Prusik knot

Prusik knot (technically a hitch) is a very versatile hitch used in abseiling, pulley systems, prusiking up the ropes. In some of the applications it can be replaced by tibloc and various traxions and similar devices which provides improved comfort of use by unidirectionally moving seamlessly on the rope while providing the same stopping functionality as prusik.

Prusik knot
Other names	Prusik, prusik hitch
Use(s)	abseiling, advanced rope techniques including (self-)rescue techniques
Pros	Fast, clean, just an accessory cord or a sling needed
Cons	Compared to traxion, tiblocs and such it is a bit tedious to get loosen in some cases and it must be moved actively
Category	Hitch
Strength	~5-8 kN when a 5-7mm accessory cord is used

Tying

Number of loops varies based on required amount of friction.

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  Wrap an accessory cord around the rope (1)

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  Do it few more times (2)

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  Dress the prusik by pulling the rest of the accessory cord (3)

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  Test if it blocks (4)

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  Perform visual inspection (5)

Diameter recommendations

this section is not yet inspected thoroughly, statements might be incorrect and/or misleading!

Based on the cord load limits, 5 mm (5.1 kN) and 6 mm (10 kN) reep cords are generally recommended for tying prusiks. General rule of a thumb is that to ensure reliable blocking, prusik cord should have roughly 1/2 of a diameter of the rope on which the prusik is tied on. For a standard climbing rope (~9.7 mm), the slightly-above-recommendation 6 mm cord has the advantage that it is easier to loosen and the loading limit of the cord is substantially higher than in case of the 5 mm cord. However, in some rope-prusik combinations, it might not block readily enough. In some cases, 5 mm prusik is hard to loosen under and after load. Both for 5 mm and 6 mm cord, testing in safe environment is highly recommended.