Anchor warp question. Nylon or polyester?

[John B]

I know the argument for nylon.
We've had what I believe to be a polyester warp for the last 20 years. Whatever it is ,its good and seen us through some savage gales.
The question is , when I buy a new one, should it absolutely, unequivocably be nylon ? or are there arguments out there against it.

[ 12-07-2004, 06:16 PM: Message edited by: John B ]

[Venchka]

Dunno. Good Grief! Now I have to worry if my nylon rode is the right stuff or not? JohnB, if I loose sleep over this, it's all your fault. :D

Wayne
In the Swmap. :D

[Hwyl]

The "rubber band" theory of nylon, has never held any appeal for me. Seems to me that when it's blowing, it's all stretched out anyway. It's down to strength and abbrasion resistance.

[John B]

every pimple faced kid in the chandlerys say nylon. Out of the 2 rope manufacturers I've contacted so far , 1 says polyester, one says" the list says nylon".
I'm nervous about the concept like you Hywl.

It won't affect you Wayne. Yours will be probably be over spec anyway given the size and weight of your boat.

we're about 6.5 or 7 tons and I'm thinking about 20mm laid polyester right now. there doesn't seem to be an 18 mm and 16... seems a bit light to me even if only from the grip point of view?

[NormMessinger]

What you really need is my advise. So, how much chain do you have between the road and the anchor?

[Concordia..41]

Yale Cordage's nylon Brait is on my watch list. I think it's pretty new. Not much turned up in a quick search.

http://www.apsltd.com/Tree/d27000/e24748.asp

Scroll down page to info on Brait and I'll try to scan the ad that caught my eye.

- M

http://www.imagestation.com/picture/sraid149/pecb6b63a06a0387cdcfc0a68ba093d1f/f5fcb6c4.jpg

[ 12-07-2004, 06:43 PM: Message edited by: Concordia..41 ]

[Hwyl]

Margo, if it's cheaper picked up at the factory. Let me know. I work close by.

[MAGIC's Craig]

I'll reach back to some of my time on tugs, here. We would sometimes tow barges with braided nylon whenever there was some occasion (shallow water, usually) where the normal 2-5/8" wire cable would not be suitable. The 12-strand braided nylon was able to handle the surges of wave crests and different momentums.

In some ways, riding to an anchor on a gusty day in a choppy seaway tends to create similar changes in loading. The boat yaws about, the seas pitch the bow up and down. The nylon will go a long way towards "evening out" the peak surges. Poly, with its reduced elasticity, tends to come up tight with a jerk.

And there you have another person's $0.02 worth ;)

[NormMessinger]

Ah, but is heavier road a good thing?

[John B]

Can't remember Norm. Probably the usual boat and a half length or so. and I'll put down a sentinel if it looks nasty. I can get a fair old weight on down there and I'm not worried about that.Its tried and proven to my satisfaction.
I don't want braided because I want to be able to re splice normally from time to time.

Polyester v Nylon. See 30 or 40 %plus ( some say) stretch anchored amongst other boats sounds like a recipe for disaster to me.

[Figment]

I agree that differential elongation is an issue in a tight anchorage. For this reason I'm always a bit leery of anchoring too near to a boat that's showing chain, lest I swing wide while she swings tight.

BUT... I don't think it prudent to let this drive your decision. First keep the boat hooked to the bottom. Worry about the neighbors second.

As an aside, if it's blowing hard enough to stretch your rode 30% you probably have larger concerns than how much your neighbor's rode has stretched.

[John B]

Weeeeel that was interesting.. I just spoke to rope guru at one of the larger rope suppliers and he says polyester without a doubt. Much better rope. Nylon gets hard with age,( it 'work hardens') , it absorbs 15% water unlike the polyester .In his opinion .. get the polyester.

[Peter Malcolm Jardine]

I've heard that in salt water nylon gets harder with age. Who knows for us fresh water guys. I carry 250 feet of 5/8 nylon with a 35 pound bruce and 25 feet of chain. Oh.. and a 60 pound folding kedge for emergencies.

[Scott Rosen]

I like three-strand nylon. It's impervious to UV, incredibly abrasion resistant, has good stretch, easy to handle and is stonger per a given thickness than just about anything else. The stretch makes it much gentler on your boat and gives you an easier motion at anchor in a blow.

But if polyester has worked for you all of these years, then I see no reason to switch. If your ground tackle is going to fail, it's probably not going to be from the rode parting because of tension. Chances are your anchor will drag, the splice or shackle will fail, or it will get fouled on something, or you will have too much chafe. Better to focus on the weak points of the system.

[Dave Hadfield]

John, if you have a sentinel to use, then does the stretch factor of nylon matter very much? I doubt it, for regular use.

I made and used one last summer for the first time (3 10lb cast-iron barbel weights on a chain linked to snatch block and sent halfway down the rode). Should've made one years ago -- really worked, and eased the motion.

On the other hand, what if your anchor holds and some big gin-palace drifts hard onto you? Maybe the ultimate stretch factor of nylon would then be best.

