Types of Rope

You can save money and handle homestead towing and tying tasks more safely if you know the different types of rope.
By the MOTHER EARTH NEWS editors
May/June 1981
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Seven types of rope, from left to right: three-strand nylon, braided nylon, three-strand polypropylene manila imitation, three-strand polypropylene, three-strand manila, three-strand sisal, and three-strand cotton.
PHOTO: MOTHER EARTH NEWS STAFF
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Over the last 20 years, the once simple act of picking out and using a length of rope has become pretty complicated: A profusion of new synthetic lines has joined the natural varieties on hardware store shelves, forcing baffled buyers to choose among well over a dozen combinations of fiber and twisting style.

Of course, each of the numerous ropes available are better suited for some tasks than others, and the material that a cord is made of will likely require specific care. So we decided that it might be helpful to describe several of the more common types of rope and tell you what they're good for, as well as what steps should be taken to get the maximum life from each.

Twisting the Right-A-Way

In its most simple form, rope consists of long fibers that are first twisted (usually in a clockwise fashion) to form yarns. Then a number of the wound strings are spun together, in the opposite direction, to yield strands ... which are in turn twisted back in a right-hand direction (in groups of three) to make "hawser-laid" rope.

The combination of these counterdirectional twists gives the finished cord more strength than that of the individual fibers composing it, since the friction between the fibers, yarns, and strands increases the line's resistance to stretch. Furthermore, the winding process prevents the material from unraveling. (In fact, if you take a good piece of three-strand rope and attempt to untwist it in the middle, you'll notice that, after about one quarter-turn, it vigorously resists unwinding.)

There are, however, a number of other ways to "lay-up" a rope. Although they are somewhat rare, it's possible to locate left-hand-laid three-strand ropes, and even four-strand ropes. But braiding is by far the most common of the alternative twist techniques. It's accomplished by weaving eight (or more) strands together in a "diamond" pattern and produces a rope that's very flexible, doesn't tend to curl, and stretches even less than does a twisted rope made of the same material and of equal diameter. (Not surprisingly, braided—sometimes called plaited—line's superior qualities result in its having the highest average price tag of all ropes.)

Synthetic vs. Natural

From a utilitarian point of view, synthetic rope has a number of advantages over natural fiber rope. For a given diameter, they are stronger, more resistant to most types of decay, and only slightly more expensive than the nonsynthetics.

Such "artificial" lines are, for the most part, manufactured from by-products of the oil refining process and therefore depend upon nonrenewable raw materials. (In fact, polyethylene ropes are made from ethylene, a petroleum substance that can also be used to produce ethyl alcohol, or fuel ethanol.) Compounds obtained from the hydrocarbons are extruded and drawn, and—depending upon the fastidiousness of the production process can be formed into threads that extend for the entire length of a rope (a feature not possible with natural fibers). The finest nylon lines are made by this "continuous filament" method, and are easy to distinguish from the fuzzier "spun" nylon ropes.

Despite the advantages of synthetic fibers, many folks still prefer the relatively strong, easy-to-handle, economical natural lines. Manila is the most popular of the plant-derived ropes (it comes from abaca, a banana-like plant). In fact, among seafarers (and landlubbers) who do fancy work with rope, manila is considered the only choice. A less preferred—and less expensive—option is sisal, which takes its raw materials from a species of Mexican cactus. And hemp, which was once a common top-quality rope made from fibers in the stems of Cannabis (marijuana) plants, has become quite difficult to find.

The relative strengths of the-common natural and synthetic ropes (as well as their resistance to the elements and their stretch, cost, etc.) are compared in the chart that accompanies this article. (It is important to note that the performance of two firms' versions of the same kind of rope is likely to vary more than will the performance of two different kinds from the same manufacturer. Be sure to check the factory specifications, which will be available for many quality ropes.)

For general farmstead needs, the two most useful types of line are manila and nylon. The former has very little stretch, takes knots well without slipping, and can easily be spliced and employed in permanent applications. Nylon, on the other hand, has a significantly higher breaking strength than any other common rope, and has a tremendous ability to stretch and absorb shock loads. In addition, it's unaffected by water, sunlight, and alkaline chemicals and is very easy to handle.

Rope Care

Whatever a particular rope's durability and resistance to the elements may be, the line won't last long at all if it's abused. Proper care begins with putting it away after each use.

Ropes—whether they are synthetic or natural—should always be coiled up and hung in a dry place for storage. Of course, when a line is brand-new, you'll find that it won't stay in a neat coil. One way to convince an "unruly" rope to cooperate is to coil it once or twice in a left-hand direction (for hawser-laid ropes) and then coil it in a clockwise fashion (If, however, you invest in a braided rope, you'll find it easiest to coil it in a figure-eight pattern.)

One should never leave frayed ends on a good piece of rope. Once the line has begun to unravel, that "unwound" portion will have to be discarded! Natural fiber ropes should be whipped (a method of (continued from preceding page) binding the line's tips) with either a good synthetic whipping twine or a natural fiber such as waxed linen. There are a number of different ways to whip a rope's end, but "common" and "sailor's" whipping are two of the more popular approaches.

