Copyright © 1997, Peter Suber.

Six Exploding Knots

Overview & Quick Start
  • I call these six hitches "exploding" knots because they untie easily and completely with one tug of the ripcord. Unlike slipped knots that untie with a ripcord, these knots leave absolutely no tangle. Yet they give up nothing in strength or ease of tying.
  • To learn to tie them, jump to the illustrations and skip the commentary.
  • In each illustration, the line labelled "R" is the ripcord ("running part"). The line labelled "S" is to be attached to the load ("standing part"). Tighten the knot with the "S" line.
  • To decide which of these knots is best for which application, see the table at the end, which presupposes some of the text you might have skipped.
  • After learning to tie the knots from the illustrations, read the text if only for safety issues.
  • These knots are "probably original" in Clifford Ashley's sense of this phrase.

If you've ever tried to untie a taut-line hitch on a cold morning, then you know why slipped and exploding knots are a good idea. If the knot is tight, especially if the cord is also wet or thin or both, then fingernails will tear on it. Teeth might work, even if you were foolish enough to use them, but most people can't put their mouths the six or seven feet off the ground where the taut-line hitch often resides. If the cord is thin, the knot cannot be worked with gloves on, and if the morning is cold, the knot cannot be worked with gloves off. If you have to cut your knots, then you don't belong in the wilderness.

Slipped and Exploding Knots

A slipped, slipping or slippery knot is one that replaces the end of the cord with a bight (the end doubled over itself) at the last step, to stick through the last opening before tightening. Just yank the ripcord, the end that hangs free, to undo the knot. This is a vast improvement over unslipped knots.

Don't mistake a slipped knot for a sliding knot. A knot slides if it moves over the cord, like a noose. Bowlines don't slide, for example. A taut-line hitch should slide; it would be nice if it also slipped. Most knots designed for strength should not slide.

The only trouble with slipped knots is that, after slipping, the cord is usually tangled and must be untangled. Certainly untangling the kind of tangle we're talking about is always easier than untying, and one is lucky to have grievances so small when one is cold, hungry, tired, wet, and bug-bitten. But it would be elegant and desirable to overcome this little problem. The exploding knot is a refinement of the slipped knot that does just that. When you pull the ripcord of an exploding knot, the ends fly apart, leaving no tangle at all.

Exploding knots are not merely elegant and fun, as you will see in the field. If exploding knots save your cord, or your fingernails (or teeth!), your time, or your temper, they can save your trip.

We need a few more terms before we begin. The standing part of a cord is the end attached to the load. The running part is the other end. The running part "runs" because it is the end in motion when the knot is tied. With exploding knots, however, just as much of the action takes place on the standing part, as we'll see. In the illustrations below, "S" stands for the standing part, "R" for the running part. Don't mix these up! With most exploding knots, if you mistake the running and standing parts, then the load will be attached to the ripcord. Ouch!

A bight is technically distinct from a loop. But any of these knots can be tied with loops instead of bights if you wish. Technically, a loop allows the ends of a doubled section of cord to cross, while a bight does not.

A sliding knot locks if some simple tug will tighten its grip on the standing part so that it will no longer slide. Another simple bend or twist should unlock it.

Exploding with a Bang or with a Whimper

Exploding knots require a balance of opposites: the knot must be tight enough to hold its load securely, but loose enough to let the ripcord slide through. A well-tied exploding knot will achieve this balance. The load on the standing part will always tighten the knot while preserving an island of relaxation somewhere inside where the ripcord lies like a sleeper in a tent in a thunderstorm. Learning to tie them so that they achieve this balance is the most difficult aspect of exploding knots.

A general tip for achieving this balance is to tighten these knots flat (except #1). Don't let them curl up into balls or cubes. If they are kept flat while tightened, then the further tightening that comes from the load will not cause them to curl up.

If the knot is overtight, the ripcord may become too tightly bound inside the knot to pull. If the knot is well-tied, this overtightening will never arise from the tug of the load on the knot. But imperfect tying, combined with the added friction on the cord from rain or dew, may occasionally clutch the ripcord. Even with a clutched ripcord, however, an exploding knot is much easier to release than a non-exploding knot.

For all the knots presented here, the problem of tight ripcords can be cured either by unlocking in the usual way (described for each locking knot), or by an alternate kind of exploding release we may call whimpering. If the knot is grabbed like a knob, and pulled in a certain direction, then the bight that composes the ripcord will simply pull out, freeing the knot in a quiet explosion --not a bang, but a whimper.

Sliding knots will not whimper. When you pull a sliding knot, it will either slide or tighten. Whimpering knots, essentially, have two ripcords, one hanging free and one running around a spar or attached to the load. Hence, even though the two non-sliding, whimpering knots here (knots #1and #2) tighten as the load pulls, it is possible to whimper the knot if the load pulls in the "right" direction. So whimpering knots should not take critically heavy loads.

