Rope
:
This article is about non-metallic ropes. For other uses, see Rope (disambiguation). |
Coils of rope used for long-line fishing |
A
rope (
IPA: ) is a length of
fibers, twisted or
braided together to improve strength for pulling and
connecting. It has
tensile strength but is too flexible to provide
compressive strength (i.e., it can be used for pulling, not pushing). Rope is thicker and stronger than similarly constructed cord, line, string, or twine. Common materials for rope include natural fibers such as
Manila hemp,
hemp,
linen,
cotton,
coir,
jute, and
sisal.
Synthetic fibers in use for rope-making include
nylon,
polypropylene,
polyethylene, such as
Spectra, a high
modulus polyethylene,
aramid such as
Kevlar, and
polyester such as
polyethylene terephthalate. Some ropes are constructed of mixtures of several fibers or use co-polymer fibers. Ropes can also be made out of
metal fibers. Ropes have been constructed of other fibrous materials such as
silk,
wool, and
hair, but such ropes are not generally available.
Rope has been an essential tool since
prehistoric times. It has been andstill is of paramount importance in fields as diverse as
construction,
seafaring, exploration, sports and communications. In order to fasten rope, a large number of
knots have been invented for various uses.
Pulleys are used to redirect the pulling force to another direction, and may be used to create
mechanical advantage, allowing multiple strands of rope to share a load and multiply the force applied to the end.
Winches and
capstans are machines designed to pull ropes.
The use of ropes for hunting, pulling, fastening, attaching, carrying, lifting, and climbing dates back to prehistoric times and has always been essential to mankind's technological progress. It is likely that the earliest "ropes" were naturally occurring lengths of plant fiber, such as vines, followed soon by the first attempts at twisting and braiding these strands together to form the first proper ropes in the modern sense of the word. There is evidence of rope being made in this fashion dating as far back as 17,000 BC.
[[Image:Ancient_Egypt_rope_manufacture.jpg|thumb|200px|Ancient Egyptians were the first to develop tools for ropemaking]]
The ancient Egyptians were probably the first civilization to develop special tools to make rope. Egyptian rope dates back to 4000 to 3500 B.C. and was generally made of water reed fibers. Other rope in antiquity was made from the fibers of
date palms,
flax,
grass,
papyrus,
leather, or animal hair. The use of such ropes pulled by thousands of workers allowed the Egyptians to move the heavy stones required to build their monuments. Starting from approximately 2800 B.C., rope made of hemp fibers was in use in China. Rope and the craft of rope making spread throughout Asia, India, and Europe over the next several thousand years.
In the Middle Ages (from the thirteenth century to the eighteenth century), from the British Isles to Italy, ropes were constructed in so-called
rope walks, very long
buildings where strands the full length of the rope were spread out and then
laid up or twisted together to form the rope. The cable length was thus set by the length of the available rope walk. This is related to the unit of
length termed
cable length. This allowed for long ropes of up to 300 yards long or longer to be made. Short ropes are useless on tall ships which require ropes to be long, relatively uniform in diameter, and strong. Short ropes would require splicing to make them long. The strongest form of splicing is the short splice, which doubles the diameter of the rope at the area of the splice. This would cause problems in the rigging hardware such as buckles and pulleys.
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A German ropemaker, around 1470 AD |
Leonardo da Vinci drew sketches of a concept for a ropemaking machine, but just like many other of his
inventions, they never got built. Nevertheless, remarkable feats of construction were accomplished without advanced technology: In 1586,
Domenico Fontana erected the 327 ton
obelisk on Rome's
Saint Peter's Square with a concerted effort of 900 men, 75 horses, and countless pulleys and meters of rope. By the late 1700s several working machines had been built and patented.
Rope continued to be made from natural fibers until the 1950s when
synthetic fibers such as nylon became popular. Despite the changes in materials and technology, rope making today remains little changed since the time of the ancient Egyptians.
Laid or twisted rope
Laid rope, also called
twisted rope, is historically the prevalent form of rope, at least in modern
western history. Most twisted rope consists of three strands and is normally right-laid, or given a right handed twist. Typically, a three strand laid rope is called a plain or hawser-laid rope. A four strand rope is usually called
shroud-laid, and a rope twisted out of 3 or more ropes is called
cable-laid.
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Rope making using the twisted rope method on a 1928 Metters Rope Making Machine |
Twisted ropes are built up in three steps. First,
fibers are gathered and spun to form
yarns. A number of these yarns are then twisted together to form strands. The strands are then twisted together to form the rope. The twist of the yarn is opposite to that of the strand, and that in turn is opposite to that of the rope. This counter-twisting helps keep the rope together. On the other hand, rope constructed in this manner untwists under tension, which is the cause of spinning,
kinking, hockling and stretching. Any rope of this type must be
bound at its end by some means to prevent untwisting. Twisted ropes have a preferred direction for
coiling. Normal right laid rope should be coiled
with the sun, or clockwise, to prevent kinking. Coiling this way imparts a twist to the rope. One of the drawbacks of this construction is that every fiber is exposed to abrasion numerous times along the length of the rope. This means that the rope can degrade to numerous inch-long fiber fragments, which is not easily detected visually.
