rode and dockline forces and sizing lines accordingly. Length matters.


Sail Delmarva: Can Nylon Rope Melt Due to Load Cycling --- Myth Semi-Busted

I have great respect for your empirical approach, which has produced a lot of information of value to all of us.

However, I don't think you're right here. 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.

Whether it is from heating or not, I don't know -- that's what dozens of sources say, but I can't say that I have any independent knowledge of the engineering involved. But whatever the cause, it is a fact that in real life, nylon ropes in the water break under cyclical loads, at loads far less than their spec.

This is extensively described by Steve Dashew in The Right Rode, https://www.google.se/url?sa=t&rct=j...ATCHXQ&cad=rja


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.

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.

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. So to equal the strength of my chain, I would need nylon with breaking strength of nearly 19 tons. 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.

To try to design a snubber which also adequately belays the chain is such a wild conflict of design parameters, as to be ridiculous. It's like trying to design a spinnaker pole which is at the same time an excellent halyard. When designing the snubber you should be free to make it rather lighter, so that it will be stretchy enough within a reasonable length, and easy to handle. You should be free to accept some risk of chafing, too, which comes with stretchiness. This freedom can only come from having an independent means to belay the chain.


I do agree with you that the typical cruiser's snubber is far too short. I carry a variety of snubbers on board for different "tuning" in different conditions, and the shortest one is 10 meters long.



I think your own (as usual very well written and logical) article supports this completely. You say that the practical working load of 3/4" nylon is only 1400 pounds or only 636kg. That's equivalent to 1/4" (!) chain. You describe very well all the hazards of chafe, on top of this.

So what size nylon snubber would I have to have, to be "properly sized" to belay my 1/2" chain? You say there's no problem as long as the snubber is properly sized, but "properly sized" to account for the realistic strength of it plus chafe will make it unusable as a snubber.

If you dinghy through the anchorage and check what size snubbers cruisers are actually using with what size chain, I daresay you won't find a single snubber which has even 20% of the realistic practical strength of the chain.

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

[GrowleyMonster]

Originally Posted by UNCIVILIZED

Do you happen to have a link to some online instructions that you'd recommend for doing said above splicing? It would help the less rope inclined types of us.

There are a few things I didn't learn from the internet, and splicing is one of them, so I don't have links. I learned to splice 8 strand by simply taking a splice apart tuck by tuck and then redoing it, but I know both the New England Ropes site and the Samson site have instructions for splicing 8 strand, and the Chinese Handcuff method for 12 strand. I use a full tuck method that I developed myself, for 12 strand that I can describe if you like but it will take a while. Other people have developed similar methods for tuck splicing 12 strand. As it will take a couple of hours to type out, I won't post it unless you actually have need of it, i.e. you have the actual line in hand and are ready to get to it. And if so, we should probably make a new thread.

To crown the 8 strand through a chain link, just pass a right hand and left hand pair in one direction through the link, crossing them normally. Pass the other two pairs through the opposite way, following the first two pairs back up the standing part. Each pair follows the pair it is married to, over and under. After three rounds of tucks, cut 1/3 or 1/4 the yarns from each strand to reduce its diameter. Next tuck, cut another increment of yarns. Then another. Roll it underfoot to make it pretty. Whip it if desired.

If you have never spliced 8 strand, first practice by making an eye. Then try an end for end. Then a chain splice will be easy sneezy. The Samson guide for 8 strand is quite similar to the usual method used on ships and of course by me.

In addition to the manufacturer's websites, there is a German document called the "Schpleissebuch" or something like that. It was kind of hard to follow as it is in German but I believe it has since been translated to English and can be found online. I don't have it but I have seen it in hardcopy and online in German.

BTW, what the New England Ropes splicing guide calls a 12 strand tuck splice is what we call a handcuff splice. Still strong, but not a true tuck splice as strands are tucked down a row of pics, rather than follow standing part strands. The full bury splice isn't something I can recommend. The lock stitch splice is a little better but probably won't be flexible or compact enough for the OP's purposes, I don't know.

You might want to check Brian Toss's well regarded rigging book and see if he has instructions.

[estarzinger]

Originally Posted by BigBeakie

What do you think of this causal vs effect aspect of nylon melting?I dont know enough about nylon to have much of an opinion.

What Dashew was talking about was cyclic loading - constantly stretching in and out up from zero to working load on say a 10 second cycle time; which I could imagine heating up the rope, but I never had the equipment to simulate that.

My understanding is that he ran his conclusions by two of the big rope manufacturers and they concurred.

I have not run across another application (in commercial rope work) like this (big cyclic) where the pro's use nylon.

PS. Is your site going to be up again soon, pleeeze?

Sorry its down for good. It is all pretty dated at this point anyway.

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

[Jim Cate]

Originally Posted by JPA Cate

Oh, man,

Okay. Our chain is backed by nylon three strand. Our snubber is nylon double braid, 16 mm. It still is stretchy, when tested by enough wind. This snubber replaced an 8 plait one. The 8 plait was soft, and likely to snag on *stuff*.


