GEAR SPECIAL Edited by Dave Durkan Modern Ropes For Modern Folks by Chris Gore

For many mountaineers and rock climbers the two main rope specifications presently supplied by manufacturers arethe number of UIAA test falls the rope can sustain and the price, the latter often being the deciding factor when purchasing. There is ahost of technical information av ailable, at trade or organisation level, but what little actually filters through to the end user is either incomplete, self-serving or presented as complex specifications and ta bles. Although of great value, this data needs to be fully understood by "modern" climbers, who are using ropes in ways outside the scope of the original tests. The question thus arises: are these tests still pertinent today, or should they be re-evaluated and extended to encompass today's usage? Another most important aspect is the life expectancy of the rope, which depends as much upon the user as the user relies upon the rope. This is a grey area of our knowledge and a question that can never be fully answered. Rope Construction There are two main types of rope: hawser laid and kernmantle. The former has an open braided construction, and has gener ally fallen into disuse by serious climbers in favour of the superior handling and technical qualities of kernmantle. In view of this, this article will only deal with kernmantle ropes. The name kernmantle describes the two main parts of the rope (a direct translation from its German name is "core-sheath"). The material used in the construction of both core and sheath is known as "nylon 6". Nylon 6 has greater properties of energy absorption than its counterpart "nylon 6.6", but has a lower melting point. A disadvantage is thus the possible fusing (melting) of the sheath should a fall cause excess friction. The quality of the nylon is assessed through perfect continuity of fibres in the yarn throughout the length of the rope. All manufacturers use the best quality of nylon available. Before the yarn is twisted into the filaments for the core and sheath it undergoes heat treatment, which has the effect of increasing its energy absorption properties. The core ofthe rope is made from a specific number of filaments, depending on the strength and diameter required. Each filament has either a clockwise (S) or counter clockwise (Z) twisted construction, which en ables the rope to 'stretch' under stress. Core filaments are of approximately equal num bers between 'S' and 'Z' type giving equal bias to the twist of the rope. This method of internal construction is used by the majority of manufacturers although some still use a less advanced braided core. The sheath gives the rope its 'feel' and ac tually contributes to the strength of the sys Above: The author takes flight. Numerous short fails are bad for ropes, whereas longer falls tem in proportion to its weight and the weight with more rope out absorb energy more gently and are thus better for the rope, but could ofthe core (approximately 25 - 30%). The ten be terminal for the climber I Photo: Al Phtzacklea. Opposite: Rope making at Edelrid; - sion of the sheath around thecore is of Top: the tape weaving machine, and Centre: the sheath and core threads being brought paramount importance to the rope's handling together in one process. Photos: SteveAshton. Bottom: The core of the rope (Beat) dismantled properties. A tight sheath gives a very stiff showing S' wound Fibres on left and 'Z' wound fibres on the right Photo: Chris Gore. rope, but helps to resist the entry of grit or dirt, whereas a loose sheath increases sup pleness (a much sought-after quality) though unfortunately such ropes are prone to sheath failure slippage, entry of grit and snagging of the sheath on the rock. Like the core the sheath is also constructed of 'S' and 'Z' twisted filaments. Waterproofing, to produce an 'everdry' rope, involves either individual sheath and

36 „__ core fibres being impregnated with a silicone solution before construction, or by means of capillary attraction along the fibres (choice of silicone, paraffin or Teflon) after construc tion. This latter method is generally regarded as being superior. UIAA Tests and Rope Specifications Standards for rope performance are set by the Union Internationale des Associations d'Alpinisme (UIAA). This organisation, based in Geneva, first came into being on an inter national basis in May 1965. Since then it has established tests methods and performance standards for ropes, , ice axes, harnesses, helmets, accessory cords, tape and stitched tape slings. The standards laid down by the UIAA for the performance of ropes have to be met by all manufacturers who wish to use the label of recognised safety on their ropes. These labels are valid for two years, after which manufacturers must have their ropes reas sessed. What follows is an explanation of the various tests a kernmantle rope must un dergo, the standards it has to attain and what this means to the user. Drop Test The main test is the 'drop test' or simulated leader fall, which determines the energy ab sorption capability or "impact force" of a rope. The impact force (measured on sensi tive electronic equipment) is the maximum load placed on a rope after all the energy from a fall has been absorbed by the stretch ing capacity of the rope. The maximum impact force allowed on a single rope (11 mm - 10 mm) is 12 kilo- Newtons (kN) and on a double rope (8.5 mm - 9 mm) 8 kN. (A Newton is the standard international unit of force. Therefore a kilo Newton is a thousand of these units - see note 1). The figure of 12 kN is based on physiological limits. It has been found that the human rib cage can withstand a load fifteen times greater than its own bodyweight for a brief period, therefore the body can withstand an approx imate maximum force of 1200 kg or 12 kN (note 1). The set apparatus for the UIAA drop test consists of a fixed point (), an orifice (similar to the cross sectional shape and size of a ) for the rope to pass through and a weight: this weight is either 80 kg for a singje rope or 55 kg for a double rope tested as a single. The drop test is conducted with a piece of rope 2.8 m long, with 0.3 m of this rope between the anchor and the orifice, leaving the remaining 2.5 m to be dropped 5 m, giving a fall factor (ff) of 1.78. The energy from the fall is absorbed over the entire length of the rope (2.8m). The fall factor determines the severity of a fall and is defined as the distance fallen divided by the total length of rope between climber and belayer. The weight of 80 kg was the original weight used for the testing of ropes. As technological advances have been made, this weight has remained the same, only the number of falls a rope must sustain has been increased. The British Council (BMC) argue that this weight should be increased rather than the number of falls and propose that a test be included that breaks the rope on the first drop. Although this test will have little relevance on the cliffs it will give a clear cut lines as to which is the 'strongest' rope when assessed with the other UIAA tests. The value of 55 kg is used since the stress involved for a 9 mm rope and 55 kg weight is comparative to that of an 11 mm rope and 80 kg weight. One shortcoming of the test is that a double rope is tested as a single rope with the lower weight. With British double rope technique, when the climber falls he in variably falls on only one rope. It would there fore seem sensible from the British point of view to test the double rope with the greater weight (80 kg) thus giving more relevance to the testing of a double rope system as used on the crag. Originally it was assumed th?t a fall factor of 2 was theoretically the most severe fall Above Left: The Edelrid test rig showing rope passing over karabiner simulator edge, which can be replaced with others of varying dimensions (Opposite Top). Above Right: looking up the dynamic test rig.

Below: This sequence shows the static breaking strength test. At left is the rope prior to loading, centre shows the same section loaded to 2500kg, and right, the rope catastrophically failing at 2675kg. Note the airborne rope debris still visible. Photos: Steve Ashton. i op: varying edges over which the ropes are passed for the t del rid dynamic rope test. Below: The Edelrid abrasion test rig. Photos: Ashton.

possible (e.g. climber 10 ft from belay with no protection, falls 20 ft, i.e. ff 2) and that dis tance had little to do with the severity. This has since been disproven. Arova-Mammut conducted a number of tests to show that longer falls have a greater effect on the rope and produced some very interesting results. In an old quarry, they simulated the UIAA test fall (i.e. a ff of 1.78) but instead of using the standard 5 m drop they increased the drop to 30 m. The results were horrific; of all the 11 mm and 10.5 mm ropes tested not one of them held more than one fall. Under current standard UIAA test condi tions, a rope must survive a minimum of five falls. A detailed report of the test must be made, giving all values measured and any supplementary observations that have been noted. The majority of manufacturers con tinue testing until the rope breaks (it is only recommended that they do this and is not specified) and give the final number of falls in their catalogues. The value of the impact force is only taken from the first fall.

Static Elongation Test It would be relatively easy to construct a rope that has highly elastic properties (thereby re ducing the impact force) so that the climber would have a 'comfortable' fall. This would, however, result in excessive 'stretch' in the rope, allowing the climber to fall a greater distance and increasing the danger of hitting the ground, ledges etc. On the other hand, if the rope has too little stretch, more of the force of the fall is imparted to the climber. It was to assess the correct level of elasticity in climbing ropes that the UIAA instigated the Static Elongation test. This test is conducted with two different lengths of rope, both of which must be over 1.2 metres. The rope is loaded with an 80 kg weight for 10 minutes then left without the weight for a further 10 minutes. After this period, a 5 kg weight is attached and a 100 cm section of the rope is measured off. Finally an 80 kg weight is added again and the elonga tion of the measured section is recorded and given as a percentage. These are 8% for single ropes and 10% for double ropes. This test only gives an indication of how the rope behaves with a climber hanging on the end. A test for impact force elongation i.e. a dynamic test to measure the stretch in volved when the rope is actually fallen on, would be more relevant. A number of man ufacturers do give figures for impact force elongation and the degree of elongation, prior to the rope snapping.

((notability and Sheath Slippage These two tests investigate the handling characteristics of the rope. To assess knota- bility an overhead knot is made in a rope of -■} sufficient length which is then weighted to tighten the knot. Whilst under load it must be impossible to introduce a conical rod into any part of the knot. The sheath slippage test utilises a complex piece of equipment wherein a piece of rope 2.2 metres in length must show no more than 40 mm of sheath displacement. This test is especially relevant to jumaring and . Diameter and Mass per Unit Length Manufacturers often make claims that their ropes are lighter yet stronger than the com petition; this seldom holds true unless it is backed up by technical.data (see twin ropes spec) but on the whole a heavier rope has a higher energy absorption.

39 Rope designation: Left: single rope. Centre: Double Rope, Right: twin rope techniques (see text). Drawings by Roger Durban.

Rope Designation and in the belief that these ropes last longer. fallen divided by the total length of rope Another obligatory regulation, although not It is often assumed that the novice will not between climber and belayer), would it be a test laid down by the UIAA, is the designa go on climbs with complicated route finding, safe to alternatively clip the ropes. If twin tion of ropes for use as either single or dou thus causing rope drag, but this is a fallacy, ropes are used correctly, they have consider ble. Further to the tests laid down by the UIAA for many fine classic routes have deviating able advantages with regard to easier handling many manufacturers continue with their own lines. and higher capacity to absorb a fall. This has testing to try and improve on previous stan Double rope technique is the most com been shown in an independent test by the dards. Such tests as sheath abrasion and monly used system in Britain, where the vast University of Stuttgart (commissioned by the water absorption prove to be most useful to number of routes have complicated lines DAV) where several ropes were drop tested the consumer, although unfortunately only a which would result in rope drag if a single over edges of different radii, from 1 mm - 5 few manufacturers give these specifications. rope were used. Protection is clipped alter mm (5 mm being the radius of a carabiner). It seems reasonable to assume that the more nately or consecutively depending on the line The results show that all ropes tested far ex specifications a manufacturer gives the of the route to optimise free running of the ceed the UIAA standards. greater confidence they have in their own rope. Double ropes have considerable advan At present, the UIAA only states that ropes ropes. tages over single ropes for abseiling and should be designated single or double, All the tests laid down by the UIAA are provide back-up should one rope be 'chopped' grouping sub-9mm ropes with 9 mm (double- carried out under controlled conditions, and (emergencies only). ropes). Some manufacturers do refer to them the UIAA label indicates that a rope is safe Disadvantages include extra weight, cost as twin ropes in an attempt to inform the when bought new. Ropes without a UIAA ap purchaser of the difference. It would be useful proval should not be considered. and more complicated handling at the belay. Twin ropes have caused a great deal of for the UIAA to adopt this third designation Single, Double or Twin Rope Technique concern recently because they are some (twin rope). There are three main rope techniques used times used as a double rope system which in climbing today: single, double and twin can be dangerous. Rope to Suit Your Needs rope. All have different uses, some overlap Twin rope technique using sub-9mm ropes Once a decision is reached as to which ping, some not. involves both ropes being used as one, i.e. technique is best for your own style of climb Single ropes are used with great efficiency, both ropes go through every point of protec ing, you must choose between the various particularly in Europe and the USA where the tion. It is better for the rope and karabiner diameters from 12 mm through to 10 mm majority of routes tend to go straight up with that each piece of protection has a separate (single ropes), 9.4 mm through to 9 mm little variation of line. Beginners and middle karabiner for each rope. Only after rope has (double ropes) and 8.8 mm through to 8.5 climbers in Britain traditionally buy an been run out and points of protection placed mm (twin ropes). 10.5 mm is a fairly new 11 mm rope, usually for reasons of economy, (thus reducing the fall-factor, i.e. distance diameter which has proved popular, because 40 it is robust enough to be used as a single rope, yet light enough to be incorporated in o a double rope system should the need arise. . Twin ropes are a more difficult choice, as the diameter varies from manufacturer to manufacturer. As a general principle the larger the diameter the stronger the rope, which does leave the consumer in a bit of a quandary., as the usual reason for purchasing twin ropes is for their lightness. Length is an important consideration, and although many manuals still advocate 45 m, 50 m rope is preferable. With a view to prog ressing beyond small crags and outcrops to mountainous areas and/or long routes, the extra 5 m, although adding another 350g (ap- prox) to the rope, proves invaluable. For example a leader falling near the end of a has more usable rope, better belays can be reached on long pitches and there's more room to manoeuvre on abseils. For these reasons the climber should consider 50 metres. An expensive decision is whether or not to buy an 'everdry' rope. Waterproof ropes are invaluable for snow and as stan dard ropes easily become saturated and heavy, more difficult to handle through belay The knot in a belay system can absorb factor, on one end of the rope, thus causing brakes and abseil devices, and cause more much of the impact force, up to 30% in some considerable wear and tear (often shown by friction through runners. If the ropes freeze instances (when the fall factor is greater than a 'furring' of the rope). Up until now the ex in this condition, they lose a considerable 1.5, source Troll Products Ltd.). A figure-of- tent of damage this sort of activity causes amount of strength. Cost is a big drawback, eight knot should be used in preference to a has been unknown. however, and can increase the price tag by bowline. The bowline works by means of self- An independent test conducted by Andy up to 30%. tightening and can result in knot slippage; it Perkins (Troll Products Ltd) and the author, Although cost is the most important con can also Be incredibly difficult to untie when set out to ascertain the reduction in strength sideration for many climbers, ropes are good constantly fallen on. Whatever knot you caused by multi-fail use on a rope that had value for money, being extremely well made. choose to use it should always be made safe had no severe falls (over ff 1), i.e. a rope used You only have to look at other high-tech with a hitch or fishermans knot. constantly for modern hard routes. These sports to see how little climbers need spend After absorbing a fall, a rope deforms tests were on used ropes of a known history: by comparison. permanently in terms of fibre extension and the use of one person's rope can never be structural deformation. This can be seen duplicated and as such the test results can Care of Ropes through the successively higher levels of im only hold true for that particular rope, though From the moment you uncoil your new rope pact force-recorded after each drop test, the the results do allow room to predict the pos the process of deterioration starts. Indepen impact force becomes greater until the rope sible condition of other ropes. dent tests (note 2) have shown that a rope snaps due to the inability to absorb energy A rope (UIAA fall spec. 7) that had had con stored from new, preferably in the cool and sufficiently. stant use for four months and was considered dark, will retain its performance for up to When a high ff is incurred (above 0.5 ff) of dubious worth by the owner was able to eight years (although this figure should be you should lower down, untie, then retie the sustain 4 UIAA falls (this does not meet with treated with caution). It is important to note knot, thus replenishing its properties of ab UIAA standards). Whereas another rope that that if a rope is used only once with no falls sorption. It must be stated quite categorically was two years old and had had prolonged occurring and then put back in storage, de that you should never tie a loose knot for the multi-fall use but no massive falls, could terioration will have started. purpose of absorption, your knot should al survive only one UIAA fall. A great many chemicals react adversely ways be hand tight. Once on the ground it is with rope nylons. ..i general, acids are a advisable to allow the rope to 'rest' for at The life of a rope is variable, dependent on rope's worst enemy, but sunlight and UV can least 10 minutes, thus regaining the 'stretch' conditions of use, but a few guidelines can also have a dramatic effect. Slings used as of the rope. be given. Even a rope used only occasionally threads on cliffs that are constantly exposed Abseiling at speed causes high friction, should not be kept beyond 4 years. Under to sunlight can be in a very dangerous condi which in turn causes the fibres to 'ruse', caus normal use (weekends) 2 years is a reasonable tion with little or no visual damage to the ing a bulking of fibres, hard internal sections working life. For the vast number of climbers exterior. This also holds true for display ropes and reduction in the rope's capacity to absorb active on a full-time basis the life expectancy or those that have been used in shop windows impact forces. Always abseil with care. of their rope can be anything from 3 months under constant heat and light from the sun Jumaring also has a detrimental effect upon to one year, although I'm pretty sure that very and spotlamps. When travelling you should the rope, speeding up the wear and tear few climbers retire their ropes after 1 year, take care of the ropes. Don't place them on process. let alone 3 months! the back shelf of the car, again sunlight and Another method of reducing the impact Notel heat cause deterioration. Wherever possible force on a rope is the dynamic belay; once A Newton is a unit of force which imparts to a mass of 1 kg keep the rope in a sack or in some sort of again this can reduce the impact force by up an acceleration of 1 metre per second per second. With grav bag. Remember the boot of a car can contain to 30%. From this it can be realised that it is ity having an approximate value of 10 metres par second battery acidf per second a 1 kg mass when acted upon by gravity exerts far better for the rope and leader that a De a force of 10 Newtons (1 decs Newton daN>. When a rope becomes wet it should ideally layer (assuming that the rope goes from lead Manufacturers very seldom use kilo Newtons (kN) to de be dried naturally in a shaded place, preferably climber to belayer via a friction device) has note the impact force of their ropes in the various catalogues; in a breeze. Should the rope become sodden below is a list of comparison figures as used by the major a certain amount of freedom in his move manufacturers. or at any time heavily soiled it should be ment. This can of course mean that the be washed in warm water (30 - 40 degrees) with 1 kilo Newton (Kn) = 100 deca Newtons (daN) = layer can be pulled off his feet, but this can 1000 Newtons (N) a mild natural soap. only lessen the impact force upon the leader. 1 kilogrammes-force (kgfl = ION = 1 daN Obviously a certain amount of discretion 1 kilopnd (kp) o ION ° 1 kgf = 1 daN. Prolonging the Life of Your Rope should be used, any situation in which a Note 2 A rope's life is generally a hard one. It gets moveable second could endanger himself or Tests as appeared in La Monlagne and. Alpinisme No. 140 in an article by Claude Bourdon. fallen on, trodden on and abused. When the leader should be avoided (eg. constricted using a rope, a little thought and care should ledges, trees above the belayer, hanging be Note 3 extend its usable life. lays!). Choosing a Climbing Rope - Article by Kevin O'Connell; Summit magazine No. 130. The greatest threat to a rope's life and one Many factors can reduce the life expec that could terminate it, is the falling climber, tancy of a rope: chemicals, damage from rock Acknowledgements so every possible method of reducing the im fall, sharp edges causing severe sheath I would like to thank a number of people for pact force on a rope should be applied. damage and of course falling off. Given a assistance, notably John Keighley of the BMC As was explained in the UIAA drop test, an reasonable safety margin, a rope should be technical committee, Andy Perkins and Troll 80 kg weight is dropped onto a static anchor. retired if it sustains more than one fall with for helping me with tests and allowing the When it comes to the falling climber, matters a fall factor of over 1.0. use of their test equipment, Michel Beal for change. The anchor point (belayer) is generally information on construction. My thanks also dynamic, the insertion of a body and harness Modern Abuse and Over Use go to all those who read the draft versions to replace the 80 kg weight can reduce the With modern well-protected routes, ropes un of the article and offered valuable advice, par impact force by up to 20% (this was proved dergo a phenomenal amount of punishment ticularly Kim Carrigan of Mammut and Dave and tested by Paul Seddon of Troll taking a in a short amount of time; this is mainly due Durkan. Finally, my thanks to Europa Sport 1.78 ff on the Troll test rig). It can be seen to modern climbing techniques: hangdogging, for all their administrative help. from this that the climber actually becomes multi-falls, frigging etc. This kind of activity a 'cushion' for the rope during a fall. Chris Gore is technical advisor generally involves a lot of short falls of a low to Beai Cordes and Europa Sport. SHOCK FORCE.