Braided rope
Braided ropes are generally made from
nylon,
polyester or
polypropylene. Nylon is chosen for its elastic stretch properties and good resistance to
ultraviolet light. Polyester is about 90% as strong as nylon but stretches less under load, is more abrasion resistant, has better UV resistance, and has less change in length when wet. Polypropylene is preferred for low cost and light weight (it floats on water).
There are many different kinds of braided line. Double braid line has an outer and inner braid that may be of the same or different material. Single braid has no core at all.
Kernmantle rope has a core (kern) of long twisted fibers in the center, with a braided outer sheath or mantle of
woven fibers. The kern provides most of the strength (about 70%), while the mantle protects the kern and determines the handling properties of the rope (how easy it is to hold, to tie knots in, and so on). In dynamic climbing line, the core fibers are usually twisted, and chopped into shorter lengths which makes the rope more stretchy. Static kernmantle ropes are made with untwisted core fibers and tighter braid, which causes them to be stiffer in addition to limiting the stretch.
Braided ropes (and objects like garden
hoses,
fiber optic or
coaxial cables, etc.) that have no
lay, or inherent twist, will uncoil better if coiled into
figure-8 coils, where the twist reverses regularly and essentially cancels out.
Other types
Plaited rope is made by braiding twisted strands, and is also called
square braid. It is not as round as twisted rope and coarser to the touch. It is less prone to kinking than twisted rope and, depending on the material, very flexible and therefore easy to handle and knot. This construction exposes all fibers as well, with the same drawbacks as described above.
Brait rope is a combination of braided and plaited, a non-rotating alternative to laid three-strand ropes. Due to its excellent energy-absorption characteristics, it is often used by arborists. This type of construction was pioneered by Yale Cordage.
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Cordage aboard the French training ship Mutin |
Rope made from
hemp or nylon is generally stored in a cool dry place for proper storage. To prevent kinking it is usually coiled. To prevent fraying or unraveling, the ends of a rope are bound with twine, tape, or heat shrink tubing. The ends of plastic fiber ropes are often melted and fused solid. If a load-bearing rope gets a sharp or sudden jolt or the rope shows signs of deteriorating, it is recommended that the rope be replaced immediately and should be discarded or only used for non-load-bearing tasks.
Ropes are also used to tie down culprits for especially severe
physical punishment in exposed
positions on various contraptions.
Furthermore, ropes can be used for whipping, of widely different impact depending on length, weight and whether the target zone is bare; working in knots or hard objects gives a fiercer bite.
Thus aboard ships, a
rope's end was frequently used to administer the lightest on-the-spot discipline to boys and adult sailors, but considered merely a tangible warning as even a few informal strokes of the
bosun's cane for somewhat worse offenders were not formally recorded.
The fearsome
cat o' nine tails was usually made of rope, as were the milder
knittles.
The
Royal Navy used a similar implement for summary discipline: a rope of about 18 inches long, dipped in hot tar to make it heavier and brittle, usually with a knot on the striking end.
The rope is also a
metonymical expression, as is
the noose, for capital punishment by
hanging.
*
Jump rope for
rope skipping*
Knot*
Rope bondage*
Ropework*
Tight-rope walking *
Whipped rope*Lane, Frederic Chapin, 1932.
The Rope Factory and Hemp Trade of Venice in the Fifteenth and Sixteenth Centuries, Journal of Economic and Business History, Vol. 4 No. 4 Suppl. (August 1932).
*Plymouth Cordage Company, 1931.
The Story of Rope; The History and the Modern Development of Rope-Making, Plymouth Cordage Company, North Plymouth, Mass.
*Sanctuary, Anthony, 1996.
Rope, Twine and Net Making, Shire Publications Ltd., Cromwell House, Princes Risborough, Buckinghamshire.
*Teeter, Emily, 1987.
Techniques and Terminology of Rope-Making in Ancient Egypt, Journal of Egyptian Archaeology, Vol. 73 (1987).
*Tyson, William, no date.
Rope, a History of the Hard Fibre Cordage Industry in the United Kingdom, Wheatland Journals, Ltd., London
*Smith, Bruce&Padgett, Allen, 1996.
On Rope. North American Vertical Rope Techniques, National Speleological Society, Huntsville, Alabama.
*Gaitzsch, W.
Antike Korb- und Seilerwaren, Schriften des Limesmuseums Aalen Nr. 38, 1986
*Gubser, T.
Die bäuerliche Seilerei, G. Krebs AG, Basel, 1965
*Militzer-Schwenger, L.:
Handwerkliche Seilherstellung, Landschaftsverband Westfalen-Lippe, 1992
*Nilson, A.
Studier i svenskt repslageri, Stockholm, 1961
*Pierer, H.A.
Universal-Lexikon, Altenburg, 1845
*Schubert, Pit.
Sicherheit und Risiko in Fels und Eis, Munich, 1998
*Strunk, P.; Abels, J.
Das große Abenteuer 2.Teil, Verlag Karl Wenzel, Marburg, 1986
*Hearle, John W. S. & O'Hear & McKenna, N. H. A.
Handbook of Fibre Rope Technology, CRC Press, 2004
*
Tension Technology International offers resources on rope fiber characteristics*
CorPun.com (punitive use)
