A rope is a group of yarns, plies, fibres, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting. Rope is thicker and stronger than similarly constructed cord, string, and twine.
Rope may be constructed of any long, stringy, fibrous material (e.g., rattan, a natural material), but generally is constructed of certain natural or synthetic fibres.[1][2][3] Synthetic fibre ropes are significantly stronger than their natural fibre counterparts, they have a higher tensile strength, they are more resistant to rotting than ropes created from natural fibres, and they can be made to float on water.[4] But synthetic ropes also possess certain disadvantages, including slipperiness, and some can be damaged more easily by UV light.[5]
The twist of the strands in a twisted or braided rope serves not only to keep a rope together, but enables the rope to more evenly distribute tension among the individual strands. Without any twist in the rope, the shortest strand(s) would always be supporting a much higher proportion of the total load.
Construction
Three-strand natural fibre laid line
Construction of cable
Hawser-laid rope (Seaman's Pocket-Book, 1943)
Size measurement
Because rope has a long history, many systems have been used to specify the size of a rope. In systems that use the inch (Imperial and US customary measurement systems), large ropes over 1 inch (25.4mm) diameter – such as those used on ships – are measured by their circumference in inches; smaller ropes have a nominal diameter based on the circumference divided by three (as a rough approximation of pi). In the metric system of measurement, the nominal diameter is given in millimetres. The current preferred international standard for rope sizes is to give the mass per unit length, in kilograms per metre. However, even sources otherwise using metric units may still give a "rope number" for large ropes, which is the circumference in inches.[6]
Rope has been used since prehistoric times.[7] It is of paramount importance in fields as diverse as construction, seafaring, exploration, sports, theatre, and communications. Many types of knots have been developed to fasten with rope, join ropes, and utilize rope to generate mechanical advantage. Pulleys can redirect the pulling force of a rope in another direction, multiply its lifting or pulling power, and distribute a load over multiple parts of the same rope to increase safety and decrease wear.
The use of ropes for hunting, pulling, fastening, attaching, carrying, lifting, and climbing dates back to prehistoric times. It is likely that the earliest "ropes" were naturally occurring lengths of plant fibre, 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. The earliest evidence of suspected rope is a very small fragment of three-ply cord from a Neanderthal site dated 50,000 years ago.[8][9] This item was so small, it was only discovered and described with the help of a high power microscope. It is slightly thicker than the average thumb-nail, and would not stretch from edge-to-edge across a little finger-nail. There are other ways fibres can twist in nature, without deliberate construction.[10]
A tool dated between 35,000 and 40,000 years found in the Hohle Fels cave in south-western Germany has been identified as a means for making rope.[11] It is a 20cm (8in) strip of mammoth ivory with four holes drilled through it. Each hole is lined with precisely cut spiral incisions. The grooves on three of the holes spiral in a clockwise direction from each side of the strip. The grooves on one hole spiral clockwise on one side, but counter-clockwise from the other side.[12] Plant fibres have been found on it that could have come from when they fed through the holes and the tool twisted, creating a single ply yarn. Fiber-making experiments with a replica found that the perforations served as effective guides for raw fibers, making it easier to make a strong, elastic rope than simply twisting fibers by hand spiral incisions would have tended to keep the fibres in place.[11][13] But the incisions cannot impart any twist to the fibres pulled through the holes.[14] Other 15,000-year-old objects with holes with spiral incisions, made from reindeer antler, found across Europe are thought to have been used to manipulate ropes, or perhaps some other purpose.[15] They were originally named "batons", and thought possibly to have been carried as badges of rank.[13][16]
Impressions of cordage found on fired clay provide evidence of string and rope-making technology in Europe dating back 28,000 years.[17]Fossilized fragments of "probably two-ply laid rope of about 7mm[0.28in] diameter" were found in one of the caves at Lascaux, dating to approximately 15,000 BC.[18]
The ancient Egyptians were probably the first civilization to develop special tools to make rope. Egyptian rope dates back to 4000 to 3500BC and was generally made of water reed fibres.[19] Other rope in antiquity was made from the fibres 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 2800BC, rope made of hemp fibres was in use in China. Rope and the craft of rope making spread throughout Asia, India, and Europe over the next several thousand years.
