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Loop — mid-line

Alpine Butterfly

Interlock · Climbing

DiagramsHow to tie it

Does not pick a knot

This page does not pick a knot for you. DNA, molecules, quantum braids and vortices stay off Decide.

Alpine Butterfly, finishedAlpine Butterfly, finished

Finished structure

Drawn from a rope model of this knot: which strand passes over which comes from where the rope actually lies.

Failure modes

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

Alpine-butterfly family

A mid-line eye that can take load in three directions.

  • !Twists not nested — the eye distorts under side load
  • !Tied as an overhand on a bight, which will not take three-way load
  • !Eye sized after it was already loaded
Fails when
  • !The lifted turn was laid over the other turns but not tucked under them, so it slides straight out as the knot comes off the hand.
  • !The turns separated while sliding off the hand and the tuck came out of place, leaving loose coils instead of a knot.
  • !It was set on only the loop or only the standing parts, so it sits twisted and can change shape under its first real load.
Geometry

  • Wrong wrap order

    Body inverts into a slip loop

    Fingertip turn must wrap around the other two before it leaves the hand · step 02

  • Twisted body never loaded on all three parts

    One standing part slips through under load

    Dress by pulling the loop and both standings · step 04

  • Used as an end-loop

    Wrong job — a bowline or figure-8 would untie easier

    This is a mid-line loop, not an end-eye · step 01

If you saw this

  • Loop distorts or one standing part slips through

    Check

    • ?Square body
    • ?Loop standing perpendicular
    • ?Both standings leaving opposite sides

    Then

    • →Untie and retie the hand wraps
    • →Load all three parts to dress

  • Wrong wrap order

    Check

    • ?Body inverts into a slip loop
    • ?Inspect step 02

    Then

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

  • Twisted body never loaded on all three parts

    Check

    • ?One standing part slips through under load
    • ?Inspect step 04

    Then

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

  • Used as an end-loop

    Check

    • ?Wrong job — a bowline or figure-8 would untie easier
    • ?Inspect step 01

    Then

    • →Retie. Do not dress a defective structure and call it seated.
This failed — start Diagnose

What holds it

  • ·A mid-line loop is tied on a bight. Both standing parts stay load-bearing.
  • ·Alpine butterfly and bowline-on-a-bight are different geometries for the same job class. Invariants do not rank them.

What topology does not predict

  • ·Direction of pull (one standing part vs both) is mechanics, not knot type in the Jones sense.
  • ·No working-load table is attached here.
  • ·Capsizing under ring load is a physical defect, already a Diagnose story.

Not for

  • ·An end-of-line terminal eye
  • ·Using this page to override a Decide elimination
  • ·An end-loop (use bowline / figure-8)
  • ·A loop you will tie and untie every five minutes in stiff hawser

Same pattern, different job

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

Sources