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An in-depth look at the common thread that binds all boaters.
Photo: Frank Lanier
Whether an adamant stinkpotter or the most vociferous of rag-bagging blow boaters, there is a common thread that binds us all – rope. From anchor lines and halyards to sheets and docklines, cordage has played an integral role in maritime history since caveman Ogg first used a poison ivy vine to keep his new river-crossing log from floating away.
The quality and variety of rope available to boaters has increased dramatically since then, however, so has the difficulty in matching the right rope to the job at hand. Choosing rope may make you feel like heading to the marina bar instead of the marina chandlery, but it doesn’t have to be that way. Rope is our friend, so sit back and relax while we talk line-lingo and explore the fascinating world of cordage.
Terminology Basics
“Rope” is the generic term for cordage over 1 inch in circumference, while smaller stuff is known as cord, twine, line, or string. Finer still is thread and double yarn.
The term “rope” is commonly used to describe bulk material, such as a spool of rope at the chandlery, while “line” is generally defined as rope cut from said spool and used for a specific task on board (a spring line for example). For the purpose of this article, we’ll view the terms “rope” and “line” as interchangeable.
Despite the seemingly endless number of polysyllabic words that rope manufacturers use to describe their products, selecting the right one boils down to three things: material, method of construction, and what you want the rope to do.
Rope Construction
The vast majority of lines found on board today are synthetic fibers like nylon, polyester, and polypropylene, compared to 70 years ago when organics such as hemp, sisal, and cotton ruled the waves.
Synthetic lines have numerous advantages over their organic counterparts, such as increased strength and resistance to rot. The variety of synthetic lines available also allows boaters to better match line characteristics with function.
Ironically, natural fiber rope, once the mainstay of thrifty sailors everywhere, is now often more expensive than man-made fiber rope as there’s simply not as much of it made these days.
Basic rope construction begins with fibers, which are formed into yarns, strands, and finally twisted or braided into rope. It’s that last step that determines how the fibers lay or align with the finished line and thus defines the properties of the line itself.
For example, in a twisted or laid rope such as three-strand (the traditional form of manufacture since the early days of natural rope), fibers are not aligned with the line’s axis. This means the line will have more stretch than braided or parallel core, because the fibers straighten out as the rope comes under tension.An easy way to picture this is to imagine how the coils of a Slinky toy straighten or stretch out when pulled – exactly what your twisted rope does, although hopefully not as much.
Braided rope on the other hand, has more fiber in the line’s cross section, translating to less stretch and consequently greater strength. Braided rope is torque-free (i.e., minimal tendency to spin or rotate under load), has good abrasion resistance, and is less susceptible to kinking than traditional laid rope.
Plaited or single-braid rope is the simplest and most prevalent type of braided rope, however other common types include balanced double-braided (a braided cover over a braided core of the same material), core-loaded double-braid (braided cover over a braided, lower-stretch core of different material), and parallel core, a braided cover surrounding a bundled core oriented parallel to the line’s axis.
Care & Feeding Of Ropes
We’ve made much ado about the pros and cons of old school versus new and how to select the best rope for the job at hand, however, after proper selection, the final word has to be maintenance and care. While not fiber specific, the below guidelines are good overall advice on caring for most any line.
- Chafe remains the worst enemy of any rope. Visually inspect masthead, blocks, guides, chocks, cleats, windlass drums, and so on, for burrs or sharp edges, while taping all cotter pins and split rings in turnbuckles and blocks. >> Frequently wash rope and running rigging with fresh water to remove dirt and salt, which can cause excessive wear and premature failure. Soak lines in warm water with a mild detergent (some recommend soap powder instead) and, while you’re at it, live it up a little by adding a dash of fabric softener to make them nice and soft — but only in recommended amounts. Fabric softener won’t chemically damage your line, but if used in excessive quantities, it can prevent proper drying (which could damage some types of line).
- Rinse thoroughly, then hang up to dry. If done at the end of the season when laying up, your lines will be clean and ready to go in spring when you are.
- Although synthetic fibers have pretty good chemical resistance, exposure to harsh chemicals such as acids and alkalis should be avoided whenever possible. The same is true of sunlight, as all fibers degrade due to UV light over time. Cover or remove lines and bag or store belowdecks when possible.
- As for line handling, always begin coiling a line at the end that’s made fast, which allows any twists or kinks to be removed at the loose end. Unless properly coiled, kinks and snags will result. As most all laid ropes are right-handed, coils should be clockwise to ensure the line pays out smoothly. Placing a kinked line under load weakens and damages it, often resulting in hard spots caused by excessive friction heat that can literally fuse filaments together.
