Polyester over nylon rode?

[Unity]

Originally Posted by roland stockham

The simple answer is a length of chain through the rollers then attach the rode to that. Far more effective than chafe protector. I would only ever use nylon octiplait fo anchor rodes theselect the size to give the right amount of stretch. If it behaving like a bungy cord it is simply to small.

I understand many prefer pure Nylon - its what we are all used to and has performed well. Doesn’t necessarily mean it’s now the best, but perhaps it is? For me, I dislike the stretch both for long scope (sailing on nylon) and for kedging (elasticity can be dangerous but some is desirable)

And sorry ... I didn’t understand the “chafe protector” comment. What might you be referring to? In case you are referring to the polyester over nylon, take a look at the Yale specifications - it is not about chafe but instead about balancing the loads across different fibers to find a medium in elongation between pure nylon and pure polyester.

[Unity]

REPOSTING TO FIX IMAGE UPLOAD PROBLEM

Thank you everyone for some great feedback and advice. I went ahead and dove much deeper into this and thought I would share my analysis.

First, the critical question about the rode starts with determining the appropriate working load. ABYC has a nice chart that describes a simple set of rules for this (the actual calculations for true load, based on windage, waves and current are too complex but if somebody has a simple formula I'd be very interested).



Some say this chart is too conservative, resulting in too large a system. However, in my case my boat is 52 feet and as for "Violent Storm" I'd want around 6700 lbs working load. To help confirm this, my anchor chain is 7/16 grade 43 (G4) high test, sized for my windlass, which has a working load of 7200. So this number of around 6700-7200 makes sense to keep the chain and rope in consistent holding power.

The next thing I did was to locate a variety of rode types and looked up their specifications (it is disappointing how many vendors have poor specifications online, with Yale Cordage being a notable exception). I sized the rodes to come close to the correct working load, so there is a variety of diameters based on the rode type. I also applied the typical 5:1 (20%) tensile strength to working load factor (except 17% for nylon, as it loses 15% strength in water).

I built a chart then of elongation to understand how much the line will stretch when using 150' of rode (even though I will have 300' or more, 150' is a decent number to use for typical scope / depth).



For grins, I included polyproplyene even though I'd never use it for this application (and worth noting, I did not find one big enough for the working load). For Dyneema, I used one that has an outer shield of polyester so it can be easier to handle and tie down.

My take away from this analysis is that Dyneema has too little stretch and will be unacceptable without a bridal of something like nylon (only 1 foot of stretch at working load!) But more importantly, nylon stretches a lot and if in a serious storm with waves (hitting as much as 50% breaking strength) the elongation is substantial at around 30 feet. And if putting out the full scope (300 feet, which you would do in a serious blow) the elongation is more than a boat length. While the shock absorption is fantastic, it would mean a lot of sailing on the anchor as gusts stretch out the line and then pulling you back forward again.

100% double braid polyester is better at storm strengths, but ends up being pretty tight when used for typical weather anchoring (only 3.3 feet of shock absorption at normal working load). A nice mix does come from the polyester over nylon, where normal weather would see 7.8 feet of elongation, and serious weather (50% breaking strength) would be at 15 feet. Additionally the diameter of the line is substantially less for the polyester/nylon line for the same working load (7/8" vs. 1-1/4" brait or 1-1/8" double braid nylon).

From this, it seems that polyester over nylon for a primary anchor makes sense. Worth noting, I do not take into account any length of chain, which of course changes the numbers and makes nylon a better choice especially at shorter scopes (less elongation at short scopes, but minimal change in elongation at full deployment).

For grins, I also took at look at weight, where 3 strand nylon is quite heavy (200 lbs for my application at 300 feet) and 8-strand brait or polyester over nylon are almost half that.



Now weight isn't that big of a deal overall, except for kedging. On my boat, I can't use a standard anchor for kedging - it's just too heavy (100 lbs for my Spade) or too massive (FX-85 for my Fortress). To handle on the dinghy, I'm using an FX-37 (21 lbs), which has a holding strength of 3,600 in soft mud. Using nylon 3-strand, the appropriate diameter is 7/8 line which is 45 lbs at 150 feet (sorry, this isn't in the spreadsheet, but the links to the web site data are there to look up different diameters). That's a total of 66 lbs. Workable for sure, but I dislike the stretch on nylon when using it to kedge. Switching to the polyester over nylon I could use a 5/8 line (easier to handle) which would weight 27 lbs for a total of 48 lbs, and would have a more acceptable stretch for this application.

