Knots by Function: Hitches, Bends and Loops

Knots are chosen by function, not by appearance. A hitch holds a rope to a post, rail or another rope; a bend joins two ropes; a loop stays open under load; a binding grips an object and does not slip. Each family fails in its own way, and the breaking point usually sits where the rope bends most sharply, not where the knot looks weakest.

A practical directory of these families, sorted by use rather than by name, is set out at knots by function, which groups hitches, bends, loops and bindings with a difficulty scale. The sections below take the same four families in turn and describe what each one does, how it is tied, and where it breaks.

Hitches: what holds a rope to a post or a rail?

A hitch attaches a rope to a support: a post, a rail, a ring, or the standing part of another rope. The clove hitch is the standard answer for a post or rail. Two turns cross over each other around the support, and the tail is tucked under the second turn. Under steady tension the knot grips; under a load that swings or reverses, it can creep along the post, so a stopper knot or an extra half hitch on the standing part is common practice on a mooring line or a tarpaulin ridge.

The prusik is the other hitch worth knowing, and it works on a different principle. A thin cordlette is wrapped two or three times around a thicker load-bearing rope and then through itself. Unloaded, it slides freely up and down the host rope; loaded, the wraps pinch the host and hold. That property makes it the basis of ascending systems and of any arrangement where a rope must be gripped at a point that can be moved. The prusik fails when the cordlette is too close in diameter to the host rope, or when the wraps are too few for the slickness of the sheath.

Bends: how are two ropes joined?

The sheet bend joins two ropes, and it is the bend to use when the diameters differ. The thicker rope forms a bight; the thinner rope passes up through the bight, around behind both parts of the bight, and back under itself. The double sheet bend adds a second turn of the thin rope, which matters when the difference in diameter is large or when the rope is stiff. A sheet bend can shake loose when the ropes are slack and the load is intermittent, so the tails are usually left long.

Where the two ropes are of similar diameter and the join must run over a pulley or through a fairlead, a bend with a lower profile is preferable. The principle is the same in every case: the two ropes must be locked against each other so that tension on one does not simply pull the other through. A bend that has been loaded and then slackened should be inspected before it is trusted again, because the turns can settle into a different configuration from the one that was tied.

Loops: which knots stay open under load?

A fixed loop is a knot that forms an eye which does not close when the rope is loaded. The bowline is the reference example. A bight is formed in the standing part, the working end passes up through it, around behind the standing part, and back down through the bight. The result is an eye that holds its size under tension and, in the classic formulation, can be broken by a flick of the wrist once the load is off. That last property is why the bowline is used for rescue work and for any application where the knot must be untied after a heavy pull.

The figure-eight loop is the alternative when the loop will be loaded in more than one direction or when the rope is stiff and the bowline is hard to set. The figure-eight is tied in the bight, which makes it easy to inspect: the shape is symmetrical and any error is visible. It is the standard tie-in for climbing harnesses for that reason. A figure-eight loop is harder to untie after a severe load than a bowline, and it consumes more rope.

Ligatures: which knots will not slip?

The constrictor knot is the binding that will not slip. It is tied around an object, with the working end crossing over the standing part and then tucked back under the crossing turn. Once set, it grips the object and holds even when the ends are cut short. It is used to clamp a hose, to bind the end of a rope to stop it fraying, and to hold two objects together where a temporary but firm grip is needed. The constrictor is difficult to untie, and on a soft object it can crush or cut; on a hard, smooth object it can be the most secure binding available.

Bindings differ from hitches in that they grip the object itself rather than a support. The load path runs around the object, and the knot's job is to maintain tension in that loop. A binding that is too loose will not grip; one that is too tight may damage the object or jam. The constrictor sits at the firm end of that range, and it is the knot to choose when the requirement is that the binding must not move at all.

Where do these knots actually break?

Breaking points in knots are not where the knot looks weakest. They are where the rope bends most sharply, because a tight bend concentrates stress on the fibres on the outside of the curve. A bowline typically retains around two thirds of the rope's straight-line strength; a figure-eight loop rather less, because the rope passes through more tight curves. A sheet bend is weaker still when the two ropes differ greatly in diameter, since the thin rope takes the load over a small bearing area.

The practical consequences are simple. Use a knot with fewer tight bends when the load is near the rope's limit. Leave long tails so that a knot which slips a little does not come undone. Inspect any knot that has been loaded and then slackened. And match the knot to the function first: a hitch for a post, a bend for two ropes, a loop for an eye, a binding for an object that must not move. The name of the knot matters less than whether it does the job it was chosen for.

What should be checked before trusting a knot?

Four things. First, the family: is this a hitch, a bend, a loop or a binding, and does that match the task? Second, the dressing: are the turns neat, parallel where they should be, and free of crossings that will jam? Third, the tails: are they long enough to allow for settling, and are they secured where the load is intermittent? Fourth, the history: has the knot been loaded, slackened, or exposed to grit and water since it was tied?

A knot is a small working model of a larger intention, and the same habit of checking applies elsewhere in the field. Anyone who keeps a scale model or replica on a shelf, whether of a boat, a building or a piece of equipment, learns to look past the silhouette to the joins, the fixings and the finish. The page on what collectors check sets out those points in order, and it reads as a useful companion to this one: both are about judging how a thing is put together, and whether it will hold.

Knot work rewards the same habit as most practical tasks: name the problem before changing anything. A hitch that slips in the wet is a symptom, not a verdict, and the fix is usually a different form or a better dressing rather than a new rope. The same discipline applies indoors, where diagnosing a computer fault means reading the symptoms, checking memory and storage, and only then replacing a part. Both are field craft of a kind, learned slowly and kept in working order.

La terminologie employée ici suit l'usage courant : une boucle se forme autour d'un objet, un nœud de jonction relie deux cordes, un nœud d'amarrage tient sous tension. Pour vérifier une méthode avant de la reproduire sur le terrain, Animated Knots by Grog reste une source publique utile : les séquences y sont photographiées étape par étape, ce qui permet de comparer un nœud de chaise ou un cabestan avec ce que l'on exécute de mémoire, souvent dans de mauvaises conditions. La page ci-dessus classe ces nœuds par fonction plutôt que par nom, ce qui correspond à la façon dont on choisit réellement un nœud sur le terrain.