Some basic truths, simple math and common sense.

Okay, you're climbing, your rope and harness are secure, the anchor is bomb proof, and you feel pretty safe. The thought of falling doesn't upset you. Every 20 m thing's cool. Maybe. But every fall creates an enormous amount of energy. We are, after all, relatively large creatures, and gravity is a formidable force — as any belayer who has caught a screamer can attest. the force of one climber's What's more, the shock Your life depends on weight (80 KG) in a worst- force from the fall is trans the stretch of the rope. case fall (Fall Factor 2) to mitted all through your secu Fall factor is one of the not more than 12 kN. Thus, rity system, and is nearly elements that govern shock the rest of the gear can be doubled at the anchor or pro force. The other two are the designed to work with this on top. And every element nature of the rope, and the known maximum force.* in the chain has to sustain weight of the falling object. Obviously, the more the shock without breaking That is, you. rope out, the more stretch if your fall is going to cause Obviously, the only part there is to absorb a fall. you nothing worse than of this equation that can Which explains why a Fall scrapes and bruises. 4m reduce the force of any fall Factor 2 drop of four meters is the bungee-like stretch of Fall factor explained. develops almost the same the dynamic rope (unless, shock force — 9kN — as A lot of climbers don't of course, you can lose really understand the fall one of 20 meters (Fig. A), weight real fast). Thus, factor concept; however, it's assuming a dynamic rope climbing safety systems pretty simple, even if you is used that conforms to are designed around the hated math (this is math UIAA standards. That is, shock-absorbing quality of the increasing length of the you can use in later life. In dynamic rope. It cushions fall (and the greater shock fact, you can use it to have 20m the fall, reducing the impact a later life). force that goes with it) is force and the chance of compensated by the greater Fall Factor is simply the system failure. In fact, the length of the fall divided by length of the rope available dynamic rope is the one to cushion its arrest. the length of the rope from "given" in the whole sys faller to the fixed point, tem. It is designed to limit whether belayer or anchor. The equation looks like this: 4m

Length of Fall Fall Factor ■ LengJh of Rope Out

Fall Factor 2 is the max 0.6 m imum you should encounter in a typical climbing fall, 0.6 m since the length of an arrest ed fall can't exceed two times the length of the rope. Normally, a Fall Factor 2 can only occur when a leader Hg. A who has placed no protec Fig. B Fall: 1.2 m Fall: 1.2 m tion falls past the belayer, Static rope or Dynamic rope or the anchor if it's a solo sling length: length: 0.6 m climb. As soon as protection 0.6 m Fall Factor: 2 is placed, the distance of the Fall Factor: 2 Shock Force: fall as a function of the rope Shock Force: 7kN length.is lessened, and the 18 kN Fall Factor drops below 2.

•Interestingly, the UIAA safety standards which govern climbing equipment manufacture are actually based on military research regarding the opening impact of a parachute on the human body. The conclusion was reached that 12 kN (a kiloNcwton equals 22-1.8 lbs. of force) was the maximum force a body could take without injury. Applying this to the shock force of an arrested fall,. thetl UIAA came up with standards for dynamic rope. "Friction* Fear, Friends and Falling (by John Wylie)" - Contemplations of a Climbing Physicist

.... Consider one of the new-generation rock shoes on a rock plane, inclined at angle @ to the horizontal.

A standard treatment would allow one to calculate the maximum angle for which the shoe will not slide down the plane. Balancing the componets of the forces along the inclined place reveals.

mg sin@ = uN = umg cos@

Where u is the coefficient of static friction between the sole of the shoe and the surface of the plane. This gives tan@ - u. This isn't a startling result until one realizes that u ~= 1.2 for this new rubber on smooth granite. This corresponds to an angle of 50 degrees. Disconerting for the beginner, but often commonplace for experienced climbers to walk up and down slopes approaching this angle.

This sheds some light on a good climber's style (on friction routes) The body out away from the rock results in a greater normal force thus leading to an increased firctional force. Too much weight distributed on the hands and the frictional force isn't nearly as good.

Consider the application of the above to more vertical ground., say a "Chimney".

The principle of opposition is the same, the resultant force on a climbers leg due to the rock wall (in order for the climber to remain in a comfortable equilibrium) should be directed along the long bones of the straight leg. As before, this requires that tan @ - u, but here the climber faces some decisions. At an angle of less than this amount the frictional force is larger and the climber is more secure, but at the expense of increased stresses in the leg muscles and hips. Flexibility is also a factor as well. Each person has an optimal angle arrived at naturally through experience. Wouldn't it be nice if climbers could extend or contract the length of their legs so as to always be using their optimal angle? This is the impetus behind one of the major revolutions in protection technology... pioneered by the Lowe's to some extent and primarily by Ray Jardine.

The solution might be something like this...

"Let's create a device with two cams (legs) hinged at a central shaft (body) that mimics the climber's motion. The climber had his/her legs at an optimal position for a particular size of chimney, thus the device should be usable in a range of crack widths and always funtion at it's optimal angle. These "cams" would have to be designed with an expanding radius r so as to maintain a constant angle @ as the width of the crack widens, (viola a SLCD called a "Friend")

Forces which act on a "Friend" when it's placed in a vertical crack are as follows:

There is a normal force N due to the wall, a reaction force R acting

- 1 - on the axle, a load weight, W and a frictional force (Ff«uN) between the rock and the cam. Balancing horiz. and vert, forces gives....

W = uN

Choosing a pivot at the point of contact allows us to write the torque equation

Rr sin @ = Wr cos @

Combing these 3 equations yields the fundamental design reqt.

tan @ = u — constant...

What shape fits this reqt.? Any mathematician will know the answer immediately.

The shape of the cam is a logarithmic spiral!

If you plot this w respect to a coefficient of friction of .3 (aluminum on smoot granite) and using a contact angle of ~= 17degrees you see that the shape of the spiral is independent of the scaling parameter and the origin is an asymptotic point. The spiral continuously approaches the origin but never arrives, much in common with a fractal.

Friends are produced with varying sizes for a range of cracks and all cams are sections of the same spiral. These cams will undergo structural failure before they slip from a crack (in most cases). This occurs at a load of well over 1 ,OOOkg.

(rock texture, surface consistency all play a factor in this) Soft sandstone surfaces can shear, allowing the cams to slip out at much lesser forces.

fr

.... Imagine taking a fall ontoa rope with little or no dynamic characteristics. After falling some distance, a climber attains a downward momentum that is arrested and reduced to zero in a time dt by the action of the rope. Denoting the change in the climbers momentum by dp the average force,

Fav = dp/dt

exerted on the climber and on the protection attaching the rope to the rock can be immense if the time is small and the fall is long. This load placed on the protection may cause it or the surface of the rock to fail.

This is why climbers use "dynmaic" ropes. The initial potential energy a climbers carries into a fall is, to a very good approx. dissapated as heat as the rope stretches.

The UIAA sets the following standards for a rope to bear their approval. A mass of 80kg held by 2.8m of rope falling 5m must generate an impact force of no more than 1,200kg on the first test

- 2 - fall. (We forgive them for using kg as a unit of force... the figure should be roughly 1 2kN. A rope is rated by the number of such falls it can sustain before failing completely.

The quality of a rope is characterized by it's "rope modulus" M = EA the product of it's Young's Modulus E and it's cross-sectional area A. Typically M ~= 40kN. Young's Modulus is defined as

E - H / A dl

Where F is the tension in a rope of length I that induces and extension of dl. Jj: - r *-

The ration of the height of a fall to the length of rope between a leader and his belayer is called "fall factor", this term is oftne j * f= H used to describe the seriousness of the fall. A fail factor of 2 $■ c * —TT indicates no protection point between the leader and his belay.

Energy considerations require the work done by the rope in arresting a fall to match the fall's potential energy. That is,

mgh « F dl

where m is the mass of the climber and h is the height of the fall (g is accel. due to gravity)

The tension in the rope is them

F = mg + mgh/dl

since the rope must arrest the fall and support the climber's weight. From the definiton of the rope modulus we have dl = Fl/M so that....

F = mg + Mmgh/FI = mg + Mmg@/F

(where @ is the Fall Factor)

Solving for F we choose the F > 0 solution from the resulting quadratic...

F » mg/2 + sqroot( (mg/2)A2 + @Mmg)

With UIAA test data, we calculate that F ~= 8kN and dl ~= 56cm fora fall factor of @ = 1,8

This corresponds to a 20% elongation factor. A factor 2 fall puts bot the leader and belayer in peril as the nylon fibers in the core of a climbing rope may be stretched beyond their elastic limit or may tear altogether.

Under lesser conditions (less fall factor) a climber can count on 5-10% "rope stretch" to ease the impact force.

In all of the above, we've ignored the mass of the rope itself (about 73g/m). It would pose an interesting problem to determine it's significance on the scenarios presented above.

What is to be learned by all this?

-3- Well a, "safe" fall isn't necessarily a short one., it's the one with the smaller fall factor. A long length of rope between the leader and the belay will result in less impace force on the climber and protection (provided protection is in place)

One must move conservatively and place pro frequently towards the beginning of a pitch of climbing, than later on in the pitch, with more rope out.

An Exercise for the Reader:

2 climbers are ascending a steep face.. The leader is secured by a rope that is held by the attentive second, who is below. The rope between them is 10m long and passes through a krab connected to a friend placed in a crack, 6m below the leader. The mass of the leader is 80kg. The leader pumps out after flashing the crux section and takes a whipper, the rope catches her straight down fall. The jerk she experiences is called the "catching shock", this is lessened by the elasticity of the rope.

1. What is the Fall Factor of this scenario? 2. What is the value of the "catching shock"? 3. What is the deceleration of the leader due to the rope as a fraction of the acceleration due to gravity? 4. How much does the rope stretch? 5. Describe how a fall with a "fall factor" of 0 might occur and calculate the "catching shock" for such a case

