Description
The alpine butterfly loop is a knot used to form a fixed loop in the middle of a rope.
Use
The loop is typically attached to a climbing harness by carabiner.
It can also be used to isolate a worn section of rope, where the knot is tied such that the worn section is isolated in the loop (which of course does not receive a carabiner nor bear any loads in this case). The loop portion is isolated when the other two legs are loaded, and in fact the butterfly can be tied as a bend with the ends emerging where the loop would be.
Releasing
Non-jamming
Security
Forms stable, secure loop after initial setting. Allows for the knot to be loaded three ways; by each end of the main line and the loop.
Other names
Butterfly Loop, Alpine Butterfly Knot, Butterfly Knot, Lineman’s Loop, Lineman’s Rider.
Tying
1. Form a bight in the middle of a rope.
2. Twist it twice to create two loops, one on top of the other. Make the one on top larger.
3. Bring the top loop down over the bottom loop, folding it at the junction between the two loops. Now the bottom loop should be essentially inside the first loop.
4. Take the farthest edge of the bottom loop from the first loop and bring that through the second (smaller) loop.
5. Tighten all the way.