How to Tie the Twin Bowline Bend
Usage
The Twin Bowline Bend joins two ropes end-to-end when at least one of them is thick, stiff, or a different size than the other — heavy mooring lines, towlines, large-diameter cabling. It isn't a new knot: it's two standard bowlines, one in the end of each rope, hooked through each other's eye so the loops interlock and cross at roughly 90 degrees. Each half holds the way a bowline always holds; the only new part is that crossing point.
Why Learn the Twin Bowline Bend?
If you can tie a bowline, you already know most of this knot — tie one, thread the second rope through its eye, tie a second. It lets you join two ropes of very different size or material, each getting its own bowline sized to itself, and take them apart again just as easily. What it isn't is compact or fast: two full knots, more rope spent, and bulkier than almost anything else that joins two lines.
The whole bend rests on tying a clean bowline twice, which is worth drilling until it is automatic. The Knot IQ app lets you rotate a finished bowline in 3D and watch the collar form before you try it with two ropes at once.
Common Uses
This is a joining bend, used for mismatched or heavy rope and for joins that must come apart easily afterward.
Boating / Marine
- Joining hawsers, heavy mooring lines, and towlines — its original, best-documented job since the age of sail
- Joining large-diameter cabling and mooring lines where the rope is thick and stiff
Utility (Everyday Life)
- Joining two ropes of dissimilar size or material
- Joins you'll want to untie quickly once the load comes off
ABOK Number
(Ashley Book of Knots)
Other Names
Category
|
Variations
|
Notable Features
- Builds on a knot you already know. No new mechanism — the familiar bowline, tied twice and interlocked.
- Handles mismatched rope. Each rope gets its own bowline, so a thick rope and a thin one don't distort the knot the way a single shared bend can.
- Strong under a straight, sustained pull. A genuine service record joining hawsers and towlines under heavy load.
- Comes apart easily once slack. Each half unties with the bowline's own collar-break.
Similar Knots
Zeppelin Bend vs. Twin Bowline Bend
- Advantage: the Zeppelin Bend is compact, holds its shape when slack, and doesn't jam — the better pick for similar-size ropes or a join that will slack-cycle.
- Disadvantage: it has to be learned as its own knot, and it has less of a track record on grossly mismatched or stiff rope.
Sheet Bend vs. Twin Bowline Bend
- Advantage: the Sheet Bend is faster to tie and far less bulky — the better everyday, light-duty join.
- Disadvantage: it is a single tuck holding the whole join. Sailors are split on which handles mismatched sizes better, but the Twin Bowline Bend has the edge for heavy loads and for coming apart after a hard pull.
Double Fisherman's Bend vs. Twin Bowline Bend
- Advantage: the Double Fisherman's Bend is the standard for life-safety and rescue joins — compact, checkable at a glance, secure even when slack.
- Disadvantage: it famously jams after a heavy load, where the Twin Bowline Bend's two bowlines fall open easily once the tension is off.
Security Level
There is no lab-tested breaking-strength number for this exact bend; the assessment rests on its structure and on Ashley's own period pull-testing, which found the rope broke outside the bowlines every time, not at the crossing. Each half holds by the same nipping-loop grip as a standard bowline, so the bend is only as secure as two bowlines tied well and dressed correctly — secure under a steady pull, but not something that locks itself shut. Because it is built from two bowlines, either one working loose when the line goes slack ends the whole join.
Downsides
- Bulky: two protruding eyes and two tails. It won't run cleanly through blocks, chocks, or fairleads.
- Uses more rope: two full bowlines per join, which limits it on short lines.
- Chafes at the crossing: under sustained rocking or cyclic movement the two ropes wear against each other where they cross — a durability concern on moorings left in place.
- Shakes loose when slack: a bowline can work itself loose if left slack or cycled on and off, and here that applies twice over.
- Not for climbing, rappelling, or search and rescue: this bend is not built for life-safety joins.
How to Tie the Twin Bowline Bend
Step 1
Tie a standard Bowline in the end of the first rope, leaving an eye — see that article for the full step-by-step.
Step 2
Tie a second, independent bowline in the end of the second rope — but first pass that rope's end through the first bowline's eye, so the two loops interlock. Same bowline, same five moves, just formed through the first eye instead of in open air:
- Pass the second rope's working end through the first bowline's eye before you start — this is the only thing that's different from tying a plain bowline.
- Form the rabbit hole loop in the second rope's standing part.
- Pass the working end up through the loop, around behind the standing part, then back down through the loop, same as Step 1.
- Dress and set this bowline just like the first: tail inside its own eye, tail length 10–12 rope diameters.
Step 3
Dress both bowlines individually, exactly as you would a single bowline: collar snug against the standing part, tail lying inside its own eye.
Step 4
Seat the two eyes flat against each other so the ropes cross cleanly at that 90-degree point, with no twist between the loops, then set each knot by hand and load the bend gently so the interlock seats without either bowline cocking sideways.
Two ropes of different diameter make the difference obvious, and a spool of 750 lb bushcraft paracord alongside a heavier line is an easy way to practise the mismatched-rope case this bend exists for.
History
The technique goes back to the age of sail. Richard Henry Dana Jr. documented it in The Seaman's Friend (1841), and Hasluck's 1907 knotting manual describes the same method — tie a bowline in one rope, thread the other rope's end through its bight, tie a second bowline — as something "often used to join hawsers together."
Ashley catalogues it in The Ashley Book of Knots (1944) as ABOK #1455, under the title "Two Bowlines, or the Bowline Bend," and calls it "about the most common of all Hawser Bends" of that period. One thing worth being precise about: the phrase "Twin Bowline Bend" never appears in Ashley's text. That name comes from later knotting literature, not from him.
FAQ
What knot do you use to join two ropes of different diameters?
The Twin Bowline Bend is built exactly for this. Instead of one knot trying to grip two mismatched ropes at once, each rope gets its own bowline sized to itself, so a thick rope and a thin one — or two different materials — can be joined without distorting the knot.
Is the Twin Bowline Bend strong enough to join two ropes for a heavy load, like a tow or mooring line?
Yes — that's its original job. It's been used since the age of sail for joining hawsers, heavy mooring lines, and towlines, and Ashley's own period pull-testing found the rope broke outside the bowlines every time, not at the crossing. There's no modern lab-tested breaking-strength number for this exact bend, but the service record for sustained, straight-line heavy pulls is solid.
Can you untie the Twin Bowline Bend after it's been under load?
Yes, and easily, once the tension is off. Each half is a plain bowline, and a bowline's collar breaks open by hand even after a hard pull — that's exactly why sailors used this bend when they wanted a heavy join apart again afterward. It cannot be untied while either rope is still under load; slack the line first, then release each collar in turn.
Is the Twin Bowline Bend safe to use for climbing or rescue?
No. Its bulky, chafe-prone profile is the opposite of what those uses call for. Use a purpose-built bend, like a Double Fisherman's Bend, for any life-safety join instead.
Important Notes on Safety
Don't mistake this for the Double Bowline (sometimes called the Eskimo Bowline) — that's a single-rope knot with a reinforced loop, not two bowlines joining two ropes. Dress each half exactly like a single bowline: collar snug against the standing part, tail lying inside its own eye. Seat the two eyes flat against each other at the crossing with no twist between them, since a twisted crossing is where the chafe problem shows up. Do not use this bend for life-safety joins such as a rappel rope join or a rescue haul system, and never try to untie either half while the line is still loaded — take the tension off first.