- Ensure your ropes wear evenly by occasionally swapping or changing them end for end. — F.L.
The number and types of rope available can seem overwhelming without a little research beforehand. Photo: Frank Lanier
Getting Your Fiber
While exotic, man-made rope-making material seemingly crops up daily, the three standbys remain nylon, polyester, and polypropylene. Nylon is the strongest, followed closely by polyester and, finally, polypropylene.
Nylon’s strength, excellent abrasion resistance, and good elasticity make it an ideal choice for applications involving shock loads, such as anchor- and docklines. This same characteristic, however, makes it unsuitable for halyards and other uses where you want very little stretching.
Known to many boaters as Dacron (DuPont’s trade name for the material), polyester combines the desirable characteristics of strength and minimal stretch, making it a good all-around line suited for most purposes on board. It also has good abrasion-resistance, doesn’t shrink when wet, and maintains flexibility in high temperatures. Purchased prestretched, it’s ideally suited for halyards, sheets, and control lines on sailboats.
The lightest and lowest strength of the three is polypropylene. It’s inexpensive and floats, making it the rope of choice for dinghy painters, ski tow ropes, mooring pennants, and other applications where a submerged line might snag your propeller. Downsides include less strength than nylon or polyester, susceptibility to UV degradation, chafe, and a tendency to melt under high friction.
After the three basic types of rope above, choices grow more complex and expensive. Times were a lot simpler when all you had to remember was to use nylon for anchor and docklines and polyester for halyards. Now buzzwords like high-modulus, HMWPE, aramid, and LCP define the cutting edge.
The overall benefit of high-modulus (a fancy way of saying low-stretch) line is that it takes a much smaller line to achieve the same strength. This generates a reduction in weight not only in line, but also the smaller gear (e.g., blocks and winches) required to control it.
A good example of this weight savings would be Spectra. Pound-for-pound 10 times stronger than steel and three times stronger than polyester of equal weight, it has a strength-to-size ratio matching wire cable, yet a 3.5-inch hawser of Spectra is so light that it floats in water!
High molecular-weight polyethylene (HMWPE) line gets its strength using the same principle as the lowly plastic shopping bag – molecular alignment. During the manufacturing process, molecules align themselves in the same direction as the load, making them much stronger than random orientation (which is why those plastic bag handles seem to stretch forever without breaking).
In the case of HMWPE line, that initial stretching is done during manufacture, meaning it doesn’t stretch when first placed under load by the customer. Trade names include Spectra, Amsteel and Dyneema.
HMWPE is a strong, lightweight, low-stretch material good for running rigging, as well as running backstays and other applications where light weight and low stretch are critical. It also resists weather and abrasion, doesn’t soak up water, and doesn’t shrink. The downside is that it’s very slippery, and the core is subject to creep (elongation under continuous high load), meaning it will slowly stretch without returning to its original length.
Here you can see the construction of both three-strand and double-braid ropes.
Aramids are a family of nylons used to make anything from bulletproof vests to puncture-resistant tires. You’ll recognize them in the names Kevlar (DuPont’s trade name for aramid), Technora, and Twaron. In addition to their high strength, aramid fibers possess minimal stretch and low creep characteristics.
Downsides include poor UV-resistance and susceptibility to abrasion, particularly when subjected to high bending loads (i.e., use with blocks or cleats), making them best suited for applications such as standing rigging.
Liquid crystal polymers (LCP) are thermoplastic fibers with exceptional strength and rigidity (pound for pound five times stronger than steel) and roughly 15 times the fatigue resistance of aramid. A common trade name for LCP is Vectran. LCP lines have exceptionally low-stretch characteristics and no creep. Water absorption is low, and resistance to abrasion and flex fatigue (failure due to repeated sharp bending) is excellent, however the lines do have low UV-resistance. They’re best suited for uses like running rigging that can be covered or removed and stored away from sunlight.
As you can see, high-tech lines have quirks just like their low-tech brethren (e.g., creeping, extreme slipperiness), and some of these peculiarities cause them to perform radically different under otherwise familiar situations – knots being a good example.
Knots that have served sailors well for centuries can severely damage high-modulus line to the point of early failure. Knots weaken all ropes because they distort the fibers – a bowline for example, reduces the strength of polyester or nylon line by as much as 40%. That same bowline can cut a high-modulus line’s strength by 70% or more, leaving little or no safety margin. This means that all termination points in high-modulus lines should either be splices or end fittings instead of knots.
Though nylon, polyester, and polypropylene still serve the average boater well, there are many tasks where these high-tech lines can be extremely useful. The advent of these space-age lines may require a little more research to ensure you’re buying the best line for the task at hand, however, it doesn’t have to be rocket science.