Prusiks for Climbing
This page shows a few of the prusik knots and mechanical ascenders which you may find useful for climbing.
A prusik loop is a length of 5 or 6mm cord tied into a loop with a double fisherman's knot. They can be any length, but the most useful is tied from between 1.2m and 1.5m of cord, when formed into a loop it should reach roughly from the end of your outstretched fingers to the inside of your elbow.
Prusiks act as a releasable rope grab and have a variety of uses. Most commonly they are used as a backup for an abseil, so that if the climber inadvertently lets go of the rope they will not fall. Prusiks can also be used for ascending ropes, a useful skill if you're climbing on sea cliffs, and they are also important for securing a loaded rope in rescue techniques, including crevasses rescue. Securing the rope in this way makes it possible for the leader to escape the system so that they can either go for help, or perform a rescue themselves.
It is important to remember that prusik knots can slip, and it is a good idea to secure the rope with a knot. The prusik will hold the rope while you do this, but is best not trusted on its own.
This is the most commonly used prusik knot. It is quick to tie and doesn't jam. Most climbers would use one of these attached to a leg loop to protect an abseil. It is tied by making 4 or 5 wraps around the rope, and then clipping the two ends into a karabiner.
The kleimheist is tied in the same way as the French prusik, except that when it is clipped into a karabiner one end is first threaded through the other. it is best to thread the lower end through the upper as this creates more leverage and gives the knot greater holding power - which is its advantage over the French prusik. It is difficult to release under load, which makes it less suitable as an abseil backup.
If you have enough equipment with you the Bachman is a useful prusik to know. It is easy to slide up and down the rope, but locks hard when you load the end.
This is tied by threading the loop through itself with each wrap of the rope, like a repeated larksfoot.
There are many varieties of mechanical ascender on the market. They make the job of ascending a rope quicker and safer. They are really suited to the times when you know you will be ascending a rope rather than as a 'just in case' precaution, although the Petzl Tibloc and Wildcountry Ropeman are popular with cragging climbers.
The Traxion is an ascender and pulley all in one. It is useful for crevasse rescue, big wall hauling and, in my case, tensioning long slacklines. It can also be used for roped soloing.