Constrictor Knot
Interlock · Constriction
Does not pick a knot
This page does not pick a knot for you. DNA, molecules, quantum braids and vortices stay off Decide.
Finished structure
Drawn from a rope model of this knot: which strand passes over which comes from where the rope actually lies.
When this family fails, it fails as these. The recovered end still outranks the name.
Directional bite on a standing part — slide-test before you trust it.
- !Turns on the wrong side of the load
- !Failed slide-test, still used
- !A clove where a rolling or icicle third turn was the job
- !It is tied on a flat surface, where the turns cannot grip and the knot loosens
- !The end is tucked under itself only, leaving a clove hitch without the clamped overhand that grips
- !It has been pulled hard and needs to come off, as it is often impossible to untie and has to be cut
Left as a clove — no riding-turn tuck
Bind walks; this is not a constrictor
The tail must tuck under the standing part and the first turn · step 03
Expected to untie after a hard dress
Knife job on a bind you needed to release
Animated Knots: usually cut rather than untied · step 04
Used as a join
A bind is not a bend
Pick a sheet bend or Zeppelin if you needed a join · step 01
Bind walks, or will not come off when you need it to
Check
- ?Crossed riding turn over the two ends
- ?Tail under both
Then
- →Finish the tuck
- →Cut it if it has seated
- →Use a reef knot if you needed a release
Left as a clove — no riding-turn tuck
Check
- ?Bind walks; this is not a constrictor
- ?Inspect step 03
Then
- →Retie. Do not dress a defective structure and call it seated.
Expected to untie after a hard dress
Check
- ?Knife job on a bind you needed to release
- ?Inspect step 04
Then
- →Retie. Do not dress a defective structure and call it seated.
Used as a join
Check
- ?A bind is not a bend
- ?Inspect step 01
Then
- →Retie. Do not dress a defective structure and call it seated.
Same failure class, different geometry. Open the plates — Diagnose still starts from the symptom.
What holds it
- ·Reef / square is a binding knot around a parcel. Opposite-direction throws lock; same-direction throws are a granny and walk.
- ·Johanns et al. (2023) locate that difference in friction, geometry and plastic set — not in crossing count. Granny is not among these knots.
What topology does not predict
- ·Reef is not a bend for two working ropes under load. Seamanship already forbids that job.
- ·Surgical throw security is not a Palomar rating.
- ·No suture-material number is copied onto nylon dock line.
Not for
- ·Joining two ropes as a bend — use a sheet bend or a recognised bend family
- ·Letting a surgical paper pick your fishing knot
- ·A bind you must release (reef knot)
- ·A join
Same pattern, different job
Two stacked turns on the spar, working end tucked under the second. Turns must stay together.
Clove HitchConstrictor is a clove hitch plus a riding turn that jams.
- Johanns et al. — Strength of surgical knots (Sci. Adv., 2023) — Square vs granny is friction, geometry and plastic set — not crossing count.
- Reef knot (Wikipedia) — Binding knot. Capsizes. Opposite-throw pair is the granny — not in these knots.
- EPFL — Mechanics of the ideal surgical knot (2023) — Public summary of Johanns et al. Alternating throws lock; same-direction throws walk.
- Animated Knots — Constrictor Knot (Rope End Method)
- ITS Tactical / Imminent Threat Solutions — How to Tie the Constrictor Knot - ITS Knot of the Week HD — Cited tying video already attached to this record.