-4- Equipment

A Short Course in Rope Physics

by Dennis Turville

No other piece of the of steel cable and rubber band; it would stop manufacturer's rating, not that of the UIAA. system requires as much blind faith as the the falling climber gently, but it would do so The rating itself is an average usually, mean rope does. While climbers often use a couple with a minimum of stretch to keep the fall ing that a given nine-fall rope holds an aver of good anchors for a rappel, or a series of distance as short as possible. While we may age of nine falls, not exactly nine falls. Some nuts strung out on a pitch, there is seldom any be able to send men to the moon, we can't as manufacturers give a range for fall capacity, backup system for a rope. Ropes are fun yet build the perfect climbing rope. Since we such as seven to nine falls, and this is closer damental, but few climbers have a good can't integrate the qualities of steel and rub to the truth than a single number. working knowledge of what happens to the ber, all climbing ropes are studies in com There are many reasons why the UIAA test rope during a fall, which falls are the worst promise. If one aspect of rope performance is fall cannot happen in the real climbing world: ones to take in terms of the forces generated, given design preference, it can only come at 1) The iron weight stops abruptly, some or which ropes do the best job of stopping the expense of other qualities. Remember: thing the human body cannot do. This results falls. Most of us accept what we are told about one never gets something for nothing in the in a reduction of impact force by a factor of 2.5 ropes, and willingly follow the advice of world of physics. If we suddenly have a rope or 10 to 15 percent, depending on whether friends, shop personnel, and the claims of that holds 13 test falls instead of five, we must you choose to believe Beal or Edelrid respec manufacturers without question. have given up something. No amount of tively. Rope physics is far from simple and, in a advertising to the contrary can change that— 2) The block is stopped statically with the desire to oversimplify a complex issue, many as long as we know better. If what you're rope tied to a fixed point in the test. Static climbers buy ropes for the wrong reasons. about to read sounds different than what belays don't happen in the field since body Buying a rope intelligently, based on avail you've heard before, it is probably because belays and mechanical belaying devices both able data, is difficult at best. Ten years of marketing and mathematics are seldom the allow some slippage of the belay rope. experience in the retail climbing industry same. 3) To achieve a high fall factor (over 1) the helps, and so does a physics degree, but if The biggest misconception about climbing climber must fall past the belayer, something one doesn't have that information to draw on, ropes comes from the way they are tested which doesn't happen very often because of hopefully this article will let climbers know and then marketed to the climbing public. The nuts and other anchors in the system. what is really happening in the rope business, UIAA is to be commended because they do 4) The fall must occur on vertical rock or clear up some myths, and expose outright exist when similar organizations are practi near vertical ice or the fall energy will be marketing hype. This article is based solidly cally nonexistent in other fields, but the tests dissipated by friction. on the physics of the real climbing world. It is advocated by them do not accurately reflect The difference in the real climbing world not opinion. The writer's intent is to help clim what happens in the real climbing world, nor from the UIAA test fall laboratory explains bers choose the best climbing rope for their do they give the consumer meaningful data to why we have never broken a modern climb style of climbing and level of expertise. choose a rope by. ing rope. Since all ropes must now hold five Before we discuss what a rope should be, At the heart of the matter is the extreme falls, and the old ropes held two falls more let's think about what ropes have accom UIAA test fall, a fall so severe that rope manu severe than any one fall we can ever take on plished over the years. One startling fact facturers themselves admit it is impossible to the rock, it's pretty obvious why ropes never should alter your thinking about ropes, their take in a real climbing situation. If we cannot break. If we can't break a two-fall rope, why lifespan, and their place within the climbing take a fall as nasty as the UIAA test fall, why do we need a 13-fall rope to be safe, as some system: no kemmantle rope of a 9,10 or 11 do we test ropes with it? If you manufactured, like to tell us? Simply put, we don't. Actually, a millimeter diameter has ever broken in climb ropes the last thing you would want is a law 13-fall rope will hold 13 falls on each and so ing use. Period. Many have been cut over suit brought by the estate of some poor clim it's really a 26-fall rope anyway. Twenty-six sharp edges or damaged by falling rocks, and ber who managed to break one, so naturally falls when we can't take one in the real world. one was even slashed by the hardware you would feel better if your rope was tested All of this means that buying a rope based dangling around a falling climber, but no mod with the most extreme situation possible. The on its test fall capacity is basically nonsense. ern climbing rope has ever been broken by a UIAA test fall is just that. Two manufacturers When one manufacturer came out with a rope falling climber. This one unalterable fact has of raw rope fiber have refused to let their that would hold more test falls than anyone great significance for all who use ropes be products be used in twisted climbing ropes or else's, they suddenly had a marketing edge; cause there is an amazing amount of overkill for other uses with risk, so the question of they started telling us their rope was SAFER because it held more falls, and we believed built into the system. liability is a very real one. Overbuilding is fine by itself, especially In the UIAA test fall, an 80 kg iron block is them. Multi-fall ropes are not safer than ropes considering the consequences of the oppo dropped five meters and held by 2.8 meters of which hold fewer falls, but no one was around site, but it shouldn't force climbers into buying rope. This yields a fall factor of 1.78. (Fall to tell the climbing public in a way which ropes that are heavier or more expensive factor is the distance fallen compared to the would get them to believe it. Not only are than they need be. The first kernmantle ropes rope used to hold the fall. A fall factor of 2 is multi-fall ropes not safer than their counter barely held two UIAA test falls, but no climber therefore the worst one possible.) In order to parts, but a strong case can be made sug was ever able to break any of them. This obtain UIAA sanction, a rope must hold five gesting that some multi-fall ropes are actually suggests an obvious question: if climbers such falls, whether they are achieveable in less safe, for both beginners and hard-core couldn't break two-fall ropes, why are people actual climbing situations or not. Testing is climbers alike. now telling us we need ropes which hold nine done by labs selected by the UIAA commit A falling climber is energy in motion, and a or more falls to be sale? If that question intri- tee, not the UIAA itself. Ropes are simply rope must largely absorb that energy. A rope is a shock absorber, one that breaks when it ques you, kindly read on. given a pass/fail test for five falls, so any rope The ideal rope would be a masterful blend showing a higher fall capability exhibits the cannot absorb any more fall energy. The rope

56 stretches during a fall in two basic ways: mechanical elongation which recovers after the fall, and fiber elongation which is perma nent. Every time a rope holds a severe fall (over a fall factor of 1), it loses some of its ability to stretch and hence its ability to absorb fall energy. Stretchy ropes can absorb more energy and so they can hold more falls, but a fall which occurs on them is longer and more dangerous to the climber. Stretch should be kept to a minimum in good climbing ropes. Impact load or impact force is the amount of shock that is transmitted to the climber's body and the rest of the climbing system dur ing a fall. If the impact force goes up, every thing in the system is more likely to fail. Since we know that ropes don't break, it follows that the belay or the protection placements are more likely to fail if the impact load increases. All rope manufacturers must show a figure for impact force, but they use different units of measurement, so when shopping make cer tain you are comparing similar units. (The table of rope statistics on page 59 has been converted into kg from daN, kN, kfg and KP.) A low impact force is obviously very impor tant, but it must be considered in conjunction with stretch. An excessively stretchy rope may have a low impact force, but we still don't want to fall any farther than we have to, thank you. So stretch and impact load must both be kept to a minimum. Stretch is measured in many ways: working elongation with an 80 kg load, impact force elongation and elongation at failure. Of these, impact elongation is the most useful for choosing a rope, but unfortu nately it is seldom listed in rope data. Or it is estimated. It requires sophisticated machin ery to measure impact elongation, and many manufacturers don't list this figure, particular ly since they are not required to do so by the UIAA. Impact force elongation measures how much the rope stretches when you fall on it-, a very important feature to leave out of rope statistics, but if climbers only bought ropes with published data about impact elongation, perhaps the manufacturers would wake up. The UIAA should address this important point, but curiously they have chosen not to. The UIAA is suggesting that manufacturers all use kilograms as their impact force unit, which is a mass unit and technically incorrect to use as a force measurement, but for lay Let down: Merrill Bitter taking a flyer on the second ascent of The Coffin Overhang, Little man climbers not concerned about the differ Cottonwood Canyon, Utah. Photo: Dennis Turville. ences, it represents a welcome step toward consistency. nylon with some expensive chemical proces you pay for in climbing ropes; a rope with a Impact load, impact stretch, and fall capac sing that creates a nylon with a higher elonga small price tag might not be the bargain you ity: this is where safety and value come in. In tion at rupture, but which doesn't appreciably want, so buyer beware. order to facilitate multi-fall rope the UIAA change impact load or working elongation Now when we look at the table of rope raised its limit on working elongation. At this while giving more test falls. This option is the statistics, things start making sense. If we see point manufacturers had three major ways of most expensive one, however. a five-fall rope with a relatively high impact increasing a rope's fall capacity: So, in order to get a multi-fall rope, it must force and low price tag next to one which is a 1) One can make a tighter wrap of fibers in be heavier, have more stretch, have a higher nine-fall rope with a lower impact force and a the core or increase the diameter of the core impact force, cost more, or have some com hefty price tag, we know why. The first rope is which will give more test falls, but only at the bination of the above. Multi-fall ropes which a price point rope,'one sold as cheaply as expense of increased working load stretch, achieve high fall capacity at the expense of possible, while the other one, so long as its impact load, and weight. impact loading are less safe than ropes which impact force is low, is a more expensively 2) The mechanical stretch could be in simply hold fewer falls, particularly for begin made rope of processed nylon fibers. But creased. ners. But beginners are usually who the remember that rope data doesn't tell the 3) The manufacturer could treat the basic cheapest ropes are aimed at. You get what whole story. Impact force elongation is still a

57 murky item and before you say that increas UIAA test fall capability doesn't determine main enemies. Alcohol, gasoline and other ing your fall by, say, six inches is unimportant, how long a rope will last, the sheath does. hydrocarbon solvents do not affect nylon che keep in mind that a fall six inches longer can The sheath is actually more important than mically, so do not worry if you spill some on mean the difference between a good bar most climbers think. Not only does it dictate your rope. It is certainly not a reason to dis story and a compound fracture. Whether rope when we will ultimately retire a rope; it has card it. Battery acid is another matter; even data is lacking through manufacturing secre much to do with handling characteristics as the fumes are harmful to ropes. A rope may cy, testing inadequacy, or by product anxiety well. A poorly-woven sheath will cut easier receive more damaging UV while riding on is unimportant to us. The important thing is for against rock crystals and will wear sooner. A the back of your pack than while actually climbers to know as much about ropes as magnifying glass will show interesting differ climbing, so keeping a rope in a rope bag possible so they can make good, sound ences in sheath weaving for anyone willing to makes good sense. choices. look. A sheath that slips against the core The amount of abrasion resistance a rope So, a prudent climber will buy a rope with a signals a poorly-made rope. The sheath will take is really what ultimately determines minimum static stretch and a low impact should be firmly woven to the core so there is when its life is over. The life of the sheath is force. A wise one will select a rope which is little or no slippage, otherwise the rope will this subjective life of the rope, and the subjec light and has good handling characteristics not take as much abrasion nor will it handle tive life is what we all gauge our ropes by. So as well, perhaps paying for that lightness, but very well. how can a 13-fall rope last longer than a passing on the multi-fall monsters, knowing Once again, not all manufacturers list man five-fall one? The concept is silly because full well a rope won't break. tle slip data and those who do use different they both have the same subjective lifespan if Whatever rope is chosen won't break, but' terms. The mantle slip test uses a two-meter their sheaths are the same. how long will it last? The useful lifespan of rope which is pulled through a displacement Now it starts getting sticky again. Some ropes is a very controversial issue, with esti apparatus several times. The slippage manufacturers have gone to thinner sheaths mates ranging from several years to a couple should not exceed 30 millimeters maximum so they can put more core material into the hundred hours; but whatever the objective life after five tries, but less slippage is still better. rope and still stay at a given diameter. This of the rope is, it is obvious that no climbers Some data show only a number expressed in chicanery gives a higher number of test falls, have managed to exceed it. Considering the millimeters and other show a maximum figure but you can guess what it does to the life of many types of people who are climbers — in millimeters. Either way, the lower the num the sheath. So it may well be that those who everything from the garbage scroungers of ber the better. advertise longer lasting ropes because of lower Yosemite to plastic surgeons who pay Other important aspects of abrasion resist their increased test fall capacity are actually their way onto expeditions — it seems very ance are waterproof and other rope coatings. less abrasion-resistant because of their thin unlikely that climbers are magically all retiring It has been shown that a rope will withstand ner sheaths. We replace a rope when we no their ropes at just the same time. We must be 33 percent more abrasion cycles with a longer trust it, or we use it on less serious putting our ropes out to pasture long before waterproof coating than one without. Other routes, but the life of the rope in terms of the we need to. coatings limit the absorption of damaging way we use it has nothing to do with the Since it is impossible to wear out a rope by ultraviolet rays by the rope. Coatings do more number of artificial test falls it holds on falling on it, and since reliable test data on the for a rope's longevity than the number of test average. aging properties of ropes are not available, a falls it allegedly holds. A couple of things should be clear. One is rope's objective life is open to conjecture. Not all coatings are equal, as you might that the number of test falls a rope holds Most climbers retire a rope when it looks expect. Some European manufacturers use doesn't have much to do with a rope's safety hammered, when the sheath is badly worn, a paraffin compound which comes off the or its durability. Another is that the rope indus perhaps cut in spots, and when they no lon rope quickly. The two other coatings which try should standardize its terms and stop hid ger trust it — not when it has held bad falls. are most often used are silicone and ing behind inconclusive data. Most climbers Many climbers do not realize that it is the fall fluorochemicals, the latter being more dur buy ropes based on fall capacity alone, and factor that determines impact force, not the able generally. Other than rockfall, which is that means they haul heavy or expensive distance fallen, so they don't actually know the leading cause of death among climbing ropes around when a lighter, cheaper one what a bad fall is in terms of rope dynamics. ropes, UV and industrial pollution are a rope's might fit his or her needs exactly. On a 20-

58 W.R. Publishing Co. Presents

mile hike into a route, a rope that is a pound VERTIGO GAMES and a half lighter is an obvious joy, and it's a delight to have it trailing behind you on a pitch instead of some 11.5mm monster. On big by Glenn Randall walls an 11mm rope is a good investment because of the abuse it must take there due to jumaring. A thin superstate line could be used for big wall hauling to save weight and bulk, but static lines (ropes that stretch very little under body weight) should not be used where falls are possible because of their high impact loads. Normal crag climbing can easi ly be done using 10.5 and even 10mm ropes without worry. For glacier work and alpine ice, use 8mm and 9mm respectively. Why lug around more rope than you need to? Double ropes make a great deal of sense, particularly in the area of rope cutting, but Americans don't seem to use them much. Double lines have much lower impact figures, but they also stretch more. In an area of sharp rock they are the safest choice.

Unlike the first ascent party on the Mat- terhorn, today's climbers do not have to worry about their ropes breaking. They are depend able and strong. If climbers voice their collec tive opinion through the ropes they buy, manufacturers will be forced to create the best ropes for climbers, instead of confusing the issue with meaningless and/or incom plete data and misleading advertising. The ideal rope may be a while off yet, but thought ful climbers can sort through the claims and counterclaims to find just the right rope to follow them into the clouds.

The author would like to thank the following for their help in preparing this article: Dick Newell of Bluewater, Helmut Lenes of Climb High, John Cooley and Steve Olson of Rob- bins, Mike Reeves of SMC, Frank Petran of Liberty, and Gary Tauber of Chouinard Equipment.

Skip Guerin makes the second ascent of Silly Putty. Vertigo Games is a pictorial history of extreme rock and ice climbs in Colorado, USA. From the Diamond on Lons's Peak to the depths of the Black Canyon, this book is a unique look at the faces behind some of the boldest routes in the country. Vertigo Games is now available from your local mountaineerins store, or send $20.00 to: W.R. Publications 223 Cloverleaf Court Sioux City, Iowa 51103 walls, a stiffer, firmer boot also helps to pre vent aid slings from constricting the foot. However, if you want maximum performance on slabs, smearing, and cracks, squeeze your foot into one of the new generation of "sticky rubber" boots and you will be amazed. Finally, when considering your choice of boot, remember this. Footwear is the second most overused excuse for failing on a route. ("Out of shape" holds first place.) I've heard climbers complain because boots are too tight, too loose, too stiff, too flexible, too new, or too worn out. Whenever I hear myself ab out to mutter one of these platitudes as I'm being lowered to the ground, I think of Bob Kamps, whose includes some of the most depressingly small hold face climbs and boulder problems. He climbed most of them in hiking boots.

