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Our ropes are much stronger than we believe



Pit Schubert, President UIAA Safety Commission

The fear of a rope failure comes from the time, when hemp ropes were used, until the end of the fifties. Many of those hemp ropes were broken. I lost two friends at that time. If hemp ropes were wet and later on dried, they dried only at the surface. Because of the capillary effect, the dampness stayed for a long time in the rope, and because hemp is a natural product, the hemp rotted. At that time it was possible to tear a used 15 mm rope by hand force.

A broken rope by influence of acid.
Figure 1 - A broken rope by influence of acid. All photos: Pit Schubert

A broken rope by influence of a sharp rock edge (the climber was killed).
Figure 2 - A broken rope by influence of a sharp rock edge (the climber was killed).

Filaments of a rope broken by influence of a sharp rock edge.
Figure 4 - Filaments of a rope broken by influence of a sharp rock edge.

Filaments of a rope which was cut by a knife.
Figure 5 - Filaments of a rope which was cut by a knife.

Simulated rope damage by a stone fall (1/3 of the sheath and the core).
Figure 6 - Simulated rope damage by a stone fall (1/3 of the sheath and the core).

Tape for quieting (or calming).
Figure 7 - Tape for quieting (or calming).

...like a bad middle marking.
Figure 8 - ...like a bad middle marking.

The simulated damaged rope on the static load test machine.
Figure 10 - The simulated damaged rope on the static load test machine.

Filaments of a rope broken by influence of acid.
Figure 3 - Filaments of a rope broken by influence of acid.

Two of my friends tested their hemp rope at the end of the climbing season in such a way. They fixed the rope at a door handle. Together they pulled with their body weight, the door handle withstood the force, but not the rope. - At that time the rope was intended while climbing only to help the second climber, if he had not enough power (and for abseiling). For the first climber it was not allowed to fall, because of the possibility of rope failure. - If nowadays sport climbers use hemp ropes we would have hundreds of thousands of injured or killed climbers each year.

This danger ended with the use of ropes made from Polyamide (Perlon, Nylon), since the end of the fifties. From that time on the number of rope failures decreased dramatically, because Perlon and Nylon can not rot and because of their better strength (more correctly: because of the higher energy absorbing capacity of this plastic material).

The table shows all rope failures amongst German and Austrian mountaineers and climbers since the end of the sixties. Until 1982 a maximum of two rope failures each year happened. Not more! All climbers were killed.

From 1983 until today, that is, within the last 19 years, there were only two rope failures amongst German and Austrian mountaineers and climbers. And this under circumstances of hundreds of thousands of falls amongst sport climbers each year. This shows that our ropes nowadays are much stronger than we believe (more correctly: our ropes have higher energy absorbing capacity).

The second reason, why rope failures have reduced since 1983, is, that from that time on the German and Austrian climbers used twin ropes more and more, when alpine climbing, also on routes of low difficulty. If one rope breaks, there is redundancy, the second rope may absorb the rest of the falling energy. And twin ropes have an energy absorbing capacity over sharp edges which is, depending on the sharpness of the edge, up to double that of a normal single rope.

All rope failures in the table happened with single ropes and in the alps while alpine climbing. During this time no complete rope failure happened with twin or half ropes (used double). And no rope failure happened in a Klettergarden or at an artificial climbing structure as they are often used indoors.

But, it is necessary to add eight(!) rope failures more in the time since 1983 amongst German and Austrian mountaineers and climbers. The causes were either a misuse of the rope or the rope was already damaged by some kind of polyamide contaminant, such as acid. The details are as follows.

The misuse was using a half rope or a twin rope in a single strand. This happened five times out of nine times altogether. The reason why they are not recorded in the table is because it is a misuse. Such misuse happened in 1973 on the "Schreckhorn" in Switzerland, in 1981 on the "Olperer" in Austria, and in 1990 on the "Grossglockner", also in Austria (all three climbers were killed), and two rope failures in the last year (2001), one when toprope climbing (bottom lowering), the other during abseiling by a mountain rescue team of two persons and a stretcher a few meters above bottom level (all three survived).

...when the damaged rope went through the figure of eight.
Figure 9 - ...when the damaged rope went through the figure of eight.

