Peter Minkowski

2013-11-25T06:45:05Z

18.111.7.212:

{{redirect3|Square knot|For the mathematical version of this knot, see [[Square knot (mathematics)]]|for another knot known as "square knot"|Friendship knot}}
{{Infobox knot
| image=Square_knot.svg
| name=Reef knot
| names=Square knot, Hercules knot
| type=binding
| type2=bend
| origin=Ancient
| related=[[Thief knot]], [[Granny knot]], [[Grief knot]], [[Surgeon's knot]], [[Shoelace knot]]
| releasing=Jamming
| strength=
| caveat=Not secure as a bend. [[Knot#Capsizing|Spills]] easily if one of the free ends is pulled outward. Does not hold well if the two lines are not the same thickness.
| uses=Joining two ends of a single line to bind around an object.
| abok_number= #74, #75, #460, '''#1204''', '''#1402''', #2096, #2573, #2574, #2577, #2580
| instructions= [http://www.animatedknots.com/reef/]
}}
The '''reef knot''' or '''square knot''' is an ancient and simple [[binding knot]] used to secure a rope or line around an object. Although the reef knot is often seen used for [[List_of_bend_knots|tying two ropes together]], it is not recommended for this purpose due to potential instability of the knot.

A reef [[knot]] is formed by tying a left-handed [[overhand knot]] and then a right-handed overhand knot, or vice versa. A common [[mnemonic]] for this procedure is "right over left; left over right", which is often appended with the rhyming suffix "... makes a knot both tidy and tight". Two consecutive overhands of the same [[handedness]] will make a [[granny knot]]. The [[working end]]s of the reef knot must emerge both at the top or both at the bottom, otherwise a [[thief knot]] results.

==Naming==
The reef knot is at least between 4,000 and 9,000 years old. The name "reef knot" dates from at least 1794<ref name="steel">{{citation|title=The Elements and Practice of Rigging and Seamanship|year=1794|place=London|publisher=David Steel|author=David Steel|url=http://www.hnsa.org/doc/steel/index.htm|page=183}}</ref> and originates from its common use to [[Reefing|reef]] sails,<ref name="lever">{{Citation|last=Lever|first=Darcy|authorlink=Darcy Lever (author)|title=The Young Sea Officer's Sheet Anchor|year=1998|origyear=1819|edition=2nd|publisher=Dover Publications|location=Mineola, NY|page=83|ISBN=978-0-486-40220-8}}</ref><ref name="aksday">{{citation|author=Cyrus Lawrence Day|title=The Art of Knotting and Splicing|edition=4th|location=Annapolis|publisher=Naval Institute Press|year=1986|page=42}}</ref> that is to tie part of the [[sail]] down to decrease its effective surface area in strong [[wind]]s. To release the knot a [[sailor]] could collapse it with a pull of one hand; the sail's weight would make the collapsed knot come apart. It is specifically this behavior which makes the knot unsafe for connecting two ropes together.<ref name="ashley258">{{citation |last=Ashley |first=Clifford W. |title=The Ashley Book of Knots |url= |accessdate= |origyear= |year= 1944 |publisher=Doubleday |location=New York |isbn=978-0-385-04025-9 |page=258}}</ref>

The name "square knot" is found in [[Richard Henry Dana, Jr.|Dana's]] 1841 maritime compendium ''A Seaman's Friend'', which also gives "reef knot" as an alternative name.<ref name="ashley220">Ashley, p. 220.</ref><ref name="seamans">{{citation|author=Richard Henry Dana, Jr.|url=http://books.google.com/?id=8VwBAAAAQAAJ&pg=PA30#v=onepage&q=Square%20knot|title=The Seaman's Friend: A Treatise on Practical Seamanship|edition=14th revised and corrected|place=Mineola, NY|publisher=Dover|origyear=1879|year=1997|page=49|isbn=0-486-29918-X}}</ref>

== Uses ==
The reef knot is used to tie the two ends of a single line together such that they will secure something, for example a bundle of objects, that is unlikely to move much. In addition to being used by sailors for [[reefing]] and [[Furl (sailing)|furling]] sails, it is also one of the key knots of [[macrame]] textiles.<ref name="ashley399">Ashley, pp. 399-400.</ref>

The knot lies flat when made with cloth and has been used for tying [[bandage]]s for millennia. As a binding knot it was known to the [[Ancient Greece|ancient Greeks]] as the [[Hercules]] knot (''Herakleotikon hamma'') and is still used extensively in medicine.<ref name="hage">{{citation|doi=10.1007/s00268-007-9359-x|last=Hage|first=J. Joris|periodical=World Journal of Surgery|date=April 2008|volume=32|issue=4|pages=648–655|title=Heraklas on Knots: Sixteen Surgical Nooses and Knots from the First Century A.D.|url=http://www.springerlink.com/content/ft83233774k358v1/|pmid=18224483}}</ref> In his ''[[Natural History]]'', [[Pliny the Elder|Pliny]] relates the belief that [[wound healing|wounds heal]] more quickly when bound with a "Hercules knot".<ref name="plinynh">{{citation|title=The Natural History|author=[[Pliny the Elder]]|url=http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D28%3Achapter%3D17|page=28.17|editor1-first=John|editor1-last=Bostock|editor1-link=John Bostock (physician)|editor2-last=Riley|editor2-first=H. T.|editor2-link=Henry Thomas Riley|accessdate=2009-08-23}}</ref>

It has also been used since ancient times to tie [[belt (clothing)|belt]]s and [[sash]]es. A modern use in this manner includes tying the [[Obi (sash)|obi]] (or belt) of a [[martial arts]] [[keikogi]].

