Alpine butterfly knot

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Alpine butterfly knot
Alpine butterfly loop.jpg
An alpine butterfly knot with a carabiner.
Names Alpine butterfly knot, Alpine butterfly loop, Lineman's Loop, Butterfly Loop
Category loop
Efficiency 53% with both ropes loaded
67% with loop loaded
Origin Ancient
Related Farmer's loop, Artillery loop, Span loop
Releasing Non-jamming
Typical use Used by climbers and mountaineers. Can be used to isolate a worn section of rope.
ABoK #331, #1053


The Butterfly Loop, also known as the Lineman's Loop or alpine butterfly loop, is a "non-jamming loop on the bight", a loop which may be tied in a rope with two fixed ends, and can take loads on both ends of the original rope, and on the loop. The alpine butterfly loop is a symmetrical and more secure version of the butterfly loop.

Tying an alpine butterfly on the bight.

Usage

The Butterfly Loop has a high breaking strength and is regarded by mountaineers as one of the strongest knots to attach climbers to the middle of a rope, such that they have room to move around even when the main rope goes tight, and they can be supported in either direction from the main rope. 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 used for the centre of the loop.

Advantages

  • Does not reduce the strength of the rope by very much
  • Will not slip (after initial settling)
  • Allows for the knot to be loaded three ways (each end of the main line and by the loop)
  • Relatively easy to undo after loading (more difficult if wet)

Disadvantages

  • Difficult to adjust the size of the bight
  • Difficult to tie one-handed
  • Difficult to casually inspect
  • Requires some training/practice to master

See also

External links