How to Tie the Double Alpine Butterfly (Bi-Directional Loop)
Usage
The double alpine butterfly puts two independent, fixed loops mid-rope, dressed opposed — one on each side of the mainline, at roughly 90 degrees to it. That opposed dressing is the whole point: it gives attachment points on both sides of a running line from a single knot. It's the single alpine butterfly knot doubled and set counter-directionally, each loop keeping its own nipping collar so loading one doesn't collapse the other.
Why Learn the Double Alpine Butterfly?
Most mid-line loop knots give one attachment point; this gives two, on opposite sides of the rope, without untying or re-threading an end — useful wherever a line must serve gear from both directions, or to bracket a damaged section between two loops. The single alpine butterfly remains the better choice whenever one loop is enough.
Common Uses
Search and Rescue
- Clip-in points on a shared safety line, each loop independently loadable without disturbing the others.
Climbing and Rigging
- Multiple secure mid-line attachment points where the rope's ends aren't reachable.
- More roll-resistant than a bowline on a bight or a figure-8 double loop, which can both roll under an off-angle pull.
Utility
- Distributing load across two loops, or isolating a damaged section.
Other Names
Category
|
Notable Features
- Tied in the Bight: No rope end needed — both loops form mid-rope, so it works on lines with gear already attached past the knot.
- Non-Collapsing: Each loop keeps its own nipping collar, so loading one eye can't collapse the other.
- Four-Way Loadable: From both loops and ends, either loop to either end, end-to-end with loops free, or loop-to-loop.
Similar Knots
Spanish Bowline vs. Double Alpine Butterfly
- Advantage: Purpose-built for a loaded mainline that keeps running past the knot, loops staying independent.
- Disadvantage: The Spanish Bowline's two adjacent, adjustable loops suit an improvised rescue seat around a person — a job this knot isn't shaped for.
Security Level
Each loop is a full alpine-butterfly nipping collar, and every source agrees the loops won't collapse under normal use. The one caveat: the bi-directional function is entirely dressing-dependent — uneven dressing lets one collar overload, and the traditional geometry's weak-side eye jams first. One enthusiast's field pulls put it at roughly 400 kg before binding hard, versus an improved variant easy to untie past 1,000 kg — directional, not lab data. Stiff rope worsens the jam risk.
Downsides
- Careful Dressing Required: The opposed 90-degree set is the function — mis-dress it same-direction and you still have two loops, but lose the bi-directional capability with no obvious visual sign.
- Jams Under Heavy Shock Load: The weak-side eye can bind hard after a heavy or shock load, especially in stiffer rope.
- Fiddlier Than the Single Loop: A fourth palm wrap, a second collar, and the counter-directional set add time and extra ways to get it wrong.
- Not a Life-Safety Tie-In: No source positions this as a primary harness attachment. It's a utility, SAR, and rigging clip-in — use a discipline-certified tie-in for primary life-safety attachment.
Structure
The double buys independence at the cost of twist. Each loop keeps its own nipping collar, so the two eyes are mechanically independent — which is why it loads safely from four directions, with the opposed collars pointing to opposite sides of the line. The trade-off is a half-twist in the traditional geometry's eye legs — a stress concentrator that makes the weak-side eye jam first under heavy load, while the single alpine butterfly stays famously easy to untie.
History
No pre-modern source documents the double-loop form directly — it postdates the single alpine butterfly's early-1900s appearances and has no Ashley Book of Knots number of its own. Modern references, including Wikipedia, treat it as a derivative of the single alpine butterfly / lineman's loop and the harness/artilleryman's loop family. The fullest account of how it's tied comes from enthusiast knot-tyer field testing.
How to Tie a Double Alpine Butterfly
This is the hand-winding method — the single alpine butterfly's motion with one extra wrap and a second loop to dress. Practise on a length of 750 lb paracord until the wrap-and-lift becomes automatic.
Step 1
Wrap the rope across your open palm four times.
Step 2
Position turns 2 and 3 — the two middle wraps — near your fingertips.
Step 3
Pick up turns 2 and 3 and tuck them under the other two turns.
Step 4
Slide the resulting loops off your hand.
Step 5
Tighten by pulling on the loops and both standing ends. Dress each collar separately so both loops sit clean, then set them opposed — one emerging on each side of the mainline, at roughly 90 degrees to it. Snug each collar in turn, evenly, so neither one steals slack from the other. A half-twist in the eye legs at this point is normal for the traditional geometry, not a mis-tie.
Loop size locks in once the collars set, so size both loops during the wrap in Step 1 — the easiest place to end up lopsided.
If the wrap-and-lift is hard to picture, the Knot IQ app shows it in full 3D — the counter-directional dressing is hard to judge from flat diagrams.
How to Untie a Double Alpine Butterfly
Remove all load from both loops and ends first. Flex the knot body to break each collar's set, then peel each off its eye legs — working the weak-side eye first if the knot has carried a heavy load. After a heavy load, expect that eye to need real effort, a couple of minutes per side.
FAQ
What makes the double alpine butterfly bi-directional?
Its two loops are dressed opposed — one on each side of the mainline at roughly 90 degrees — giving attachment points on both sides of the rope. Dress both the same direction and you still have two loops, but lose the both-sides capability — the whole reason to tie it over a plain double loop.
I see a half-twist in the eye legs — is that a mis-tie?
No. In the traditional double-eye geometry a half-twist in the eye legs is unavoidable, not a tying error. Insert a carabiner into a finished double butterfly, then untie it back to a single butterfly without opening the gate — the ring stays trapped, proving the twist is structural.
How many ways can you safely load a double alpine butterfly?
Four: from both loops and ends together; either loop to either end; between the two ends with loops free; or between the two loops with ends free.
Can you tie it mid-rope with no access to either end?
Yes. It's tied in the bight, so you never need a free end — which is why it works as a clip-in point along a shared safety line running past the knot in both directions.
Important Notes on Safety
- Not a life-safety tie-in. No source endorses it as a primary harness attachment, and it reads clean even when mis-dressed — poor inspectability for a life-safety knot. Use a discipline-certified tie-in instead; the single alpine butterfly or a Spanish bowline fit that role better.
- Dress the opposition every time. The 90-degree opposed set is not cosmetic — it's the function. Check it before loading, not after.
- Heavy shock loads can jam the weak-side eye, especially in stiff rope — a rigging risk, not a strength failure. The knot holds; the untying afterward costs you time.
- Watch for lookalikes. It shares the nickname "Alpine Bunny Ears" with the unrelated figure-8 double loop, and the traditional vs. girth-hitch geometries look nearly identical — confirm which a tutorial taught you before relying on it.