A Short Course in Rope Physics — A Rebuttal

by Helmut F. Microys

This response to Dennis Turville's article {Climbing #83) first addresses the state ments that "no kernmantle rope of a 9,10 or hold faster than you could say "Watch me." sticky sole. Unappetizing yellow color. 11 millimeter diameter has ever broken in The boots below are not pure edging boots Vasque Escalar climbing use," and "multi-fall ropes are no but are more rigid in length, with a harder Flexible sole, firmer rubber, and too much safer than ropes which hold fewer falls." rubber than the ones above. The harder rub room in the toe, made the boot perform only Secondly, it will discuss the importance of ber has the advantage of lasting longer, but it adequately. impact force and impact elongation. Finally it will not stick as well on smears. The more will make comments on a number of other rigid sole is an advantage on steep edging Fit matters raised in the article. since it lends some support to the calves. Most serious climbers claim that an excru The statement that no kernmantle rope has Asolo Diamond ciatingly tight shoe helps them feel the rock. ever broken in climbing use is, of course, This shoe had many fans in its earlier mod This is overrated, since I've known some who perfectly correct based on the nice use of the els who liked its stiffness lengthwise. It is now could climb anything in a sloppily fitting pair, word "broken." The fact that one employs more flexible, has a firm rubber, and it still but I have to admit that I feel more secure on a more precise language, i.e., that ropes are edges well. It is the only shoe I reviewed with small hold when my toes are crammed to the cut, to describe the phenomenon does not a tread sole which could be invaluable on wet end. make it go away. Ropes do "break" in climb and sand-covered rock. As a result, it would Be warned, though, that years of wearing ing use—over an edge as they have always be an excellent choice of alpine rock climbs or tight rock shoes can cause numerous mala done. This edge may be a carabiner, the rock, long face climbs with an approach. dies, including toes that appear to be fused or a piece of equipment. Asolo Choulnard and Asolo Red Dot together, the dreaded malformation known Multi-fall ropes are safer than ropes which I had a hard time finding any difference in as the "potato chip toenail syndrome" and an hold fewer falls, in that they do not cut as performance between these two models. The altered gait. Manufacturers do not help this easily over sharp edges. Every rope in the rubber is moderately firm, although the red situation either, since unlike street shoes UIAA drop test is tested over an edge having model is perhaps a bit softer. Both are com (and feet) most rock shoes come in one width a radius of 5 mm (a carabiner). A multi-fall petent shoes, but these are Buicks and not only and that is narrow. If you are cursed by a rope is simply able to hold more falls over this Ferraris. wide foot, you will be hard pressed to enjoy edge. Pit Schubert of the German Alpine Club Galibier Contact even the highest quality climb since your only has shown that these ropes also hold more The stiffest boot in length, the Contact was thought will be to remove the shoes as soon falls over edges having smaller radii. Thus a the only one in which you could stand com as possible. multi-fall rope is less likely to be cut over an fortably with your toe straight on an edge. edge than a five-fall rope. Based on this crite Unfortunately, it had a softer sole and the Advice rion multi-fall ropes are indeed safer than combination produced a disconcerting Which boot is right for you? It depends. If ropes which hold fewer falls. tendency to roll off edges. you are a beginner or an occasional weekend The maximum forces in the system are Latok Hummingbird XP climber lacking the massively developed calf determined by the belay method employed, Very similar to the Asolo Chouinard, but muscles of the rock jock, a stiffer sole may and are totally independent of the UIAA test has a firmer rubber and a stiffer sole. Nice help reduce the "sewing machine leg" phe impact force. Thus for a dynamic belay, blue color reminiscent of the old favorite of big nomenon. If you are looking for a boot to wear forces are between 1.5 kN (body belay) and wall climbers, the Galibier "Robbins." on long free climbs or mixed free and aid 4kN (friction hitch; direction of pull down). It San Marco Berhault routes, a looser fitting pair with firmer rubber makes no difference if the rope's maximum Flexible sole but firm rubber make the boot and stiffer soles may be more comfortable listed impact force value is 850kN or 1200 an average performer due to the lack of a and will last longer. On predominately aid big kN.

61 Based on a dynamic belay — and Turville mass of only 55 kg, and when used doubly proof. Only if a safety criteria is established— agrees that there are no static belays — and the impact force is approximately doubled. say, the rope must still hold two falls — and the above listed values, it can be shown that The end result is an impact force similar to or the retired ropes are tested can one come to variations in the UIAA impact force elonga higher than for a single rope. (Theoretically it some conclusion. The fact that ropes get re tion (20 percent to 30 percent) are of no im can be 33 percent higher). tired in one piece does not mean that they are portance in the field. For a belay force of 4 kN Turville's advice to use 8 mm or 9 mm safe. the increase in distance fallen is about 0.5 ropes for alpine ice (taken singly, it is Turville argues that the sheath and its abra percent, far less than the slippage of about 15 assumed) is a poor and dangerous recom sion resistance will determine rope life, and percent. For a body belay this is still less, mendation. A fall on a hard snow slope of 45° that the number of test falls a rope holds although slippage will be much more. corresponds to 90 percent of a free vertical doesn't have much to do with a rope's safety Finally a number of comments based on fall. Add the usual long lead-out, the possibil and durability. All this is again offered without recent conversations with the three major ity of wet and frozen ropes which lose 30 substantiation. That a multi-fall rope is safer rope manufacturers (Edelweiss, Edelrid and percent or more in capacity, and one has the has, hopefully, been established. Mammut), the representatives to the UIAA perfect ingredients for disaster. A further Two simple arguments can be presented to Material Commission of the U.S., Canada, point to keep in mind is that 8 mm kernmantle show that it is also more durable. Durability is , and available research. line is a low stretch rope and not designed to here defined as retaining a certain energy The manufacturer's fall capacity rating is take falls. (This does not refer to a half rope absorption capacity — i.e., fall capacity. generally the lowest value determined from climbing rope but to 8 mm line sold by the Ropes hold fewer and fewer UIAA falls as tests. For the minimum five-fall rating, itmust meter off a spool.) they get older while being used. It will surely be the lowest value. "Double ropes make a great deal of sense, take longer to go from twelve to two falls than The impact force reduction (rigid mass vs. particularly in the area of rope cutting." This is it will from five to two. Thus, multi-fall ropes human body) is probably closer to Edelrid's precisely the reason we have multi-fall ropes. are more durable, i.e., last longer. estimate than Beat's. With this comment, Turville contradicts his The second argument goes as follows: The maximum mantle slip of 30 mm is earlier statement that multi-fall ropes are no Multi-fall ropes are heavier. There is more wrong. The UIAA hasrecommended a value safer than, say, five-fall ropes. When two 9 material to use up. This will take longer than of 40 mm until December 31,1984. A value mm diameter double ropes are tested for a regular five-fall rope. It is left to the will be fixed, most likely at the fall meeting of together under the UIAA condition for a single reader to make up his own mind based on the UIAA Material Commission this year, and rope (not a UIAA standard!), the number of these arguments. To argue that the sheath may be binding after the above date. falls can go as high as 30. One cannot de solely determines rope life is silly — why do The UIAA uses only SI units; the latest duce from the data given for a 9 mm rope we bother with a core? Also, UV rays and publication of their standards does likewise. (tested only with 55 kg) the number of falls for industrial pollution have a negligible effect on Force is measured in Newtons, mass in kg, two 9 mm ropes tested with 60 kg. Single 9 rope life in normal use. energy and work in joules. mm ropes hold about one fall with 80 kg. The three rope manufacturers questioned Turville's approach to increasing a rope's A tighter wrap of fibers in the core or an do not use thinner sheaths. They are the capacity is naive. The rope manufacturers all increase in the diameter of the core will not same or thicker. That a rope with a thinner made it clear that there was a lot more to increase the working load stretch. Impact sheath is less abrasion-resistant lacks proof making a good multi-fall rope than playing load depends on rope construction and may as well as logic. with the fibers and/or stuffing more material go up, but more likely will stay the same or Finally, some personal opinions. When into it. very nearly so. A perusal of the rope data buying a rope it should be from one of the top Rope Coatings: good coatings increase provided by Turville allows only the general producers such as Edelrid, Edelweiss or abrasion resistance and, therefore, rope life. conclusion that multi-fall ropes are heavier. Mammut. It may cost more, but then there is However, coatings do not limit absorption of They do not necessarily have higher impact some guarantee of quality; they have a repu UV radiation. Some of these coatings are forces or elongation in use. They cost more, tation to lose. One should beware of any rope waterproof coatings while others serve speci but one does get more rope for the money. where the manufacturer is not known. For fically to reduce abrasion. The rope manufacturers do not treat the instance Chouinard ropes are apparently The damage due to jumaring per se basic fiber at all if two of the major producers made by Beal now — they used to be made appears to be nearly negligible, according to are any indication (Edelweiss and Mammut). by somebody else and they could be made by a recent study. Major damage may, however, The producer of Edelrid wanted to make no a different producer tomorrow. Know who occur because of rope abrasion at contact comment on this matter. makes the rope. points, particularly edges. "Whatever the objective life of a rope is, it is (A more detailed, fully documented version of the Double lines have much lower impact fi obvious that no climbers have managed to above is available from the author at 1029 Hiilcrest gures because they are tested singly with a exceed it." This statement is given without Avenue S.W., Calgary, Alberta, Canada T2T 0Z3).

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62 > Impact Force = Fall Factor / 2 * Max Impact Force

Nope, impact force is not a linear function of fall factor.

In a frictionless model where the rope acts like a perfect spring, the fall force is given by

F = mg + sqrt((mg)A2 + 2Rumg), where F is the tension in the rope, m is the mass og the climber, g is Earth's gravitational constant, R is the fall factor, and u is a constant expressing the spririginess of the rope

In an earlier article I posted arr Incorrect recollection of this formula, forgetting the leftmost term which represents the climber's weight at rest. '

This ignores friction, which reduces the force felt by the belayer when the rope runs overcarabiners or rock. One Way to account for friction is to think of it as increasing the effective fall factor.

In an earlier article, I mentioned that, due to friction, the tension ratio at the top carabiner is 50%, thus exerting 150% of the fall force on the top carabiner. I got this number (approximately) from three references, at least two of which claim independant verification, but have been informed that more recent testing at Black Diamond and REI showsthe force on thetdp carabiner is 1.63 to 1.7 times the tension.

Ken- ■ ■ : ■ -'.:■ ' ; , ■•'■

2/28/98 Re Impact force [warning -' bor Page 1 CLIMBING ROPES 131 ■ ■■/

g = acceleration due to gravity; about 32 feet per sec Afl-C Climbing Ropes ond squared, ft/sec- (9.8 meters per second squared, m/sec") Helmut F. Microys, Ph.D. h = distance the mass is raised i.e. the climber ascends in feet, ft (meters, m).*

1. Introduction: Thus when a 180 lb (81.6 kg) climber ascends for 50 ft (15.2 m) the total acquired energy is 288000 ft-lb/sec2 or ft-poundals (9000 ft-lbf, The following article is not quite the final report of the Rope Deterioration Study undertaken in 1974 by the . Part of the statistical 12155 kg-m2/sec- or newton meters, N*m). data is still missing. This was done in cooperation with the Union Internationale Another form of energy is the kinetic energy (energy of motion). des Associations d'Alpinisme at the instigation of our honorary member, Fritz Every moving body possesses kinetic energy. The kinetic energy is ex H. E. Wiessner. Many of the regional mountaineering clubs of North America participated in the financial support necessary to carry this project through. pressed by the equation The AAC hereby gratefully acknowledges the ongoing assistance given by the K.E. = (i/S)mvi! Alpine Club of Canada, the Appalachian Mountain Club, the Arizona Moun tain Club, the Mazamas, the Mountaineers, the Potomac Appalachian Trail where m is again the mass of the climber and v its velocity in feet per Club and the Sierra Club. second (meters per second). A relationship is now required which ties the above expressions to gether. This is found in the principle of the conservation of energy:

_ 'LIMBING ropes arc chosen for a In a closed system the total energy, i.e. the sum of potential and variety of reasons, such as the reputation of a manufacturer or retailer, kinetic energy, remains constant- the advice of an expert climber, the type of construction, and, last but not least, the price. Because accidents caused by rope failure are rare, One can now consider a falling climber under these aspects. Before the most climbers have no occasion to be seriously dissatisfied with their fall he possesses the potential energy mgh and his kinetic energy is obvi choice. Yet there are differences which affect the operation, the forces ously zero. During the fall, after he has fallen a distance h, his potential developed in a fall situation, and the lifespan of a rope to a significant energy has been reduced by the amount mgh. The principle of the con degree. servation of energy states, however, that the sum of kinetic and potential The most important link in the belay chain is the climbing rope. The energy is a constant. Thus it follows that the kinetic energy must have theoretical aspects of this chain are complex. The following is an attempt grown by the same amount. At the point when the rope starts to arrest to describe the energy and force effects of a fall. From these consider the fall, the total original potential energy has been converted into kinetic ations follow important consequences for choosing and using climbing energy. From these considerations one can write the equation ropes. The requirements of the UIAA (Union Internationale des Asso ciations d'AIpinisme) will be given together with other rope data. Com ments on the life expectancy of ropes and a summary of the properties where v is the velocity at the point where the rope starts to act and h of some of the presently available ropes conclude this report. is the height of the fall. From this relationship one can derive an equa tion for the maximum velocity in terms of the height of fall: 2. The Energy and Force Balance v = >/2gh 2A The Energy Equations: During his ascent, a climber acquires potential energy (energy of position)—the ability to do work. Such forms * The British system and (in brackets) the SI system of units will be used. of potential energy are known from everyday life: a lifted mass can, while Mass and acceleration are defined as shown and the force is in poundals it descends, lift another. The value of the potential energy is given by i.e. ft-lb/sec2 (newtons, N, i.e. nvkg/sec2). Because many readers may have ■» better feeling for force if it is expressed in pounds (pound-force, lbf) this P.E. = mgh conversion is also given where considered useful. It will precede the SI units in brackets. To convert from poundals to pound-force divide by g, the accel where m = mass of the climber in pounds, Ib (kilograms, kg) eration due to gravity.

130 132 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 133

2.2 The Action of the Rope: It has been shown that during a fall duced to zero. For changes in impulse, however, forces are responsible. the potential energy is converted into energy of motion. It is this energy Now changes in impulse or in velocity do not occur instantaneously, which is first absorbed by the elongation of the rope and subsequently rather they take place over a certain time interval (T). During the dissipated. In order to demonstrate the action of a modern climbing rope, total time interval, T, the belayer must exert a force which reaches its one often makes a comparison between ropes made of wire and rubber. maximum at the point of the maximum extension of the rope. A graph Because of its limited ability to stretch, a wire rope has very little ca ical representation of this is shown in Figure 1. pacity to store energy. The instant the rope is loaded, nearly the total The maximum force reached is called the impact force. The area energy would be passed on to the belayer and the leader and other mem under the curve is equal to the total impulse of the falling climber. One bers of the belay chain (, slings, carabiners). The results would be can derive an equation for this maximum force, the impact force. For devastating. a static belay it depends only upon the mass of the climber, a material A properly dimensioned rubber rope, on the other hand, would store constant (the modulus of the rope which depends upon the cross-sec nearly all of the fall energy and then force upon the climber a harmonic tional area of the rope, the fibre content, and so on) and the fall factor up and down motion. Despite air and internal friction (in the material) which is defined as the distance fallen divided by the amount of rope this process would last a long time. Furthermore, because of the ex paid out. This maximum force is given by [1]*: tremely high stretch of the rubber rope, the danger of hitting a ledge or the ground would be increased. Nylon (Perlon) ropes offer a compromise. Part of the kinetic energy is already converted into heat while the rope elongates. This is a result where I = impact force in poundals (newtons, N) of friction between the individual nylon fibres in the core of the rope. M = rope modulus in poundals (newtons, N) Additional energy is lost through friction heat when the rope runs through carabiners. The remaining energy results in up and down motion of the f = fall factor = (distance fallen)/(amount of rope paid fallen climber and is again changed into heat. out) and the other terms are as defined earlier. 2.3 Impact Force and Impulse: So far only energy balances have The amazing fact emerges that the maximum impact force is independent been considered. Now follows a look at the forces which act on the of the absolute height of fall. Thus a fall of 5 ft (1.5 m) will induce belay chain. Another quantity needs introduction—the impulse of the the same force as a fall of 50 ft (15.2 m). falling climber. This quantity is the product of mass and velocity (mv). Another interesting aspect is discovered when one puts f = 0 in the One can then interpret the arresting of a fall the following way: the expression, the case where a climber is vertically below his belay without impulse of the falling climber, or in this case his velocity, must be re- slack in the rope and falls off. The equation reduces to I = 2 mg. Thus Figure 1 Force-lime Diagram. a free fall into the rope without slack for a 180 lb (81.6 kg) climber produces a maximum force equal to 11520 poundals (360 lbf, 1.6 kN**). For further clarification, two examples will be considered:

1) Last protection placed is 5 ft (1.5 m) above belayer. Leader falls from a point 5 ft (1.5 m) above this last protection: height of fall 10 ft (3.0 m), total rope paid out 10 ft (3.0 m), fall factor is 1.

2) Last protection placed is 20 ft (6.1 m) above belayer. Leader falls from a point 20 ft (6.1 m) above this protection: height of fall 40 ft (12.2 m), total rope paid out 40 ft (12.2 m), fall factor is 1.

In both cases the impact force is the same although the height of fall in the* second example is four times larger than in the first example. This 2.2

* See list of references at end. ** kN = kilonewton = 1000 newton. 0.1 0.2 0.3 0.4 0.5 time in seconds i'34 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 135

fact may be explained intuitively, namely the energy of the falling climber and the energy absorption capacity of the rope are directly proportional to the amount of rope paid out. However, there is a significant difference in the two examples. In the second case, the impulse is twice the value of the first and the time over which the falling climber must be held has increased considerably. Thus the impact force alone is not a true measure of the severity of a approximately 21 fall. The time period over which the forces act is an intrinsic part of on carabiner and it. As it is well known that rather large forces but of short duration can be withstood by equipment and the human body alike, it is of para mount importance to avoid such severe falls as given in the second example.

