Constrictor knot

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Constrictor knot
Left: constrictor knot
Right: double constrictor knot
NamesConstrictor knot, gunner's knot
Category Binding
Related Clove hitch, transom knot, strangle knot, miller's knot, boa knot, cross constrictor knot
Releasing Jamming
ABoK #176, #355, #364, #430, #1188, #1189, #1249, #1250, #1251, #1252, #2052, #2097, #2489, #2560, #3441, #3700, #3853

The constrictor knot is one of the most effective binding knots. [1] [2] [3] [4] Simple and secure, it is a harsh knot that can be difficult or impossible to untie once tightened. It is made similarly to a clove hitch but with one end passed under the other, forming an overhand knot under a riding turn. The double constrictor knot is an even more robust variation that features two riding turns.



First called "constrictor knot" in Clifford Ashley's 1944 work The Ashley Book of Knots , this knot likely dates back much further. [5] Although Ashley seemed to imply that he had invented the constrictor knot over 25 years before publishing The Ashley Book of Knots, [1] research indicates that he was not its only originator --but his Book of Knots does seem to be the source of subsequent knowledge & awareness of the knot. [6] Ashley's publication of the knot did bring it to wider attention. [7]

Although the description is not entirely without ambiguity, the constrictor knot is thought to have appeared under the name "gunner's knot" in the 1866 work The Book of Knots, [8] [9] written under the pseudonym Tom Bowling. [lower-alpha 1] The knot is described in relation to the clove hitch, which he illustrated and called the "builder's knot". He wrote, "The Gunner's knot (of which we do not give a diagram) only differs from the builder's knot, by the ends of the cords being simply knotted before being brought from under the loop which crosses them." [10] But Bowling is simply an extraction & translation of the knotting work contained in the huge French Traite de L'Art de la Charpenterie, ca. 1840, which says "Le noeud de bombardier, que nous n'avons point figure', ne differe du noeud d'artificier qu'en ce que le outs du cordage sont croise's en noeud simple, avant de sortir de dessous la ganse qui les croise, fig.46." When J. T. Burgess copied from Bowling, he changed this text to merely state "when the ends are knotted, the builder's knot becomes the gunner's Knot." [11] Although a clove hitch with knotted ends is a workable binding knot, [lower-alpha 2] Burgess was not actually describing the constrictor knot. In 1917, A. Hyatt Verrill illustrated Burgess's clove hitch variation in Knots, Splices and Rope Work. [12]

The constrictor knot was clearly described but not pictured as the "timmerknut" ("timber knot") in the 1916 (2nd) edition of the Swedish book Om Knutar ("On Knots") by Hjalmar Öhrvall. [13] Finnish scout leader Martta Ropponen presented the knot in her 1931 scouting handbook Solmukirja ("Knot Book"), [14] one of the first published works known to contain an illustration of the constrictor knot. [5] Cyrus L. Day relates that, "she had never seen it in Finland, she wrote to me in 1954, but had learned about it from a Spaniard named Raphael Gaston, who called it a whip knot, and told her it was used in the mountains of Spain by muleteers and herdsmen." [7] The Finnish name "ruoskasolmu" ("whip knot") was a translation from Esperanto, the language Ropponen used to correspond with Gaston. [5] But even this explicit occurrence of the constrictor remains in doubt, as the name "whip knot" is not applied to the constrictor in other works, and otherwise is used for the strangle knot, tied in the ends of whip tails. Also in 1931 --and so of essentially same date as for Ropponen--, James Drew presented the constrictor (as a strangle knot that can be tied in the bight (sans use of ends)) in Lester Griswold's Handicrafts book; but Drew did not show it in his on book of knots later published. (As Drew & Clifford Ashley, it is suspected that he might have learned the knot from him; Ashley does praise Handicrafts in his Book of Knots.)


The method shown below is the most basic way to tie the knot around a post (that is, using a working end). [15]

  1. Make a turn around the object and bring the working end back over the standing part.
  2. Continue around behind the object.
  3. Pass the working end over the standing part and then under the riding turn and standing part, forming an overhand knot under a riding turn.
  4. Be sure the ends emerge between the two turns as shown. Pull firmly on the ends to tighten.

There are also at least three methods to tie the constrictor knot in the bight and slip it over the end of an object to be bound.

Twisting method [16]

Using both hands when the end of the object to tie to is available:

If one or both of the ends are folded in between the two loops and lead in the opposite direction, the knot becomes slipped.

Folding method [17]

Using one hand when the end of the object to tie to is available:

If the rope is to be stretched in tension, the grabbing at stage 2 may first tighten the top side rope, the bottom side rope may be pulled to tighten the knot itself, and the bottom rope side may be tightened by the knot at the next pole. If one or both of the ends are folded and led in the opposite direction before the last loop is folded over the objects end, the knot becomes slipped and therefore easier to untie: It also makes it possible to stretch either side rope tight by pulling at the slip loops.


