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Where the theory applies
Bend — two lines

PR Bobbin Knot

Wrap stack · 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

No drawing of this exact knot yet. The written steps are the reference.

Failure modes

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

FG / Alberto family

Braid wrapped onto a heavier leader, then locked so the join cannot hinge.

  • !Hinge at the material transition — the join clicks, then parts
  • !Wraps not packed on the heavier line before the lock
  • !Lock or tag on the wrong side of the braid, so the column unzips
Fails when
  • !The tight wraps have gaps or slack, so the stack slides along the leader when braid and leader are pulled apart
  • !The leader turned with the bobbin while wrapping, so few real turns were laid to grip it
  • !The half hitches are loose, missing or tied away from the stack, so the wraps unwind from the braid tag end
  • !The flame scorched the braid wraps or the leader beside the melted bump
Geometry
  • Wrap stack slides on the leader

    The connection lets go progressively under a sustained run

    Grip is the product of wrap tension and wrapped length. Slack bobbin drag gives neither. · step 03

  • No half hitches over the wrap stack

    The stack unwinds from the end once load cycles

    The hitches are what stop the last wrap from backing off. · step 04

  • Leader spun with the bobbin, few real wraps laid

    Looks wrapped, grips almost nothing

    If the leader turns with the bobbin, no relative wrap is accumulating. · step 02

  • Wrapped section too long for the guide train

    Knocks through the guides and costs casting distance

    Guide passage is set by the length and taper of the wrapped section. · step 03

If you saw this
  • The wrap stack slides along the leader when you pull it

    Check

    • ?Pull the braid and leader apart and watch whether the stack moves at all

    Then

    • Retie with more bobbin drag
    • Extend the tight return wraps to a full two to three inches
  • The wraps end without half hitches over them

    Check

    • ?Look for the locking hitches sitting on top of the wrap stack

    Then

    • Add the half hitches and the three-wrap finish; the stack unwinds without them
  • The connection knocks or catches going through the guides

    Check

    • ?Draw it through the tip guide by hand before fishing

    Then

    • Shorten the wrapped section
    • Trim and melt the leader stub flush
  • Wrap stack slides on the leader

    Check

    • ?The connection lets go progressively under a sustained run
    • ?Inspect step 03

    Then

    • Retie. Do not dress a defective structure and call it seated.
  • No half hitches over the wrap stack

    Check

    • ?The stack unwinds from the end once load cycles
    • ?Inspect step 04

    Then

    • Retie. Do not dress a defective structure and call it seated.
  • Leader spun with the bobbin, few real wraps laid

    Check

    • ?Looks wrapped, grips almost nothing
    • ?Inspect step 02

    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 bend captures two working ends. Holding is constriction and the seated wrap or barrel — not a closed-knot invariant.
  • ·Unequal diameters and slick pairs (braid to fluoro) are material problems. Crossing number does not rank FG against a Double Uni.

What topology does not predict

  • ·A Jones polynomial does not pick a braid-to-leader family.
  • ·Published retention bands stay as cited on the knot record. This page does not invent one.
  • ·Guide-click and tag-trim are field geometry, not topology.

Not for

  • ·Attaching a single line to a spar or cleat — that is a hitch
  • ·Reading this page as a recommendation from Decide
  • ·Anywhere the bobbin tool is not to hand — this knot is defined by the tool
  • ·Quick leader changes on a drifting boat

Same pattern, different job

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

Sources