Table 1 Relationship of Fall Factor (f) and Impact Force for 180 Ib (81.6kg) Climber.

impact force, I impact force, I belayer fallen leader

Table 1 shows the relationship between fall factor and impact force Figure 2 Forces in Belay Chain. for a modern kernmantel (core-and-sheath construction) rope and a climber whose mass is 180 Ib (81.6 kg). As can be seen, the forces 2A Conclusions: The impact force is the force acting on the belay involved are considerable. Impact forces above 56300 poundals (1750 chain, the belayer, and the falling climber at the instant of the maximum lbf, 7.8 kN) may lead to serious injuries. Only via chest and seat har elongation. This force is independent of the absolute height of fall but nesses can these forces be distributed in a favourable way on the climber. depends upon the fall factor. The impact force alone is not a measure of the severity of a fall. Of Table 2 Relationship of Climber's Mass and Impact Force for Fall importance is also the time period over which this force acts. The larger Factor 2. the impulse, the longer the time required to arrest the fall. The following deduction can be made:

i) A fall, even with an unquestionable belay stance, is at all times dangerous and should not be risked consciously, especially in the mountains or where assistance is not readily available. ii) The belayer must at all times be in a position to hold a force of about 74000 poundals (2300 lbf, 10.2 kN) and that independent of the expected height of fall. That is about the weight of a loaded Table 2 shows the impact force for various masses when the fall factor Volkswagen. is two. The impact force with a fall factor of two is a guide post for iii) Protection should be placed as soon as possible after leaving the strength considerations of other elements in the belay chain. It should belay stance in order to keep fall factors low. be noted, however, that protection elements above the belayer such as TV) Intermediate protection should be placed to keep fall factors and carabiner, piton, nuts, and slings must at all times be capable of sup impulse low. It is more important, and should be placed more porting twice the impact force which occurs under the given circum frequently, in the first half of the pitch than in the second. stances (Fig. 2). 136 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 137

v) If possible, belay stances should be established after crux moves statically up to a certain force (the maximum force developed) after rather than before to keep the fall factor low in a potentially dan which the rope will start to slide, i.e., the rope will run through the device. gerous situation (this assumes the crux can be protected), Generally this run-through cannot be stopped simply by holding the rope vi) Tieing in around the waist is strongly discouraged. Only with a harder but will stop once the energy of the fall has been dissipated. Thus chest-seat harness can the maximum impact force be tolerated safely. in a severe fall, skin burn may result on the Delayer's hands if no pro vii) Shoulder and hip belays are totally inadequate in a maximum fall tective gloves are worn. It is obvious that a certain amount of rope situation. Severe falls with high fall factors can only be held with must be reserved at the end of each lead for this run-through. The forces a modern dynamic belay. generated during dynamic belays vary from device to device but are viii) Intermediate protection must be capable of withstanding approx much less than the ones occurring during static belays. Fortunately, ex tremely severe falls and perfectly static belays are a rarity in practice. imately twice the impact force. For a high fall factor this may be about 128700 poundals (4000 Ibf, 17.8 kN). Tie-in points at a Very few people are willing to make long leads without protection and many a burned hand and body have supplied an unwilling, although belay stance are loaded by the impact force only but this force may act in various direction. This means, for instance, that the strongest effective, dynamic belay. Otherwise many climbing accidents would have more serious consequences. carabiners are not necessarily required at the belay stance.

It should be pointed out again that a static belay was assumed in the derivation of the impact force. It has been known for a long time 3. UIAA Guidelines [1, 15] that these forces can and should be reduced in order to avoid The UIAA (Union Internationale des Associations d'Alpinisme) has belay and equipment failure and possible injury to leader and belayer established certain guidelines for the testing of climbing ropes [2]. Ropes alike. falling within these guidelines are given the UIAA label which is at Various devices are on the market, such as the Munter plate, which tached to each new climbing rope. have been designed for dynamic belays. Not all of them do what they Fig. 4 shows schematically the drop-test set-up prescribed by the are supposed to. The UIAA has tested, approved and recommended the UIAA. This drop-test (or Dodero Test after its inventor) uses a mass of Munter hitch shown in Figure 3. In all instances each method acts 176.4 lb (80 kg) for full weight ropes or ropes which may be used singly and 88.2 lb (40 kg) for half weight ropes or double ropes because they are designed to be used doubly. For double ropes it is also permitted to use two strands and test them with 176.4 lb (80 kg). The fall factor is 1.79 and the UIAA standard prescribes a maximum allowable impact force of 85112 poundals (2646 Ibf, 11.77 kN) for single ropes or two double ropes and 42556 poundals (1323 Ibf) 5.88 kN) for one strand of a double rope. The standard requires the rope to hold at least three drops without breaking. It should be noted that the impact force given on a UIAA rope label refers to the impact force at the fall factor of L79 and not to the higher value at fall factor two. Furthermore, the impact force limitation is applied to the first drop only. The magnitude of the impact force increases with each subsequent drop. This is a result of the permanent deformations which take place during each loading which the rope experiences. A further test measures the elongation in use. This is a static tension test in which a force of 5674 poundals (176.4 Ibf, 784 N) is applied. Figure 3 The Munter Hitch. The elongation of the rope under this force may not exceed 7% and This is copied out of Mountain No. 32 February 1974 where it is called f&% for single and double ropes, respectively. In practice, this cor the Italian hitch because Munter demonstrated the method in Italy (at responds to a climber on tension, a situation where little elongation is UIAA meeting) for the first time. desired. • 138 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 139

The elongation at impact force is the elongation which occurs under the UIAA impact force in the drop test. This value can be calculated from the data obtained in the drop test but is not subject to any UIAA drop weight in starting position standard. As the total height of fall includes the rope elongation, it is of benefit if this value is as low as possible. The danger of hitting a ledge or the ground because of rope extension is minimized. A relatively recent (1973) addition to the rope standard measures the knotability of the rope i.e. how well a rope maintains a knot. This does not measure the strength of the knot but its durability. This is an im portant aspect as it has happened on several occasions that a tie-in knot has come undone only by the movements of the climber. In order for a manufacturer to retain the UIAA label, he must have samples of his ropes tested by an independent testing laboratory every two years.

4. Strength of Knots

The rope strength is not only reduced by an edge such as a carabiner, but also by knots. The literature [3, 4, 5, 6, 14] gives a considerable range of values, depending when the tests were made, the rope type used, the rope diameter, the speed of load application and the type of test carabiner set-up. It appears that all knots slip considerably during testing and in type edge many cases to failure i.e. the knot slips open without the rope actually breaking. Note should be taken on how to tie the figure of eight loop knot. The difference of strength achieved in doing it the right or wrong way is about 8% for a kernmantel rope [4, 14] as shown in Figure 5.

wrong rght

Figure 4 Schematic Drawing of UIAA Drop Test. Figure 5 Figure of Eight Loop Knot. 140 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 141

Table 3 Relative Strength of Knots for Single Kernmantel Rope. about 11260 ft-poundals/ft to 12870 ft-poundals/ft (350 ft lbf/ft to 400 ft lbf/ft, 1560 N-m/m to 1780 N-m/m), the energy of a severe fall, the rope should be retired. If the new rope has a WCOE of, say, 27350 ft-poundals/ft (850 ft-lbf/ft, 3780 N-m/m) it would only be a matter of finding the loss in the WCOE per hour of use in order to predict the service life of a rope. In 1971 the BMC estimated an average loss of 14.2 ft-poundals/ft (0.44 ft-lbf/ft, 2 N-m/m) per day of use while the OAV came up with Table 3 shows the approximate relative strengths of some of the more a value of 567 ft-poundals/ft (17.6 fHbf/ft, 78 N-m/m) per day. These commonly used knots. differences were partly due to the use of different statistical approaches and evaluation procedures. Furthermore, the initial values of the new 5. Life Expectancy ropes were not known exactly. More recently (1973) the OAV (Dr. Kosmath) estimates the loss of the WCOE per hour as [5]: During its use, a climbing rope ages due to climatic and mechanical influences. In general, the service life of a rope depends on the frequency 70.9 ft-poundals/ft (2.2 ft-lbf/ft, 9.8 N-m/m) for easy climbs of its use, its handling, the kind of terrain, the weather conditions, dam 141.9 ft-poundals/ft (4.4 ft-lbf/ft, 19.6 N-m/m) for difficult climbs age beyond normal use (rock fall, , etc.), and the actual age 283.7 ft-poundals/ft (8.8 ft-lbf/ft, 39.2 N-m/m) for artificial routes of the fibres and the rope itself. In addition to these major factors many The recent Swiss study [10] found a loss of 156.0 ft-poundals/ft (4.9 other influences enter the picture. It is, therefore, not surprising that ft-lbf/ft, 21.6 N-m/m) per day for their ropes; certainly a much closer few hard facts are available to the rope user. result. It should be mentioned that in this study the initial properties of Although synthetic fibre ropes (nylon and Perlon) have been around the ropes were known precisely. Furthermore, the rope history (hours for about 30 years, very few investigations have been carried out ragarding of use, weather, rock type, etc.) was properly documented. the aging of these ropes. Initially this may have been based on the fact Questionable in the OAV results is the higher value for artificial that nylon ropes do not rot like hemp ropes. Although various conjec routes. One of the reasons may be found in the climbing techniques tures about the service life of ropes were made now and then, it is only used in Europe, namely, much tension climbing, a very sparing use of in the last few years that serious inquiries have been carried out. slings to reduce friction drag and the abundance of limestone climbs The first studies were carried out in the U.S., however, they dealt (Dolomites), where continuous crack systems are rare. It is certainly solely with hawser-laid ropes. Extensive studies on kernmantel ropes possible that proper technique on aid routes may put less wear on a were only carried out by the (OAV, Dr. Kosmath) rope than many a free climb of moderate difficulty. [7] and the British Mountaineering Council (BMC) [8]. Specific prob The problem now is that (UIAA approved rope or not) there is not lems were investigated by the Federation Franchise de la Montagne a single rope manufacturer who lists the WCOE with the data supplied (FFM) as well as by the manufacturers of Mammut ropes, AROVA— on the various labels which come with a rope. Only AROVA—Lenzburg, Lenzburg AG [9]. A common finding in all these studies was the con the manufacturers of Mammut ropes, give this information in their siderable spread of the results. This is partly due to the small sample catalog on mountaineering equipment. They even add a note saying that size and the inadequate data (uncertainty of properties of new ropes this value—the larger the better—is an indicator of the rope's life ex and inexact records of use) but it also indicates the complexity of the pectancy. The reason other manufacturers do not supply these values is problem. The recommendations for the life time of a rope ranged from not only because theirs may be lower than that of a competitor or be 40 to 240 hours. cause the UIAA does not require it. There is some disagreement as to The work by the OAV and the BMC as well as the recent AROVA— its validity because it is measured statically while in reality the loading Lenzburg publication [101 express the aging in terms of the working occurs dynamically. There is even some justification in this reluctance capacity over an edge (WCOE)*. Once the WCOE reaches a value of because ropes have held one fall in the drop test while WCOE data "predicted failur^. Furthermore, one would expect that the rope with the * Obtained by statically testing a rope to failure while it runs over an highest WCOE would hold the most falls, an expectation which has not edge with a 5mm radius. The WCOE is the total area under the resulting been confirmed. load-elongation curve. It is generally expressed per unit length of the rope. 142 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 143

Nevertheless, at the present time the only way out of this dilemma 5) A rope marketed as being resistant to water absorption held 2 is to assume that generally the WCOE increases with the number of falls falls less than in the manufacturers' own "wet test" condition held (and this may be true for a dynamically measured WCOE) and (less saturation than in the German test). use this number to estimate the service life of a rope. Nearly every UIAA approved rope shows on an attached label the number of falls 7. Single or Double Rope held in accordance with the UIAA standard. Dr. Kosmath [5] of the OAV found that this assumption is reasonable and recommends the A single or full weight rope is by definition (UIAA) a rope which is adequately safe by itself. A half rope or double rope, on the other hand, following values for single ropes: is safe only if two ropes together are used. To clarify this further: the No. of VIA A Approx. Average UIAA drop test uses a 176.4 1b (80 kg) mass for the test of single ropes, Falls held Service Life (hours) but only 88.2 1b (40 kg) for the test of one strand of a double rope.

2 50 No diameter is specified but single ropes vary from 10.5mm to 12mm while double ropes vary from about 9mm to 10.5mm. 4 200 Various advantages arise from the use of two ropes on routes of a 6 400 high technical standard, on rappels, for hauling, and on difficult maneu vers as a safety rope [13]. Additional benefits arise when one rope gets 6. How Strong Are Wet and Iced-over Ropes? damaged by crampons or rock fall during a climb or when a 10.5mm

The testing for the UIAA label is done with dry ropes at room diameter double rope is mistakenly used as a single (full weight) rope [5, p. 90].* temperature. The minimum requirement asks that three falls be held without a rope break. In the use of double ropes care has to be exercised that both ropes Tests at — 45 °C were carried out by Dr. Odriozola [11] who found are clipped into a particular runner (use two carabiners) when climbing a reduction in static breaking strength of 30% for iced ropes. free passages with little intermediate protection. There is still the The suspicion that the working capacity is reduced not only for iced- question whether on some climbs it would not be prudent actually to climb over ropes but also for wet ropes was verified by tests done by the with two single (full weight) ropes. This should be considered on big manufacturers of Edelweiss ropes [12]. According to the manufacturers, combined climbs where ropes may get wet and frozen or damaged by their new ropes which held 3 to 4 UIAA falls in the standard test, held rockfall or crampons. The added safety and the advantage of clipping only one or none after they were exposed to a sprinkler arrangement in alternately (reduced drag) may well be worth the extra weight. It is and absorbed about 37% of their own weight in water. preferable in the latter case not to clip both ropes into the same runner The German Alpine Club [5] carried out a series of tests on a variety even when protection is far apart as the sum of the impact forces of both ropes is larger than the impact force of a single rope in the same fall of ropes. They tested wet ropes and wet-cold ropes (saturated ropes situation. were stored for 10 to 14 hours in a refrigerator). They came to the following conclusions: 8. Properties of Available Ropes 1) Ropes in wet and wet-cold conditions will generally hold fewer falls than dry ropes. Properties of some of the most commonly available ropes are listed in Table 4. Three ropes produced in the U.S. are included in this table. 2) The effect on wet or wet-cold ropes was approximately the same. It may surprise that the static breaking strength has not been listed. It 3) The reduction of falls held on some products was as much as 3 has been omitted intentionally as the strength per se gives no indication falls for full weight ropes. of the quality of a rope. Too many climbers do base their selection on 4) Some ropes held the same number of falls as indicated by the this relatively unimportant quality. manufacturers for the dry condition. This was not taken to mean Only one double rope listed was tested as a single strand with 88.2 1b. that some ropes are capable of holding the same number of This^ results in a very high number of UIAA falls held and a low impact UIAA falls whether dry or wet but rather that some ropes held force. It is highly unlikely that the testing of two strands would produce more falls in the dry condition than indicated on the label (where obviously the lowest value has to be given). * A double rope, assumed to be a single rope, broke when the leader fell. 144 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 745 s

Sco <

00 <*}00 rf \O OON'tOO't O 00«*jr-;»OCM NO « m V) « Noteson Table4

&jj§«ri «riri-h cs r4 ~ ci — ro c4 r4-«ri ri — ciri oj CHOU1NARD —Data from1976 production.

poop <>*omoo no p o © © »n •5S 2 p **)qqo o i EDELRID —Data from1975 production but1976 production appears to > g rive~d«o —«Xo'-^6no c4c4 \o -*o\ c^r^o—*^ havesame properties.

— Notwilling toprovide WCOE values.

^«_ "t^ ci"<5r.Tt^t^ "* "^ ^ ■* TtTtTtTt"*■ "^ Tf-Tt-^trf — Notethat double rope is tested assingle strand with 88.2 lb

< o2n ^ vo oovdvdno so* no* vo novd vdvdvovdno no"\© vo no no mass.Double the impact force toobtain representative value. 35^ >*" 00 r** r- r-r-»r~ r<- r^ r- r- r-r- r^ r»r-» ?-r- t~» r» EDELWEISS —Data from1975 production.