I have put all this in a public shared spreadsheet on Google Sheets for anyone that wants to look at the analysis:

https://docs.google.com/spreadsheets...it?usp=sharing

As usual, I'd love critique on this analysis. I know there are tons of stories about "how my boat holds great", but I thought I'd try to take a more factual / technical view on this decision.

Chris

[Simi 60]

Dragging this one back out as I am looking for a new snubber for our 60ft high windage 70 tonne vessel.
Currently using 20mm 3 strand nylon 5m long attached to chain with soft shackle for 30knots+ never had an issue .
For everyday anchoring we use a shorter length with a chain hook, shorter so it stays out of the water and doesn't go green.
Unlike some here, we get a couple of years of the nylon before replacing, not because it looks suspect or even worn but more as a preventative maintenance thing.


In larger gusts the 3 strand hockles/twists and the chain wraps around the snubber so this time around I am looking at 8 strand as I am told this will solve the problem.

Online, I cant find short lengths of 8 strand nylon and do not want or need a 125m roll for over $1000.

I can find short lengths of polyester 8 strand described as "dockline", 10m for $75.

Proceans' premium pre-spliced 8 strand polyester line are designed to stretch, absorbing sudden shocks with ease. They are extremely strong yet remain flexible for many years.

https://www.whitsundaydiscountmarine...ing-sleeves-50

Thoughts on suitability?
Will it stretch enough?

[thinwater]

Originally Posted by Unity

Thank you everyone for some great feedback and advice. I went ahead and dove much deeper into this and thought I would share my analysis.

First, the critical question about the rode starts with determining the appropriate working load. ABYC has a nice chart that describes a simple set of rules for this (the actual calculations for true load, based on windage, waves and current are too complex but if somebody has a simple formula I'd be very interested).



Some say this chart is too conservative, resulting in too large a system. However, in my case my boat is 52 feet and as for "Violent Storm" I'd want around 6700 lbs working load. To help confirm this, my anchor chain is 7/16 grade 43 (G4) high test, sized for my windlass, which has a working load of 7200. So this number of around 6700-7200 makes sense to keep the chain and rope in consistent holding power.

The next thing I did was to locate a variety of rode types and looked up their specifications (it is disappointing how many vendors have poor specifications online, with Yale Cordage being a notable exception). I sized the rodes to come close to the correct working load, so there is a variety of diameters based on the rode type. I also applied the typical 5:1 (20%) tensile strength to working load factor (except 17% for nylon, as it loses 15% strength in water).

I built a chart then of elongation to understand how much the line will stretch when using 150' of rode (even though I will have 300' or more, 150' is a decent number to use for typical scope / depth).



For grins, I included polyproplyene even though I'd never use it for this application (and worth noting, I did not find one big enough for the working load). For Dyneema, I used one that has an outer shield of polyester so it can be easier to handle and tie down.

My take away from this analysis is that Dyneema has too little stretch and will be unacceptable without a bridal of something like nylon (only 1 foot of stretch at working load!) But more importantly, nylon stretches a lot and if in a serious storm with waves (hitting as much as 50% breaking strength) the elongation is substantial at around 30 feet. And if putting out the full scope (300 feet, which you would do in a serious blow) the elongation is more than a boat length. While the shock absorption is fantastic, it would mean a lot of sailing on the anchor as gusts stretch out the line and then pulling you back forward again.

100% double braid polyester is better at storm strengths, but ends up being pretty tight when used for typical weather anchoring (only 3.3 feet of shock absorption at normal working load). A nice mix does come from the polyester over nylon, where normal weather would see 7.8 feet of elongation, and serious weather (50% breaking strength) would be at 15 feet.

From this, it seems that polyester over nylon for a primary anchor makes sense. Worth noting, I do not take into account any length of chain, which of course changes the numbers and makes nylon a better choice especially at shorter scopes (less elongation at short scopes, but minimal change in elongation at full deployment).

For grins, I also took at look at weight, where 3 strand nylon is quite heavy (200 lbs for my application at 300 feet) and 8-strand brait or polyester over nylon are almost half that.



Now weight isn't that big of a deal overall, except for kedging. On my boat, I can't use a standard anchor for kedging - it's just too heavy (100 lbs for my Spade) or too massive (FX-85 for my Fortress). To handle on the dinghy, I'm using an FX-37 (21 lbs), which has a holding strength of 3,600 in soft mud. Using nylon 3-strand, the appropriate diameter is 7/8 line which is 45 lbs at 150 feet (sorry, this isn't in the spreadsheet, but the links to the web site data are there to look up different diameters). That's a total of 66 lbs. Workable for sure, but I dislike the stretch on nylon when using it to kedge. Switching to the polyester over nylon I could use a 5/8 line (easier to handle) which would weight 27 lbs for a total of 48 lbs, and would have a more acceptable stretch for this application.