The reason of the other three rope failures out of nine times altogether, which are not recorded in the table, is the influence of polyamide contaminants (acid). This was found out by the chemical institute of the German criminal investigation department. Fortunately no climber was killed. One of these rope failures happened in the "WilderKaiser" during abseiling. The second rope failure happened during a training of mountain rescue teams on a not very steep slope and the third rope failure happened during a flying fox (Tyrolean traverse) activity. In all three cases the load was so low, that a breakage of the rope is unbelievable, except if already damaged by acid or some other polyamide aggressive contaminant.

There are two characteristics indicative of polyamide rope failure due to acid contamination. One characteristic is the general appearance: Figure 1 shows a rope broken by the influence of acid (both ends look similar), and Figure 2 shows a broken rope, loaded over a sharp rock edge (both ends look quite different).

The second characteristic is the microscopic appearance of the ends of the polyamide filaments. Figure 3 shows the effect of acid, no heads at the ends of the filaments, because the rope does not absorb energy; I tested ropes which came in contact with acid on the Dodero-test-machine, they break like a shoelace. Figure 4 shows the effect of a sharp rock edge, small heads on the ends of the filaments, because the rope absorbs a part of the energy.

And Figure 5 shows the filaments of a rope failure, due to being cut by a knife. - Every man should be careful, if he wants to get rid of his wife [1]. Cutting can be recognized under the microscope. Last year, when I told this to some German mountain guides, one of them asked: Okay - but what shall we do then?

All rope failures in the table since 1979 were investigated by myself. The reason for all was a sharp rock edge, nothing else.

During my work for the DAV (German Alpine Club), during 32 years, I investigated many old ropes from time to time, when I received them from climbers and mountaineers, who wanted to know whether their rope was still good. Some of these ropes were 15, 20, 25 and even 30 years old. They were tested by a UIAA-approved test laboratory. The result: All ropes hold minimum one fall on the Dodero-test-machine, most of them more than one fall; and no rope broke in the knot, always at the orifice.

My resume: Because the fall on the Dodero-test-machine is much stronger than in practice (in practice no rigid falling mass, no strictly static belay), it is not possible for a rope which holds one fall on the Dodero-test-machine to break in practice - not in the knot, not in the running belay, not at the belaying device, only when the rope is loaded over a sharp edge, normally a rock edge. And this happens as the table shows very, very seldom.

At the end a funny story, which shows again, that our ropes are much stronger than we believe. Two friends of mine, both mountain guides, tried to climb Marmolada South face, the route, which is called "The Way through the Fish". It is a hard route, 37 pitches, fifth, sixth, and seventh degree. My two friends climbed up nine pitches, then a stone fell on the ropes and damaged one third of one strand of the twin rope (Figure 6). Initially they did not know what to do. First of all they used a tape from their first aid kid and put it around the damaged rope (Figure 7) and so the rope didn't look so bad, like a bad middle marking (Figure 8). Then they discussed what to do next. They didn't like to descend, to abseil, because of the low strength of the one strand, as they thought. They were most afraid. So they decided, to continue the climb, and this very carefully. If nobody would fell, the rope would not be loaded and could not break. They climbed up five pitches more. But then came a thunderstorm and now they had to descend, to abseil. And now they were very fearful, especially then, when the damaged rope went through the figure of eight (Figure 9). But nothing happened, no rope failure. They reached the bottom of the wall and survived.

Later on they told me this story. But the damaged rope was no longer available. So I made tests with twin ropes used by me (one year old, used frequently). I damaged one third of the cross section of one strand, and sent it to a UIAA-approved test laboratory, and there the rope was tested together with a non damaged strand in the Dodero-test-machine. The result: The rope withstood 8 (!) falls. - Then I loaded one test sample of a such damaged rope on a static load test machine as shown (Figure 10). The result of two samples: Breaking strength 15 kN and 17 kN. When abseiling there is only a load of about 2 kN, not more.

So the fear of both my friends was absolutely unfounded. But they did not know it. Our ropes are much stronger than we believe.

Rope Failures amongst German and Austrian Climbers 1969 - 2002

YearNumber of rope failuresMountain or mountain rangeResult
19691Wetterstein(+)
19721Piz Palü(+)
19741Fluchthorn(+)
19751Sellaturm(+)
19771Gesäuse(+)
19782Grundschartner, Eiger(+)(+)
19792Geislerspitzen, Westl. Zinne(+)(+)
19812Sella, Laserzwand(+)(+)
19821Hörndlwand(+)
19931Hörndlwand(#)
19941Gehrenspitze(+)(+)
Years not shown: No rope failures   (+) = killed, (#) = survived
all climbers died except 1993

[1] Editor's comment: or the other way round

   






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