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Bend — two lines

Double Sheet Bend

Wrap stack · Constriction · Nets / textiles

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.

Double Sheet Bend, finishedDouble Sheet Bend, 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.

Sheet-bend family

Bight in the thicker rope; tails same side; extra turn if the diameters differ.

  • !Bight in the thinner rope — the join spills
  • !Tails on opposite sides (left-handed sheet bend)
  • !Only one turn on a mismatch job — that is a single sheet bend asked to do double work
Fails when
  • !Only one turn taken around a much thicker bight
  • !Bight formed in the thinner rope
  • !Tails finish on opposite sides of the knot
  • !Tails left short, especially on the thinner rope
Geometry

  • Bight in the thin rope

    Mismatch join spills

    The thick rope makes the bight · step 01

  • Only one turn

    This is a single sheet bend on a mismatch job

    The extra turn is why this hitch exists · step 03

  • Tails opposite sides

    Same slip as a left-handed sheet bend

    Tail side is the lock on both versions · step 04

If you saw this

  • Thinner rope pulls out

    Check

    • ?Two turns on the thin rope
    • ?Bight in the thick rope

    Then

    • →Retie the double
    • →Splice if this is permanent

  • Bight in the thin rope

    Check

    • ?Mismatch join spills
    • ?Inspect step 01

    Then

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

  • Only one turn

    Check

    • ?This is a single sheet bend on a mismatch job
    • ?Inspect step 03

    Then

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

  • Tails opposite sides

    Check

    • ?Same slip as a left-handed sheet bend
    • ?Inspect step 04

    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
  • ·Equal thin lines where a single sheet bend already holds
  • ·HMPE without a splice

Same pattern, different job

Sources