The Alpine Butterfly Knot

The alpine butterfly is mainly used in climbing when one needs to tie into the middle of a rope that may come under tension from either side. In this respect it is better than the figure of eight as strong side forces can deform that knot.

Attribute	Notes
Strength	70%
Ease of Tying	Not too difficult
Recognisable	Familiarity is best in this respect. The knot has the appearance of two interlocked overhand knots.
Also known as	Lineman's loop
Usage	Tying in to the middle of the rope. Isolating a damaged section of rope.
Advantages	Very strong. Once set, will not slip. Allows three way loading. Easy to undo.
Disadvantages	Difficult to tie one-handed. Requires some training/practice to master