Nylon or polyester octoplait for anchor

DoubleEnder

DoubleEnder

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I am going to extend my 8mm anchor chain by splicing on 20 metres of 8 strand 14mm octoplait. I can get this made of nylon or of polyester. I believe nylon stretches more, but that polyester stretches enough. I do not envisage any extreme anchoring conditions. I am quite interested in how the rope will lie in the anchor locker, how it will handle, how much water it will hold ( I have a wooden boat).

I'm guessing it isn't super critical, but does anyone have any practical experience of both?

thank you

Graham
 
That's a pretty thick and short rode if you want to get decent shock absorption - with that rode I'd add a thick rubber snubber to allow a bit more. My preference would be a smaller diameter rope - we use 12mm on a heavily loaded 42 footer which is often anchored in 40-50 knots plus gusts.
 
I am no expert, but I believe that over time and exposure to water, nylon tends to become stiff, which might create a stowage problem in your chain locker.
 
I suggest that nylon will have far more shock absorbance than any rubber insert "snubber". The extension provided by a short rubber snubber might be a few cm. A nylon rope will give something like 10-15% (30% near breaking point) of its length. At 20m you suggested that's about 2m extension.
Polyester has almost no stretch.
Nylon will hols about 30-40% its own weight in water. Polyester will hold 10-15% its own weight of water.
Nylon is less UV resistant than polyester.
 
MM5AHO said:
I suggest that nylon will have far more shock absorbance than any rubber insert "snubber". The extension provided by a short rubber snubber might be a few cm. A nylon rope will give something like 10-15% (30% near breaking point) of its length. At 20m you suggested that's about 2m extension.
Polyester has almost no stretch.
Nylon will hols about 30-40% its own weight in water. Polyester will hold 10-15% its own weight of water.
Nylon is less UV resistant than polyester.
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Unless the OP has a very large boat - perhaps 50 foot plus - then he won't get anything even fractionally near that stretch in most anchoring conditions so a typical 14-16mm rubber snubber adds 40-50cm shock absorption at much lower loads which keeps the boat comfortable - and if the wind is much higher then will just keep that stretch as the nylon takes over.

Rubber snubbers make a remarkable difference to sleeping and even keeping glasses from falling over in light to moderate conditions and in the unlikely event they snap (hasn't happened over many years) the rope takes over at the expense of that comfort. But they do need replacing after a season containing a few nights of strong winds.
 
My boat is 34 feet weighs 5 1/2 tons. I will use 14mm as it will splice well to my existing chain. I appreciate that nylon is stretchier than polyester, but quite often I will be lying to all chain, and I will use a rubber snubber as necessary, so the stretchiness or lack thereof is kind of by the by.

I am mostly interested in the rope's other characteristics: ease of handling/flaking, how much water it will soak up and carry in to my wooden chain locker, whether it goes stiff and nasty very quickly . . . . that sort of thing

thank you
 
If you have a windlass that will accept both rope and chain then the specification of the windlass will dictate the size of the rope that will fit. If the rope is too thick it will not fit the windlass and you would need retrieve by hand then transfer the retrieval to the windlass (and the act of transferring will be a real hassle - such that you will not use the rope). If you are retrieving 8mm chain by hand then you can cancel your gym membership but maybe need the service of a physiotherapist if you anchor frequently.

I would store the rope, neatly coiled, on a hook (of some sort) so that it drains and dries out. Alternatively I would keep the rope in a separate section of a locker (but most lockers do not allow this). If your chain sits on the rope then the rope will be constantly soaked (as you retrieve the chain) and the wet rope will increase the corrosion of the chain factorially.

For a vessel that demands 8mm chain then 14mm is a bit oversized and 12mm would be better - but its at the bitter end and you will have catenary offering snubbing and the elasticity of the rope is a minor consideration. However assuming you have a decent length of chain - you will still need a snubber (as you may not deploy the rope portion, especially in a tight anchorage) and I'd be suggesting a boat length snubber, or more, of 12mm nylon (and if your vessel is actually small - I'd think of 20m of 10mm nylon). For a snubber recycled climbing rope is definitely the way to go - its should be free and is 'almost' perfectly designed for stretch. You cannot use it to extend your rode - it is basically impossible to splice. If you retrieve by hand this will not matter.

You do not define how much chain you have and basically all answers you get might or might not be useful to you. You also do not define the size of your vessel - so any quantitative data in any recommendation is a complete guess.

