3 Strand Dock Lines

ryley

Super Anarchist
5,544
682
Boston, MA
BTW, stretchy dock lines are also noisy on the cleat. One way to combat this is to make some dyneema loops to go on the cleats and the docklines to the loops. Works very well, I only have issues with noise when it blows really hard. 

 

Blue Crab

benthivore
16,539
2,719
Outer Banks
BTW, stretchy dock lines are also noisy on the cleat. One way to combat this is to make some dyneema loops to go on the cleats and the docklines to the loops. Works very well, I only have issues with noise when it blows really hard. 
My experience was the reverse. At that same dock mentioned above there is a couple hundred m of fetch so there was generally small wind wave action unless it was dead calm. Sleeping in the bow, I eventually switched from double braid to 3S on the windward side which stopped that awful groan. I've often wondered since if the noise was just salt crystal build up.

I have had good luck with American Rope. https://americanrope.com/ . I bought a 300 foot spool of pretty blue double braid for about 40% of West Marine. Made a complete set of dock lines plus a couple of spares. 
THX. I've used them in the past. Same ol same ol about the 8 plait stretch. I quote, "Predictable Elongation."

Wonder why specs are so hard to come by?

 

Jules

Super Anarchist
8,676
3,461
Punta Gorda
I know double braid is much nicer to hand but I've found 3 strand's greater stretch is more important than feeling nice momentarily and I don't have that inner need to color coordinate everything. So, replacing dock lines and glanced at West catalog. They have 1/2" economy line priced at $17 for 25'. Premium is $45 for 25'. 

I cannot believe that (likely) American line is worth 3 times the price of the doubtless Chinese stuff for this application. I'll shop around but the question remains is there any reason whatsoever to pay for premium? This is a 7K displacement boat so ultimate strength isn't a factor. 

This is just a question about pricing. In the end, I'll buy a hunk of spooled rope and make my own lines.
We just replaced double braid with 3-strand on the bow and stern lines at our dock.  I shopped out online, including West Marine and Defender.  For me, breaking strength took priority.  As for price, I looked at it in relation to the dock line's ability to protect the boat from damage or sinking.

 

Blue Crab

benthivore
16,539
2,719
Outer Banks
There were two questions here as it turned out. Initially, the question was:

Is American nylon worth 3X the price of Chinese nylon? I think mgs answered in the negative by mentioning the labor costs here are likely 3x higher than in China. The quality assurance is another issue but I'd say that Chinese dock lines have been around long enough to have proven up.

My main concern was stretchiness. Little question that 3S wins over double braid by like double. Go figure. Then 8 plait was mentioned as stretchier than 3S. Apparently it is but nobody wants to list their specs. No biggie, 3S is stretchy enough for docklines as proven over quite a few years of seafaring around the globe. 

For reference, double braid is ~ a third stronger than 3S in nylon, and 3X the strength in polyester per Atlantic Braids.

Thanks all.

 

Blue Crab

benthivore
16,539
2,719
Outer Banks
I've been slaying dragons. Can one of you just lay out an elongation comparison between 8 plait and 3 strand at the same load? 

 

Blue Crab

benthivore
16,539
2,719
Outer Banks
OK coffee in hand, 1/2" Yale 8 plait has 10% stretch at WL 1660# Maximum Working Load 5:1 **(Lbs) with this caveat: ** Working load is based on static or moderately dynamic lifting/pulling operations. Instantaneous changes in load, up or down, in excess of 10% of the rope’s rated working load constitute hazardous shock load and would void the normal working-load recommendation. I'm guessing this is in the fine print of every rope.

Samson Pro Set 3S stretches 10% at 20% of BS or ~1500#   This seems close enough to the Yale 8 plait for govt work.  Slight advantage to 8 plait.

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Tough finding comparative data but another tack is Yale 8 appears to elongate ~28% at breaking strength of ~7470 #.

ERigging 1/2" 3S elongation at break: 20-34%  (5850# for Walmart brand, E-Rigging 5670#).

Down the rabbit hole: I found an study of nonlinear behavior of 8 plait but think for boating, linear is key.

