Reef Knot
Interlock · Constriction · Surgery
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
No drawing of this exact knot yet. The written steps are the reference.
When this family fails, it fails as these. The recovered end still outranks the name.
A binding that holds two parts, or a hitch that tightens as you drag.
- !Reef knot used as a bend — it spills
- !Granny form (both tucks the same way)
- !Timber hitch with too few wraps on the object, so it walks
- !The two ropes are pulled end to end as a join, so the knot capsizes and comes apart
- !One end is pulled harder than the other, so one rope pulls straight and the other slides along it as a loop
- !The two ropes differ in thickness, which lets the knot capsize
- !Both half knots cross the same way, making a granny knot, which Animated Knots says holds even worse
Used as a rope-to-rope join
Capsizes and slips under standing load
Animated Knots: always a binding knot at sea — never a bend · step 01
Granny — same hand twice
Will slip as soon as the reef takes strain
Second half-knot must reverse the first · step 02
Capsized or unequal-diameter bind
Already failing as a reef
The knot must sit flat on similar ends · step 03
Knot capsizes and slips under standing load
Check
- ?Flat nested half-knots
- ?Binding a reef or bundle, not joining two ropes
Then
- →If you needed a join, retie a sheet bend or Zeppelin
- →If you needed a bind, retie left-right then right-left
Used as a rope-to-rope join
Check
- ?Capsizes and slips under standing load
- ?Inspect step 01
Then
- →Retie. Do not dress a defective structure and call it seated.
Granny — same hand twice
Check
- ?Will slip as soon as the reef takes strain
- ?Inspect step 02
Then
- →Retie. Do not dress a defective structure and call it seated.
Capsized or unequal-diameter bind
Check
- ?Already failing as a reef
- ?Inspect step 03
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
- ·Joining two ropes (it slips as a join)
- ·Unequal diameters
Same pattern, different job
No sourced twin among these knots. Related knots stay on the Library card.
- 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 — Square Knot (Reef Knot) — Binding / reefing only. Must never be used as a rope-to-rope join.
- AnimatedKnots — How to Tie a Square Knot (Reef Knot) — Cited tying video already attached to this record.