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Where the theory applies
Loop — fixed

Surgeon’s Loop

Interlock

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.

HTH · Reference layout

Surgeon’s Loop — finished-state checks, on the shared reference layout

Surgeon’s Loop — finished-state checks, on the shared reference layout
Hook the Horizon reference plate
Failure modes

When this family fails, it fails as these. The recovered end still outranks the name.

Fixed-loop family

A loop that stays the size you made, with a return that cannot cinch.

  • !Loop cinched around the hardware — action is dead
  • !Return path reversed, so it becomes a slip loop
  • !Fluoro in a lock that only behaves on mono
Fails when
  • !Seated on the standing line alone, leaving the tag side loose so the tag pulls back inside
  • !Tag trimmed before the knot fully closed, leaving it loose
  • !Strands of the double crossed over each other inside the knot
  • !Loop changes size under a test pull, showing the knot has not seated
Geometry
  • Single pass only — not a Surgeon's loop

    May slip and the eye walks

    Double pass is the minimum; one pass is an overhand loop · step 02

  • Messy multi-pass body

    Weaker eye, bulk that ticks

    Clean passes keep the lump compact and load-bearing · step 02

  • Passes not completed through the loop

    Unreliable — the eye never locked

    Every pass must go through the loop before the seat · step 03

If you saw this
  • Too bulky for small guides or keepers

    Check

    • ?Compare to Perfection Loop size

    Then

    • Use Perfection Loop
    • Drop to double surgeon
  • Finished check failed — Single overhand only

    Check

    • ?Double overhand completed on the doubled line
    • ?Loop size stable after draw
    • ?Tags exit cleanly

    Then

    • Retie. Incomplete double overhand fails as a fixed loop.
  • Single pass only — not a Surgeon's loop

    Check

    • ?May slip and the eye walks
    • ?Inspect step 02

    Then

    • Retie. Do not dress a defective structure and call it seated.
  • Messy multi-pass body

    Check

    • ?Weaker eye, bulk that ticks
    • ?Inspect step 02

    Then

    • Retie. Do not dress a defective structure and call it seated.
  • Passes not completed through the loop

    Check

    • ?Unreliable — the eye never locked
    • ?Inspect step 03

    Then

    • Retie. Do not dress a defective structure and call it seated.
Same family

Same failure class, different geometry. Open the plates — Diagnose still starts from the symptom.

This failed — start Diagnose

What holds it

  • ·A fixed loop is a standing eye. The collar or figure-eight body must survive a straight pull without becoming a noose.
  • ·Bowline and sheet bend are the same crossing pattern under different load. That identity is seamanship, not a reason for Decide to swap one for the other.

What topology does not predict

  • ·Fixed vs slipped is a load-path question. Invariants do not choose bowline over figure-eight.
  • ·Ring-loading and slack-shaking failure are physical. Topology does not grade them.
  • ·No UIAA or manufacturer number is inferred here.

Not for

  • ·A lure that must swing on a non-slip loop — this standing eye is a different job
  • ·Letting a climbing identity pick your fishing knot
  • ·When the absolute smallest loop knot is required
  • ·Very fine tippet where the double-overhand bulk matters

Same pattern, different job

No sourced twin among these knots. Related knots stay on the Library card.

Sources