With both ends tucked (slipped) it becomes a good way to tie [[shoelaces]], whilst the non-slipped version is useful for shoelaces that are excessively short. It is appropriate for tying plastic garbage or trash bags, as the knot forms a handle when tied in two twisted edges of the bag.

The reef knot figures prominently in [[Scouting]] worldwide. It is included in the international membership badge<ref name="scoutemblem">See [[:File:World Scout Emblem 1955.svg]] for an image of the emblem.</ref> and many [[Square knot insignia|scouting awards]].<ref name="squareawards">{{citation|title=Square Knots - Meaning and Placement|url=http://www.boyscouttrail.com/square-knots.asp|accessdate=2009-08-17}}</ref> In the Boy Scouts of America demonstrating the proper tying of the square knot is a requirement for all boys joining the program.<ref name="bsareq">{{citation|url=http://www.scouting.org/scoutsource/BoyScouts/AdvancementandAwards/joining.aspx|title=Boy Scout Joining Requirements|author=[[Boy Scouts of America]]|accessdate=2009-08-23}}</ref> In [[Pioneering (Scouting)]], it is commonly used as a [[binding knot]] to finish off specialized [[lashing (ropework)]] and [[whipping knot]]s.<ref name="Square Knot">{{cite web |url=http://scoutpioneering.com/2013/06/15/foolproof-way-to-always-tie-a-square-knot-right/ | title=Foolproof Way to ALWAYS Tie a Square Knot Right | work=www.scoutpioneering.com | accessdate=2013-06-17}}</ref>

<gallery>
File:Egypte louvre 279 couple detail reef knot.jpg|Detail of [[Ancient Egypt|Egyptian]] statue dating from 2350 BC depicting a reef knot securing a belt
File:Ancient Greek jewelry Pontika (Ukraina) 300 bC.jpg|Ancient Greek jewelry from [[Chersonesos Taurica|Pontika]] (now in Ukraine), 300 BC, in the form of a reef knot
File:Kreuzknoten-slip.jpg|Singly slipped reef knot
File:Shoelace_knot.svg|Diagram of common shoelace bow knot, a doubly slipped reef knot
</gallery>

==Misuse as a bend==
[[Image:Capsizereefknot111.jpg|thumb|150px|upright|right|The reef knot can capsize (spill) when one of the free ends is pulled outward.]]
The reef knot's familiarity, ease of tying, and visually appealing symmetry conceal its weakness. The [[International Guild of Knot Tyers]] warns that this knot should never be used to [[bend knot|bend]] two ropes together.<ref name="igktwarn">{{citation|author=[[International Guild of Knot Tyers]]|title=Sea Cadet Knots|url=http://www.igkt.net/beginners/sea-cadet-knots.php|accessdate=2009-08-23}}</ref> A proper bend knot, for instance a [[sheet bend]] or [[double fisherman's knot]], should be used instead. Knotting authority [[Clifford Ashley]] claimed that misused reef knots have caused more deaths and injuries than all other knots combined.<ref name="ashley18">Ashley, p. 18.</ref> Further, it is easily confused with the [[granny knot]], which is a very poor knot.

==Physical analysis==
An approximate physical analysis<ref>Maddocks, J.H. and Keller, J. B., "Ropes in Equilibrium," SIAM J Appl. Math., 47 (1987), pp. 1185-1200</ref> predicts that a reef knot will hold if <math>2\mu e^{\mu\pi} \ge 1</math>, where μ is the relevant [[coefficient of friction]]. This inequality holds if <math>\mu \gtrsim 0.24</math>. Experiments show that the critical value of μ is actually somewhat lower.<ref>Crowell, "The physics of knots," http://www.lightandmatter.com/article/knots.html</ref>

==Related knots==
{{Reef knot family}}

== See also ==
{{commons category|Square knot}}
{{Wiktionary|square knot}}
* [[Shoelace knot]]
* [[Granny knot]]
* [[Thief knot]]
* [[Surgeon's knot]]
* [[List of bend knots]]
* [[List of binding knots]]
* [[List of knots]]
* [[Square knot (emblem or insignia)]]
* [[Reefing]]

==Notes and references==
{{reflist}}

==External links==
* [http://symboldictionary.net/?p=3030 Knot of Hercules]
* [http://www.solnyc.com/webcat_retail/wc_greek/info/asymbols.htm Ancient symbolism of Hercules knot]

{{Knots}}

{{DEFAULTSORT:Reef Knot}}
[[Category:Scoutcraft]]

formulasearchengine - User contributions [en]

Peter Minkowski