We broke one of these nylon double braid 16 mm snubbers, once. We had a strong wind change, and 2 m. seas came into the anchorage, at about 45 kn. When it broke, the chain ran out backwards. It had made a very loud noise just prior to the windlass running backwards. I was on deck. I didn't like it much! [This occurred in Skeleton Bay, Tasmania.]

Ann

With Ann's permission, I'm going to amend the above statements a bit.

The chain/rope rode she quotes was on our previous boat, not this one which is all chain (85 m of 10mm "L grade") Only rope portion is at the bitter end for emergency slipping. Anchor is 60 lb Supreme, no swivel, boat is circa 11.5 - 12 tonnes laden for cruising.

The snubber that broke was 14 mm octo nylon, not double braid. We experienced an unforecast vigorous wind shift, the chain snagged up short on a big boulder and the sea got up quickly... snubber broke shortly thereafter. So, I think it was overstress rather than chafe that did it in, but can't be sure. We now do use the 16 mm double braid nylon for snubbers. Typically deploy around 8 m of it, and find the combination of chain weight and its stretch to be adequate for shock load absorbtion. We very seldom anchor in water less than 25 feet of depth. If anchoring in shallower water, I'd want a stretchier snubber I think.

Our kedge/stern anchor has 1/2 " three strand plus ~7 m of 10mm chain. If replaced, I'd use octo dacron by preference, although that is kinda hard to find here in Oz. The octo nylon that is available is ok, but very soft lay and snags easily as SnowP mentions. And I'd seriously consider replacing the chain with dyneema as others have suggested...

We don't carry dedicated shore lines, but if I needed to fit one here I'd likely use what is called "silver line" locally. It is three strand and apparently made of recycled plastics of some sort. Kinda nasty stuff IMO, but cheap, floats, reasonably stretchy and seems to resist chafe pretty well. Most local boats use it for dock lines successfully (except for UV degradation).

Finally, worrying about the difference between the stretch of octo and three strand seems academic at best. The differences are small, and in practice will not materially alter the performance of one's anchoring system.

Jim

[Ironman162]

I have a galvanised 10mm short link chain rode with a 1 metre rubber snubber and a Bruce anchor. It works well but it is heavy.
When you are on anchor this weight comes into its own.
The main reason for this was that the windlass takes this size chain.
You do however need a chain lock mechanism.

[estarzinger]

Originally Posted by GrowleyMonster

Chinese Handcuff method for 12 strand. I use a full tuck method

Just as an aside, the heavy lift guys use a tuck splice when doing big dyneema 12 strand hollow braid (and I mean BIG rope - for mooring oil rigs and such). I asked why and they said it cost a couple hundred $ per foot and the tuck used less than a 62x bury and was worth the extra labor in the tuck

samson tuck . . . . http://www.samsonrope.com/Documents/...e_HMPE_WEB.pdf

[Sunsetrider]

Not convinces that all chain benefits outweigh the deficits in small to medium size boats. Lots of weight in the bow, so the only real benefit - once you get 20 or 30 feet beyond the anchor - is brute strength. It will be stretched taut under stress anyway.

[EveningTide]

You sure ask a lot of questions! I don't have that many answers.

My boat is 24 feet and 8000 lbs with not too much windage. It is 15 years old and I anchor at least 40 times per year. Anchoring conditions vary from calm to gusting 40 knots. Water conditions are usually swell less than 4 feet and chop less than 2 feet.

I am using double braid nylon from New England Rope, 7/16 inch diameter. There is 20 feet of 5/16 inch chain at the anchor. The bow anchor is a 22 lb Delta. The stern anchor is a 10 lb Fortress. Both rodes are 300 feet long.

This rode has held up well for 15 years. I would use it again but possibly use 1/2 inch. Double Braid is very easy to push into the anchor locker (I have no windlass). Nylon has good shock absorbing ability and even though 3-strand is better in this quality double braid is OK.

In my area we don't have named storms. My anchor system was designed for winds up to 40 knots but has a bit of extra strength.

I looked at ABYC rode recommendations, West Marine, and several books. They are all about right although cruisers should perhaps upgrade a little. When the line was new my strength was probably about right but after 15 years I wonder how much strength may have been lost. The line is kept in "lockers" out of the sun. I may have suffered a small bit of chaff where the line can rub at the bow but now I always use chaffing gear to protect it.

Hopefully, these rodes will last until I am forced to give up sailing. Trouble is I seem to be getting younger, not older so perhaps these lines may have to last quite a while.








- Do you think that the ABYC rode recommendations are accurate? Too conservative? Or perhaps the reverse? Why?
- How much/how many rodes do you keep onboard? And of what length(s)? Where are they stored?
- Fiscally what do you consider to be the best choice when it comes to rope rodes? And where do you shop for them?
- Chain rodes aside, if cost isn’t part of the equation, what would you have in terms of rope rode?
- What rope rodes; types, or brands, & or, suppliers would you avoid?
- What kind of lifespan do you get with your rode(s)?
- Do you think that UV resistance is a big factor in rode lifespan?
- What else significantly lengthens or shortens rode lifespans in your experience?