I went with 5/8 nylon braid 3 years ago, and got an eye spliced into each end when I picked it up. No complaints, even anchoring amongst rocks (15ft of chain) and hit occasionally by thunderstorms while at anchor.

[JimConlin]

Norm-
It seems to me that a cordage anchor rode must be strong enough to drag the anchor when chafed half through and fat enough for human hands to grasp it well. Beyond that, there are trade-offs. My priorities are stretchiness, being supple enough to slump and stow easily, and chafe resistance. Increasing size works ageinst some of these.
Bear in mind that braids are generally less tolerant of chafe than laid lines and that if there's any distance between the foredeck cleat and the chock, a stretchy line will chafe more at the chock. I've felt that three-strand nylon held up well, but got (tolerably) stiffer with age. That Brait is stretchier than three-strand is an advance. I used to be that braids were less stretchy, which, with cost and low chafe tolerance, made braid easy to reject.
I'll be buying anchor rodes for the new boat next year. I think i'll try Brait. (and get very religious about chafing gear)

[Todd Bradshaw]

I'm certainly not a rope expert, but I've been dealing with the nylon vs. polyester fiber question in one way or another for many years - from selling backpacking and climbing gear, to flying and working on balloons, to building sails. I'm a bit surprised that your rope guru didn't go deeper into the actual differences in the fibers and how they perform.

Nutshell Nylon fiber vs. polyester (Dacron) fiber comparison (kind of a "Fiber For Dummies" thing - no offense to those already in the know):

If we assume that the weaves and weights of the fibers used for making up items are similar, the major difference between the nylon and polyester versions is caused by the somewhat stretchier nature of nylon and could be called "The Buddy System". The stretchy nylon fibers make good buddies. If a whole lot of strain is placed on one fiber, he stretches to try to hold the load, but his neighbors help out, pulling and stretching a bit to take part of the strain off of the first guy. He may fail and break, but the whole team is going to help in the fight with the strain being distributed over a fairly large area and in several directions. The tear, if it happens, will be ragged and will affect many fibers in the area.

Polyester fibers, on the other hand, aren't particularly good buddies. In fact, they often act as if they are complete strangers. If you place a big load on one, he stretches as much as he can to hold the load, but he's not quite as strong as the nylon guy was and doesn't generally stretch as far. What's even worse, the fibers next to him pretty much ignore him as if it's just not their problem. He either takes the whole load by himself or breaks trying. If he fails, the entire load is then passed on to the next in line, who likewise gets little or no help from those around him. If he can't hold it and breaks, it's passed on to the next guy, etc...etc.. This is a bit oversimplified, but you get the picture. A polyester tear will usually be a clean, straight line with little damage anywhere other than the spots where the fibers failed.

In the real world, this type of thing happens quite fast. It's called "explosive tearing" and is generally a catastrophic failure. Remember those lime green A-Cup spinnakers that Cayard had? It's the same reason that I can put a small slit in the heaviest weight of Dacron sailcloth you can find, grab it by the corners and in one quick motion, rip it in half. The same reason that top to bottom catastrophic tears on some early hot-air balloon envelopes were almost exclusively polyester fabric. These traits and the low stretch products that they yield aren't all bad though. They make for mainsails and jibs which hold their shape and mainsheets which resist stretching under a load, so that a trimmed-in sail stays trimmed-in. The trick to success is just being sure that the polyester product has a working load far above anything it should ever actually encounter in use.

Trying the sailcloth-ripping test on a piece of similar weight ballistic or cordura nylon, instead of Dacron sailcloth has a much different effect. First of all, you'd better be damned strong if you plan to tear it and secondly it's going to distort like crazy and stretch as the fibers work together to fight you. Nylon fiber is also somewhat more abrasion resistant than polyester. Both will eventually degrade from UV, but polyester may last longer (depends greatly on added absorbers to either formula). Nylon likes alkaline conditions (pH greater than 7) Polyester likes acidic conditions (pH less than 7). Continued use of either in the wrong conditions will speed up deterioration (so get one of those aquarium kits and test your water :D ). Most nylon products will stretch about twice as far under heavy work load. Shock-loaded webbing, for example, stretches 6%-8% for nylon, 3%-4% for polyester. Nylon does tend to shrink a bit more with age and absorbs a bit more water, but compared to fibers like polypropylene (1/2%) or some natural fibers like cotton or linen (up to 40% or better) both nylon and polyester would be in the same range. You would have to have a pretty big chunk of rope to physically tell much difference in weight gained when wet.

For a piece of rope, the weave also comes into play. Some methods of rope making (like 3-strand or braided-core kernmantle construction - climbing rope, regular yacht braid, etc.) have more stretch and shock absorbing ability than others (like parallel-cored kernmantle constructions similar to many of the ultra low-stretch yacht braids).