I have put all this in a public shared spreadsheet on Google Sheets for anyone that wants to look at the analysis:

https://docs.google.com/spreadsheets...it?usp=sharing

As usual, I'd love critique on this analysis. I know there are tons of stories about "how my boat holds great", but I thought I'd try to take a more factual / technical view on this decision.

Chris

I think it would help to read the full text of ABYC H-40. Above there are several assumptions that are different from those in H-40, and thus table 1 has been taken out of context.

• Table 1 is for "DESIGN LOADS FOR SIZING DECK HARDWARE," not rode tension. Folks often use if for rode tension, but that is incorrect. The above is the exact title (pasted). The table you posted is not from the current H-40. The current version does not state wind speeds.
• ABYC uses 12.5% BS for the WLL of nylon.
• ABYC assumes nylon, as follows: "1. Only nylon rope is shown in Ap.Table I because of its elasticity and ability to absorb shock loads. Working loads for nylon rope are based on factors of safety, line strength loss due to knots and splices and additional factors including abrasion and aging."

There are some other things you might consider.

• You will have several hundred feet of chain out, so it is unlikely more than 1/2 of the rode is nylon. But do your own figuring.
• You don't need to have the same WLL with chain as nylon. If you want a WLL of 6500 pounds, you'll need 1 1/4-inch rope.
• Nylon rope is only good for <50 cycles at 50% BS brand new. If you actually believe such forces are possible, and the rope has been in service a while, then it's too small. However, with rope the forces won't be nearly that great.

In fact, ABYC is clear as mud when it comes to sizing nylon rode.

[NevilleCat]

wondering about this stuff as a snubber.
Has rubber woven into it. I'm pretty sure they used to have longer lengths of it called towing line.
Anyone tried it? BL about 4T so maybe not enough for you SIMI?

[rslifkin]

Originally Posted by Simi 60

Dragging this one back out as I am looking for a new snubber for our 60ft high windage 70 tonne vessel.
Currently using 20mm 3 strand nylon 5m long attached to chain with soft shackle for 30knots+ never had an issue .
For everyday anchoring we use a shorter length with a chain hook, shorter so it stays out of the water and doesn't go green.
Unlike some here, we get a couple of years of the nylon before replacing, not because it looks suspect or even worn but more as a preventative maintenance thing.


In larger gusts the 3 strand hockles/twists and the chain wraps around the snubber so this time around I am looking at 8 strand as I am told this will solve the problem.

Online, I cant find short lengths of 8 strand nylon and do not want or need a 125m roll for over $1000.

I can find short lengths of polyester 8 strand described as "dockline", 10m for $75.

https://www.whitsundaydiscountmarine...ing-sleeves-50

Thoughts on suitability?
Will it stretch enough?

Does Defender ship to Australia at a reasonable price? If so, they'll sell you 8 strand nylon by the foot. Or double braid, if you wanted. Double braid would be less stretchy, but it's stronger per diameter and a bit more chafe resistant.

[Simi 60]

Originally Posted by rslifkin

Does Defender ship to Australia at a reasonable price? If so, they'll sell you 8 strand nylon by the foot. Or double braid, if you wanted. Double braid would be less stretchy, but it's stronger per diameter and a bit more chafe resistant.

They do, 60 ft of nylon rope landed will cost about $360 aud

Double braid is too hard to splice (for me) and chafe has never been a problem for us
If its less stretchy would it put it back to about where the less stretchy than nylon, 8 strand polyester I linked to earlier?

[Uncle Bob]

Originally Posted by Simi 60

Dragging this one back out as I am looking for a new snubber for our 60ft high windage 70 tonne vessel.
Currently using 20mm 3 strand nylon 5m long attached to chain with soft shackle for 30knots+ never had an issue .
For everyday anchoring we use a shorter length with a chain hook, shorter so it stays out of the water and doesn't go green.
Unlike some here, we get a couple of years of the nylon before replacing, not because it looks suspect or even worn but more as a preventative maintenance thing.


In larger gusts the 3 strand hockles/twists and the chain wraps around the snubber so this time around I am looking at 8 strand as I am told this will solve the problem.

Online, I cant find short lengths of 8 strand nylon and do not want or need a 125m roll for over $1000.

I can find short lengths of polyester 8 strand described as "dockline", 10m for $75.

https://www.whitsundaydiscountmarine...ing-sleeves-50

Thoughts on suitability?
Will it stretch enough?