+ + + + 4- + — WCOE ofdouble ropes is for a singlestrand only. Double

thefigure toobtain representative value.

GOLDLINE —Data from1975 production.

— Onlythe first sample was tested tofailure while the second

and thirdtest specimen were removed undamaged after

fourdrops. The number of UIAA fallsheld is, therefore,

around10 to 14.

co ^" t/%co vi ^^ NO NO nO00 f^l *7 *7 ^r *7 ^r — Thisrope is not UIAA approved.

MAMMUT —Data from1976 production.

& MSR —Data from1976 production. O^OO©©© ^ O\ N ON O «*i © ©-*-h^

f*ioo c^4ro c*4no r^»cm r**^f v*> *^ *-*oo no ^d — Thisrope is not UIAA approved. o 3 o' © o> ^^^^ ^n o\ ^5Os ^^ ^^ ^^ ^^ oo On onoo NEBTEX —Data from1976 production.

ROCCA —Data from1975 production.

«o *rt © > O m

© — O exactlythe same number of fallsheld or resultin merelytwice the > impactforce shown. It should also be rememberedthat one strand ofa

doublerope will most likely not hold a singleUIAA fallwith 176.4 lb. g O < < < ^ e>

Furthermore,thatthe test condition assures uniform loading ofboth

strands,a condition which rarely exists inreal life.

The numberof falls listed isalways the least number from three

gSI^2 °^^ Z C*2,'Z

UJUJ UlOl Ll) Ll] tilttl maximumnumber of falls held can easily betwo. j uJ ZjUJ j uJ uJuj uj*juj 3 uj3 w w W ri3 UJuj

m flQ1-4 i—I On ropelabels theimpact force isoften giveninkilopond (kp) and fflM OQ *-Jta-J CQ M ^-1QQ M-l i_J nQ h-UAQ ^J ^J ^J DOO DOOpO O dOdO O O ddOO sometimesinkg. The values are identical asa kilogram—force iscalled I 5 °5S °5S°5 S ozog z zoozz a kilopondinsome European countries. coQ co coO co co Q co Q co co Q co coQ Q co oo

ThreeU.S. made ropes are listed: GOLDLINE, produced byCo

lumbianRope Co. in Auburn, N.Y.; MSR, produced byMountain Safety Q QQQ U uuww Research,Inc.in Seattle, Washington; andNEBTEX, produced byNew 1—H M I I < < « ed 5 BedfordTextile Co. in New Bedford,Mass. Only the NEBTEX rope QQQQ a <5< hasbeen submitted tothe UIAA andsatisfied allits requirements and zzzz a: UIAAlabel. 2 cua. cu uj hasbeen granted the 8 > QQQQ pppz uj HHHW § Q 5$CO co 9. Conclusions

UJ O

Z -■%Climbing ropes, like most products, differ from manufacturer to uj < li5 manufacturer.Inorder to make a goodchoice one has to become fa UJ b;cq 0 Q Q w u o miliarwith the many varieties available. TheUIAA normwas partly

LU UJ S Z 06 createdtohelp climbers andmountaineers selecta safe rope. However, 146 THE AMERICAN ALPINE JOURNAL CLIMBING ROPES 147 it provides a minimum standard and thus the UIAA label on a rope does 11. Odriozola, J.A., "Bergseile verlieren bei Nasse und 45 Grad Kalte 30% not necessarily guarantee highest quality. an Zugfestigkeit," Alpinismus, Vol. VII, No. 6, June 1969. For a certain price the choice of a rope should be based upon the 12. Neue Ausriistung 73, "Everdry"—Ein neues Berseil auf dem Markt, Alpinismus. VoL XI, No. 8, August 1973. highest number of UIAA falls held (think of the life expectancy here), 13. March, W., "Two Ropes," Off Belay, No. 20, April 1975. the smallest impact force elongation and the lowest weight per unit 14. Prohaska, H., "Die Festigkeit des Bandknotens im Kernmaterial," Der length. The WCOE should be as high as possible while the impact force Bergsteigerf Vol. 43, No. 5, May 1976. should be as low as possible. For these last two points one should keep 15. Leonard, R., and Wexler, A., "Belaying the Leader," Sierra Club Bulletin, San Francisco, 1946. in mind that presently the WCOE is obtained statically and thus not a true indicator of the working capacity in a real fall situation and that the magnitude of the impact force has to a large extent lost its impor List of Other References Used: tance because of the possibilities of providing reliable dynamic belays. This fact is reflected in the rather high impact force values of recently 1. Hanschke, T., "Alles liber Seile," Der Bergsteiger, Vol. 41, No. 6, June manufactured ropes which, of course, hold more UIAA falls than before 1974. while maintaining the same unit weight. This last development is a 2. Munter, W., "Mehr Sicherheit in Fels und Eis," Alpinismus, Vol. DC, No. 6, June 1971. direct result of the work carried out by the UIAA and its recommenda 3. Bram, G., "Die Belastung der Sicherungskette," Alpinismus, Vol. V, tion of the Munter hitch for dynamic belays. No. 6, June 1967. 4. Kosmath, E., "Sicherung and Sicherheit in Fels und Eis,'* Wissenschaft- liche Alpenvereinshefte, Heft No. 19. Massimo Verlag, Wien, Innsbruck, Acknowledgment 1966. Members of the A AC Equipment Committee, Brad Snyder (former 5. Flora, G., "Der Tod am Seil," Alpinismus, Vol. VII, No. 10, October member of the committee), Peter Turner (ACC) and Wolfgang Weber 1969. (AROVA—Lenzburg) have reviewed this manuscript and their valuable suggestions have been incorporated. The cooperation of the European rope manufacturers for supplying data and of the U.S. manufacturers who furnished test samples and provided the test results is hereby ac knowledged.

References:

1. Wexler, A., "The Theory of Belaying," American Alpine Journal, Vol. VII, No. 4 (1950). 2. UIAA Bulletins No. 35, August 1969; No. 37, December 1969; No. 52, December 1972; No. 64, May 1975. 3. Pope, J.F., "Tests on Knots," Summit, Vol. 18, No. 3, April 1972. 4. Borwick, G.R., "Mountaineering Ropes," Off Belay, No. 15, June 1974. 5. Tatigkeitsbericht 1971-73, Deutscher Alpenverein, 1974. 6. Wheelock, W., Ropes. Knots and Slings for Climbers, Revised (Royal Robbins) Edition, La Siesta Press, 1967. 7. Kosmath, E., and Kaminger, P., Bericht uber die Seitatterttngsforschung des Sicherungsreferates das Osterreichischen Alpenvereins von 1964 bis 1973, Austrian Alpine Club, 1973. 8. Borwick, G.R., Colligan, I., Walker, S., New Thoughts on Old Ropes, National Engineering Laboratory in collaboration with the Equipment Sub-committee of the BMC, February, 1973. 9. Der Einfluss von ultra-violetten Strahten attf die physikalischen Eigen- schaften von Bergseilen. AROVA—Lenzburg AG., Switzerland, 1973. 10. Wie lange bleibt ein Bergseil sturzsicher?', AROVA—Lenzburg AG., Switzerland, 1974. you continue to discuss or temporarily Steering Committee Notice adjourn upstairs for a quick snack in the June 1990 conveniently located coffee shop. Although Rock Thompson the days will be quite full {8:00am to approxi Rock Exotica, Inc. mately 10:00pm), the two hours off between Centerville, Utah USA 5:00 & 7:00pm will allow you to sample other restaurants in the vicinity 'on you Keith Schafer own1 or in company with other registrants. Springville, Utah USA

The "Bonntiful" meeting location in John Peleaux Centerville is but a short drive (21 kilometers) Innovative Access, Inc. from Salt Lake City with its airport. All Evergreen; Colorado USA classes of accommodation are available in the city though recommended as being Arnor Larson more convenient to the meeting location is Rigging for Rescue the Cottontree Inn, 1030 N. 400 EM North Invermere, B.C. Canada Salt Lake, UT 84054 phone (801)292-7666.

Registration

The $50.00 US fee will include mid International Rope morning and afternoon breaks. Checks or money orders (in US funds) made out to IRSW'90 must be received here before Science Workshop August 15th to insure your registration. At- tendance will be very limited and you are Sponsored by advised that this is a firm date! Please keep ! November 5-8, 1990 in mind that 2 weeks is not an unheard of British Columbia Council delivery time for letters handled by the of Technical Rescue Centerville, Utah USA international +pony express1. Further de tails, schedules and maps will be mailed (near Salt Lake City) Rock Exotica upon receipt of your registration. A specialized inquiry into the physics and engineer ing of rope/rope systems Endorsed by Those interested in contributing to and the testing thereof. this workshop should write: Mountain Rescue Association Papers, Panel Discussions, IRSW'90 - Amor Larson - Research Section Rescue Technology Com. British Columbia Council of Technical Rescue Test Equipment Workshop Box 399, Invermere, B.C. Canada V0A1K0 Contact Address: ropes is welcomed. Expected presenters Test Equipment Workshop include Quality Control Engineers, Fall Arrest Specialists. Development Engineers. IRSW'90 c/oBCCTR Thursday, November 8th will be a Standards Critics and Technical Rope Box 399. Invermere field day at the Rock Exotica facility where Users. B.C., Canada VOA 1K0 a drop tower and other test apparatus are available. All participants are encouraged Panel discussions will be arranged to bring any and all portable equipment to augment some of the principle presenta they have (such as load cells & associated electronics Objectives tions and explore some areas of uncer or other activation, measurement or recording devices) tainty or contested issues in rope systems and/or samples of materials or systems This year's theme is 'The Testing of testing. The following is just a sample of being tested in their own research pro Systems that use Fibre Ropes for Life Sup the types of topics that may promote lively grams. This opportunity to compare notes, port." Since informative pure research is discussion among the participants: interchange equipment and isolate difficul sought in addition to the applied, it is ties encountered in the physical test setup hoped that participation will extend well could be as valuable as all the presenta beyond the limited scope of the rescue Sheath Adherence to Core in Kernmantle tions and panels. community that initiated this workshop. Ropes and its influence on Me This day will serve a double purpose Researchers from academic institutions chanical Rope Clamp Cam Actions by being open to drop in observers. The and from the industrial fall arrest field are under Static and Impact Forces. dates have been arranged so that early encouraged to participate as are manufac arrivers to the North American Technical tures of rope, rope handling devices and The Influence of Bent/Straight Rope on the Rescue Symposium (Nov.9-11 in Salt Lake City), testing equipment. We are hoping for a Gripping and Time/Distance Delays who may not have a scientific background small group of questioning critics that can of the Prusik/Triple Sliding Hitch in but who are still interested in how this drag out the best in each of us. Fall Arrest. work is done, may drop by to view, discuss and perhaps supply some of their gear for This workshop will provide an A Comparison of Drop Test Methods; Free destructive tests. It is clear that open opportunity for the exchange of new infor Falling Body to Track & Anvil dialog with rescuers who use rope systems mation and ideas between those engaged in Systems. extensively in the field can give new leads the theoretical study and physical evalu for further research and uncover concerns ation of rope and it's tasks. IRSW90 is Speed of Loading & Extensibility of mate about the relationship of past and present about rope, the tools that are used with rial as it affects Knotted Rope testing to the way ropes are handled during Strengths rope and how we can learn more about the actual use. interaction that takes place between these elements in static and dynamic situations. Rope Grab "Settling In" vs. Slippage; It's Significance in Result Interpretation Travel & Lodging Presentations & Panel Discussions At Which End of Your Rope?: Force Differ ences within Systems Undergoing Bookings for travel and accommo Drop Tests dation are the responsibility of the partici We encourage all persons interested pants. A map to the meeting and test in giving a presentation on a technical rope Extensible Materials Slow Pull Test Re workshop locations, showing nearby topic to advise us as soon as possible. sults: Constantly Applied Tension restaurants and accommodation will be Requests for participation in IRSW90 (CAT) vs. Hydraulic or Screw Type available to registrants. For noon lunch must arrive at the above address before, Machines you are on your own, but you are welcome August 15th. Any research involving fibre to *brown bag it' in the meeting room as International LEKI SKI POLES Distributors • STUBAI MT. EQUPT. • EDELWEISS Incorporated • SECURA BINDINGS ■ POMOCA SKINS • LOWA BOOTS

Dear Dealer:

We have been requested by several of our dealers to respond to the recent Blue Water Dealer letter and advertisement referring to its rope tests dated April 14, 1989.

We have been aware, through various conversations with Blue Water representatives, that they were concerned with our Stratos advertisement. I was informed by them that they claim to manufacture a rope which holds- a fall over an edge and that the Stratos failed to hold an edge fall. When I requested samples of their rope and copies of the test, I was advised that neither the rope nor the test results were available. I advised them that we had tested several of their models and none that we tested held an edge fall.

After the Las Vegas Trade Show, our office received several telephone calls from individuals who indicated that they represented Blue Water, and each caller requested to know the radius of the edge that was used in our Stratos test. In each instance we gave them the information and advised them upon receipt of a written request, we would provide the complete test results. As of this date, we have not received a written request.

In April, we were notified by Woody Keen, one of our sales representatives, that Blue Water had invited him to observe tests of several of their ropes, the Stratos, and at least one other company's rope. Apparently the test was designed to reproduce results described in their April 14 report.

He observed the test and reported the following results:

1) No rope tested on that day survived a fall over a .5mm radius edge.

2) When the edge was changed to a .75mm, 3 separate Stratos were tested, each survived and sustained very little damage, only one side of the sheath was torn and the core was not affected. It was his impression that all observers were very impressed.

3) He could not remember how many different Blue Water ropes were tested on the .75mm edge, but he estimated that it was approximately 5. Of this total, only one Blue Water rope held one fall, all the other ropes tested failed to hold one fall. The rope that survived the test incurred very severe core damage.

4) The Blue Water representatives were unable to explain why the one rope held the one fall when all their other ropes failed.

Route 203 P.O. Box 110 Spencertown N.Y. 12165 (800)445-6664 (518)392-3363 TELEX 7400953 (Dist U.C.) FAX (518) 392-3380 5) He also indicated that the Blue Water representatives said that they had previously performed a drop test of the Stratos over a standard carabiner edge. After 12 standard falls they stopped the test, not because the rope failed but they got tired of resetting the machine 1 The rope still looked as if it vas hardly used. You'll find it interesting that we only rate our Stratos as a 9. fall rope.

Since we did not participate in the Blue Water tests, we can not explain or defend the methods used. What we know is that the Stratos has proven itself time and time again; not only was it the consistent "winner" of this test, it has proven itself by having recently received patent for its unique design and its ability to perform where others fail!

We have not overestimated or exaggerated the performance of the Stratos. Both Charlie Campbell and I personally have, at different times, witnessed a drop test of the Stratos over a .5mm edge— no smoke, no mirrors, —the rope works and the Stratos' patent documents it.

We do have major concerns about the comparison that Blue Water is making in their recent advertisement. They state that their test was conducted to duplicate our claim "using the available literature from Omni International", and that our test over a .5mm edge "was run using a granite edge". The actual fact is that they NEVER REQUESTED XH£ AVAILABLE LITERATURE. We use a Steel Edge and we have NEVER claimed to use a granite edge.

However, the most serious concern about their comparison is their attempt to establish a clear equality of their Enduro and Flashpoint models to the Stratos. The problem is very simple, they knew that the Stratos held every fall on the .75mm edge, a 100% success rate, while their ropes FAILED at least 80% of the time! The development of a comparison that so distorts the actual performance of their product raises significant questions about their motivation. However, because of their failure to fully disclose the full test results, the only conclusion one can draw from reading the report is that the ropes are equal; while obviously they know that this is not the case. To use their own words, Blue water "is using poor judgement in the attempt to sell more ropes".

Since the Blue Water claim has been circulated, we requested Edelweiss to conduct a retest of virtually all manufacturer's products including the Blue Water ropes. The results will be available at the Outdoor Retailer Show August 14TH-17TH, and you can draw your own conlusions. After you see the results you know why Edelweiss has clearly established a standard that others aspire to achieve.