From the Middle Ages until the 18th century, in Europe ropes were constructed in ropewalks, 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 (270m) long or longer to be made. These long ropes were necessary in shipping as short ropes would require splicing to make them long enough to use for sheets and halyards. The strongest form of splicing is the short splice, which doubles the cross-sectional area of the rope at the area of the splice, which would cause problems in running the line through pulleys. Any splices narrow enough to maintain smooth running would be less able to support the required weight.[citation needed] Rope intended for naval use would have a coloured yarn, known as the "rogue's yarn", included in the layup. This enabled the source to be identified and to detect pilfering.[20]
Leonardo da Vinci drew sketches of a concept for a ropemaking machine, but it was never built. Remarkable feats of construction were accomplished using rope but 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 18th century several working machines had been built and patented.
Nylon was discovered in the late 1930s and was first introduced into fiber ropes during World War II. Indeed, the first synthetic fiber ropes were small braided parachute cords and three-strand tow ropes for gliders, made of nylon during World War II.[21]
Laid rope, also called twisted rope, is historically the prevalent form of rope, at least in modern Western history. Common twisted rope generally consists of three strands and is normally right-laid, or given a final right-handed twist. The ISO 2 standard uses the uppercase lettersS and Z to indicate the two possible directions of twist, as suggested by the direction of slant of the central portions of these two letters. The handedness of the twist is the direction of the twists as they progress away from an observer. Thus Z-twist rope is said to be right-handed, and S-twist to be left-handed.
Twisted ropes are built up in three steps. First, fibres are gathered and spun into yarns. A number of these yarns are then formed into strands by twisting. The strands are then twisted together to lay 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. It is this counter-twist, introduced with each successive operation, which holds the final rope together as a stable, unified object.[22]
Rope making using the twisted rope method on a 1928 Metters Rope Making Machine
Traditionally, a three strand laid rope is called a plain- or hawser-laid, a four strand rope is called shroud-laid, and a larger rope formed by counter-twisting three or more multi-strand ropes together is called cable-laid.[23] Cable-laid rope is sometimes clamped to maintain a tight counter-twist rendering the resulting cable virtually waterproof. Without this feature, deep water sailing (before the advent of steel chains and other lines) was largely impossible, as any appreciable length of rope for anchoring or ship to ship transfers, would become too waterlogged– and therefore too heavy– to lift, even with the aid of a capstan or windlass.
One property of laid rope is partial untwisting when used.[24] This can cause spinning of suspended loads, or stretching, kinking, or hockling of the rope itself. An additional drawback of twisted construction is that every fibre is exposed to abrasion numerous times along the length of the rope. This means that the rope can degrade to numerous inch-long fibre fragments, which is not easily detected visually.[citation needed]
Twisted ropes have a preferred direction for coiling. Normal right-laid rope should be coiled clockwise, to prevent kinking. Coiling this way imparts a twist to the rope. Rope of this type must be bound at its ends by some means to prevent untwisting.
While rope may be made from three or more strands,[25] modern braided rope consists of a braided (tubular) jacket over strands of fibre (these may also be braided). Some forms of braided rope with untwisted cores have a particular advantage; they do not impart an additional twisting force when they are stressed. The lack of added twisting forces is an advantage when a load is freely suspended, as when a rope is used for rappelling or to suspend an arborist. Other specialized cores reduce the shock from arresting a fall when used as a part of a personal or group safety system.
Braided ropes are generally made from nylon, polyester, polypropylene or high performance fibres such as high modulus polyethylene (HMPE) and aramid. Nylon is chosen for its strength and elastic stretch properties. However, nylon absorbs water and is 10–15% weaker when wet. Polyester is about 90% as strong as nylon but stretches less under load and is not affected by water. It has somewhat better UV resistance, and is more abrasion resistant. Polypropylene is preferred for low cost and light weight (it floats on water) but it has limited resistance to ultraviolet light, is susceptible to friction and has a poor heat resistance.[citation needed]
Braided ropes (and objects like garden hoses, fibre optic or coaxial cables, etc.) that have no lay (or inherent twist) uncoil better if each alternate loop is twisted in the opposite direction, such as in figure-eight coils, where the twist reverses regularly and essentially cancels out.
Single braid consists of an even number of strands, eight or twelve being typical, braided into a circular pattern with half of the strands going clockwise and the other half going anticlockwise. The strands can interlock with either twill or panama (Basked) or seldom plain weave. Kyosev introduced the German notation in English, where the floating length (German: Flechtigkeit) and the number of yarns in a group (German: Fädigkeit) in more natural way for braiding process are used, instead of the pattern names in weaving.[25] The central void may be large or small; in the former case the term hollow braid is sometimes preferred.
