Knot: Difference between revisions

There is a large variety of knots and each knot has specific properties and suitability for a [[Knot#Categories|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.

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 [[spelunking|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 [[lanyard]]s and [[Net|netting]].  In [[ropework]], the frayed end of a rope is held together by a type of knot called a [[whipping knot]].  Many types of [[textile]]s use knots to repair damage. [[Macrame]], one kind of textile, is generated exclusively through the use of knotting, instead of [[knitting|knits]], crochets, weaves or felting.  Macrame can produce self-supporting three dimensional textile structures, as well as flat work, and is often used ornamentally or decoratively.

Knots invariably weaken the rope they are made in.  When knotted rope

is strained to its breaking point, barring any flaws or damage in

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.  ''Always consult experienced practitioners before using ropes and knots in situations where safety of life, limb, or property is involved.''

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:

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 will unravel and fail.  This behavior in knots can be worsened when the knot is repeatedly strained and let slack, dragged over rough terrain, or subject to repeated impacts 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)|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 (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 manner have a tendency 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#Overuse|reef knot used as a bend]].  Sometimes a knot is intentionally capsized as a method of tying another knot, such as the [[Bowline#Tying|"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.

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|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 employed.

[[image:BightLoopElbow.jpg|frame|right|Knot components]]

;'''Bight'''

{{main|Bight (knot)}}

:*'''Two round turns''' circles the object twice; requires three passes.

;'''Working end'''

;'''Working part'''

:Section of line between knot and the working end.

The [[list of knots]] is extensive, but common properties allow for a useful system of categorization. For example, [[loop (knot)|loop]] knots share the attribute of having some kind of an anchor point constructed on the [[standing end]] (such as a loop or overhand knot) into which the working end is easily hitched to using a [[round turn]]. An example of this is the [[bowline]]. Constricting knots often rely on friction to cinch down tight on loose bundles; an example would be the [[Miller's knot]].

;[[loop (knot)|Loop]] :A knot used to create a closed circle in a line. [[List of loop knots]].

;[[Plait]] (or Braid):A number of lines interwoven in a simple regular pattern. [[List of plait knots]].

;[[Seizing]] :A knot used to hold two lines or two parts of the same line together. [[List of seizing knots]].

;[[Sennit]] :A number of lines interwoven in a complex pattern. [[List of sennit knots]].

;[[whipping knot|Whipping]] :A binding knot used to prevent another line from fraying.

*[[Clifford Ashley|Clifford W. Ashley]] [[The Ashley Book of Knots|''The Ashley Book of Knots'']]. Doubleday, New York. ISBN 0-385-04025-3

*J.C. Turner and P. van de Griend (ed.) (1996). ''History and Science of Knots''. World Scientific. ISBN 981-02-2469-9

*[[List of knots]]

*[http://www.tollesburysc.co.uk/Knots/Knots_gallery.htm Animated knots] (GIF format)

*[http://www.geocities.com/roo_two/knotindex.html The Notable Knot Index]

*[http://www.draftlight.net/lifeonaline/ Underground rope rescue knots]

[[Category:Knots| ]]

[[Category:Ropework]]

[[de:Knoten]]