Double constrictor knot

If a stronger and even more secure knot is required an extra riding turn can be added to the basic knot to form a double constrictor knot. It is particularly useful when tying the knot with very slippery twine, especially when waxed. [2] Adding more than one extra riding turn does not add to its security and makes the knot more difficult to tighten evenly.

  1. Make a turn around the object and bring the working end back over the standing part.
  2. Make a second turn following the same path as the first
  3. Pass the working end over the standing part, then thread it back under the standing part and both riding turns, forming an overhand knot under two riding turns.
  4. Be sure the ends emerge between the turns as shown. The double constrictor may require more careful dressing to distribute the tension throughout the knot. After working up fairly tight, pull firmly on the ends to finish.

Slipped constrictor knot

This variation is useful if it is known beforehand that the constrictor will need to be released. Depending on the knotting material and how tightly it is cinched, the slipped form can still be very difficult to release.

  1. Make a turn around the object and bring the working end back over the standing part.
  2. Continue around behind the object, and then again over the standing part back to the side of the first turn.
  3. Pass a bight of the working end under the point where the first riding pass and the standing part cross to form a slip loop.
  4. Be sure the slip loop bight and both ends emerge from in between the two turns as shown.
  5. To release, tug on the working end so that the bight passes back through the knot.

The slipped constrictor can also be tied in the bight and slipped over the object to constrict. Despite its advertised advantage (quick release), the slipped constrictor knot can also be hard to release when worked extremely tight in certain rope materials.

Cross constrictor knot

This variation is similar to the double constrictor knot but has the two riding turns crossing each other rather than riding along. It is unclear whether it is more secure than the double constrictor, and has the unhelpful aspect of being thicker at the bridge of the knot, with three rope diameters.

There are two types depending on which direction the two riding turns cross. When the bottom riding turn is along the grove of the ends wrapping around each other on their way out, it gives a slightly lower knot height and may be seen as a strangle knot with an extra riding turn across.


A constrictor knot prepared for tightening using two metal rods and marlinespike hitches Constrictor-knot-Marlinespike-hitches.jpg
A constrictor knot prepared for tightening using two metal rods and marlinespike hitches

The constrictor knot is appropriate for situations where secure temporary or semi-permanent binding is needed. Made with small-stuff it is especially effective, as the binding force is concentrated over a smaller area. When tying over soft material such as the neck of a bag, take care to keep the wraps of the knot together. The constrictor knot can damage or disfigure items it is tied around. [3] To exert extreme tension on the knot without injuring the hands, one can fashion handles using marlinespike hitches made around two rods. [2]

Constrictor knots can be used for temporarily binding the fibres of a rope (or strand ends) together while splicing, or when cutting to length and before properly whipping the ends. Constrictor knots can also be quite effective as improvised hose clamps or cable ties [ citation needed ]. The knot has also been recommended as a surgical knot for ligatures in human and veterinary surgery, where it has been shown to be far superior to any of the knots commonly used for ligation. [4] Noted master-rigger Brion Toss says of the constrictor: "To know the knot is to constantly find uses for it" [2]

For spearguns, the constrictor knot is the usual knot used to secure modern, toggled, Dyneema, cord wishbones into the hollow, bulk-rubber loops, which are used to power the spear. Usually tied with braid, Kevlar or Dyneema cord of approximately 1.4-2mm diameter.


Cutting the riding turn Constrictor-Releasing.jpg
Cutting the riding turn

A heavily tightened constrictor knot will likely jam. If the ends are long enough, one can sometimes untie it by pulling one end generally parallel to the bound object and a bit up away from it, and prying it into the opposite end's part to open the knot. Tools that can be forced between parts of the knot (such as picks and marlinespikes) may help.

If the ends have been trimmed short, or the knot is otherwise hopelessly jammed, it can be easily released by cutting the riding turn with a sharp knife. The knot will spring apart as soon as the riding turn is cut. If care is taken not to cut too deeply, the underlying wraps will protect the bound object from being damaged by the knife. [18]


The constrictor and double constrictor are both extremely secure when tied tightly around convex objects with cord scaled for the task at hand. If binding around a not fully convex, or square-edged object, arrange the knot so the overhand knot portion is stretched across a convex portion, or a corner, with the riding turn squarely on top of it. [2] In situations where the object leaves gaps under the knot and there are no corners, it is possible to finish the constrictor knot off with an additional overhand knot, in the fashion of a reef knot, to help stabilize it. Those recommendations aside, constrictor knots do function best on fully convex objects.

If the constricted object (such as a temporarily whipped rope) ends very close to where a constrictor binds it, a boa knot may prove a more stable solution.