Double braid, also called braid on braid, consists of an inner braid filling the central void in an outer braid, that may be of the same or different material. Often the inner braid fibre is chosen for strength while the outer braid fibre is chosen for abrasion resistance.
In a solid braid, (square braid, gasket, or form braid[26] there are at least three or more groups of yarns, interlacing in complex (interlocking) structure. This construction is popular for gaskets and general purpose utility rope but rare in specialized high performance line.
Kernmantle rope has a core (kern) of long twisted fibres in the center, with a braided outer sheath or mantle of woven fibres. 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, core fibres are usually twisted to make the rope more elastic. Static kernmantle ropes are made with untwisted core fibres and tighter braid, which causes them to be stiffer in addition to limiting the stretch.
Other types
Plaited rope is made by braiding twisted strands, and is also called square braid.[27] 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 fibres 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. It is also a popular rope for anchoring and can be used as mooring warps. This type of construction was pioneered by Yale Cordage.
Endless winding rope is made by winding single strands of high-performance yarns around two end terminations until the desired break strength or stiffness has been reached. This type of rope (often specified as cable to make the difference between a braided or twined construction) has the advantage of having no construction stretch as is the case with above constructions. Endless winding is pioneered by SmartRigging and FibreMax.
Rock climbing
Dynamickernmantle rock climbing rope with its braided sheath cut to expose the twisted core yarns and core yarn pliesSection through kernmantle rope
The sport of rock climbing uses what is termed "dynamic" rope, an elastic rope which stretches under load to absorb the energy generated in arresting a fall without creating forces high enough to injure the climber. Such ropes are of kernmantle construction, as described below.
Conversely, "static" ropes have minimal stretch and are not designed to arrest free falls. They are used in caving, rappelling, rescue applications, and industries such as window washing.
The UIAA, in concert with the CEN, sets climbing-rope standards and oversees testing. Any rope bearing a GUIANA or CE certification tag is suitable for climbing. Climbing ropes cut easily when under load. Keeping them away from sharp rock edges is imperative. Previous falls arrested by a rope, damage to its sheath, and contamination by dirt or solvents all weaken a rope and can render it unsuitable for further sport use.
Rock climbing ropes are designated as suitable for single, double or twin use. A single rope is the most common, and is intended to be used by itself. These range in thickness from roughly 9 to 11mm (0.35 to 0.43in). Smaller diameter ropes are lighter, but wear out faster.
Double ropes are thinner than single, usually 9mm (0.35in) and under, and are intended for use in pairs. These offer a greater margin of safety against cutting, since it is unlikely that both ropes will be cut, but complicate both belaying and leading. Double ropes may be clipped into alternating pieces of protection, allowing each to stay straighter and reduce both individual and total rope drag.
Twin ropes are thin ropes which must be clipped into the same piece of protection, in effect being treated as a single strand. This adds security in situations where a rope may get cut. However new lighter-weight ropes with greater safety have virtually replaced this type of rope.[citation needed]
Rope made from hemp, cotton or nylon is generally stored in a cool dry place for proper storage. To prevent kinking it is usually coiled. To prevent fraying or unravelling, the ends of a rope are bound with twine (whipping), tape, or heat shrink tubing. The ends of plastic fibre ropes are often melted and fused solid; however, the rope and knotting expert Geoffrey Budworth warns against this practice thus:[28]
Sealing rope ends this way is lazy and dangerous. A tugboat operator once sliced the palm of his hand open down to the sinews after the hardened (and obviously sharp) end of a rope that had been heat-sealed pulled through his grasp. There is no substitute for a properly made whipping.
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.[29][30]
The average rope life-span is 5 years. Serious inspection should be given to line after that point.[citation needed] However, the use to which a rope is put affects frequency of inspection. Rope used in mission-critical applications, such as mooring lines or running rigging, should be regularly inspected on a much shorter timescale than this, and rope used in life-critical applications such as mountain climbing should be inspected on a far more frequent basis, up to and including before each use.
Avoid stepping on climbing rope, as this might force tiny pieces of rock through the sheath, which can eventually deteriorate the core of the rope.
Ropes may be flemished into coils on deck for safety, presentation, and tidiness.
Many types of filaments in ropes are weakened by corrosive liquids, solvents, and high temperatures. Such damage is particularly treacherous because it is often invisible to the eye.[31]
Shock loading should be avoided with general use ropes, as it can damage them.[32] All ropes should be used within a safe working load, which is much less than their breaking strength.