The advantage of non-whimpering knots, then, is strength in unpredictable situations (moving or jerking loads). The advantage of whimpering knots is convenience of release when the primary ripcord is seized by moisture or overtightening. After a whimpered release, you still have all the advantages of an explosion, with no winding to unwind.

If you didn't follow a point or two of this "knot theory," don't worry. Practice the knots, and you'll see what's going on.

These Six Knots

Of the exploding knots I've developed, these six fall into a natural family (they are all hitches with various properties), they are the most versatile and easy to tie, and they have undergone the most refinement and testing. Three slide and three don't. All the sliding knots lock and unlock. Two of the three non-sliding knots whimper, one doesn't. In every case, the knots explode by pulling the ripcord, which is always the end of the running part. A table to help you pick the knot just right for your application follows at the end.

The three sliding knots (knots #3, #4, #5) are named after traditional non-sliding knots that they resemble. The resemblance, obviously, has a limitation, since these knots slide (and explode) while their namesakes do not. The names are a convenience for remembering these knots, but should not confuse you about their functions or the situations in which they might be useful or dangerous.

I describe the knots as if they were to be used to tie a load (pack, horse, canoe, clothesline, tarp) to a fixed object (spar, bollard, tree), but all of them have other applications.

I believe that the first five of these knots are original. The sixth is original only in its exploding form. None of them appears, for example, in the 600 pages of Ashley's encyclopedic Book of Knots (Doubleday, 1944). I say "original" but not "new," for it is impossible to say whether crafty sailors, cowboys, climbers, loggers, surgeons, quilters, or embroiderers have stumbled across them before.

1. Clove hitch biting a bight (exploding, whimpering, non-locking, non-sliding).

This and the sliding sheet bend (knot #4) are the easiest to tie of the six knots presented here, which makes it the easiest of the non-sliding knots. It is so easy that even when I have the time for something fancier, I will often tie this knot. It has the advantages and disadvantages of whimpering.

Start a clove hitch on the standing part. Instead of popping it over a fence or dock post, however, pop it over a bight from the running part. Tighten by pulling the standing part. Don't let the two "coils" of the clove hitch drift too far apart while tightening. There is no need to worry about tightening this knot flat; there's only one way to tighten it, and it's the right way. Whimper by pulling the knot away from the cord that forms the bight inside the clove hitch. (If the standing part came into the spar from the right and running part from the left, as in the illustration, then whimper by pulling the knot out from the spar and to the right.)

This knot, under the name Exploding Hitch, was featured as the Knot of the Month in the October 1999 issue of Boating Magazine (p. 64).

2. Figure-eight biting a bight (locking, exploding, whimpering, non-sliding).

This is easy knot to tie that also has the advantages and disadvantages of whimpering. Tie a figure-eight on the standing part, and stick a bight of the running part through it at the last moment. Tighten it flat so that it will not curl up and lock the ripcord. Whimper by pulling the knot away from the cord that forms the bight inside the figure-eight. (If the standing part came into the spar from the right and running part from the left, as in the illustration, then whimper by pulling the knot out from the spar and to the right.) Lock by holding the knot and pulling the non-whimpering cord (the line from the knot to the spar on the right on the right side of the spar). Unlock by flattening the knot.

3. Sliding butterfly (sliding, locking, exploding, non-whimpering).

I call this knot a sliding butterfly because it looks like a butterfly knot, not because it acts like one. It can even fool knot-so-smart climbers momentarily into thinking it is a butterfly, until you slide it for them. (Don't expect it to make a secure loop as a real butterfly does.)

After the running part wraps around a tree or post, lay it alongside the standing part. Grab the two lines as if they were one, and make a loop by twisting counterclockwise. Take the running part alone now, without the standing part, and wrap it over the doubled lines and stick a bight of it through the doubled loop. Tighten by pulling the standing part.

Tightening this knot proceeds in two stages. First, the slack is taken up, then the knot capsizes. "Capsize" is the nautical term for the sudden twist or transformation that takes place in some knots when they are tightened. For example, sailors start a bowline by capsizing a half-hitch. For this knot, however, we should say that it "metamorphosizes," since it is only after the transformation that it looks like a butterfly.

Lock by holding the knot and pulling on the non-sliding line. Unlock by putting your thumbs on the butterfly's "wings" and bending up and down, or by pulling the sliding ends apart hard, or by flattening the knot.

4. Sliding sheet bend (sliding, locking, exploding, non-whimpering).

This knot has to be studied closely to see its kinship to the sheet bend. If you don't see the resemblance, don't bother; just enjoy it. (It should not be used like a regular sheet bend to join two different lengths of cord.) This is my favorite sliding exploding knot.