Another way to prevent unwinding in a natural fiber rope is to back-splice it. Back splicing, however, can be used only when the rope will not have to pass through a restriction—such as a pulley block—since the splice increases the end's diameter significantly.

Synthetic lines are generally protected from unraveling by either melting the fibers in their tips or by applying a length of shrink tubing to their ends. (Alternatively, it's possible to apply whipping to the ends of synthetic rope, just as you would when dealing with natural fibers.) Whichever method you choose, it's particularly important that the binding be secure because synthetics seem to be more inclined to unravel than are the natural ropes.

Finally, you should know that some lines are more resistant to certain environmental conditions and uses than others. Manufacturers' specifications should be looked over carefully. For example, most polypropylene and polyethylene ropes can't be used where they'll regularly be subject to direct sunlight, but some factories do apply ultraviolet inhibitors to such lines, eliminating or alleviating that problem.

Rope Applications

When you're trying to decide which rope to use for a particular job, it's important to consider both the working load and the breaking strength of the cord in question. While all natural fiber lines are rated for regular working loads of about 20% of their breaking strength, nylon is usually rated for a working load that is 11% of its breaking strength because of its tendency to stretch. Hence, nylon might be perfect for a towing application where the rope needs to flex and the load will vary considerably. But in a situation where an object needs to be held in position—such as when a rope is used to temporarily guy a tower—a low-stretch manila might be a good choice.

Furthermore, there are a few basic rules for the use of any rope. When you're bending a rope around pulley blocks, for example, the diameter of the pulley should be at least eight times that of the rope. And in any application where a line is permanently affixed to either another line or to some object, use a splice rather than a knot ... since it places less stress on the fibers. Of course, there are times when a knot is the only practical choice. In such cases, find out what the right "tie" for the job is and use it (see "How to Tie the Ten Most Useful Knots", on page 80 of issue 57). You'll insure your own safety, and your rope will last longer as a result.

Even under the best of conditions, all fibers—either natural or synthetic—will wear out. You should learn to recognize the symptoms and put a deteriorating line out of service before an accident happens. Most natural ropes tend to become quite limp when they're nearing the end of their useful career. The surface will become soft and fuzzy, the color will turn to a dull gray, and the inner filaments will have crumbled to dust. Synthetic fibers, however, don't offer such clear warnings. Generally, they will become limp and soft—and, in the case of the ropes affected by ultraviolet light, the color may change—but the interior fibers may, to the eye, appear unaffected. To inspect such a rope, bend the material and study the condition of the surface fibers. If they're excessively frayed, it's time to retire the line.

But don't throw away rope that's a little too old to be trusted. There are likely to be many short sections that can be turned into all manner of useful objects. Sailors have fashioned everything from handles to door mats out of old lines, and there are numerous working applications for tired rope, too: It can be used to make bumpers and grommets, for instance.

As you pay more attention to the lines you use, you may find yourself becoming more interested in the time-honored art of ropecraft. There's a real pleasure in working a quality section of rope, and the results of an expert's handiwork can often teeter on the boundary between function and art. 


Specifications for Common 3/8" Ropes

HEMP
- Working Load: 270 lb.
- Breaking Load: 1,350 lb.
- Enemies: moisture, chemicals
- Stretch: low
- Handling: good
- Price: 2
- Comments: becoming difficult to find

SISAL
- Working Load: 225 lb.
- Breaking Load: 1,125 lb.
- Enemies: moisture, chemicals
- Stretch: low
- Handling: fair
- Price: 1
- Comments: tends to fray, has barbs that poke hands

COTTON
- Working Load: 150 lb.
- Breaking Load: 750 lb.
- Enemies: moisture, chemicals
- Stretch: medium
- Handling: excellent
- Price: 1
- Comments: very easy to handle, swells with moisture and grips

MANILA
- Working Load: 270 lb.
- Breaking Load: 1,350 lb.
- Enemies: moisture, chemicals
- Stretch: low
- Handling: good
- Price: 3
- Comments: the standard natural fiber rope

NYLON
- Working Load: 410 lb.
- Breaking Load: 3,725 lb.
- Enemies: acids
- Stretch: high
- Handling: excellent
- Price: 5
- Comments: tends to slip, very flexible if braided, unwinds easily

POLYETHYLENE
- Working Load: 420 lb.
- Breaking Load: 2,700 lb.
- Enemies: ultraviolet light
- Stretch: low
- Handling: fair
- Price: 3
- Comments: floats, stiff, slippery, may have barbs, subject to chafe, unwinds easily

POLYPROPYLENE
- Working Load: 400 lb.
- Breaking Load: 2,350 lb.
- Enemies: ultraviolet light
- Stretch: medium
- Handling: fair
- Price: 2
- Comments: floats, stiff, may have barbs, subject to chafe, unwinds easily

Price numbers indicate relative cost from least to most expensive on a scale of 1 to 5.

EDITOR'S NOTE: If you'd like to learn more about the craft of working with rope, two excellent books on the subject are The Marlinspike Sailor by Hervey Garrett Smith, published by John De Graff, Inc. ($7.95) ... and Modern Rope Seamanship by Colin Jarman and Bill Beavis, published by International Marine Publishing Company ($12.50). 


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