If you take one of those rubber dog bone things and size it to the recommended nylon rope than one dog bone has the same energy absorbing capacity as 2m of the appropriately sized nylon. Big devices have more energy absorbing capacity (obviously) but will be too big to be much use (they won't stretch). But if you assemble the dogbone device correctly it has a very limited energy absorbing capacity (because correct assembly restricts its maximum stretch) - whereas the nylon will work until it fails (to about 40% of stretch). Both the late Prof Knox and I independently tests dogbone devices and came to the same conclusion. I think you will find dogbone devices are not as cheap as 2m of nylon and the dogbones will not pass through the gypsy (if you have a windlass)

Dogbone devices are good for mooring, where lengths tend to be short, but are, in my opinion a complete waste of time and money in an anchoring situation. To be useful you would need around 4-6 of them - and then weight becomes a consideration.

Jonathan
 
My experience, FWIW:
I have been using a bow anchor rode made up of 8mm chain and 14mm nylon octoplait for the last eight years or so. Up till now there has been no tendency at all for this rope to become stiff, it still handles as when it was new.
Not sure how much water it holds, GRP boat.
For my stern anchor I used for many years a 16mm plaited polyester line (Marlow anchorplait IIRC), this became very stiff with time and I have now replaced it with 14mm nylon, 12 stranded.
 
I just use chain, and don't prat about with snubbers. But then I don't have a light high windage boat that skitters about in the wind, and I don't anchor in big waves. :D What are these "shock loads" that people mention?
 
NormanS said:
I just use chain, and don't prat about with snubbers. But then I don't have a light high windage boat that skitters about in the wind, and I don't anchor in big waves. :D What are these "shock loads" that people mention?
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Anchor in some waves and find out. Simple.

I've tested polyester line. Outside a cozy harbor, I wouldn't use it on a bet, unless I had 200' of chain in front of it.
 
thinwater said:
Anchor in some waves and find out. Simple.

I've tested polyester line. Outside a cozy harbor, I wouldn't use it on a bet, unless I had 200' of chain in front of it.
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Why would I want to anchor in waves? In God's country we're blessed with loads of anchorages, where the waves can't get into. :rolleyes:
 
I'd echo BabaYaga, octoplait doesn't really go stiff or hard over time. It still just crumples down into the locker after several years use. I would also echo Neeves exhortation to stow it anywhere other than under the chain where it will be permanently damp/muddy/grotty affecting both rope and chain.
 
There's a difference to anchoring where you want to and where you have to.
I to like to anchor in sheltered places without waves to keep me awake and or waking up to check what's happening.
But many's the time where I've anchored in calm, to wake to waves due to wind shift, or changed conditions.

And then there's anchoring where you have to, not where you want to. Two seasons back I went to the aid of a Mobo with engine failure. They were unable to use their anchor to prevent drifting onto rocks. They had an anchor of sorts, (more like a weight) and a rode of sorts (more like string), but had never used either, and that was evident by the green colour.
It's easy to forget that an anchor system is a very basic simple safety device. Under these conditions, there could easily be waves, current, any conditions that make anchoring unfavourable.
 
BabaYaga said:
My experience, FWIW:
I have been using a bow anchor rode made up of 8mm chain and 14mm nylon octoplait for the last eight years or so. Up till now there has been no tendency at all for this rope to become stiff, it still handles as when it was new.
Not sure how much water it holds, GRP boat.
.
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That’s very useful. Thank you
 
If you bring up polyester on a US forum you will laughed out of the place. On a UK forum, a few warnings, but general acceptance. I'm not clear why that is.
* US boats over ~ 35 feet predominantly use all-chain?
* US harbors for smaller boats tend to be more shallow?
* Because they have never tried it? Polyester octoplait is not sold in the US, only low-stretch polyester yacht braid. If you Google "polyester octoplait, only UK links come up. On the other hand, nylon brait is common in the US and less so in the UK. Odd.

Not much about the stretch of polyester octoplait is published. Polyester fiber itself is low stretch, but the loose weave pattern will increase stretch.

This, from Jimmy Green Marine. Unfortunately the accuracy of the information is questionable, since the elongation to break of nylon brait is 27-34%, depending on what you test. 3-strand is similar, doublebraid a bit less (but that would not be comparing apples to apples, since polyester DB is low stretch).
"Nylon is generally the solution because it is stronger and has more elongation (elasticity, stretch) than polyester.
Nylon has 20% stretch at the breaking point, whereas polyester has 15%."

Does anyone have stress/strain data on polyester octoplait? From here, it looks like polyester brait may have about 1/2 the stretch of nylon brait, but side-by-side testing would be nice.
 
Polyester - as with most things in anchoring I don't believe there is one correct answer.

If you have a lot of chain with polyester, of any construction, at the bitter end then you will enjoy the catenary effect of the chain you deploy. If you only have a short length of chain and commonly use a lot of cordage then you will have no catenary and no elasticity (if the cordage is polyester).

