As well as having a groovy name, the alpine butterfly is a super useful knot which you can use to form a fixed loop in the middle of a rope. It can be tied without access to either of the ends, providing a clip-in point which can be loaded in 2 or 3 directions.
How To Tie an Alpine Butterfly Knot
First, form a loop in the rope.
Twist the loop so it becomes two loops. Then pull the top of the upper loop behind and underneath the line of the rope.
The upper loop is now beneath the line of the rope. The next step is to push it through the original first loop.
Finally, pull it tight.
You should end up with this:
An alternative way to tie the alpine butterfly is to wrap it around your hand three times as shown below. Pull the top wrap down over the other two, then back up behind them.
Using the Alpine Butterfly Knot
You can use two opposing screwgate carabiners to attach it to your belay loop. This is really useful for glacier travel, or any other occasion where you need to tie in to the middle of the rope.
The size of the loop can be adjusted. For roping up on a glacier, a longer loop may be needed to give the climber more room to move away from the taut rope. The alpine butterfly is also easier to unfasten when it has been heavily loaded than other knots such as the figure of 8.
The alpine butterfly can be used to equalize a two-piece belay. Tie a large-looped alpine butterfly to one piece and a clovehitch to the other piece. Adjust the clovehitch to fine tune the equalization. This is useful for fixing ropes, such as on a big wall.
The alpine butterfly can also be used to isolate damaged sections of rope.
This is useful when using your rope as a fixed line or in a situation where the rope will not pass through any carabiners. Obviously, you will not be able to lead climb with a knot in your rope!