It's probably possible to weave a polyester rope to have nearly as much stretch and shock absorption as some nylon ropes by making sure there is a lot of weaving in the core. Weaving distorts under a load, causing stretch and I'm pretty sure that's how they can make a polyester anchor rope that doesn't slam you against the cabin wall every time a wave passes by. Once it's been stretched enough to take all the slack out of the weave though, it reverts back to a bunch of non-buddy, non-stretch fibers who aren't going to help each other share the load and failure is going to be one quick "pop". Probably a good reason to go up a size in line diameter if using polyester for more brute strength. All in all, I think I'd sleep better with a nylon anchor rode.

[Concordia..41]

Thanks Todd - that's a keeper!

- M

[Stiletto]

John, there are sometimes good deals for rope of several different types on trademe.co

[Magwitch]

Chain.
That's all.

IanW

[Ian McColgin]

I have one anchor with an all chain rode and the others are three strand nylon. While I still preferr three strand nylon, some very smart folk like Brion Toss are recommending dacron (polyester) double braid.

The dacron double braid is initially more chafe resistant and is stronger for the weight. Absent chafe, it may keep its good properties a bit longer than nylon. The problems are explosive tear, as mentioned above, and greater chafe degredation. The latter is due to the somewhat counterintuitive fact that with dacron braid ever fibre strand gets to the surface sooner or later. If you have fuzzy chafe spread over a couple of fathoms of the line, each of the chains of fibers has been compromised. In well made three strand, the same fibers are at the surface and the fuzz you see with age does not so seriously compromise the warp.

Nylon stiffens with age and can suffer ultraviolet degredation but as nylonw goes bad, it's obvious. Three strand nylon that's been over-stressed with hockle (the strands jump up) any you know that that line has had it's day. Braided lines do not show this problem so obviously. Three strand nylon is also very easy to set up with nicely thimbled eyes or with rope-chain splices. Large diameter double braid eyes are perfectly doable with training and strength.

There are some new fibres more in use in the towing industry that would also make good anchor warps - some double braid but more twelve strand braid. Very cool stuff.

The bit about stretch is way over done in my opinion. A bit of stretch is nice. I remember being caught in Vinyard Have - a shallow anchorage at barely two fathoms - in a howing northwester. Even with 250' of chain out, it was so shallow that there was not enough room for a good catenary and the anchor and boat were subject so some very severe impact strains. I moved rather than risk an impact caused anchor dragging.

But contemporary screw moorings - very short scope - are usually provided with spectra pendants that have no stretch. The thinks is that if the impact does not hurt the anchor, it won't hurt the boat.

Also, under really high loading, the stretch can be amazing and can lead to chafe under the chafe guard. After one hurrican here I saw a boat u p on the beach. The chafe gear was fine but the nylon pendant had melted and parted inside the chafe guard. In that same blow, I was hidden back in my favorite cove riding on about 300" of 7/8" nylon to a pair of anchors in series. The anchors were up on land about 6' above the highest water. My bow is about 6' up. In the highest gusts - about 85 kt - the stretch was such that we set back about 75' - that's 25% stretch repeatedly. To my amazement, the rode was not hockeled at the end of all that and I still use it. The rode was proud of the water its whole length in those gusts and, as also happenes with a tug's tow line under strain, we could see the water ring out of it. I had a perfectly fair lead to several wraps on the foremast so the problem of heat inside the chafe gear was minimized and the degredation of the line at a cleat or a knot was also minimal.

I like three strand nylon because I know it quite well, it's very workable, and has excellent strength. As with epoxy brands, knowing the stuff trumps any theoretical edge of a product you don't know. I might be inclined to one of the newer 12 strands if a pile of it was available really cheap or if stowage was the most significant thing on my mind.

Regardless of the rode, I believe that a roller is so far superior to a plain chock that I'd despoil the look of a bow to have a proper roller with good, well rounded edges and an upper keeper. You still want chafe gear but there's nothing so reassuring as to see that roller turn under strain.

[jwaldin]

I'd go with braided poly. 1/4" thicker then you are sure you need and 300' longer than you are sure you need.
Have a look at what professional tow boat operators and the coast guard use.

[Ian McColgin]

What we used on tugs was not the same as off the shelf yacht chandelry dacron double braid. Also, tow boat use is harder on the strain, shorter over time, and far better protected from chafe than yacht anchor use. Different functions require different forms.

I'm not saying a good commercial 12 strand braid is out - far from it! - but for an anchor line good quality 3 strand nylon is still an excellent choise.

If you've the room, keep a huge roll of your storm and deep anchoring line on a drum and have maybe 50' (a boat length anyway) of chain and 100' of line that slake into a locker for normal use.

All the choises are vastly stronger than your anchor will hold anyway, when new. The problems are degredation due to aging, UV, chafe and knots. Nylon might be a little more vulnerable in the aging department. Certainly more vulnerable to UV but this is easy to protect. 3 strand nylon is more easily harmed by pure rub chafe at the superficial level but stands up better long haul, but more vulnerable to heat damage. All the lines are harmed by knots.

It's not an obvious call.