  1. The name "Tom Bowling" was widely associated with nautical themes, see The Adventures of Roderick Random and Charles Dibdin. The Book of Knots is most often attributed to Paul Rapsey Hodge or Frederick Chamier. For additional discussion see Ashley(1944), p. 11.
  2. A clove hitch finished with a full reef knot is still used for securing cabling in aerospace applications. See Cable lacing#Styles.

Related Research Articles

Knot Method of fastening or securing linear material

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.

Overhand knot

The overhand knot, also known as a a knot and half 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, and water knot. The overhand knot is a stopper, especially when used alone, and hence it is very secure, to the point of jamming badly. It should be used if the knot is intended to be permanent. It is often used to prevent the end of a rope from unraveling. An overhand knot becomes a trefoil knot, a true knot in the mathematical sense, by joining the ends.

Millers knot

A miller's knot is a binding knot used to secure the opening of a sack or bag. Historically, large sacks often contained grains; thus the association of these knots with the miller's trade. Several knots are known interchangeably by these three names.


A shank is a type of knot that is used to shorten a rope or take up slack, such as the sheepshank. The sheepshank knot is not stable. It will fall apart under too much load or too little load.

Clove hitch

The clove hitch is a type of knot. Along with the bowline and the sheet bend, it is often considered one of the most important knots. A clove hitch is two successive half-hitches around an object. It is most effectively used as a crossing knot. It can be used as a binding knot, but is not particularly secure in that role. A clove hitch made around the rope's own standing part is known as either two half-hitches or buntline hitch, depending on whether the turns of the clove hitch progress away from or towards the hitched object.

Although the name clove hitch is given by Falconer in his Dictionary of 1769, the knot is much older, having been tied in ratlines at least as early as the first quarter of the sixteenth century. This is shown in early sculpture and paintings. A round turn is taken with the ratline and then a hitch is added below. The forward end is always the first to be made fast.

The difference between two half hitches and the clove hitch is that the former, after a single turn around a spar, is made fast around its own standing part, while the latter is tied directly around the spar.

Truckers hitch

The trucker's hitch is a compound knot commonly used for securing loads on trucks or trailers. This general arrangement, using loops and turns in the rope itself to form a crude block and tackle, has long been used to tension lines and is known by multiple names. Knot author Geoffrey Budworth claims the knot can be traced back to the days when carters and hawkers used horse-drawn conveyances to move their wares from place to place.

Marlinespike hitch

The marlinespike hitch is a temporary knot used to attach a rod to a rope in order to form a handle. This allows more tension than could be produced comfortably by gripping the rope with the hands alone. It is useful when tightening knots and for other purposes in ropework.

Zeppelin bend

A Zeppelin bend is an end-to-end joining knot formed by two symmetrically interlinked overhand knots. It is stable, secure, and highly resistant to jamming. It is also resistant to the effects of slack shaking and cyclic loading.

Overhand knot with draw-loop

A slipped half hitch is a knot in which the weight of the load the rope carries depresses the loop sufficiently to keep it in place until the load item is placed in its location. When no longer required the free end may be pulled and draw the loop through and so release the load.

Cats paw (knot)

The Cat's paw is a knot used for connecting a rope to an object. It is very similar to the cow hitch except there is an additional twist on each side of the bight, making it less prone to slipping.

The cat's-paw is the common hook hitch for slings. It is the same basic form as the bale sling hitch but has additional twists. Brady says "two or three altogether," and Steel, who mentioned the name in 1794, says "three twists." It is the best of all sling hitches and is often recommended for a slippery rope. But no hitch can slip when tied in a slings since it has no ends. All that is needed is a hitch that cannot jam, and this requirement the cat's-paw fills admirably. The knot spills instantly when removed from the hook. It is the hitch always used for heavy lifts.

Stopper knot

A stopper knot is a knot that creates a fixed thicker point on an otherwise-uniform thickness rope for the purpose of preventing the rope, at that point, from slipping through a narrow passage, such as a hole in a block. To pass a rope through a block, or hole, is to reeve it. To pull it out is to unreeve it. Stopper knots prevent the rope from unreeving on its own.

Buntline hitch

The buntline hitch is a knot used for attaching a rope to an object. It is formed by passing the working end around an object, then making a clove hitch around the rope's standing part and taking care that the turns of the clove hitch progress towards the object rather than away from it. Secure and easily tied, the buntline hitch will jam when subjected to extreme loads. Given the knot's propensity to jam, it is often made in slipped form.

The buntline hitch, when bent to a yard, makes a more secure knot than two half hitches, but is more liable to jam. It differs from two half hitches in that the second half hitch is inside instead of outside the first one.

Halter hitch

The halter hitch is a type of knot used to connect a rope to an object. As the name implies, an animal's lead rope, attached to its halter, may be tied to a post or hitching rail with this knot. The benefit of the halter hitch is that it can be easily released by pulling on one end of the rope, even if it is under tension. Some sources show the knot being finished with the free end running through the slipped loop to prevent it from working loose or being untied by a clever animal, still allowing easy but not instant untying.