A rope under tension – particularly if it has a great deal of elasticity – can be dangerous if parted. Care should be taken around lines under load.
Terminology
"Rope" is a material, and a tool. When it is assigned a specific function it is often referred to as a "line", especially in nautical usage. A line may get a further distinction, for example sail control lines are known as "sheets" (e.g. A jib sheet).
Whipping knot– Binding around the end of a rope to prevent it from fraying
Related Research Articles
A knot is an intentional complication in cordage which may be practical or decorative, or both. Practical knots are classified by function, including hitches, bends, loop knots, and splices: a hitch fastens a rope to another object; a bend fastens two ends of a rope to each another; a loop knot is any knot creating a loop; and splice denotes any multi-strand knot, including bends and loops. A knot may also refer, in the strictest sense, to a stopper or knob at the end of a rope to keep that end from slipping through a grommet or eye. Knots have excited interest since ancient times for their practical uses, as well as their topological intricacy, studied in the area of mathematics known as knot theory.
Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. Thread is a type of yarn intended for sewing by hand or machine. Modern manufactured sewing threads may be finished with wax or other lubricants to withstand the stresses involved in sewing. Embroidery threads are yarns specifically designed for needlework. Yarn can be made of a number of natural or synthetic materials, and comes in a variety of colors and thicknesses. Although yarn may be dyed different colours, most yarns are solid coloured with a uniform hue.
A whipping knot or whipping is a binding of marline twine or whipcord around the end of a rope to prevent its natural tendency to fray.
The timber hitch is a knot used to attach a single length of rope to a cylindrical object. Secure while tension is maintained, it is easily untied even after heavy loading.
A braid is a complex structure or pattern formed by interlacing three or more strands of flexible material such as textile yarns, wire, or hair. The simplest and most common version is a flat, solid, three-stranded structure. More complex patterns can be constructed from an arbitrary number of strands to create a wider range of structures. The structure is usually long and narrow with each component strand functionally equivalent in zigzagging forward through the overlapping mass of the others. It can be compared with the process of weaving, which usually involves two separate perpendicular groups of strands.
Rope splicing in ropework is the forming of a semi-permanent joint between two ropes or two parts of the same rope by partly untwisting and then interweaving their strands. Splices can be used to form a stopper at the end of a line, to form a loop or an eye in a rope, or for joining two ropes together. Splices are preferred to knotted rope, since while a knot typically reduces the strength by 20–40%, a splice is capable of attaining a rope's full strength. However, splicing usually results in a thickening of the line and, if subsequently removed, leaves a distortion of the rope. Most types of splices are used on three-strand rope, but some can be done on 12-strand or greater single-braided rope, as well as most double braids.
Whipcord is the name for either a fabric or a form of braided cord.
Kernmantle rope is rope constructed with its interior core protected by a woven exterior sheath designed to optimize strength, durability, and flexibility. The core fibers provide the tensile strength of the rope, while the sheath protects the core from abrasion during use. This is the only construction of rope that is considered to be life safety rope by most fire and rescue services.
Twine is a strong thread, light string or cord composed of string in which two or more thinner strands are twisted, and then twisted together (plied). The strands are plied in the opposite direction to that of their twist, which adds torsional strength to the cord and keeps it from unravelling. This process is sometimes called reverse wrap. The same technique used for making twine is also used to make thread, which is thinner, yarn, and rope, which is stronger and thicker, generally with three or more strands.
Parachute cord is a lightweight nylon kernmantle rope originally used in the suspension lines of parachutes. This cord is now used as a general purpose utility cord. This versatile cord was used by astronauts during the 82nd Space Shuttle mission to repair the Hubble Space Telescope.
Wire rope is composed of as few as two solid, metal wires twisted into a helix that forms a composite rope, in a pattern known as laid rope. Larger diameter wire rope consists of multiple strands of such laid rope in a pattern known as cable laid. Manufactured using an industrial machine known as a strander, the wires are fed through a series of barrels and spun into their final composite orientation.
A fid is a conical tool traditionally made of wood or bone. It is used to work with rope and canvas in marlinespike seamanship. A fid differs from a marlinspike in material and purposes. A marlinspike is used in working with wire rope, natural and synthetic lines, may be used to open shackles, and is made of metal. A fid is used to hold open knots and holes in canvas, and to separate the "lays" of synthetic or natural rope for splicing. A variation of the fid, the gripfid, is used for ply-split braiding. The gripfid has a jamming cleat to pull a cord back through the cord split by the fid's point.
