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KA

Diagram

Double Uni Knot

Double Uni · Uni to Uni

Reliable way to join two lines of similar or moderately different diameters. Works for mono-to-mono, fluoro-to-mono, and many braid-to-leader pairings when wrap counts are adjusted.

Line-to-line · Beginner · Monofilament / Fluorocarbon / Braid · 5 steps

ApplicationsHow to tie it
Double Uni Knot, finishedDouble Uni Knot, finished

Finished structure

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

  1. Lay the two line ends side by side, overlapping, tags pointing opposite waysThe ends of two lines lie side by side along a long overlap, their tag ends pointing in opposite directions.
    1First line's tag end
    2Second line's tag end
    Move 1 of 1Lay the two line ends side by side, overlapping, tags pointing opposite waysYou should now see: Two lines lying parallel along the overlap, each tag reaching past the other line's end of the overlap with length to spare.

    Step 01

    Lay the ends of the two lines side by side, tags pointing in opposite directions, so they overlap by at least 15 cm (6 in).

    You should now see

    Two lines lying parallel along the overlap, each tag reaching past the other line's end of the overlap with length to spare.

    If it goes wrong

    Too short an overlap. It shows during the second uni, when the tag runs out before the turns are finished.

    Fix: Separate the lines and lay them out again with more overlap before tying anything.

    Why: Each tag has to make a complete uni knot around the other line, so the overlap supplies the working length for two knots.

  2. Double the first tag back into a loop and wrap both lines five times through itThe first line's tag doubles back into a loop over both lines and winds five open turns round both of them inside the loop.
    1Five turns round both lines
    Move 1 of 2Double the first tag back into a loop and wrap both lines five times through it
    Pull that tag to close the turns into a barrelThe five turns close into a tight barrel round both lines, sitting out on the overlap and free to slide.
    Move 2 of 2Pull that tag to close the turns into a barrelYou should now see: One closed barrel of even turns on the overlap, still able to slide along the other line when pushed.

    Step 02

    Double one tag back into a loop over both lines, wrap it around both lines and through the loop 5 or 6 times, or 6 to 8 times for braid, then pull that tag to close the turns.

    You should now see

    One closed barrel of even turns on the overlap, still able to slide along the other line when pushed.

    If it goes wrong

    Turns crossing each other or going around only one line, seen as a lumpy barrel. It happens most with slick braid when the loop twists during wrapping.

    Fix: Unwind the tag to the loop and wrap again with the loop held flat, keeping each turn beside the last and around both lines.

    Why: Braid is slippery and needs more turns to grip than mono. For a braid-to-mono join NetKnots gives 6 to 8 turns with the braid and 5 or more with the mono.

  3. Tie a second uni with the other tag, facing the opposite wayA second barrel, the mirror image of the first, closes round both lines at the other end of the overlap, with line between the two.
    1First barrel
    2Second barrel
    Move 1 of 1Tie a second uni with the other tag, facing the opposite wayYou should now see: Two closed barrels on the overlap, mirror images of each other, with a stretch of line still between them.

    Step 03

    With the other tag, tie a second uni the same way facing the opposite direction: loop, wrap around both lines and through the loop, then pull its tag to close the turns.

    You should now see

    Two closed barrels on the overlap, mirror images of each other, with a stretch of line still between them.

    If it goes wrong

    Giving this uni fewer turns than it needs. On a braid-to-mono join, the side with too few turns is the side that slips when loaded.

    Fix: If the count is short, open this second barrel and wrap it again with the full count before sliding anything.

    Why: Each uni is a noose on its own line that closes around the other line. The join holds only as well as the weaker of the two, so the slicker or thinner line needs its full count.

  4. Wet both knots and pull the two standing lines until the barrels meetPulled from both standing lines, the two barrels slide together along the overlap and press against each other.
    Move 1 of 1Wet both knots and pull the two standing lines until the barrels meetYou should now see: The two barrels touching end to end with no gap, and both standing lines leaving the join in a straight line.

    Step 04

    Wet both knots and slowly pull the two standing lines in opposite directions until the barrels slide together and press firmly against each other.

    You should now see

    The two barrels touching end to end with no gap, and both standing lines leaving the join in a straight line.

    If it goes wrong

    Stopping while a gap remains between the barrels, or pulling a tag instead of a standing line. The join bends at the gap and the lines leave it at an angle.

