knot

1 a tight cluster of people or things; "a small knot of women listened to his sermon"

2 any of various fastenings formed by looping and tying a rope (or cord) upon itself or to another rope or to another object

3 a hard cross-grained round piece of wood in a board where a branch emerged; "the saw buckled when it hit a knot"

4 something twisted and tight and swollen; "their muscles stood out in knots"; "the old man's fists were two great gnarls"; "his stomach was in knots" [syn: gnarl]

5 a unit of length used in navigation; equivalent to the distance spanned by one minute of arc in latitude; 1,852 meters [syn: nautical mile, mile, mi, naut mi, international nautical mile, air mile]

6 soft lump or unevenness in a yarn; either an imperfection or created by design [syn: slub, burl]

7 a sandpiper that breeds in the arctic and winters in the southern hemisphere [syn: grayback, Calidris canutus]

1 make into knots; make knots out of; "She knotted der fingers"

2 tie or fasten into a knot; "knot the shoelaces"

3 tangle or complicate; "a ravelled story" [syn: ravel, tangle] [ant: unravel, unravel] [also: knotting, knotted]knotting See knot

English

Verb

knotting

1. present participle of knot

A knot is a method for fastening or securing linear material such as rope by tying or interweaving. It may consist of a length of one or more segments of rope, string, webbing, twine, strap or even chain interwoven so as to create in the line the ability to bind to itself or to some other object - the "load". Knots have been the subject of interest both for their ancient origins, common use, and the mathematical implications of knot theory.

Usage

There is a large variety of knots and each knot has specific properties and suitability for a range of tasks. Some knots are well-adapted to attach to particular objects such as another rope, cleat, ring, or stake. Other knots are made to bind or constrict around an object. Decorative knots usually bind to themselves to produce attractive patterns. Choosing the correct knot for the job at hand is one of the most fundamental aspects of using knots well.

Learning

The number of books, websites, videos, and other resources available to those interested in learning about knots is a testament to the value they hold for humankind. While some people possess an innate ability to look at a diagram or photo and tie the illustrated knot, for others the initial stages of learning are best accomplished by being shown knot tying methods by a person who already knows them. Knot tying skills are often transmitted by sailors, scouts, climbers, cavers, arborists, rescue professionals, fishermen, and surgeons. After mastering a few basic knots, the diagrams and photos become easier to interpret and use to continue the learning process. As more knots are learned, patterns begin to become evident in their structure and methods of tying. The learning of knots rewards practice and patience.

Applications

Knots are essential in many industrial, occupational, recreational, and domestic settings. Even simple activities such as running a load from the hardware store to home can result in disaster if a clumsy twist in a cord passes for a knot. Truckers needing to tie down a load may use a trucker's hitch, gaining mechanical advantage. Knots can save the spelunker from foolishly becoming buried under millions of tons of rock. Whatever the activity, such as sailing on the water or climbing on a cliff-side rock, learning well-tested knots prior to some hazardous activity introduces a critical measure of safety. In addition to safety, appropriate knots can prevent the necessity of cutting lines.

Knots can be applied in combination to produce complex objects such as lanyards and netting. In ropework, the frayed end of a rope is held together by a type of knot called a whipping knot. Many types of textiles use knots to repair damage. Macrame, one kind of textile, is generated exclusively through the use of knotting, instead of knits, crochets, weaves or felting. Macramé can produce self-supporting three dimensional textile structures, as well as flat work, and is often used ornamentally or decoratively.

Properties

Strength

Knots invariably weaken the rope they are made in. When knotted rope is strained to its breaking point, it almost always fails in or near the knot, unless it is defective or damaged elsewhere. The bending, crushing, and chafing forces that hold a knot in place also unevenly stress the rope fibers and ultimately lead to the reduction of strength. The exact mechanisms that cause the weakening and failure are complex and are the subject of continued study.

The relative knot strength, also called knot efficiency, is the breaking strength of a knotted rope as a proportion of the breaking strength of the rope without the knot. There are many difficulties in determining an overall numeric knot efficiency for a given knot. This is due to the many factors that can affect the results of a knot efficiency test: the type of fiber, the style of rope, the size of rope, whether it is wet or dry, how the knot is dressed before loading, how rapidly the knot is loaded, whether the knot is repeatedly loaded, and so on. With those limitations noted, most common knots have an efficiency between 40% and 80%.