When mastered, this knot is not only very easy, but enjoyable to tie, leading the hand into unusual, efficient hand-gestures. A few twists, with almost no pokes or pulls, and you are done. Until mastered, however, it will often fall apart in your hands before it is finished. Tighten flat, not in a ball. It can make so tight a grip on the standing part that you may have to unlock it a bit before it slides. That should give you some comfort if you use it as a taut-line to hold your clean wet clothes. For a variation of this knot for heavier taut-line applications, see the sliding Chinese crown (#5).

Make a bight in the standing part between the spar and your load. Grab the running part (already wrapped around the spar) and make a loop in it by twisting counterclockwise. Slide the original bight through this loop, making a new loop on the other side. (With practice, this step can be done in the same counterclockwise twist that created the loop.) Stick a bight of the running part through this new loop, and tighten by pulling on the standing part.

Lock by holding the knot and pulling on the non-sliding line. Unlock by pulling the two sliding ends apart hard, or by flattening the knot.

After posting the first edition of this page I learned that the present knot is already known by the name of Mooring Hitch. So all that's new here is the observation that the slipped mooring hitch explodes.

5. Sliding Chinese crown (sliding, locking, exploding, non-whimpering).

This may be the hardest to tie of the knots presented here, although it can be tied in three or four seconds with practice. The slide is controlled by one more bend in the rope than the sliding sheet bend (knot #4) which makes it stronger when locked. For taut-line applications meant to hold heavier loads, like wet tarps, it is better than the sliding sheet bend. But don't let its "difficulty" stop you from trying it even for light loads, like a sliding "buckle" belt. (Slide it tight around your waist, then lock; explode when diarrhea attacks.) Like the sliding sheet bend, it can grip the standing part so hard that you may have to unlock it a little before you can slide it.

This knot is a sliding and exploding variation on the Chinese crown (Ashley #808, #1032). It also bears a certain resemblance to a non-sliding double Carrick bend (see knot #6). You could use it to amaze your friends who know that double Carrick bends don't slide, if you had any friends like that. Like the double Carrick bend, this knot should be tightened flat, otherwise it will become a cube that will neither slide nor explode. Because it slides, do not use it like an ordinary double Carrick bend to join two lengths of cord together.

Make an S-shaped curve in the standing part, with the bottom of the "S" toward the spar and the top of the "S" toward the load. Stick the running part up through the lower right-hand curve of the "S" from behind. Wrap the running part over the top of the "S" and when it emerges at the bottom of the "S" stick a bight of the running part through the upper lefthand curve from the front. Hold the new loop that results as you tighten by pulling the standing part.

Lock by holding the knot and pulling the non-sliding line. Unlock by pulling the sliding ends apart hard or by flattening the knot.

6. Double Carrick bend (locking, exploding, non-sliding, non-whimpering).

Make a loop in the standing end by grabbing it and twisting counterclockwise. Pass the running part under this loop (not through it yet) and over the top of the standing part. Then pass it under the next length of standing part. Make two bights at this point: (1) find the running part that passed under the original loop, and pull it up through that loop into a bight, and (2) take the end of the running part and make a bight of it. Pass the second of these through the first of these, and tighten by pulling the standing part. For best results (cleaner explosions) the ripcord should lie under the standing part it faces, not over.

This knot can be tightened into a cube, which locks the ripcord. Tighten it slowly so that it remains flat instead. Lock by holding the knot, and pulling the entire bight that holds the ripcord, or by pulling either of the non-ripcord lines. This knot has the advantages and disadvantages of non-whimpering.

The traditional (non-exploding) double Carrick bend is rated the strongest known bend (knot for tying two cords together). The variation that makes it explode should not affect its strength, although it will increase the chances of misadventure from another cause. To use it as a bend, follow the same directions, but treat the two ends of cord that come around the spar as if they were the ends of two distinct cords.

Do not use any of the other five knots as bends (for tying two cords together). Either one cord will be the ripcord for the knot, or it will slide through it. (I have another, more original, exploding bend that I'll put on the web soon.)

Despite its unmatched strength, the double Carrick bend is seldom used by mountaineers because it has been difficult to tie. I'd like to think that this version, with or without the exploding variant, might revive its use.

Six Exploding Knots
(2 bend)
(1 bend)
Sliding Chinese
crown (#5)
butterfly (#3)
Sliding sheet
bend (#4)
Double Carrick
bend (#6)
Clove hitch
biting a bight (#1)
biting a bight (#2)

This article has been translated into Dutch by Pieter van de Griend, "Zes Exploderende Knopen," Het Knoopeknauwertje, 9 (December 1997) 8-13.

Also see my page of Knots on the Web.

[Blue Ribbon] Peter Suber, Department of Philosophy, Earlham College, Richmond, Indiana, 47374, U.S.A. Copyright © 1997, Peter Suber.