For the windier days have you considered lengthening the snubber, perhaps running the fixed end back to a midship or even aft cleat but still keeping the hook just out of the water. This should prevent the hockling by allowing the force to spread over a much longer distance.

[Benz]

Originally Posted by Simi 60

Dragging this one back out as I am looking for a new snubber for our 60ft high windage 70 tonne vessel.
Currently using 20mm 3 strand nylon 5m long attached to chain with soft shackle for 30knots+ never had an issue .
For everyday anchoring we use a shorter length with a chain hook, shorter so it stays out of the water and doesn't go green.
Unlike some here, we get a couple of years of the nylon before replacing, not because it looks suspect or even worn but more as a preventative maintenance thing.


In larger gusts the 3 strand hockles/twists and the chain wraps around the snubber so this time around I am looking at 8 strand as I am told this will solve the problem.

Online, I cant find short lengths of 8 strand nylon and do not want or need a 125m roll for over $1000.

I can find short lengths of polyester 8 strand described as "dockline", 10m for $75.

https://www.whitsundaydiscountmarine...ing-sleeves-50

Thoughts on suitability?
Will it stretch enough?

8-strand poly will stretch enough in that diameter. I splice a lot of docklines for superyachts in double braid and 8-plait up to 1 1/2" (about 32mm). Anything bigger in diameter than an inch is polyester, simply because nylon has too much stretch when you get into bigger sizes and the lengths proportionate to them.
I like nylon up to 3/4", and on my ten ton boat, I use it oversized in order to not max out the stretch and to lessen the rubber band factor. So my storm rode is 200' of 3/4" 3-strand (I'll go 8-plait next time), and I usually put it all out and ride comfortably.

[rslifkin]

I'm not sure on the stretch level for the 8 strand polyester, but for nylon, it's typically about 10% at 20% load for 3 and 8 strand and about 5% at 20% load for double braid.

[slug]

Originally Posted by Unity

I’ve been looking for a lower stretch rode for my backup rode (I’m all chain, but I want a backup in case I must release my primary). Done tons of reading and googling here and come to conclusion that I’d be better with less stretch than 100% nylon and 8-plait is preferred for ease of handling. In my case, I need 1” @ 400 feet, so this is not a trivial investment.


Rocna has a nice KB where they say:



Source: Rope (Rocna Knowledge Base)

I’ve heard about Octoplait (I believe 100% polyester) but have not found a US source under that name. I can order from UK
but felt like I may be missing the mark on my searches. And I’m unable to find the polyester over nylon that Rocna recommends.

Any recommendations for a source/brand of lower stretch rode (but not Dyneema/etc as that is too little stretch for me)?

Thanks all!

Chris

On a 54 ft boat how will you handle a one inch diameter rope ?

A normal self tailing winch is maxed out at about 18 mm

[Simi 60]

Originally Posted by Uncle Bob

For the windier days have you considered lengthening the snubber, perhaps running the fixed end back to a midship or even aft cleat but still keeping the hook just out of the water. This should prevent the hockling by allowing the force to spread over a much longer distance.

Foredeck is 3 steps higher than the deck where mid and aft cleats are attached.
Rope would cut into deck step down and also cut into cabin sides.

Attachment point up front is a proper telegraph post sized Sampson post running all the way down to the deadwoods/keelson.
Rear cleats are no where near as robust

[Simi 60]

Originally Posted by Unity

I’ve heard about Octoplait (I believe 100% polyester) but have not found a US source under that name. I can order from UK
but felt like I may be missing the mark on my searches. And I’m unable to find the polyester over nylon that Rocna recommends.

Any recommendations for a source/brand of lower stretch rode (but not Dyneema/etc as that is too little stretch for me)?

Thanks all!

Chris

Yale Cordage :: Larger Polyester Brait

Or maybe even 8 strand tiger line/Dan line?
Different material but low stretch, good abrasion and UV characteristics

https://www.sydneyropesupplies.com.a...index&cPath=27

[Jim Cate]

Simi, a couple of years ago I was able to get 8 plait nylon from Emmets Ropes in Wakerly. They have been good sources for us over the years, and with decent prices.

Jim

[Simi 60]

Originally Posted by Jim Cate

Simi, a couple of years ago I was able to get 8 plait nylon from Emmets Ropes in Wakerly. They have been good sources for us over the years, and with decent prices.

Jim

Thanks, its who we have used before as well
when we had a car or came out of the water in Brisbane.

This year the GC yards are 1/2 the price of our usual "Yard" so I am trying to find an online supplier.
Ill give them a call, they may be able to post
Thanks