    Fix: Wet the join and keep pulling the standing lines apart until the barrels meet. If a barrel has opened up, cut the join out and tie it again.

    Why: Fishtrack stresses snugging the two knots tightly against each other. Butted barrels support each other under load, while a gap leaves a spot where the join can fold.

  5. Test the join with a firm pull, then trim both tags shortThe finished double uni: two tight barrels pressed end to end on the join, each with a short trimmed tag.
    Move 1 of 1Test the join with a firm pull, then trim both tags shortYou should now see: A compact join with two short tag stubs, and barrels that stayed pressed together through the test pull.

    Step 05

    Give the join a firm test pull on both standing lines, then trim both tags close to their barrels, leaving a short stub on each.

    You should now see

    A compact join with two short tag stubs, and barrels that stayed pressed together through the test pull.

    If it goes wrong

    Trimming before the test pull, or cutting so flush that a tag slips back inside its barrel as the knot settles.

    Fix: If a tag has pulled inside its barrel or the barrels moved apart on the test pull, cut the join out and tie it again.

    Why: A short stub gives the tag room to draw in slightly as the barrels settle under load. A tag cut flush has no margin and can pull through.

HTH · Construction plate

Double Uni Knot — construction sequence

Double Uni Knot — construction sequence
Hook the Horizon reference plate
Failure modes

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

HTH · Advanced failure modes

Double Uni Knot — what fails and what to do

Double Uni Knot — what fails and what to do
Hook the Horizon reference plate
Uni family

A barrel that is formed, then slid to the eye or the other barrel.

  • !Barrel locked short of the eye or the other Uni
  • !Crossed wraps in the barrel
  • !Tag buried back into the barrel instead of exiting
Fails when
  • !Braid side tied with too few turns
  • !Gap left between the barrels, so the join folds at the gap
  • !Tag trimmed flush and pulled back inside its barrel
Geometry

  • Crossed wraps in one Uni barrel

    That side slips and the join dumps

    Each Uni needs parallel wraps; one bad barrel fails the pair · step 02

  • Barrels never butted

    The join separates under load

    Double Uni locks when the two barrels meet and seat together · step 04

  • Tag buried in a barrel instead of exiting

    That barrel unravels

    Each tag must exit after its barrel is formed · step 05

  • Barrels not collinear — a hinge join

    Clicks in the guides, then parts

    Inline barrels, not a folded pair, carry Double Uni load · step 04

If you saw this

  • Two Uni knots separate under load

    Check

    • ?Confirm barrels touch
    • ?Count wraps on each side

    Then

    • →Retie and seat until barrels butt
    • →Add wraps on braid side

  • Too bulky for guides

    Check

    • ?Pass through rod tip slowly

    Then

    • →Use FG or Alberto for braid-to-leader slimness
    • →Reduce unnecessary wraps

  • One barrel remains open while the other is tight.

    Check

    • ?Look for: One barrel remains open while the other is tight.

    Then

    • →Retie the weak side; ensure both barrels form fully.

  • Barrels pass through each other instead of meeting.

    Check

    • ?Look for: Barrels pass through each other instead of meeting.

    Then

    • →Pull standing lines so barrels slide together and meet.

  • Braid side creeps under load.

    Check

    • ?Look for: Braid side creeps under load.

    Then

    • →Increase braid-side wraps; retest.

  • Connection hangs after repeated casts.

    Check

    • ?Look for: Connection hangs after repeated casts.

    Then

    • →Trim tags flush; consider FG/Alberto for guide-heavy work.

  • Finished check failed — one barrel remains open while the other is tight

    Check

    • ?two barrels seat against each other cleanly
    • ?braid side has enough wraps for the material
    • ?no tag movement appears under a hard pull test

    Then

    • →Retie. braid creep or asymmetric failure.

  • Crossed wraps in one Uni barrel

    Check

    • ?That side slips and the join dumps
    • ?Inspect step 02

    Then

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

  • Barrels never butted

    Check

    • ?The join separates under load
    • ?Inspect step 04

    Then

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

  • Tag buried in a barrel instead of exiting

    Check

    • ?That barrel unravels
    • ?Inspect step 05

    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

Not ideal for

  • ×Extreme diameter mismatches
  • ×Ultra-slim braid-to-leader profiles (consider FG)

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