How to Tie the Twin Bowline Bend

Usage

The Twin Bowline Bend is what you reach for when you need to join two ropes end-to-end and at least one of them is thick, stiff, or a different size than the other. Heavy mooring lines, towlines, large-diameter wire cabling, two ropes that just won't play nice with a smaller bend — that's this knot's job.

It isn't really a new knot at all. It's two standard bowlines, one tied in the end of each rope, hooked through each other's eye so the two 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 where the two eyes grip each other.

Why Learn the Twin Bowline Bend?

If you already know how to tie a bowline, you already know most of this knot. Tie one bowline, thread the second rope through its eye, tie a second bowline — that's the whole method. Ashley called it "about the most common of all Hawser Bends" of the sailing-ship era, and it's stuck around because it does one thing well that sleeker bends don't: it lets you join two ropes of very different size or material, each getting its own bowline sized to itself, and then take them apart again just as easily.

What it isn't is compact or fast. You're tying two full knots instead of one, it eats more rope than a simple bend, and it's bulkier than almost anything else that joins two lines. If your ropes are similar in size and you want something quick and low-profile, other bends do that better. This one earns its keep specifically on mismatched, stiff, or heavy-hawser-class rope where an easy-to-undo join matters more than tidiness.

Common Uses

This is a joining bend, prized for handling mismatched or heavy rope and for coming apart easily afterward.

Boating / Marine

Utility (Everyday Life)

Other Names Bowline Bend Two Bowlines Interlocking Bowline Bend Twinned Bowline Enhanced Bowline Bend Category Bends Boating / Marine Utility (Everyday Life)

Variations Enhanced Bowline Bend – a named anti-chafe refinement at the 90-degree crossing point, meant to stop the two ropes rubbing against each other.

Notable Features

• Builds on a knot you already know. There's no new mechanism to learn — it's the familiar bowline, tied twice and interlocked.
• Handles mismatched rope. Each rope gets its own bowline sized to itself, so joining a thick rope to a thin one, or two different materials, doesn't distort the knot the way a single shared bend can.
• Strong under a straight, sustained pull. It has a genuine service record joining hawsers and towlines under heavy, sustained load.
• Comes apart easily once slack. Each half unties with the bowline's own collar-break, which is exactly why sailors reach for it when they want the join apart again afterward.

Similar Knots

Zeppelin Bend vs. Twin Bowline Bend

• Advantage: the Zeppelin Bend is compact, holds its shape even when slack, and doesn't jam. It's the better pick when the ropes are a similar size or the join will sit through slack-cycling.
• Disadvantage: the Zeppelin has to be learned as its own knot; the Twin Bowline Bend costs no new learning if you already tie bowlines, and it has a stronger 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, and it's some sailors' pick for joining mismatched rope. It's the better everyday, light-duty join.
• Disadvantage: the Sheet Bend is a single tuck holding the whole join, against the Twin Bowline Bend's two full nipping loops — sailors are split on which handles mismatched sizes better, but the Twin Bowline Bend has the edge for heavy loads and for coming apart reliably after a hard pull.

Double Fisherman's Bend vs. Twin Bowline Bend

• Advantage: the Double Fisherman's Bend is the standard choice for life-safety and rescue joins — compact, checkable at a glance, and secure even when slack. It's the one climbing and rescue practice actually endorses.
• Disadvantage: the Double Fisherman's Bend 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's no lab-tested breaking-strength number for this exact bend — the assessment here rests on its structure and on Ashley's own period pull-testing, not on modern instrumented data. What that testing found: pulled to failure, the rope broke outside the bowlines every time, not at the crossing point. 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 — which is to say, secure under a steady pull, but not something that locks itself shut.

The one real weak spot the record points to is different from strength: under repeated cyclic rocking and movement, the two ropes can chafe against each other right at that 90-degree crossing. That's a wear concern, not a sudden-failure one. And because the bend is built from two bowlines, either one working loose when the line goes slack ends the whole join — that's two chances to fail loose, not a backup for each other.

Downsides

• Bulky: larger than simpler bends, with two protruding eyes and two tails. It won't run cleanly through blocks, chocks, or fairleads.
• Uses more rope: two full bowlines consumed per join means more rope length spent than a single-knot bend, which limits its use on short lines.
• Chafes at the crossing: under sustained rocking or cyclic movement, the two ropes can wear against each other where they cross — a durability concern on things like moorings left in place over time.
• Shakes loose when slack: each half is a bowline, and a bowline can work itself loose if left slack or cycled on and off. Since either half failing ends the join, this applies twice over.
• Not for climbing, rappelling, or search and rescue: no climbing or rescue authority endorses this bend for life-safety joins. Its bulky profile is the opposite of the low-snag shape those uses call for, and rescue rigging reaches for purpose-built bends instead.

How to Tie the Twin Bowline Bend

Step 1

Tie a standard bowline in the end of the first rope, leaving an eye. If you already know the bowline, skip ahead to Step 2 — if you need the refresher, here's the standard method:

1. Form a small loop (the "rabbit hole") in the standing part, with the standing part running underneath the loop.
2. Pass the working end up through the loop from underneath ("the rabbit comes out of the hole").
3. Take the working end around behind the standing part ("around the tree").
4. Pass the working end back down through the original loop, exiting on the same side it came up ("back down the hole") — the tail finishes inside the eye.
5. Tie, dress, set: hold the eye and standing part and pull the working end (with the returning eye leg) to tighten; leave a tail of at least 10–12 rope diameters.

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:

1. 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.
2. Form the rabbit hole loop in the second rope's standing part.
3. Pass the working end up through the loop, around behind the standing part, then back down through the loop, same as Step 1.
4. 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.

History

The technique goes back to the age of sail: Richard Henry Dana Jr. documented it in his 1841 book The Seaman's Friend, and Ashley later called it "about the most common of all Hawser Bends" of that period, a judgment echoed independently by Admiral Stephen Luce, who rated it "about the best." Hasluck's 1907 knotting manual confirms the same use in its own words, describing it as a way to join two ropes by tying a bowline in one, threading the other rope's end through that bowline's bight, and tying a second bowline with it — "often used to join hawsers together."

Ashley's own Book of Knots (1944) catalogues the bend as ABOK #1455, "Two Bowlines, or the Bowline Bend" — notably, the name "Twin Bowline Bend" doesn't appear in Ashley's text at all. That specific name traces to Cyrus Day's 1953 The Art of Knotting and Splicing, where it's catalogued as its own entry immediately following "Bowline Bend" on the same page. In the modern era, the "Twin Bowline Bend" name is kept alive mainly by tutorial creators and by a dedicated feature from ITS Tactical, even though the name itself doesn't appear on most major knot-reference sites.

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 reached for 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. It has no endorsement from any climbing or search-and-rescue authority, and its bulky, chafe-prone profile is the opposite of what those uses call for. Reach for 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 completely different, single-rope knot with a reinforced loop, not two bowlines joining two ropes. Each half of the Twin Bowline Bend needs to be dressed and set 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 or uneven crossing is exactly where the chafe problem shows up.

This bend has no endorsement from any climbing or search-and-rescue authority and shouldn't be used for life-safety joins like a rappel rope join or rescue haul system — reach for a purpose-built bend there instead. And because each half is a bowline, neither can be untied while the line is under load; take the tension off first, then release each collar in turn.