A ropewalk is a long straight narrow lane, or a covered pathway, where long strands of material are laid before being twisted into rope. Due to the length of some ropewalks, workers may use bicycles to get from one end to the other.
The eye splice is a method of creating a permanent loop in the end of a rope by means of rope splicing.
A coiling or coil is a curve, helix, or spiral used for storing rope or cable in compact and reliable yet easily attainable form. They are often discussed with knots.
Rope are often coiled and hung up in lofts for storage. They are also hung over stakes in farm wagons and on hooks in moving vans, fire apparatus and linesmen's repair trucks. For such active storage coils must be well made.
A braiding machine is a device that interlaces three or more strands of yarn or wire to create a variety of materials, including rope, reinforced hose, covered power cords, and some types of lace. Braiding materials include natural and synthetic yarns, metal wires, leather tapes, and others.
A top is a hand tool with an iron loop and hook used in the creation and splicing of rope. A Top is used to simultaneously hold a piece of rope while providing a hole to separate the "lays" of synthetic or natural rope for splicing. A variation of a Top, the gripfid, is used for ply-split braiding. The gripfid has a jamming cleat to pull a cord back through the cord split by the fid's point. A variation of a Top can also be used as a rope wrench, rope separator or rope tool can be used in the manufacture of laid rope. The top is used to prevent the strands of a rope twisting together prematurely, which would lead to the rope being loose, allowing it to untwist. The amount of pressure applied to the top determines the stiffness of the final product; more pressure forces the strands together more tightly, making a rope that is harder to bend.
String is a long flexible structure made from fibers twisted together into a single strand, or from multiple such strands which are in turn twisted together. String is used to tie, bind, or hang other objects. It is also used as a material to make things, such as textiles, and in arts and crafts. String is a simple tool, and its use by humans is known to have been developed tens of thousands of years ago. In Mesoamerica, for example, string was invented some 20,000 to 30,000 years ago, and was made by twisting plant fibers together. String may also be a component in other tools, and in devices as diverse as weapons, musical instruments, and toys.
↑ Small, Meredith F. (April 2002), "String theory: the tradition of spinning raw fibres dates back 28,000 years. (At The Museum).", Natural History, 111 (3): 14(2)
↑ J.C. Turner and P. van de Griend (ed.), The History and Science of Knots (Singapore: World Scientific, 1996), 14.
↑ National Research Council (U.S.) (1975). Mechanical Rope and Cable: Report of the Ad Hoc Committee on Mechanical Rope and Cable, National Materials Advisory Board, Commission on Sociotechnical Systems, National Research Council. National Academies. pp.51–54.
↑ American Telephone and Telegraph Company (1931). Use, Care, and Maintenance of Manila Rope and Blocks.
Sources
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Gubser, T. Die bäuerliche Seilerei, G. Krebs AG, Basel, 1965
Hearle, John W. S. & O'Hear & McKenna, N. H. A. Handbook of Fibre Rope Technology, CRC Press, 2004
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).
Nilson, A. Studier i svenskt repslageri, Stockholm, 1961
Pierer, H.A. Universal-Lexikon, Altenburg, 1845
Plymouth Cordage Company, 1931. The Story of Rope; The History and the Modern Development of Rope-Making, Plymouth Cordage Company, North Plymouth, Massachusetts
Sanctuary, Anthony, 1996. Rope, Twine and Net Making, Shire Publications Ltd., Cromwell House, Princes Risborough, Buckinghamshire.
Schubert, Pit. Sicherheit und Risiko in Fels und Eis, Munich, 1998
Smith, Bruce & Padgett, Allen, 1996. On Rope. North American Vertical Rope Techniques, National Speleological Society, Huntsville, Alabama.
Strunk, P.; Abels, J. Das große Abenteuer 2.Teil, Verlag Karl Wenzel, Marburg, 1986.
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.
Further reading
Bodmer, Rudolph John; Bodmer, Amelie Willard (1914). "Rope". The Book of Wonders: Gives Plain and Simple Answers to the Thousands of Everyday Questions that are Asked and which All Should be Able To, But Cannot Answer. Presbrey syndicate. pp.353 onwards.
Herkommer, Mark (1995). FM 5-125: Rigging Techniques, Procedures, and Applications. Washington, DC: United States Department of the Army.
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