Prusik

Last updated
Prusik knot
Prusik.jpg
NamesPrusik knot, Prusik hitch
Category Hitch
Origin Karl Prusik, 1931
Related Bachmann knot, Blake's hitch, Klemheist knot, Cow hitch
Releasing Non-jamming
Typical use Climbing
ABoK #1763

A Prusik ( /ˈprʌsɪk/ PRUSS-ik) is a friction hitch or knot used to attach a loop of cord around a rope, applied in climbing, canyoneering, mountaineering, caving, rope rescue, ziplining, and by arborists. The term Prusik is a name for both the loops of cord and the hitch, and the verb is "to prusik". [1] [2] [3] More casually, the term is used for any friction hitch or device that can grab a rope (see autoblock). Due to the pronunciation, the word is often misspelled Prussik, Prussick, or Prussic.

Contents

The Prusik hitch is named after its putative inventor, Austrian mountaineer Karl Prusik. It was shown in a 1931 Austrian mountaineering manual for rope ascending. It was used on several mountaineering routes of the era to ascend the final summit, where a rope could be thrown over the top and anchored so that climbers could attain the summit by prusiking up the other side of the rope.

A prusik made from cord does little or no damage to the rope it is attached to, although some mechanical prusiks can cause damage, especially if the device slips during climbing.

Advantages

Climbers carry Prusik cords mainly for emergency use, as they are lighter than other options. Prusiks are fast to place on a rope, and with practice can be placed with one hand. The loops of cord can be used as slings, and are thus multi-functional in a climbing environment.

Prusiks will work around two ropes, even two ropes of different diameters. Prusiks provide a strong attachment that will not damage or break the rope, and so are used in some rope-rescue techniques. Prusiks are good to use in hauling systems where multiple rope-grabs may be needed, and where mechanical rope-grabs are not available.

Prusiks are far less likely to damage the main rope than mechanical rope-grabs such as a jumar. A prusik which is overloaded will initially slip, causing no damage. If loaded to great excess, the worst result is that it slides until the heat of friction causes physical failure of the prusik cord, rather than the rope. Mechanical rope-grabs when overloaded will sometimes damage the sheath of the rope, or in extreme cases sever the rope entirely.

Depending on which variant is used, Prusik hitches have the advantage of working in both directions. Most mechanical rope-grabs work like a ratchet, moving freely up the rope, but grabbing when a load is placed down on them. Traditional Prusiks (such as those shown below) will grab when pulled by the tail, either up or down, and will slide either way when pushed by the barrel.

Although the Prusik Climb technique may be seen as outdated by some, the US Army still includes it in its annual Best Ranger competition. Rangers in the competition routinely make it up a 65-foot rope in under a minute.

Disadvantages

Prusiks are ineffective upon frozen wet ropes. This is due to the necessity of friction for the Prusik to function. Mechanical devices (such as jumars) to grab the rope are available that are easier and faster to use, but heavier, more expensive, and bulkier.

After being put under a great deal of weight, the Prusik can be quite constricted and difficult to untie. This varies, depending on the relative diameter of the ropes.

Although prusik can be used in a general way, the Prusik hitch is a specific hitch. The two main alternatives are the Bachmann knot and the Klemheist knot (see also the Tarbuck knot). Each has its advantages and disadvantages, mainly in how easy they are to use for climbing a rope. Another variation is the Autoblock or French Prusik, used by some people as a backup knot while rappelling.

A Purcell Prusik is a related cord popular among cavers and rope-rescue people. A somewhat longer loop than the normal Prusik is used around the rope, then a second Prusik is used around the cord loop itself to form a foot loop. The foot loop is then easily adjusted in length and position.

A Prusik-Minding-Pulley is common in rope rescue. The rope to be pulled is passed through a pulley, and a Prusik is tied on the loaded side. When the rope is pulled, the Prusik rides against the pulley, and the rope slides through it; but when the rope is relaxed, the Prusik slides away from the pulley and grabs the rope. Thus, the combination acts as a ratchet.

The Farrimond friction hitch is a kind of taut-line hitch that is similar in form to a Prusik.

Equipment

A Prusik loop is made of narrow but strong nylon accessory cord tied into a loop using a double fisherman's knot. [4] A sling or prusik-dedicated sewn loop can also be used. Note that Dyneema/Spectra has a very low melting point and should not be used in Prusik hitches unless the cord or sling is specifically engineered for it (as seen in some sheathed constructions). The length of this loop depends on the application. For instance, the loop used for an Auto-Bloc might only be 20 cm, whereas the foot loop for climbing a rope might work better with a length of 100 cm or more. As a general rule, longer loops are preferable over shorter ones, as a loop can always be shortened by tying a knot in it.

