Monday, 22 October 2012

Ropes for rescue

It must be said that this single item of equipment in my experience is the one that has little regard paid to it, compared to other items of equipment. When new and fresh of the reel, its silky feel and colours is something to behold, after a few uses, grubby and stuffed in its bag its forgotten about until that next time its pulled out for use. It is without question the most important part of the equipment that we shall use, “line rescue” would just not exist if the line were missing. Over the years I have used lines made from both natural and synthetic fibres, Hawser laid and braided lines, everything from “Polyprop” to Kevlar (Aramid) tape.

Polyprop rope, instantly recognisable as a blue three strand twisted rope. Found on Farms, construction sites and working boats. It has two good characteristics, it floats and its cheap! It has virtually no use in rope rescue. Also shown is polyprop, in a braided version.

Is technology on top of rope construction or can we expect something radical? I think we now have the best that is available at this present time, manufactures of rope just don’t make for the rescue market, industrial users will always be the biggest consumers. But add together sports climbing with the need for specific lines together with top class sailing and we can see advances in rope design and construction that are filtering back into rescue rope manufacture.

Rope or Line? It’s like Carabiner or Karabiner? everyone has an opinion, so this is mine. I recall back in my early days as a young firefighter, being told by an individual who had worked with rope for all his life, that rope is the generic name of the manufactured product. As soon as you cut it to a specific length and designate it to a specific use, it becomes line: well, that’s good enough for me. So to recap, manufacturers make rope and rescue technicians use lines. 

Choice of rope

The optimum rope for normal use is 11mm diameter nylon rope designed for rescue use. Strong enough to provide a good safety margin 3000Kg WLL, and be also sufficiently robust enough to withstand several years of use, providing you look after it. Weight is not such a concern, as it with sports climbing, there will always be helping hands to transport kit. This same rope must be suitable for all purposes (Controlled descent, safety line, establishing anchors and belays)

When I first became involved in line rescue work, two types of line commonly were used. An 11mm Static line for all descending/ascending and stretcher work (twin line working was not common in those days) and finally a 9mm Dynamic line for establishing belays. The latest lines using modern manufacturing techniques now offer us lines that are sometimes termed low-stretch or industrial. These lines are now the automatic choice for rescue professionals; the limited stretch makes them ideal for all our applications. The Military/Law Enforcement and sports cavers will still prefer the static lines, and for Sports climbers the 9mm dynamic, for its ability to take a fall and its lightness.

For rescue work we now have the line that most suits our needs, the 11mm Semi static in working lengths up to 200m, 400m + are available, but these are monsters to handle and heavy to transport.

Special applications call for special ropes, most of my lines are 100m lengths, that for me is the all-round working rope length, not too heavy or bulky for a rope bag. However It is vitally important for any rescue team to assess the need for longer ropes, normally 200m is the longest commercially available. Longer lengths can be supplied but are special order and delivery times normally reflect this. Ropes of one continuous length can make life such a lot easier. The task of passing a knot or adding additional line during a descent can be time consuming and tiring for the rescuer.

Rope must be seen as a consumable, a new rope can be ruined first time it is used. You must be prepared for that, both emotionally and financially, believe me. A lot has been written regarding the working life of a line, in my experience lines in daily use will be worn out and require retiring long before they reach their age limit. For the record, 5 years of regular use seems to be the figure manufacturers have adopted. For rescue teams, up to 8 years is good for me. After all, the line is not being used every day and providing the line has never been shock loaded and is well maintained (as it should be, your life depends on it) it will be OK.

In my experience teams never buy long enough lengths and this failure generally proves expensive in the long term. As a supplier of equipment, including lines, it is more profitable for me to sell you two 50m lines than one 100m line. The longer has to be the most economic choice, its always the ends, sometimes the first 15-20m that will be worn the most. Even by rotating the line regularly, eventually they will have to be cut off, generally leaving a piece only 30m long, which is has very little practical use. However the 100m line can withstand having several ends cut off and still leave you with a good working line. I see this daily on the Rollgliss systems we overhaul, a too a short line was purchased initially and as only the running end that has been ruined, the entire line has to be replaced to maintain a good working length.

