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Where the theory applies
Terminal — hardware eye

Double Davy Knot

Constriction · Wrap stack

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

Double Davy Knot — finished-state checks, on the shared reference layout

Double Davy Knot — 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.

Fly / tippet family

Fine tippet at the eye, or fly-line to leader with a tube or nail.

  • !Hitch path around the eye instead of through it
  • !Single pass where two were the job
  • !Gap at the tube or nail on a fly-line join
Fails when
  • !Tag end pulled away from the eye, out from under the knot
  • !Very light tippet, about 4X to 6X, tied to a heavy-wire hook
  • !Only one tuck made on a larger fly or heavier tippet
  • !Standing line pulled before the tag, so the tag can slide out
Geometry
  • Stopped after one pass

    That is a Davy — the usual pull-out on a larger fly

    The second pass is why this knot exists · step 02

  • Second pass never seated to the eye

    Opens under load on anything bigger than a small dry

    Incomplete second pass is the Double Davy failure · step 03

  • First pass cinched so the second cannot enter

    You cannot add the security pass after a hard first seat

    Leave the first hitch open enough to take the second pass · step 01

If you saw this
  • Opens under load

    Check

    • ?Both passes visible and tight

    Then

    • Retie carefully
  • Finished check failed — Only one pass completed

    Check

    • ?Second pass completes before the final draw
    • ?Compact seat at the eye
    • ?Tag controlled and short

    Then

    • Retie. Incomplete double structure reverts to a weaker single Davy.
  • Stopped after one pass

    Check

    • ?That is a Davy — the usual pull-out on a larger fly
    • ?Inspect step 02

    Then

    • Retie. Do not dress a defective structure and call it seated.
  • Second pass never seated to the eye

    Check

    • ?Opens under load on anything bigger than a small dry
    • ?Inspect step 03

    Then

    • Retie. Do not dress a defective structure and call it seated.
  • First pass cinched so the second cannot enter

    Check

    • ?You cannot add the security pass after a hard first seat
    • ?Inspect step 01

    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

  • ·The eye is hardware. The knot is an open tangle around that eye. Ends stay ends.
  • ·Seating (wet set, even wraps, tag orientation) is the mechanical record already on the knot. Theory adds no extra rating.

What topology does not predict

  • ·Trefoil / unknot classification does not apply to a Palomar or clinch.
  • ·Fluoro glaze, pigtail slip and nick-at-the-guides are forensic, not topological.
  • ·No strength percentage is computed here.

Not for

  • ·A free-swing lure loop — use a non-slip loop family
  • ·Using an invariant as a reason to keep a glazed terminal
  • ·Absolute smallest midges where a single Davy is enough
  • ·Heavy saltwater terminals and braid

Same pattern, different job

Sources