However, perhaps the most important factors are not what a manufact urer or a distributor say about their product, but what the consumer feels. When you compare all the facts about performance, reliability and quality, you'll understand why climbers like Ron Kauk, Alan Watts, Christian Griffith, Todd Skinner, Bobbie Bensman, Mugs Stump, Jim Bridwell, Mark Wilford and Wolfgang Gullich have chosen Edelweiss as the rope that they tie into. I hope the above clarifies our position.

Best regards, S>^ HUj— Fred A Meyer The Most Advanced ROPE SURVEY Unraveling the kemmantle tangle Equipment for Vertical Operations This year the selection of dynamic the five-fall UIAA minimum is overkill. ropes available in the United States is (See "A Short Course in Rope Phy a mixture of well-proven classics and sics," by Dennis Turville, in Climbina Tools For: intriguing new designs. There are a no. 84). • Industry bewildering number of diameters The c ther three performance specs available, and if coloration is impor always given are weight per unit © Climbers tant to you. welcome to the jungle. length, static (or working) elongation, Unraveling this ball can be frustrat and impact force. Weight is important ing. European-made ropes are often to any venture at a climber's limit. Sta brought to the U.S. by a number of tic elontaation is an approximation of different distributors, some of whom the relai ive degree to which a rope will change product names, and all of stretch during a fall — more stretch "'JU '^'.ttofW / Forrest whom have their own pricing struc means a higher likelihood of hitting ^p- ^4 W ' w°nder Bar ture. Some manufacturers change someth ng. Impact force is an indica their product's colors and patterns ev tion of tljie relative degree of shock the ery few months in response to market body will receive at the end of the demand and the availability of dyed plummet — high impact force can Rescue Teams libers. American-made ropes are a bit mean more pain. According to easier to sort through, since there are Chouinard Equipment, a rope that o Ski Lift fewer brands and middlemen, but it is generates a low impact force also has Evacuations not uncommon for retail pricing to be less tendency to cut over an edge dur left to the whim of the individual re ing a fall than a rope that generates a tailer. high impact force. Fortunately, all respect the UIAA Numerous other specifications are and it's standards. Producing a rope given, depending on the manufacturer SAFETY PRODUCTS INC. without UIAA certification erasures or distributor. Of these, the accom 4550 Jackson Street. Denver, CO 80216 that product's market failure, as well it panying! tables show sheath slippage 303/399-4623 Depi CL should. Because of this respect, vir and interior knot diameter. In general, CALL OR WRITE FOR A FREE CATALOG tually all manufacturers do their own ropes with high sheath slippage UlAA-type testing, or have it done by abrade imore easily than those with independent labs, and use the results little orjno slippage, and they can for marketing purposes. Incidentally, cause updue excitement when jumar- this gives the consumer a yardstick to ing. But loose sheaths are often ALPINE compare products. i associated with flexibility, which is the It is important to note that the UIAA main component of good handling. A FOOTWEAR only "passes" ropes that meet their better, jnore objective measure of standards; product specifications are rope flexibility is interior knot dia REPAIR given by the manufacturer or their meter, which is measured inside an agents. To my knowledge, no manu overhand knot on a hanging rope that Kenko International, rhe exclu facturer or distributor blatantly misrep is weighted according to UIAA guide sive distributer for Asolo Foot resents their products. Still, it is in lines. wear, has original factory compo teresting to see specifications for the These last two specs are so infre same rope vary according to different nents and equipment to repair or quently given that it seems that most rebuild any relemark, climbing or distributors' catalogues. The variation of the industry is content to let us de is never significant, but my Water- termine handling characteristics after hiking boor. gate-lran-Contra upbringing forces we buy heir ropes. (Hats off to those me to suspect that minor embellish few who do provide such data.) Given *We use authentic climbing, ment occasionally takes place. Admit this lack of information, the best way a hiking and ski boot lasts during tedly, this variation could be due to prospective buyer can get an idea of the repair process. This ensures other factors such as typographical handling is to ask around. Good hand the original fit. errors or oversimplification of conver ling suggests not only ease in tying *We use only rhe finest re sion factors (especially with impact knots, but freedom from kinking and a force calculations). , placement materials featuring minimum of spinning when the clim Five Tennie Stealth, Scarpa, Spor- All rope manufacturers and distribu ber is suspended. tors provide four specifications that re tiva and llga Grimpeur soles. We late to product performance. These Now, about that most sought-after also stock a thin version of Five are in addition to diameter, length, and specification: price. Often, prices for Tennie Stealth for climbing slip whether the rope has been treated for the same rope vary to an astounding pers. water repellency. The most hyped of degree. During the information- *AII brands repaired. these performance specs is the num gathering phase of this survey, I found *Custom repairs welcome. ber of falls sustained before failure in a a rope which varied in list price by UlAA-simulated drop lest. As Chris nearly $60.00 between two well- Gore points out in the preceding arti known mail-order outfits. The moral: Kenko Service Center cle, however, there is no clear differ don't pay too much attention to the 8141 W. I-70 Frontage Road N ence between a rope which will sus prices gjven here, and shop around. Arvado, Colorado 60002 tain seven and ten UIAA falls, and On the other hand, it's a good idea to (300)425-1201 many think that anything more than buy from your local retailer even if his • Modal and Lengths Dry Treatment UIAA Falls Weight Elongation Impact Sheath Interior Knot Price 3 Diameter Available (m) Available1 Sustained 2 (gr/m) <% w/80kg) Force (kg) Slippage (mm) Diameter (mm) (50m)

BEAL Leader 11 mm 45, 50. 180 yos 11 79 893 n/a n/a $135, dry S167 Edllnger 10.5 mm 45,50, 180 yes 7 70 893 n/a n/a $124. dry $149.50 Laser 10 mm 45, 50 dry only 5 63 812 n/a n/a $138

BLUEWATER 11 mm 45, 50. 180 yes 10 79 5.2 890 0 11 $112.50. dry $135 10.5 mm 45, 50. 180 yes 6 70 4.2 885 18 10 $105, dry S127.50 10 mm 50 dry only 6 64 3 940 24 8.5 $127.50

CHOUINARD Single Rope 11 mm 45,50 yes 11 79 6 893 n/a n/a $135. dry S167 Guide's Rope 11 mm 50 dry only 9 79 7 940 n/a n/a $168 Single Rope 10.5 mm 45.50 yes 7 70 6 893 n/a n/a $124, dry $149.50 Falaise 10.5 mm/9.5 mm 5 50 no n/a n/a n.'a n/a n/a n/a $150 Superlight 10 mm 50 dry only 5 63 5 812 n/a S13B

EDELRID Classic MD dry 11 mm 45, 50 dry only 8 73 7.6 1005 9 S160 Hotline 11 mm 50 no 6 72 7.1 1010 9 $115 Classic XM 10.5 mm 45, 50 no 7 69 7.7 990 7.5 $118.50 Dynaloc MD dry 11 mm 45. 50 dry only 11 76 7.6 1005 7.2 $182 Dynaloc XMD dry 10.5 mm 45, 50 dry only B 69 7 975 6.8 $158.50 Dynaloc ED dry 10 mm 50 dry only 6 65 7.5 964 6.0 $148

EDELWEISS Extrem 11 mm 45, 50 dry only 9 78 914 0 n/a S 169.95 Calanques 10.5 mm 45. 50 dry only 7 70 990 n/a n/a $139.95 Verdon 10.5 mm 45. 50 no 7 70 990 n/a n/a $124.95 Stratos 8000 + 10 mm 50 dry only 10 72 914 0 n/a $199.95 Ultralight 9.8 mm 50 dry only 6 61 914 n/a n/a $144.95

MAMMUT Aro-Flex 11 mm 45, 50 yes n/a $124. dry $150 Aro-Pro 10.5 mm 45, 50 yes n/a $117, dry $142 Aro-Gelaxy 10mm 45, 50 yes n/a $118. dry $140

NEW ENGLAND ROPES Maxim 11 mm $123.50, dry $143.50 Skyline 11 mm 5 S89.50

Model and Lengths Dry Treatment UIAA Falls Weight Elongation Impact Sheath Interior Knot Price3 Diameter Available (m) Available1 Sustained2 (gr/m) (% w/BOkg) Force (kg) Slippage (mm) Diameter (mm) (50m)

BEAL Froostyle 8.8 mm 45, 50. 90 dry only 48 7.5 508 n-'a n/a $119 Superlight 8 mm *■ s 45. 50 dry only 37 12 492 n/a n/a $ 84

BLUEWATER 9 mm 50. 100 dry only 12 53 8.1 GOO 16 9 $100 8.6 mm 50. 100 dry only 8 49 4 660 9 6.5 $100

CHOUINARD Double Ropes 8.8 mm 45. 50 yes 48 7.5' 508 n/a n/a $ 97. dry $119 Superlight 8 mm (4, 5) 36. 50 dry only 37 12 492 n/a n/a $ 84

EDELRID Classic LD dry 9 mm 45, 50 dry only 12 53 7.3 i 720 7.5 $2406 Classic DUO dry 8.5 mm *• * 50 dry only 207 47 9.8? 1117 7 3.0 $119 Dynaloc DUO dry 8.5 mm 4- 6 50 dry only 257 46 9.5t 1117 7 4.2 $ 84

EDELWEISS Stratos 8000+ 9 mm 50 dry only 50 10 685 0 n/a $149.95 Calanques 8.7 mm 50 dry only 50 10 710 n/a n/a $109.95 Ultralight 9.8 mm 36. 50 dry only 46 10 685 n/a n/a $109.95

MAMMUT 9-PIU8 9 mm 45, 50. 90 yes 50 7 700 n/a n/a $ 96, dry S110 Aro-Tw/n 8.5 mm 45, 50. 90 dry only 48 6.5 690 n/a n/a $104

NEW ENGLAND ROPES Maxim 9 mm yos 48 4.2 510 n/a n/a $99. dry $116

(1) "Dry" denotes total (2) Minimum number is (4) Designated by manufacturer/ (6) Available only (8) One of the 9 falls impregnation of core and used where range of distributor as a twin rope in sets of two. was over an edge of sheath with a water- falls was given 0.5 mm (see text) repellent chemical. (5) Has nol received (7) Tested with double (3) Suggested retail UIAA certification. strand using BOkg as falling weight.

9 8 Climbing prices are a bit higher; its a lot harder dealing with some huge mail-order nouse when your rope inexplicably goes funky. * As you read on, it is likely the thought will dawn on you that there must be an easier, more complete way to compare ropes. Which designs really do resist abrasion, stay water repellent, ar-l never kink? The prob lem is that no one has found the time and money to do a complete series of objective consumer tests in the face of a continuously changing market. My advice is this: get what you can out of this survey, then start asking ques tions at the crags and in the stores. If you can't get straight answers about the rope you are interested in, espe cially in shops or from their suppliers, don't buy it.

Beal. This French rope manufactur er has been in business for over 25 years. In the U.S., Beal is represented by Climb High in South Burlington, Vermont. Five diameters of rope are brought in from the Beal line: 11mm, 10.5mm, 10mm, 8.8mm, and 8mm. Beal also makes a 9mm and variable diameter rope (10.5mm/9.5mm), but Climb High feels that the 8.8mm is as good as the 9mm at less weight, and the variable diameter rope, the Falaise, is sold under the Chouinard name. The Climb High catalogue boasts that Beal ropes have impact forces that are 10-15% lower than other ropes. A quick scan of the accom panying tables suggests their proc lamation isn't far from the mark. The catalogue also asserts that Beal has designed special machinery to ensure proper sheath tension, which provides maximum abrasion resistance without sacrificing suppleness. Of the ropes Climb High imports, only the 11 mm and 10.5mm come in both dry and untreated; the rest are dry only. According to Climb High's Bob Olsen, to produce a dry rope, Beal saturates both core and sheath with a Teflon derivative before weav ing, then saturates the rope again af ter weaving. Beat's 8mm rope, the Superlight, is designed to be used in a twin rope situation where light weight is abso lutely critical. At37g/m, the Superlight is easily the lightest rope surveyed here. But it comes at a price — the rope has not received UIAA certifica tion because it can only withstand four UIAA falls instead of the five required. With this in mind, I must complain about the 1988 Climb High cata logue — nowhere does it say that this rope is not certified; by comparing all Beal ropes in the same manner, Climb High gives the impression that it is. Each diameter of Beal rope, except one, comes in a variety of four or five color schemes, some of which are striking. The only rope that Climb High

August 1 9 8 8 9 9 offers in "bicolor," which denotes a treatment is applied to individual yarn Designed for European-style bolt- different color pattern on each half of strands in both core and sheath before protected climbing, the Falaise is the same rope, is the 8.8mm in a 90m weaving, so unexposed fibers will al 10.5mm for 10 meters at each end and length. Bicolor construction makes it ways maintain water repellency. 9.5mm in the middle 30 meters. Tran very easy to find the center of a rope Since Blue Water sells direct to re sition between diameters is marked and to remember which end has re tailers, wholesalers and distributors by a coloration change. Supposedly, ceived the most use. are eliminated. Not only does this this gives the durability of a 10.5mm allow shops to get stock in quicker and near the climber, where impact force Blue Water. Dick Newell founded make special orders, it keeps the price is the greatest, on a rope similar in this Georgia-based company in 1968 down and allows more direct consum weight to a 10mm. According to the to provide friends with static ropes er feedback. Chouinard catalogue, the rope has suitable for caving. His company grew Blue Water ropes come in seven "enjoyed considerable success" in quickly, and in 1983, Blue Water different color schemes for the 11 mm, France. started manufacturing UIAA- two for the 10.5mm, four for the 10mm However, technical specifications approved dynamic ropes. and 9mm, and three for the 8.6mm. are more or less nonexistent, and no Blue Water uses Caprolan 2000 Within this great variety are some wild where does the catalogue indicate Nylon for their yarn. Blue Water Vice combinations. All ropes are also avail that the Falaise — a*> well as the 8mm President Glenn Newell says that this able in bicolor. Chouinard Superlight — is not certi material, made by Allied Fibers, is not fied by the UIAA. Also, I was surprised only more abrasion resistant, but also Chouinard Equipment. All to see that Chouinard didn't warn that has strength and stretch characteris Chouinard ropes are manufactured by the Superlight was designed for twin tics superior to those of any other fiber Beal. According Michel Beal, there is rope technique. available. virtually no difference between Beal Four color schemes, including two All Blue Water ropes have a Stan and Chouinard ropes of the same dia for each dry rope, are offered for most dard or Dry Rockguard finish. Blue meter other than color, with the excep Chouinard ropes, except the 8mm Water has found that the standard tion of the 11 mm Guide's R6pe, which and 10mm Superlights (two colors treatment increases the life of treated is made exclusively for Chouinard. each) and the Falaise (one color). ropes up to 35% over untreated ropes, Hoever, the ChouinardfBeal line There are no Chouinard bicolors. and that it reduces surface friction, im and the Climb High-Beal line don't ex proves handling, and serves as a actly overlap. Each has different rope Edefrid. This German company shield against abrasion. lengths or dry/non-dry options avail has been making ropes since 1863 Although the standard treatment is able in the same rope, and the and is the world's largest manufactur impregnated into sheath yarn before Chouinard ropes are different in color. er of climbing ropes. California-based weaving, Blue Water notes that it can Chouinard also offers a rope Beal dis Liberty Mountain Sports is Edelrid's eventually wear off. The Dry Rock- tributes in France that is not carried by sole distributor in the U.S.. guard treatment, however, is claimed Climb High: the variable diameter The 1988/1989 Edelrid catalogue to be permanent. This water repellent Falaise. shows three lines of ropes; all but the