The effectiveness of the Prusik hitch relies on the surface area between the hitch and the main line, and the diameter of the cord used. Normally the greater difference between the diameter of the cord used for the hitch and the main line, the greater the ability for the hitch to hold. However, the smaller the diameter of the cord used, the lower its safe working load. In addition, smaller diameter cords often jam too tight when placed under load, and are hard to handle when wearing gloves.

Tying

The Prusik is tied by wrapping the "tail" of the prusik loop around the rope a number of times, usually 2-4 times depending on the materials, (each time, through the other (bow) end), forming a barrel around the rope with a tail hanging out from the middle. When the tail is weighted, the turns tighten and make a slight bend in the rope. When weight is removed, the loop can be moved along the rope by placing a hand directly on the barrel or pushing it from "behind". Breaking the Prusik free from the rope after it has been weighted can be difficult, and is most easily done by pushing the bow, (the loop of cord which runs along the barrel, from the top wrap to the bottom wrap), along the tail a little. This unwinds the barrel wraps to loosen the grip of the hitch, and makes movement easier.
Note: Step 2 is also called a girth-hitch (a single wrap), and is not a good prusik (yet). Note: Step 4 has a twist in the webbing that is inconsistent with the preceding images, but will not affect use except to make it slightly more difficult to loosen after a heavy loading. (Of course, this is not an issue when using normal round cord for the prusik.)

Many materials may be used to tie a prusik. The exemplary prusik knot illustrated above is made with webbing, however webbing is not recommended for heavier loads and/or securing a person since it has been shown to slip. [5] Adding more wraps increases the grip.

A double strap or sling for hoisting a spar at middle length. One bight is rove through the other and a tackle is hooked to the single bight.

Applications

In addition to being a useful rope-grab for rope-rescue applications, Prusiks are popular for:

When to carry (climbing, kayaking)

All sorts of climbers carry prusiks as standard equipment "just in case". Prusiks are unlikely to be needed on short climbs where the climber can be readily lowered to the ground; conversely, they may prove useful where the climber cannot be lowered, for instance from a high cliff or due to a hazard underneath the climber.

Prusiks can be tied using other climbing equipment, such as slings already carried by the climber. Three loops allow the climber to pass a knot in the rope, a difficult task without a third loop.

Kayaking: For kayaking, a prusik can be used in a similar way as in climbing; for rescuing people and equipment from a river, a prusik or two with a set of pulleys to create a Z-drag is preferred.[ citation needed ]

See also

Related Research Articles

Knot Method of fastening or securing linear material

A knot is an intentional complication in cordage which may be practical or decorative, or both. Practical knots are classified by function, including hitches, bends, loop knots, and splices: a hitch fastens a rope to another object; a bend fastens two ends of a rope to each another; a loop knot is any knot creating a loop, and splice denotes any multi-strand knot, including bends and loops. A knot may also refer, in the strictest sense, to a stopper or knob at the end of a rope to keep that end from slipping through a grommet or eye. Knots have excited interest since ancient times for their practical uses, as well as their topological intricacy, studied in the area of mathematics known as knot theory.

Truckers hitch

The trucker's hitch is a compound knot commonly used for securing loads on trucks or trailers. This general arrangement, using loops and turns in the rope itself to form a crude block and tackle, has long been used to tension lines and is known by multiple names. Knot author Geoffrey Budworth claims the knot can be traced back to the days when carters and hawkers used horse-drawn conveyances to move their wares from place to place.

Traditional climbing Style of rock climbing

Traditionalclimbing, is a style of rock climbing in which a climber or group of climbers place all gear required to protect against falls, and remove it when a pitch is complete. Traditional bolted face climbing means the bolts were placed on lead and/or with hand drills. The bolts tend to be much farther apart than sport climbs. For example, a trad bolted route may have bolts from 15–75 feet apart. A sport route may have bolts from 3–10 feet apart, similar to a rock climbing gym. The term seems to have been coined by Tom Higgins in the piece "Tricksters and Traditionalists" in 1984. A trad climber is called a traditionalist.

Climbing harness

A climbing harness is an item of climbing equipment for rock-climbing, abseiling, or other activities requiring the use of ropes to provide access or safety such as industrial rope access, working at heights, etc. A harness secures a person to a rope or an anchor point.

Klemheist knot

The klemheist knot or French Machard knot is a type of friction hitch that grips the rope when weight is applied, and is free to move when the weight is released. It is used similarly to a Prusik knot or the Bachmann knot to ascend or descend a climbing rope. One advantage is that webbing can be used as an alternative to cord. The Klemheist is easier to slide up than a Prusik. The klemheist is also a way to attach a snubber to the anchor rope of small boats, with the advantage that it is easy to undo.