Transporting ropes

Ropes should always be stored and carried in rope bags. A well-designed bag, besides being far easier to stow and handle than hanked or coiled line, will protect the line from all kinds of damage. Coiled lines will tangle or develop kinks caused by twisting the rope, I like my lines to be packed tight in a hap-hazard fashion in the bag, reducing chaffing whilst in transit, my second choice is to 'chain a rope'. Finally the environment that we work in can be harsh, it makes much better sense to wear out the bag than damage a line. A line, which is dirty, is not only destroying itself but also your hardware. Even fine grit and dust, especially the oxides from aluminium equipment can rapidly wear out metal equipment and lines alike, and once embedded it is very difficult to subsequently remove all these particles from the rope.Lines like to be kept cool, dry and in the dark. I always keep my lines in their bags, damage from Sunlight or rather, ultra violet light will degrade the line, but this takes ages, the line will be worn out long before this type of damage becomes a concern. Most important is to ensure that lines are stored clean and dry.

After each operational use, lines must be inspected for damage and washed if necessary. Apart from normal surface abrasion which is more or less obvious, the worst thing that can happen to a line is contamination by chemicals, once identified and confirmed, the line or the contaminated end must be disposed off, you just cannot take that risk. Materials used in line construction are particularly stable polymers and are affected by very few common chemicals, however, it is well known that nylon is severely affected by even quite dilute acids, and that polyesters are attacked aggressively by strong alkali's.

 Washing and inspection

Using a rope, which has become impregnated with grit, is also a recipe for disaster. Each time the rope is loaded over a pulley or squeezed through a descender a multitude of microscopic particles of grit and metal oxides are forcibly ground into the fragile yarn filaments of the kern and some weakening is inevitable. Thorough washing is important to remove as much as possible of this contamination that abrades the internal fibres of the line. A line cannot be properly inspected for any surface damage that may have occurred until it has been cleaned. Superficial dirt can be removed by simply sloshing the rope around in running water, avoid hosepipes or a Pressure washer, as these may force dirt into the core of the line.

For effective cleaning, lines can be washed in a washing machine, normal wash temperature 40C. Chaining the lines can prevent tangling. Other items, webbing or harness can be stuffed it into a mesh wash bag. Adding normal amounts of a fabric softener is useful and acceptable as it replaces the yarns normal Teflon / anti-static lubricants that are used in the manufacturing process.

Regular machine washing is not harmful to the line, remember that the same fibre used in lines is that found in ordinary clothing, which is designed to be washed every few days. I always us a detergent, it helps the cleaning process, but look for PH neutral types, I have used soap flakes in the past but have been disappointed with the results. I also ensure the lines go through a full rinse cycle, which I feel is important.

Pictured is a double jacket rope ( Orange over Black) laid over a four strand braided kern. The double jackets give excellent wear characteristics but the two mantles were prone to slippage. This is easily resolved by soaking the rope to induce shrinkage and pulling the wet rope through a descender a few times whilst under tension. Unfortunately many manufacturers have dropped this excellent design.

After washing, lines should be carefully inspected for damage or signs of excessive wear. The best method is tactile (time consuming) it consists of running the rope through the fingers a little at a time, flexing it into a bight and feeling for soft spots or areas of reduced diameter as well as looking for the more obvious mechanical damage.

The line should be allowed to dry naturally in a well-aired place, and then re-bagged but only when absolutely dry. Pack a damp line at your peril.

New ropes
There is a good reason why new rope's are best soaked before use. It shrinks the rope (up to 5% on cheap semi static) and this serves to compact the sheath and tighten it onto the core, improving it's wearing properties. This procedure also helps prevent sheath slippage during the first few time used, until sheath and core are properly bedded together.

Soak the rope in clean water, drain and squeeze out surplus water by pulling the rope through an anchored descender. Repeat process two or three times, each time pulling the rope through the descender in the same direction. Hang the rope up to dry for a few days. If the sheath has crept along the line, hot cut new ends to prevent any unravelling, ensuring you do not cut off the line’s CE identification, if unavoidable you will need to replace this label.

Marking lines

Lines must be marked with a CE number, but other useful information may be to indicate length, year put into service and serial number for record keeping. We mark our lines with bar codes; you can have so much information in a very small space. It is important that this information remains with the rope throughout its life. There are many different methods of marking, the main criteria being durability and that the information is always legible.
My preferred method is to mark the line both ends on coloured heat shrink tube (the colour denoting year in service. The information is written on this with waterproof ink, and protected by a transparent heat shrink tube, sealed with a hot melt adhesive tape. This type of marking is extremely durable and is removed only by cutting the line.

PVC tape can be used on its own (I have read much of the action of the solvent in the adhesive damaging the line, but providing the tape is applied to the very end of the line, it will do no harm). Finally, held firmly in place by transparent heat shrink tube. This method works but, in practise a film of dirty water seems to creep beneath the heat-shrink sleeve and eventually obscure the figures unless sealed with hot melt tape.

Rope, showing the braided and twisted three strand construction together with the data tape that runs the entire length.

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