Prusiks, Which, When & How?

After a conversation about Prusiks with a friend, thought i'd write this to save time explaining again & again!
The Prusik loop is a cord loop, usually made from 5mm thickness, typically cut to lengths of 150cm lengths. They where first used & invented by Dr Karl Prusik in 1930's. There is now 3 main variations of the knot; the French/Autoblock, original prusik and Kleimheist.

Author abseiling on double ropes, was tied off to take picture.

Double Fishermans - Used to attach two lengths of rope together to create either a longer piece of rope/ cord or a loop. This knot should be weighted by body weight to make sure its snug before use. See pictures opposite on how to tie.

Prusik Uses - 
* To Ascend a fixed rope
* As a backup while abseiling
* In rescue scenarios (not covered here)
* Help when dealing with heavy loads (not covered here)

French/Autoblock Prusik

Where the cord is wrapped going up or down the rope in which you are about to use. Best use is abseiling as requires a heavy load for it to engage. However as it slides really easily it's not good for ascending the rope.

Original Prusik

Used for ascending the rope or when you don't want the prusik to move often. Sometimes requires some fiddling to get it to move when it's had a heavy weight on it.

Kleimheist

Very similar to the French, but after you have curled the cord around the rope the end is passed through the loop at the start. Its brilliant for ascending the rope as bights when weighted less and does not slip as often. It is however no good for abseiling as it may not grab the rope at all.

Carrying Prusiks

When trad climbing I always carry one, (two if on sea cliffs), and a 60cm sling on a small d-shaped karabiner on the back of my harness. Its better being there and carrying the slight extra weight than not having it when it's really needed! On the left I have also included how I carry them wrapped up, there are different ways of doing this, but this is the method I prefer.
​First make a loop, then wrap the prusik up the loop a few times, when you get near the top pass the end through the two loops at the top and pull.

Abseiling With a Prusik​

To abseil with a standard belay plate and Prusik I thread the rope you're going to ab with into the belay plate as if you where going to belay with it. Then do a French prusik underneath, put a screw gate karabiner on the end of the loop and clip it to the inside of your leg loop. Weight and make sure prusik does not touch the belay plate as if it does it will not engage. If it does extend your belay plate from your harness using a short (60cm) sling, larks footed to your abseil/belay loop at one end, belay plate at the other.

Ascending The Rope

To ascend clip one kleimheist or ordinary prusik directly to your abseil/belay loop on your harness using a screwgate, then put another kleimheist above with another screwgate attached, but this time put a 120cm sling or 240cm halved into the screwgate. Use the sling to stand up on the top prusik to release the weight off the one connected directly to you, slide it up, re-weight and slide the foot one up. Repeat process until you get where you need to be!
As a backup if your ascending a long distance put knots in the rope below the prusik so that if the knot does not engage you won't slip all the way to the bottom.

Hopefully I have covered most things, feel free to comment below! :)