The reef knot, or square knot, is an ancient and simple binding knot used to secure a rope or line around an object. It is sometimes also referred to as a Hercules knot or Heracles knot. The

knot A knot is an intentional complication in Rope, cordage which may be practical or decorative, or both. Practical knots are classified by function, including List of hitch knots, hitches, List of bend knots, bends, List of loop knots, loop knots, ...

is formed by tying a left-handed

overhand knot The overhand knot is one of the most fundamental knots, and it forms the basis of many others, including the simple noose, overhand loop, angler's loop, reef knot, fisherman's knot, half hitch, and water knot. The overhand knot is a stoppe ...

between two ends, instead of around one end, and then a right-handed overhand knot via the same procedure, or vice versa. A common

mnemonic A mnemonic device ( ), memory trick or memory device is any learning technique that aids information retention or retrieval in the human memory, often by associating the information with something that is easier to remember. It makes use of e ...

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 tied as described above of the same

handedness In human biology, handedness is an individual's preferential use of one hand, known as the dominant hand, due to and causing it to be stronger, faster or more Fine motor skill, dextrous. The other hand, comparatively often the weaker, less dext ...

will make a granny knot. The working ends of the reef knot must emerge both at the top or both at the bottom, otherwise a thief knot results. The reef knot is not recommended for tying two ropes together, because of the potential instability of the knot when not stabilized; something that has resulted in many deaths (see Misuse as a bend).

Naming

The reef knot is at least 4,000 years old. The name "reef knot" dates from at least 1794 and originates from its common use to

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

sails, that is to tie part of the

sail A sail is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may b ...

down to decrease its effective surface area in strong

wind Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heatin ...

s. To release the knot a

sailor A sailor, seaman, mariner, or seafarer is a person who works aboard a watercraft as part of its crew, and may work in any one of a number of different fields that are related to the operation and maintenance of a ship. While the term ''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. The name "square knot" is found in Dana's 1841 maritime compendium ''A Seaman's Friend'', which also gives "reef knot" as an alternative name.Ashley, p. 220. The name ''square knot'' is often used for the unslipped version of reef knot. ''Reef knot'' itself then is understood as the single slipped version, while the name shoelace knot is to indicate double slipped version. Sometimes the name bowtie also may be used to indicate a double slipped version, but tying a bowtie is usually performed on flat material, and involves a slip knot of one end holding a bight of the other end i.e. not really a double slipped reef knot. The name "Square knot" is also used for completely different other knots such as the mathematical concept of square knot, or friendship knot; this last one earns the name by being flat and drawing a square on one face (and a cross on the other face).

Uses

The reef knot is used to tie the two ends of a single rope 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 furling sails, it is also one of the key knots of macrame textiles.Ashley, pp. 399-400. The knot lies flat when made with cloth and has been used for tying bandages for millennia. As a binding knot it was known to the

ancient Greeks Ancient Greece () was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (), that comprised a loose collection of culturally and linguistically re ...

as the

Hercules Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the Gr ...

knot (''Herakleotikon hamma'') and is still used extensively in medicine. In his ''

Natural History Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

'', Pliny relates the belief that wounds heal more quickly when bound with a Hercules knot. It has also been used since ancient times to tie belts and

sash A sash is a large and usually colorful ribbon or band of material worn around the human body, either draping from one shoulder to the opposing hip and back up, or else encircling the waist. The sash around the waist may be worn in daily attire, ...

es. A modern use in this manner includes tying the obi (or belt) of a

martial arts Martial arts are codified systems and traditions of combat practiced for a number of reasons such as self-defence; military and law enforcement applications; combat sport, competition; physical, mental, and spiritual development; entertainment; ...

keikogi (, 'practice', , 'dress' or 'clothes'), also known as or , is a traditional uniform worn for training in Japanese martial arts and their derivatives. Emerging in the late 19th century, the was developed by judo founder Kanō Jigorō. Origin J ...

. With both ends tucked (slipped) it becomes a good way to tie

shoelaces Shoelaces, also called shoestrings (US English) or bootlaces (UK English), are a system commonly used to secure shoes, boots, and other footwear. They typically consist of a pair of strings or cords, one for each shoe, finished off at both e ...

, 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 Scouting or the Scout Movement is a youth social movement, movement which became popularly established in the first decade of the twentieth century. It follows the Scout method of informal education with an emphasis on practical outdoor activi ...

worldwide. It is included in the international membership badgeSee :File:World Scout Emblem 1955.svg for an image of the emblem. and many scouting awards. In Pioneering (Scouting), it is commonly used as a binding knot to finish off specialized lashing (ropework) and whipping knots. However, it is an insecure knot, unstable when jiggled, and is not suitable for supporting weight. A surgeon's variation, used where a third hand is unavailable, is made with two or three twists of the ropes on bottom, and sometimes on top, instead of just one. File:Egypte louvre 279 couple detail reef knot.jpg, Detail of

Egyptian ''Egyptian'' describes something of, from, or related to Egypt. Egyptian or Egyptians may refer to: Nations and ethnic groups * Egyptians, a national group in North Africa ** Egyptian culture, a complex and stable culture with thousands of year ...

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 Pontika (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 File:Akan MHNT.ETH.2010.25.060.jpg , Weight for weighing gold dust - Knot – MHNT

Misuse as a bend

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 two ropes together. However, modern instruction teaches that it is fine for noncritical applications, especially if stabilized. A proper bend knot, for instance a sheet bend or double fisherman's knot, should be used instead. Knotting authority Clifford Ashley claimed that failures of misused reef knots have caused more deaths and injuries than failures of all other knots combined.Ashley, p. 18. Further, it is easily confused with the granny knot, which is a very poor knot.

Physical analysis

An approximate physical analysis predicts that a reef knot will hold if

2\mu e^ \ge 1

, where μ is the relevant coefficient of friction. This inequality holds if

\mu \gtrsim 0.24

. Experiments show that the critical value of μ is actually somewhat lower.Crowell, "The physics of knots," http://www.lightandmatter.com/article/knots.html

Related knots

Notes and references

External links

Knot of Hercules

{{DEFAULTSORT:Reef Knot Scoutcraft Hercules