Docking lines, 3-strand vs braided

[thinwater]

Originally Posted by RoseLoper48

I read an article in Practical Sailor discussing this subject. They favored
three strand because braided line builds up heat internally and will break down sooner.

Date, please.


The most resent article did not distinguish between DB and 3-strand. It also concluded that internal heating was a minor factor unless the rope was over 1-inch, which makes it minor for most of us. The practical conclusion was that for dock lines to overheat, there must be either considerable friction or frequent cycling to over the safe working load. Both are common, with short breast lines and sharp angles through chocks.

[JB0101]

I used 3 strand mainly because of reasons already stated. But mostly because I made snubbers out of two foot strips of bicycle inner tubes. I tucked the ends under a couple of strands as if I was braiding an eye splice. I think I had about 2.5 ft of line between the tucks. Very easy to change the length of the tube and/or distance between tucks to find smooth ride. The inner tubes were much smoother than the snubbers that were available back in those days. Got the tubes for free from cyclists.

[Dockhead]

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.

[valhalla360]

Originally Posted by thinwater

This is a false comparison. Large ships are relatively unaffected by chop and gusts and do not move quickly. Thus the energy absorption afforded by nylon is not helpful. It is more important to prevent motion from beginning.

The optimum arrangement of lines and optimum stretch is complex. Stretch helps cushion, but preventing excess motion is also important. But you don't need non-stretch lines, on small boats, to reduce movement and bouncing on lines. There are other ways.

In addition, if you are talking about large ships, dock lines can easily be 50-100' long, so even a relatively small percentage of stretch can still be a couple feet and when you are talking about vessels that weigh hundreds of tons, steel cables can stretch a surprising amount.

Comparisons to large commercial vessels is just not applicable.

[El Pinguino]

Originally Posted by thinwater

This is a false comparison. Large ships are relatively unaffected by chop and gusts and do not move quickly. Thus the energy absorption afforded by nylon is not helpful. It is more important to prevent motion from beginning..

They are - however - affected by surge. Which is why South African ports had (have?) massive coir 'docklines' that you secured your headlines/ breastlines and FSWR springs to.


Back to small boats.... if you are anywhere where any movement or surge is present the only way to go is nylon... never mind the chafe onboard... movement within 12 inches or so of the cleat wont be an issue.... if it is just use heavy reinforced water pipe... both at your fairleads and ashore if using bowlines... thinking extreme cases such as Antofagasta and 'Bravezas' here...

[inspectr]

Most of the modern large commercial vessels I worked on as 3rd and 2nd mate had tension winches pre-set to a certain load, if the tension in the mooring line got too much it would ease off - long runs, hydraulic limiting devices and large ship inertia are all irrelevant to a 40ft yacht moored in a marina exposed to wind and waves
Most marina pens require short runs, hence limited tolerance to pounding from waves and wind
Our marine in Double Bay is very exposed to the northerlies and as there is a considerable fetch, it can get very bouncy alongside
Short lines and exposed conditions mandate stretchy lines and snubbers and shock absorbers.
Im lucky as our boat is on a swing mooring with reasonable scope, but with three strand polyester line to the chain and mooring block

[inspectr]

When poly lines, both 8 strand plaited and 3 strand conventional lines first arrived on our big ships we experienced a lot of melting and degradation of the lines on Bitts as well as on the windlass drums, and had to teach the ABs new techniques of handling lines to avoid damage. The crew were used to easing out a line with three of four turns around the capstan, drum end or through the bitts and as a result even a few metres of movement could cause enough heat to massively damage the lines.
It did not take long before the ship owners introduced hydraulically operated tension winches to save the lines.
Nothing here is relevant to small boats however

[thinwater]

Originally Posted by El Pinguino

... never mind the chafe onboard... movement within 12 inches or so of the cleat wont be an issue.... if it is just use heavy reinforced water pipe....

On larger boats, heating is still an issue during hurricanes. The sharp 90 degree bend + quick cycling+ friction (even with chafe guard) = heat. It's not just urban legend, if you do the math it is there. Just rub your hands together. When you consider that most boats spend most of their time tied up in marinas, some of the chock/cleat arraignments are unforgivable. This should be a major desin point and not an afterthought.