While some rope splices can retain nearly the full strength of the rope when forming loops and bends, conventional knots are much more practical in most situations. Thus the prudent knot user will always allow for a large safety margin in the strength of rope chosen for a task due to the weakening effects of knots, aging, damage, shock loading, etc. In general, the safe working load is often specified as between 10% and 20% of the rated breaking strength of the rope being used.http://www.boatsafe.com/marlinespike/safeload.htm For safety of life applications many other factors come into play which are beyond the current scope of this article. Experienced practitioners should always be consulted before using ropes and knots when safety of life, limb, or property is involved.

Security

Even if the rope does not break, a knot may still fail to hold. A knot which holds firm under a variety of adverse conditions is said to be more secure than one that does not. The main ways knots fail to hold are:

Slipping

The tension from the load causes the rope to work back through the knot in the direction of the load. If this continues far enough, the working end will pass into the knot and the knot unravels and fails. This behavior can be worsened when the knot is repeatedly strained and let slack, dragged over rough terrain, or repeatedly impacted such as against a mast or flagpole.

Even with secure knots, some slippage may occur as the knot is first put under real tension. This can be dealt with by leaving plenty of rope at the working end outside of the knot and by dressing the knot cleanly and tightening it as fully as possible before loading. In some cases the use of a stopper knot or, even better, a backup knot can prevent the working end from passing through the knot, but it is generally better to use a more secure knot if one is observed to slip. In life critical uses backup knots are often added to already secure knots in order to maximize safety.

Capsizing

Capsizing (or spilling) a knot is changing its form, rearranging its parts, usually by pulling on specific ends in specific ways. Some knots when used in an inappropriate way tend to capsize easily or even spontaneously. Often the capsized form of the knot offers little resistance to slipping or unraveling. For an excellent example of a knot that capsizes dangerously, see the discussion of the reef knot used as a bend.

Sometimes a knot is intentionally capsized as a method of tying another knot, such as the "lightning method" of tying a Bowline. Some knots, such as the Carrick Bend, are generally tied in one form and then capsized to attain a stronger or more stable form.

Sliding

In knots that are meant to grip another object, failure can be defined as the knot moving relative to the object being gripped. While the knot itself does not fail, it ceases to perform the desired function. For example a simple Rolling Hitch tied around a railing and pulled parallel to the railing might hold to a certain tension and then start sliding. Sometimes this can be corrected by working-up the knot tighter before subjecting it to load but usually a knot with more wraps, or a different size or type of rope will need to be used.

Components

Knot theory is a mathematical analysis of different types of knots. In knot theory the ends of the rope are joined together to create a mathematical knot, this prevents the knot from being undone. Various mathematical techniques are then used to classify and distinguish knots, for example the Alexander polynomial can be used to distinguish the trefoil knot from the figure-of-eight knot and the unknot (a simple circle).

References

• Clifford W. Ashley The Ashley Book of Knots. Doubleday, New York. ISBN 0-385-04025-3
• R.S. Lee. All The Knots You Need. Algrove Publishing. ISBN 0-921335-47-4
• Raoul Graumont. Handbook of Knots. Cornell Maritime Press/Tidewater Publishers. ISBN 0-87033-030-6
• Cyrus L. Day. Knots & Splices. International Marine/McGraw-Hill Companies. ISBN 0-87742-252-4
• Geoffrey Budworth (1999). The Ultimate Encyclopedia of Knots & Ropework. Annes Publishing Limited. ISBN 1-55267-986-1
• John Cassidy (1985). The Klutz Book of Knots. Klutz Press, Palo Alto, California. ISBN 0-932592-10-4
• Des Pawson(2001). Pocket Guide to Knots & Splices. Produced for Propsero Books by RPC Publishing Ltd., London. ISBN 1-55267-218-2
• Brion Toss. The Complete Rigger's Apprentice. International Marine/McGraw-Hill Companies. ISBN 0-07-064840-9
• Allen Padgett and Bruce Smith. On Rope. National Speleological Society. ISBN 0-9615093-2-5
• J.C. Turner and P. van de Griend (ed.) (1996). History and Science of Knots. World Scientific. ISBN 981-02-2469-9

See also

• List of knots
• Knot (mathematics)
• Quipu

External links

• Ropers Knots Page Practical knots
• Knot Gallery (GIF format)
• Rock Climbing Knots
• Animated knots (Javascript)
• Knots Index

• Fishing knots
• Oskar Kirchhoff's Rope Art
• Ian's Shoelace Site
• International Guild of Knot Tyers
• Notation describing methods of tying knots
• The Notable Knot Index
• Underground rope rescue knots