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Perfect line is carried by Liberty. (The Liberty imports an 11mm, 10.5mm, Omni International of New York runs Perfect series are Edelrid's most 10mm, and 8.5mm in the Dynaloc the Edelweiss show. basic ropes — no loss to the Amer series and an 11mm, 10.5mm, 9mm, Edelweiss offers a full range of dia ican consumer.) Of the two lines im and 8.5mm in the Classic series. Both meters: 11mm, two 10.5mm, 10mm, ported, the Dynaloc series is their 8.5mm ropes are available only in 9.8mm, 9mm, 8.7mm, and 8mm. All flagship. Dynaloc ropes use specially pairs. Liberty also brings in an 11mm use what Edelweiss calls Durastrong manufactured fibers which give con rope manufactured by Edelrid specifi or Duralight fiber technology, which sistently higher fall ratings than the cally for the American market, the Hot they say significantly reduces weight fibers used in their other ropes. All shot. The hallmark of this rope is price; while increasing strength over other Dynaloc ropes also feature a Dry- it is the least expensive 11 mm rope construction methods. Sounds good, Longlife treatment, which involves im imported into the U.S. but this claim is a bit weak, except for pregnation of core and sheath fibers The yarn used in all Edelrid ropes is, Edelweiss' amazing Stratos ropes, with a silicone-based chemical before in their words, "UV stabilized," which since there are other makes of same weaving. Edelrid says this process not reportedly imparts resistance to the diameter with similar weight/falls ratio. only prevents water absorption but corrosive effects of sunlight. Liberty's All Edelweiss ropes except the also nearly triples abrasion resist Ed Banjster also points out that every 10.5mm Verdon are Everdry, which is ance. fiber of all Edelrid ropes runs the entire a trademark denoting total sheath and The next line down from Dynaloc is length bf the rope — an admirable core impregnation before weaving the Classic series. These are Edel claim not often made. with a water-repellent chemical uni rid's old stand-bys, the traditional de As far as color goes, the 11 mm and que to Edelweiss. As with other dry signs that have been in use, seeming 9mm Classics are available in three ropes, this prevents absorption of wa ly, forever (although these "classics" color schemes, the 10.5mm and ter, increases resistance to abrasion, are always being improved). All the 8.5mm Classics and 8.5mm Dynaloc and prolongs the life of the rope. The Classics offered this year have the are available in two, and the rest are Verdon is surface-treated only, which same Dry-Longlife finish as the Dyna available in only one. Edelrid offers no like other sheath-only treatments will loc, except for 10.5mm Classic-XM, bicolor ropes. eventually wear off. which is surface treated instead of im The most exciting Edelweiss de pregnated (Edelrid calls this the Long- Edelweiss. Edelrid may be the velopments for this year are the 9mm life treatment); consequently, the largest, but Edelweiss is the oldest, and 10mm Stratos 8000+ ropes. The treatment can wear off. According to dating back 356 years to the 10mm Stratos is one of the winners of the Edelrid catalogue, a Longlife treat Teufelberger family's first rope. Sur Backpacker's "Best By Design" ment can still extend a rope's life by prisingly, the Teufelbergers still own awards. The design of the Stratos in 33%. the company. In the United States, corporates a mantle of nine inner

August 1 9 8 8 1 o 1 strands, each with its own mini- surface treatment in the war against sheath. This gives superior cut protec abrasion. tion over other designs. In fact according to Edelweiss, the Stratos is Reeves also points out that most the only rope to survive a UIAA fall manufacturers, including Arova- Mammut, treat their sheath yarns dur over a 90° edge with a 0.5mm radius (the standard UIAA drop test uses an ing the dyeing process; this fixes the edge of 5mm radius), backpacker dye permanently to the yarn, makes it calls it, "an excellent piece of industrial anti-static, and reduces fiber friction design... (which) puts it at the top of as well as improving abrasion resist the pack." Unfortunately, the Stratos ance. Most manufacturers also use a is also very expensive. yarn lubricant to facilitate fiber move The Edelweiss catalogue gives the ment through weaving machinery number of UIAA falls for the Stratos and this in itself adds some degree of abrasion resistance. 5.10 Verticals 10mm and 9mm as 9 +1 e and 8 + 1 e $119.00 One nice added touch is that Mam 5.10 Friction Loafers $ 78.00 respectively. The "1 e" is not an official Dolomite Magica ly recognized UIAA designation, but mut accounts for the natural rope $115 00 shrinkage that comes with age. Mam Resin Roses $115.00 an indication by the manufacturer that of the 10 falls the 10mm survived (and mut cuts every rope 2-3% longer than -Plus- the specified length —a considera Hammers the 9 falls the 9mm survived), one was $ 75.00 over a 0.5mm radius edge. tion which all the other manufacturers Pants either don't do or forgot to mention in S 15.00 Right up there with the Stratos for and way more. their catalogues. consumer excitement is the new Four color schemes are available Call In your order today! 9.8mm Ultralight rope. This is simply the thinnest and lightest rope desig for each diameter offered, except the 10mm and the 8mm, which are avail (405)360-6647 nated as a single on the market. It will Free Shipping o Free Calalogs/lopos undoubtedly become the rope of able in three each. Three diameters choice for those who are ultra- are offered in bicolor, the 11mm, fanatical about weight. 10.5mm, and 8.5mm, but you'll have Two color schemes are offered for to call around since each distributor brings in only one or two. Two of these ^MOUNTAIN SPORTS each rope in the line, except for the Stratos 10mm and the Calanques bicolors are Duodess, which is Mam ^ Neman OK 73069 10.5mm. All are attractive. No bicolor mut's word for continuous fiber ropes — despite the change in pat ropes are offered. OKrwMenUadd7% tax tern, each fiber runs the length of the Mammut. Arova-Mammut is a rope. Swiss company with over 125 years of New England Ropes. Herb Re- experience in the rope-making busi pass, the founder and president of this ness. Four distributors bring Mammut company, developed the original ropes into the United States: Adven Goldlme in the late 1950's. In the late ture 16, Climb High, Recreational 1970's, Repass engineered a new Equipment, Inc., and SMC. rope, which became the first Amer Mammut ropes are made from the ican-made kernmantle to receive company's own exclusive yarn, de UIAA certification. veloped in conjunction with Viscosuis- New England Ropes, out of New se. The Mammut catalogue says that Bedford, Massachusetts, makes their yarn has a greater working three ropes for the lead climber, the capacity than standard yarns, giving their ropes the ability to hold more 11mm and 9mm Maxims and the 11mm Skyline II. The Maxim is avail UIAA falls and be slightly less springy fow available for Do-it able in either dry or regular. All ropes Yourselfers... than ropes of the similar weight made from standard yarn. Since virtually ev are treated with a fiber lubricant before weaving which helps reduce suscepti ery manufacturer is using their own bility to abrasion. Dry ropes are yarns, this assertion is hard to test treated after weaving by immersing Between the four distributors, five diameters of ropes are imported- the rope in a water-repellent solution exclusive to New England Ropes, and ■ EASY—Anyone con do it 11mm, 10.5mm, 10mm, 9mm, and FAST-To/res about 1 hour then cured through a non-damaginq 8.5mm. All but the 8.5mm can be heat process. purchased either Super-Dry or un treated; the 8.5mm only comes in Su The Skyline If is a three-stranded open-laid rope, similar in construction Hesole Kit Contains: per-Dry. Super-Dry ropes are manu to Goldline. Although it is not UIAA >-A pair of Rubber soles factured by impregnating core and certified. New England Ropes claims ►Resoling Cement sheath yarns with a silicon-based wa ►Instructions ter-repellent chemical after weaving that the requirement for five UIAA falls sustained has been met. The specs 1 ^ via a sophisticated immersion/heat drying process. for impact force, however, are almost scary. While the rope has nowhere Name Some companies surface-treat their non-dry ropes with a finish that near the performance characteristics of kernmantle, its price will make it Address. helps prevent abrasion, which would attractive to scramblers. Cily Stale seem to place untreated ropes such Zip _ as Mammut's non-drys at a lower ex There is one conservative color Phono ( scheme for each Maxim diameter in Shoe sizo pected longevity. Not so, says SMC's Ti(f P-°-Box '390 • Glondalo. CA 91209 Mike Reeves. According to Reeves dry and non-dry and one for the Sky (818) 7S8-30B8 line. No bicolor rope is offered. Mammut believes that good sheath construction is more important than —John Steiger 1 0 2 C I. I M B I N c,

4. Technology of the Climbing Rope

4.1 Functions and Properties of re the climber. Also, joined together by a Climbing Rope the rope, they would fall even further, as Belaying - rope manoeuvres-transpor the belay chain could not sustain the tation-rescue. high impact load. A rope of rubber, As part of the belay system the rope made strong enough to hold a fall, must prevent the climber from falling would produce a very low impact force. and, in the case of a fall, safely catch the The belay chain is spared; however, the climber. extreme elongation increases the risk of As an aid for rope manoeuvres it must hitting rock projections or the ground. allow the overcoming of otherwise in- Both types of rope are, therefore, not vinciblesections. suited for climbing. It is the task of the climbing rope designer to find a sensi As a means for transportation it serves ble compromise between these two ex to convey equipment, and in an accident treme examples. In searching for the it can be used as a means for rescue. proper material, all natural fibres, inclu A mountaineering rope must not only ding hemp were found to be unsuited. sustain the worst possible fall of a clim Perlon, a modern synthetic fibre, was ber, it must also hold the falling climber found to be the only material which gently. A sufficiently dimensioned steel when processed properly was close cable, for example, could sustain a se enoughtothis ideal. vere fall. The extremely high impact imposed, however, would severely inju 4.2 What Happens to the Rope during a Fall When stopping a fall, the rope must dissipate the energy of the climber. It stretches and produces a braking force which retards the fall. Maximum stretch occurs at the end of the fall. At this point the braking force equals the impact force. The fall energy is changed into heat by friction on edges, knots, rock, by capillary friction inside the rope, and trough external friction of the rope when a dynamic belay is used. Thus the temperature of the rope rises by several degrees. The energy stored in thestret- ched rope lets the fallen climber spring up und down a few times before it is also dissipated by friction. Only then has the fall finally come to an end. 1. Free length of rope The elongation also produces a perma 2. Payed out rope nent deformation of the material. (Mate 3. Length of free fall rial fatigue.) A part of the rope's capacity 4. Impactforceelongation for taking up strain energy is damaged 5. Overall length of fall so that the rope is unable to offerthe original safety in the event of further falls. Ropes which have had to sustain a severe fall should be discarded. For safety reasons, they must no longer be usedforclimbing.

4.3 Pendulum Fall -} M The pure pendulum fall is afallfrom ■* a horizontal or downward sloping tra verse where there is no distance ot free fall but only the distance of pendulum fall. From the very beginning of the fall. the rope influences the direction of the fall. The falling body describes an ap proximate circle whose centre is the pi ton or sling on which the impact is imposed. There is no actual impact force as the speed of the fall und thus the fall energy which corresponds to the 1. Maximum impact force length of fall, is conserved. The belay chain is loaded only with the centrifugal 2. Length of pendulum fall force which affects a body moving in a circle and which cannot be largerthan twice the weight of the falling climber. This explains why suspect pitonsin traverses very often do not break out. The danger of a pendulum fall lies in hitting the rock while swinging backand forth at speeds approaching those of a normal fall. The most frequent falls are falls from diagonal directions whereby the total length of fall is a combination of the length of free fall and the length of pendulum fall. The climberfalls verti cally at first. The tensioned rope then leads the falling body into an almost circular course around the piton hol- dingthefall. The entire fall energy of the free vertical fall must be absorbed by the rope which means an appropriate high impact force. The remaining length of pendu 1. Maximum impact force lum fall does not increase the impact 2. Length of free fall force. The resulting energy remains as 3. Length of pendulum fall kineticenergy. 4.4 Cutting Effect of sharp Edges Where the rope is loaded without pas sing over an edge the load is distributed to the entire cross-section of the rope. All the fibres of the rope are stressed evenly. When the rope is led around an edge the load affects the fibres very differently within the edge area. The fibres on the outer part of the curve are more stretched than the ones on the inner part. Thus only a portion of the rope's cross-section is fully available for the absorption of energy, and the strength of the rope is diminished corre spondingly. In general, we can say: the sharper the edge, the lower the strength of the rope. A karabiner with an edge radius of 5 mm reduces the strength of the rope to about 70%. construction elements of "Kern" and 4.5 Rope Construction "Mantle", whereby the Kern must be at Kermantle ropes meet best the require least 50% of the total weight of the rope. ments for climbing ropes. "Kermantle" The Mantle is braided around the Kern, means a rope which consists of the two protecting it against abrasion and other external influences, itisalsoessential threads having each a diameter of one because it makes it more easy to grip the twenty five thousandth of a millimeter rope. (25 it). These 50 400 threads are combi The Mantle of the classic 11 mm Edelrid ned in various braided units. "Classic" rope, for exam pie, is braided Modern Kernmantle climbing ropes around the Kern on a48-bobbin machi have a coloured Mantle. The coloured ne in cross-braiding. It consists of ap- Mantle is easy to distinguish in ice or prox. 2700 single threads. The 48-bob- snow and this helps to prevent damage bin cross-braiding with itsdiagonal to the rope by crampons. In addition, the threads was first introduced for the coloured Mantle helps to distinguish the manufacture of climbing ropes, by Edel ropes when climbing on double ropes. rid. The Kermantle construction enables The coloured Mantle also exerts a cer the manufacturer to design optimally tain control function. If the rope is the surface texture in keeping with good severely damaged the nowvisiblewhite gripping qualities of the rope. A good Kern is a distinct warning. Dangerous rope must have this "good grip" charac damage is easy to detect. teristic but, on the other hand it must not By the way do you know how many be so rough that it is liable to severe meters of thread are contained in a 40 abrasion and friction. m 11 mm Edelrid single rope? More The Kern is the construction element than 3500km! which is mainly responsible for the dynamic properties of a climbing rope. In the Edelrid 11 mm "Classic" rope, for example, it consists of 50 400 endless 4.6 Climbing Rope Standards The international organisation of alpine overall rope length gjJQQjnm clubs (UIAA) has standardised the te sting methods for climbing ropes. The following standards have been establis hed for the most important characteri stics: • impact force for the first test fall: 1200 kg (max.) at a weight of 80 kg. • numberof test falls: 3 falls (min.) without breaking. In the fall test the speed of the falling • elongation during use: weight at the end of the free fall is about 7% (max.) for the single rope. 36 km . The entire time of fall until the 10% (max.) for the half rope. weight is stopped is about 1 sec. The • ease of making knots. The clear width body is thus subjected to 12-15 times of the knot must be smaller than the the acceleration of gravity, independent rope diameter. of the type of rope used.

4.7 Rope Tests 4.7.1 The Fall Test The most important test is a dynamic load test to determine the dynamic strength of a rope. The test is performed as follows: 4.7.2 Elongation in Use To determine the elongation in use a length of 100 cm is marked on a rope stretched with 5 kg. The rope is then stretched by a force of 80 kg. The elongation in use is determined by the change of the marked measuring length.

4.7.3 Ease of Knotting A vertical hanging rope with an over hand knot is loaded with 10 kg for a period of 1 minute and again unloaded to 1 kg. The knot must then be so tight that the largest free space within the knot is smaller than the rope diameter.

4.8 Impact Force Formula 1. Fixed point. The formula for the impact force in 2. Weight before the fall. a vertical fall, wilh rigid belay and inela 3. Free rope. stic metal falling weight is as follows: 4. By-pass karabiner. 5. Weightafterthefall. 6. 2.5 m plus elongation. = (a+G) + (a + G) 1/1 + [kgf] aXG V V N Q.bif

The above values mean: This means: In a standard fall only about K = impact force (kgf) 62% of the entire fall energy results in G = weight(kg) the impact force, whilst 38% of the fall f = fall factor energy is already used up during this a = Stored upvalue, jprlirating whinh time due to deformation of the material pr. rtjrfp nf and friction. learis to the impact force. The rigid falling weight intensifies the M = rope modulus describing the con test. The impact forces arising in real nection between the braking force falls are lower by 10-15% because the P and the rope elongation L (in %) human body absorbs energy and thus when a fall is stopped according to softens the impact force. the formula P = M — L/100 For a rope with an impact force Kof approx. 1000 kgf at an impact force elongation of 20% (L « 0.2) the rope modulus M is about 5000 kgf and the stored up value approx. 0.625. 5. Technical Data examples of theirsupreme performance standard. You will find thetechnical 5.1 Climbing Ropes data of your rope in the description Out of the large selection of Edelrid attached to every rope leaving our ropes two types of rope may serve as factory.