Two half-hitches

Two half-hitches is a type of knot, specifically a binding knot or hitch knot. One variety consists of an overhand knot tied around a post, followed by a half-hitch. This knot is less often referred to as a clove hitch over itself, double half-hitch, or full-hitch.

Two half hitches is the commonest of all hitches for mooring in particular and also for general utility. Steel gives the name in 1794. The difference between two half hitches and the clove hitch is that the former, after a single turn around a spar, is made fast around its own standing part, while the latter is tied directly around the spar.

Strangle knot

The strangle knot is a simple binding knot. Similar to the constrictor knot, it also features an overhand knot under a riding turn. A visible difference is that the ends emerge at the outside edges, rather than between the turns as for a constrictor. This knot is a rearranged double overhand knot and makes up each half of the double fisherman's knot.

The strangle knot starts with a round turn and the end is stuck under two parts. It may be used to tie up a roll.It can only be tied around a cylindrical shape. If required, a loop may be stuck instead of the end, which makes a slipped knot that is one of the best for tying up sacks and meal bags. With one or two additional turns the strangle knot makes an excellent temporary whipping for the end of a rope.

Bight (knot)

In knot tying, a bight is a curved section or slack part between the two ends of a rope, string, or yarn. A knot that can be tied using only the bight of a rope, without access to the ends, is described as in the bight. The term "bight" is also used in a more specific way when describing Turk's head knots, indicating how many repetitions of braiding are made in the circuit of a given knot.

Highpoint hitch

The highpoint hitch is a type of knot used to attach a rope to an object. The main feature of the hitch is that it is very secure, yet if tied as a slipped knot it can be released quickly and easily with one pull, even after heavy loading. The highpoint hitch is a buntline hitch with an extra half turn, making it more secure.

Double overhand noose

The double overhand noose is a very secure hitch knot. It might be used by cavers and canyoneers to bind a cow tail or a foot loop to a carabiner.[ [File:Noeud double gansé.jpg|thumb|Double overhand noose binding carabiners.]]


  1. 1 2 Clifford W. Ashley, The Ashley Book of Knots (New York: Doubleday, 1944), 224-225.
  2. 1 2 3 4 5 Brion Toss, The Complete Rigger's Apprentice (Camden, Maine: International Marine, 1998), 10-13.
  3. 1 2 Geoffrey Budworth, The Complete Book of Knots (London: Octopus, 1997), 136-139.
  4. 1 2 Taylor, Howard; Grogono, Alan W. (March 2014). "The constrictor knot is the best ligature". Annals of the Royal College of Surgeons of England. 96 (2): 101–105. doi:10.1308/003588414X13814021677638. PMC   4474235 . PMID   24780665.
  5. 1 2 3 Cyrus Lawrence Day, The Art of Knotting and Splicing, 4th ed. (Annapolis: Naval Institute Press, 1986), 112.
  6. Johansson, Sten (April 1983), "Letters", Knotting Matters, London: International Guild of Knot Tyers (3): 13–14
  7. 1 2 Cyrus Lawrence Day, Quipus and Witches' Knots (Lawrence: The University of Kansas Press, 1967), 110-111.
  8. Pieter van de Griend (1992). A Letter to Lester. Århus: Privately published. ISBN   87-983985-0-4.
  9. Pieter van de Griend (July 2007). "The Constrictor Knot Revisited". Knot News. International Guild of Knot Tyers - Pacific Branch (62). ISSN   1554-1843.
  10. Bowling (pseudonym), Tom (1890) [1866], The Book of Knots (6th ed.), London: W. H. Allen, p. 8,
  11. Joseph Tom Burgess, Knots, Ties, and Splices (London: George Routledge & Sons, 1884), viii, 101.
  12. A. Hyatt Verrill, Knots, Splices and Rope Work, Third Revised Edition (New York: Norman W. Henly Publishing Co., 1917; 2006 Dover republication), 33-35. (second revised edition online)
  13. Hjalmar Öhrvall, Om Knutar, Second edition, (Stockholm: Albert Bonniers Förlag, 1916), 78.(Online version)
  14. Martta E. Ropponen, Kaarina Westling illustrator, Solmukirja, Suomen Partioliiton Kirjasia N:4 (Porvoo, Finland: WSOY, 1931), 58-59.
  15. "Constrictor Knot: Instrument Method" . Retrieved 4 May 2014.
  16. "Constrictor Knot: Twisting Method" . Retrieved 4 May 2014.
  17. "Constrictor Knot: Folding Method" . Retrieved 4 May 2014.
  18. Geoffrey Budworth, The Ultimate Encyclopedia of Knots (London: Hermes House, 1999), 159.