How To Use Prusiks

Ideas by Chris, words by Anne

Some years ago, I was sea-cliff climbing at Gogarth in north Wales. My second was on a tricky overhanging pitch, and he was really struggling. We couldn’t communicate because of the background noise from the sea, and I couldn’t lower him back down as the climb overhung the sea. My only option was to escape the system using prusik loops, climb down the rope using prusik loops, build another belay and haul my second up to it using – you’ve guessed it – prusik loops.

Standard prusik knot, used for ascending and descending a rope

Standard prusik knot, used for ascending and descending a rope

If you are regularly out on the crags, then you need to know how to use prusik loops. These simple pieces of kit can literally be a life saver if you keep them on your harness and know how to use them properly.

What are prusik loops?

Prusiks are short pieces of soft accessory cord of different thickness, tied into loops of varying length using a double fisherman’s or overhand knot.

What are they for?

The two most common uses for prusiks are:

  • a back-up when abseiling
  • personal safety when rigging top ropes

They can also be used for:

  • an extra quick draw
  • a string for your chalk bag
  • a sling to abseil from
  • escaping the system
  • setting up a pulley hoist system in an improvised rescue scenario
Attaching a French prusik to a double rope before abseiling

Attaching a French prusik to a double rope before abseiling

The prusik knot is under the right hand, and the karabiner is attached to the harness leg loop

The prusik knot is under the right hand, and the karabiner is attached to the harness leg loop

What diameter of cord is best?

This depends on what ropes you normally climb on. Generally a 4mm prusik is best on 7.5mm skinny ropes, but 5mm or 6mm works well on most normal ½ ropes (8-8.5mm) and full single ropes.

How long should a prusik loop be?

I usually carry three loops: 2 short, around 30cm, and one long, around 120cm.

The short length is perfect for making an effective French prusik, able to hold but still release under load: three turns for abseiling on a double rope, and four turns on a single rope.

The longer length is handy as an extra sling to use as a foot loop when ascending a rope, or to leave behind as abseil tat on an abseil station, or as a chalk bag string. I usually use 7mm chord for this.

Which knot?

I use two similar knots that can be used for most things - the standard prusik knot, and the French prusik knot.

I have developed my own version of the French prusik. In the usual version, the loop is wrapped round the rope from top to bottom, with the ends brought together in the middle from the top and the bottom. In my version, I tie a standard prusik knot, but I keep on wrapping the loop around the rope until I have approx 1" left at each end, and then clip the ends together. I find this is more stable because it is less prone to elongating, but it still releases under load.  

Want to know more? Want some hands-on tuition from an expert? Book yourself a place on our Rope Skills & Rescues Masterclass on 18th May 2017. Can’t wait that long? Choose a date that suits you, make a booking for a day of guiding – and you decide on the content of the day.