Anyhoo, this is tough for English majors. I'm more comfy with fig newtons than kN.

My non-engineer conclusion is 8 plait will elongate slightly more than 3S, perhaps due to its higher breaking strength. 

Big whoop.

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To the original question re price of American v Chinese nylon, I noticed that the weight and maybe specific gravity of the various brands per 100' is essentially the same ... nylon is nylon. After that the issues resolve into quality control, maybe proprietary coatings, maybe unknown to me factors but for the average guy it doesn't matter at all, imho.  

 

mgs

canoeman
1,176
273
maine
@DDW Yalon premium 3-strand. It’s in a 2007 catalog. Whether or not they still make it I can’t say. 
 

@Blue Crab while your at it try and find out why they don’t use nylon dock lines in Europe…

 

Blue Crab

benthivore
16,539
2,719
Outer Banks
@Blue Crab while your at it try and find out why they don’t use nylon dock lines in Europe…


That's an easy one. Slug could answer it but is angry at me so I turned to this guy on the nice forum who has proven to be a very reliable source in the past.






 




 













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 06-02-2019, 01:49


  #63





Dockhead
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Re: Docking lines, 3-strand vs braided

I don't use nylon docklines, which stretch and work and therefore chafe badly if there's any boat motion.


I use polyester octoplait for docklines. You don't need much stretch in bow and stern lines which are rigged as real bow and stern lines with a good angle to the dock, nor in springlines. If you have problems with snatching due to rigging short, perpendicular docklines, the answer to that is rigging them right, not using stretchy rope.



If the boat jerks around due to wave action, I add snubbing lines -- nylon octoplait with rubber buffers -- to dampen the motion. But not instead of docklines -- to supplement them. Generally at a steeper angle than the docklines so that they take the brunt of the force.


I have not been diligent enough to splice loops in all of my docklines, but I, personally, like them with spliced loops, which are compact and smooth, although bowlines work reasonably well also. As as been said, spliced loops are stronger than bowlines, but I don't believe it is possible to load a dockline to anything like ultimate breaking load so I don't think it's an issue. I've seen many docklines failed from chafing; none from overloading as far as I can recall.


As to octoplait vs. three strand -- matter of taste. Octo does snag, is more expensive, and is much harder to splice. I use it just because I love the way it hands, and no hockles.





 

weightless

Super Anarchist
5,608
587
find out why they don’t use nylon dock lines in Europe
Marketing? After the war marketing campaigns in the US hit on a message for selling stretchy line. It was remarkably successful. I think my grandfather was involved -- at least a few spools of complimentary line came our way.

 

allene222

Super Anarchist
3,962
58
SF Bay
Used 10mm climbing rope. Can't splice it but so what.

Find a climbing gym that gets rid of worn ropes and beg or buy them cheap. Super stretchy and the tightly woven cover is pretty chafe resistant.
I used climbing line for my traveler but it didn't last one summer. I would caution against it. Switched to nylon single braid at recommendation of Stan H. who had the same experience with climbing line on his traveler.
 

Son of Hans

Member
180
92
San Diego
I know it sounds rather pedantic, but it's not quite true that nylon is nylon. There is Nylon 6 and Nylon 6-6. The former has some better properties and the latter is more common (read: cheaper). Good luck getting a ropemaker to tell you which they use - but probably not relevant to our discussion.
 

SimonGH

Member
432
96
Westbrook CT
I echo the climbing rope idea. Just make sure it's "dynamic" rope (like they would use as belaying lines at a climbing gym), which is designed to stretch and reduce the impact as it arrests a fall.

There is also "static" rope, which is like a halyard - it's designed for lowering things or other situations where you don't want stretch. You wouldn't want that for dock lines.
 

slug zitski

Super Anarchist
7,104
1,469
worldwide
Three strand is inferior because it doesn’t like self tailing winches

stick with double braid..use the largest diameter that will wrap on your cleats and winches
cheap line is best…docklines get uv burnt and chafe , they never last long

black is superior for longevity …

if your dock lines are short…use nylon ….
 




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