Glossary of climbing terms List of definitions of terms and concepts related to rock climbing and mountaineering

This glossary of climbing terms is a list of definitions of terms and jargon related to rock climbing and mountaineering. The specific terms used can vary considerably between different English-speaking countries; many of the phrases described here are particular to the United States and the United Kingdom.

Rock-climbing equipment

A wide range of equipment is used during rock or any other type of climbing that includes equipment commonly used to protect a climber against the consequences of a fall.

Abseiling Rope-controlled descent of a vertical surface

Abseiling, also known as rappelling from French rappeler, 'to recall' or 'to pull through'), is a controlled descent off a vertical drop, such as a rock face, using a rope.

Self-locking devices are devices intended to arrest the fall of solo climbers who climb without partners. This device is used for back rope solo climbing for "ground-up climbing" or "top rope self belaying". To date, several types of such self-locking devices have evolved.

Belaying Rock climbing safety technique using ropes

Belaying is a variety of techniques climbers used to create friction within a climbing system, in particularly on a climbing rope, so that a falling climber does not fall very far. A climbing partner typically applies tension at the other end of the rope whenever the climber is not moving, and removes the tension from the rope whenever the climber needs more rope to continue climbing.

Stopper knot

A stopper knot is a knot that creates a fixed thicker point on an otherwise-uniform thickness rope for the purpose of preventing the rope, at that point, from slipping through a narrow passage, such as a hole in a block. To pass a rope through a block, or hole, is to reeve it. To pull it out is to unreeve it. Stopper knots prevent the rope from unreeving on its own.

Munter hitch Adjustable knot used control friction in a belay system

The Munter hitch, also known as the Italian hitch or the Crossing Hitch, is a simple adjustable knot, commonly used by climbers, cavers, and rescuers to control friction in a life-lining or belay system. To climbers, this knot is also known as HMS, the abbreviation for the German term Halbmastwurfsicherung, meaning half clove hitch belay. This technique can be used with a special "pear-shaped" HMS locking carabiner, or any locking carabiner wide enough to take two turns of the rope. The Munter hitch is named after Werner Munter, a Swiss mountain guide who popularised its use in mountaineering.

Bachmann knot

The Bachmann hitch is a friction hitch, named after the austrian alpinist Franz Bachmann. It is useful when the friction hitch needs to be reset quickly/often or made to be self-tending as in crevasse and self-rescue.

Ascender (climbing) Devices used for ascending, braking, or protection in climbing

An ascender is a device used for directly ascending a rope, or for facilitating protection with a fixed rope when climbing on very steep mountain terrain.

Single-rope technique

Single-rope technique (SRT) is a set of methods used to descend and ascend on the same single rope. Single-rope technique is used in caving, potholing, rock climbing, canyoning, roped access for building maintenance and by arborists for tree climbing, although to avoid confusion in the tree climbing community, many have taken to calling it "stationary" rope technique.

Autoblock

An autoblock is a rope device used in climbing and caving for both rappelling (downward) and ascending (upward).

Belay device Mechanical piece of climbing equipment

A belay device is a mechanical piece of climbing equipment used to control a rope during belaying. It is designed to improve belay safety for the climber by allowing the belayer to manage their duties with minimal physical effort. With the right belay device, a small, weak climber can easily arrest the fall of a much heavier partner. Belay devices act as a friction brake, so that when a climber falls with any slack in the rope, the fall is brought to a stop.

Garda hitch

The Garda Hitch is a class of climbing knots known as ratcheting knots for their ability to let the rope move in one direction, but not in the other. This class of knots has many uses in climbing and mountaineering, for example in a pulley system where a load is being hauled up a cliff, the Garda hitch prevents the load from slipping when the pulley system is reset.

References

  1. Climbing School. Barrons Educational Series Inc. pp.  78–79. ISBN   0812059697.
  2. "The Prusik Knot or Triple Sliding Hitch". animatedknots.com. Retrieved 6 March 2016.
  3. Learning to Rock Climb . Sierra Club Books. 1981. pp.  116–118. ISBN   0871562812.
  4. Gaines, Bob; Martin, Jason D. (2014-05-20). Rock Climbing: The AMGA Single Pitch Manual. Rowman & Littlefield. ISBN   9781493009626. Double Fisherman’s Knot ... is the preferred knot to use for joining nylon cord into a loop to make a cordelette or prusik loop.
  5. Steven M. Cox and Kris Fulsaal, Mountaineering: the Freedom of the Hills -7th ed. (Seattle: The Mountaineers Books, 2003), chapter 8.
  6. Ashley, Clifford W. (1944). The Ashley Book of Knots, p.300. Doubleday. ISBN   0-385-04025-3.
  7. http://ozultimate.com/canyoning/knots/french_prusik/
  8. "Geared Nema17 Extruder - RepRapWiki". Archived from the original on 27 January 2010. Retrieved 10 February 2010.

Further reading