| Type | Friction hitch |
| Needs | Thin accessory cord (smaller than the main rope) |
| Main uses | Ascending, rappel backup, crevasse rescue |
| Difficulty | Intermediate (requires instruction) |
Named after Austrian climber Dr. Karl Prusik, who described the hitch in 1931.
A prusik knot is a friction hitch tied with a thin loop of cord around a climbing rope. When weighted it grips the rope and holds; when the load is released it slides freely by hand. This lets climbers ascend a rope, back up a rappel, or build a hauling system for crevasse rescue.
It is named after Austrian climber Dr. Karl Prusik, who described it in 1931.
How it works
A loop of accessory cord, thinner than the main rope, is wrapped around the rope and passed through itself two or three times. The diameter difference makes the wraps bite under load; relax the load and the hitch loosens enough to slide. Two prusiks alternated up a rope form a simple ascending system, an alternative to a mechanical ascender.
When climbers use it
Common uses are emergency rope ascent, backing up a rappel, and rigging mechanical advantage for hauling. Because it needs only a short length of cord, many climbers carry a cordelette or dedicated prusik loops on every trad and alpine route.
Common mistakes & safety
The two critical errors are using cord that is too close in diameter to the rope (it slips) and tying a backup prusik so long it can jam against the rappel device. Always test the hitch under body weight first. This article is educational and not a substitute for hands-on instruction from a qualified climbing instructor.
Frequently asked questions
What cord do you use for a prusik?
A loop of accessory cord noticeably thinner than the rope it grips — commonly 5–7 mm cord on a 9–11 mm rope. The diameter difference is what lets the hitch bite. Cord that is too thick will slip instead of gripping.
How many wraps does a prusik need?
Usually three wraps, but more may be needed on icy, wet, or very smooth ropes to hold securely. Always test that the hitch grips under body weight before trusting it, and add a wrap if it slips.
Is a prusik knot reliable as a rappel backup?
Yes, when tied with the correct cord and number of wraps and kept short enough that it cannot reach the rappel device. It is a widely taught backup, but it must be tested and managed carefully, since a prusik jammed against the device can fail to grip.
Sources
- Self-rescue and ascending technique — American Alpine Club
- Friction-hitch technical notice — Petzl