[danielamartindm]

As with everything nautical or aeronautical, it's a trade-off. I like the superior breaking strengths of braided and the simplicity and "feel" of easily correcting twists in it; but I hate the complexity of making eye splices, and its tendency to leach in water, like a wick, to stain the decks. In the end, I've chosen braided, and the convenience of prefabricated eye splices on one end around which to build a threaded-through dock line that embodies the strength of that splice, with an adjustable bowline or cleat hitch on the other end. If you prefer three strand, I TOTALLY understand your preference.

[Auspicious]

Originally Posted by El Pinguino

never mind the chafe onboard... movement within 12 inches or so of the cleat wont be an issue.... if it is just use heavy reinforced water pipe... both at your fairleads and ashore if using bowlines... thinking extreme cases such as Antofagasta and 'Bravezas' here...

Water pipe (hose to Americans) is not a good choice for chafe gear. There is no air flow and heat builds up tremendously. Even drilling holes (tedious) isn't enough.



Leather sewn or lashed in place works great as water soaking through cools the line at the chafe point. Fire hose, when you can get it (here in the US liability concerns often make it difficult), works fine IF you strip the rubber lining out. Tea towels work pretty well as long as the lead direction doesn't change too much. Polished stainless fairleads, if maintained, work well.



Put me firmly in the camp of three-strand for dock lines. Less internal heating. Higher stretch means tying up more tightly (absent surge and tide) is okay. Cost is lower - much lower if you buy spools and splice yourself and performance is better.



If hand is an issue leather gardening or work gloves are in order. Same ones you have on hand for locking, Med mooring, and fishing. Besides, you'll look cute in gloves, too-tight bathing suit, and shower shoes. Really gets the attention of the new neighbors. I've been approached in marina watering holes to be asked "aren't you the guy wearing socks with your Crocs?" Really impresses the local ladies.

[Auspicious]

Oh I should have noted that splicing three-strand is a useful skill. I've gathered a small crowd at pubs and bars and ended up teaching others. A great way to have strangers buy your drinks.

[Capn Rick]

In general, braided line is more expensive, stronger and maintains more of its strength once it begins to abrade than three strand.

Three strand is less expensive, begins to lose strength rapidly once it abrades and has more elasticity or stretch which means it is easier on your cleats and boat when moving around in your slip.

From my experience whether it be braided or three strand it pays to buy a higher quality line. Avoid the cheapies.

[fish53]

Originally Posted by thinwater

This is a false comparison. Large ships are relatively unaffected by chop and gusts and do not move quickly. Thus the energy absorption afforded by nylon is not helpful. It is more important to prevent motion from beginning.



The optimum arrangement of lines and optimum stretch is complex. Stretch helps cushion, but preventing excess motion is also important. But you don't need non-stretch lines, on small boats, to reduce movement and bouncing on lines. There are other ways.

You are incorrect and have apparently no concept of the strain presented by 50,000 tons against mooring lines from even small movement. In fact ships move about at the dock more than small vessels simply from scale, six inches may be a lot for a small boat but is hardly noticeable to a ship yet the strain on mooring lines is significant.

[fish53]

Originally Posted by inspectr

Most of the modern large commercial vessels I worked on as 3rd and 2nd mate had tension winches pre-set to a certain load, if the tension in the mooring line got too much it would ease off - long runs, hydraulic limiting devices and large ship inertia are all irrelevant to a 40ft yacht moored in a marina exposed to wind and waves
Most marina pens require short runs, hence limited tolerance to pounding from waves and wind
Our marine in Double Bay is very exposed to the northerlies and as there is a considerable fetch, it can get very bouncy alongside
Short lines and exposed conditions mandate stretchy lines and snubbers and shock absorbers.
Im lucky as our boat is on a swing mooring with reasonable scope, but with three strand polyester line to the chain and mooring block

Not all vessels are so equipped and a prudent and competent seaman would avail themselves of the necessary skills to secure any type of vessel in the prevailing conditions.

[BigBeakie]

Fish53,

I just recently was dealing with a company that supplies docking lines to ships. Very BIG lines. They are braided HMPE lines, they do not want any stretch.

Thinwaters statement on this point appears to be correct, and I think he has established some credentials around here on lines.


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