[Ken Z]

Ive used 3 strand nylon for ever, since I switched from 3 strand manila in early 60's. I dont know the brand but i get the best i can. I like the stretch, lasts at least 14 years before it goes to dock lines. I dont use a snubber. Id use it anywhere, anytime. I carry three rodes, a 500' 9/16 mainline stored in anchor in bow danforth A 375' 9/16 in stern bilge with a forged grepnel, and a 275' 1/2" with a smaller danforth or switch to smaller grapnel, ( lunch hook).no bow roller. im about 12,000. I vary the line daily to place a new area to the chochs to lessen wear. For overnight i use 2 anchors 30-40 degrees apart, primary anchor longer by 75' or so depending on conditions. I use crosby or titan shackles and 20' chain. Hope his helps.

[puffcard]

I don't like 3 strand, doesn't handle or self coil and the cheap stuff out there now is total junk. I prefer the gold double braid from NE. The 5/8 we use is rated 15,000lbs is strong enough that it could lift our boat. 50% stronger than best 3 strand and 10 times the rating of the 5/8 at Home Depot that junk is only rated at 1,100lbs.

[Ken Z]

P.S.Twisted line coils, because it is twisted.It has a lay. Braided line is unigue to twisted and has grand advantages, and it costs more , better to sail with good than to sit and honor the wish list.😜

[GrowleyMonster]

Originally Posted by Sunsetrider

Not convinces that all chain benefits outweigh the deficits in small to medium size boats. Lots of weight in the bow, so the only real benefit - once you get 20 or 30 feet beyond the anchor - is brute strength. It will be stretched taut under stress anyway.

The benefit of chain is not strength. pound for pound I think nylon is stronger by most ways you would measure strength. Certainly, high modulus fiber rope is stronger than chain. It is weight, distributed equally along its length, that is the true advantage of chain. This forms a catenary which aborbs shock, and also reduces the angle of pull on the anchor so that it digs down at a deeper angle. Stretching the chain taut cannot eliminate all catenary. Even at its breaking point, there is still some sag with a long scope of chain. Take 100 feet of 5/16" chain. Secure one end to a fixed object. Pull with all your might. Get the kids, wife and dog to help. Shackle it to your pickup truck. Whatever. Pull, pull, pull. Sight down the chain and I bet you see some sag in the middle. Doesn't take much catenary to absorb a lot of shock. And you will always have catenary. To have sufficient breaking strength in the first place, guarantees that there will be a lot of weight there.

A good way to look at it is that the chain holds the boat. The anchor just holds the chain. With an all fiber rode, or fiber and only a very short chain to take the bottom abrasion, you don't get that effect.

[Roy M]

Okay, so after all this discussion, I'm still in a quandary. Discussion of chain focuses on strength to weight advantages of nylon. Discussion of nylon focuses on stretch over catenary. So far, no discussion of a length of chain for coral protection and catenary coupled with ultra high strength synthetic for weight and strength. Did I miss that in the previous arguments? I can pack a lot of Dyneema to back up a couple hundred feet of high-strength G-4 1/4" chain and keep a very long rode at 3:1 rode ratio.

[UNCIVILIZED]

Originally Posted by Roy M

Okay, so after all this discussion, I'm still in a quandary. Discussion of chain focuses on strength to weight advantages of nylon. Discussion of nylon focuses on stretch over catenary. So far, no discussion of a length of chain for coral protection and catenary coupled with ultra high strength synthetic for weight and strength. Did I miss that in the previous arguments? I can pack a lot of Dyneema to back up a couple hundred feet of high-strength G-4 1/4" chain and keep a very long rode at 3:1 rode ratio.

Nope, don't think that's been covered. Sure wish it had though. But unfortunately, this thread didn't turn into a survey & summary of the performance, & pro's & con's of the different types of rodes that I'd hoped that it would.

Maybe it's worth suggesting to Practical Sailor that they do such a thing, & then publish the article. Though obviously it would have to be abridged, given the volume of data that they'd get if most of those taking the survey answered the majority of the questions which I posed.
Thinwater? Thinwater? Thiwater? Anyone? Thinwater? <-- And yes, that last bit's spoken mostly in jest. Although I am tempted to see if PS would conduct such a study & publish the findings. Perhaps in something like Victor Shane's Drogue Device Database. Something like that on anchoring would rock!

[Ironman162]

I can only say again that I'm for a all chain rode. As for the length it will depend how deep the water is where you are planning g to anchor. I don't anchor in anything over 20 meter but each to his own. I've had no problems with my all chain rode but do use a rubber snubber.
Rope only creates a weak point where it is joined to the chain or when it gets damaged by sharp debris in the water. Not to mention all the so windlass issues.
So my vote is for an all chain rode and it works for me.