Having a decent amount of chain and a reasonable amount of polyester will allow an ability to anchor in deeper water (than would be possible if you did not have the polyester).

The question would be - why would you choose the polyester in the first place? Recycling running rigging would be one good reason - but it would only work if you had that reasonable length off chain.

I think the idea of rejecting it out right is wrong, using polyester with certain provisos seems sensible if for some reason you have 'excess' polyester and do not want to, or cannot, access nylon.

I don't think you need stress strain curves, though they would be 'nice' (the polyester will be strong enough if sensible sized) what would be needed is some estimate/recommendation on the proportion of chain needed to make it all work sensibly. In some anchorages chain is always going to be preferred - cordage is eaten overnight in coral

I cannot understand why construction would impact the fundamental elasticity of the cordage - once the 'lay' of the rope has been stretched taut - it will not bounce back (as nylon does) and you will be reliant on any inherent elasticity of the fibre itself (which is effectively low in polyester). Polyester will thus act a bit like chain - with no weight - and like my Kryptonite piano wire (and for the purists - from the planet Krypton) it would need a snubber.

Jonathan
 
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Neeves said:
Polyester - as with most things in anchoring I don't believe there is one correct answer.

If you have a lot of chain with polyester, of any construction, at the bitter end then you will enjoy the catenary effect of the chain you deploy. If you only have a short length of chain and commonly use a lot of cordage then you will have no catenary and no elasticity (if the cordage is polyester).

Having a decent amount of chain and a reasonable amount of polyester will allow an ability to anchor in deeper water (than would be possible if you did not have the polyester).

The question would be - why would you choose the polyester in the first place? Recycling running rigging would be one good reason - but it would only work if you had that reasonable length off chain.

I think the idea of rejecting it out right is wrong, using polyester with certain provisos seems sensible if for some reason you have 'excess' polyester and do not want to, or cannot, access nylon.

I don't think you need stress strain curves, though they would be 'nice' (the polyester will be strong enough if sensible sized) what would be needed is some estimate/recommendation on the proportion of chain needed to make it all work sensibly. In some anchorages chain is always going to be preferred - cordage is eaten overnight in coral

I cannot understand why construction would impact the fundamental elasticity of the cordage - once the 'lay' of the rope has been stretched taut - it will not bounce back (as nylon does) and you will be reliant on any inherent elasticity of the fibre itself (which is effectively low in polyester). Polyester will thus act a bit like chain - with no weight - and like my Kryptonite piano wire (and for the purists - from the planet Krypton) it would need a snubber.

Jonathan
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I'm mostly curious "why the difference between the UK and US."

Yes, weave makes a considerable difference, as much as 1/3 of the stretch. It does not make nylon into polyester, but nylon elongation to break ranges from 25-100% and polyester from about 10-18%, from what I have seen. Polyester yacht braid, which is at the low end of the range, is pretty bad in shallow water without much chain. I've used it a lot for anchor testing (less recoil), and it's no fun if the waves march in. But I never tried octoplait. Perhaps next time. There are a few sources.

Yes, polyester makes sense for extending a considerable amount of chain. I have often said so.
 
I have 15 m og 8mm chain, spliced into 14mm poyester rope. The strech comes from the chain catenary, not the polyester elogation. My boat is a 40' monohull, at 6,5 tonnes. Chain and rope all goes through the winch into the chain locker, no special treatment.
 
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thinwater said:
Yes, weave makes a considerable difference, as much as 1/3 of the stretch. It does not make nylon into polyester, but nylon elongation to break ranges from 25-100% and polyester from about 10-18%, from what I have seen. Yes, polyester makes sense for extending a considerable amount of chain. I have often said so.
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There's lots of research to delve into, as well as a certain blogsite 'Sail Delmarva' where one will find this important summary
'polyester has a much greater fatigue life than nylon, perhaps 100-1000 times greater.'
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45526681175_a16c6634eb_z.jpg

One of a series


It is also very important to note, in rope performance in repeated cyclic loadings, that being wet reduces performance of nylon markedly. The very cyclic loadings experienced, for example, in mooring and anchoring when a 'chop' causes pitching, and when towing a Jordan Series Drogue in breaking seas.

We yotties are, many of us, conditioned to do what the traditions suggest, and buy/fit what most others use. That can mean '3 strand laid rope'. It's instructive to observe what commercial fishermen and towing/mooring companies are now using, and asking why. Multiplait and braided lines, of varying diameters, are now more commonly used than traditional laid rope, for cost/benefits reasons.

I won't be using 3-strand nylon for mooring or for anchoring, and I've also long given up on 'fishermen-type' anchors. I DO have a couple of stretchy 'dynamic climbing ropes' rescued from climbing centres ( Neeves' advice ) for snubber work, but they're considered sacrificial.
 
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