Polyolefin

Polyolefin (polypropylene or polyethylene) fiber ropes are used when their flotation property is desired (e.g., for water rescue). They also have good resistance to most acids; however, polyolefin fibers rapidly degrade, especially under ultraviolet exposure. Because this fiber has low abrasion resistance, strength, life expectancy, and melting point, it is a poor choice for most life-safety applications.

Aramids

Aramids, commonly known by the trade name Kevlar, are extremely strong fibers, resist high temperatures, and have become popular for escape ropes when one desires smaller-diameter, higher-strength ropes with the ability to withstand higher working temperatures than nylon and polyester ropes. However, aramids are very susceptible to internal and external abrasion. Because these fibers cannot absorb dynamic energy and are easier to break if bent too tightly (i.e., in a knot or rappel device), they are dangerous to use in most life-safety rope applications.

Ultra-High–Modulus Polyethylene

UHMPE, more commonly known by trade names Spectra and Vectran, is a newer type of ultra-high–modulus lightweight fiber. It floats and has better abrasion resistance than do aramids, but still has too little stretch to absorb dynamic energy. UHMPE fibers have too low a melting point to be used safely with most rappelling equipment. In addition, they tend to be very slippery, and do not hold knots well under high tension.

Polyester

Polyester fibers are used in many ropes. Dacron has a melting point of about 249° C (480° F), which is in the range of nylon 6,6 and above the melting point of nylon. Polyester fiber has a high tensile strength even when wet, low elongation at break, and can be as effectively UV-stabilized as can nylon. These factors make polyester rope well suited for marine applications (e.g., for boat-rigging lines), and make it an interesting choice for life-safety applications. However, polyester fiber has low dynamic energy absorption, which means that the fiber cannot handle shock loads or repeated loading as well as does nylon fiber.

Nylon

Nylon is the most common and most suitable fiber for general life-safety use. Nylon is approximately 10% stronger than polyester, but nylon fiber may lose as much as 10% to 15% of its strength when wet; however, it regains its strength when it dries. Nylon can handle about twice as much shock loading per pound as can polyester when both are wet.

Nylon strongly resists most chemicals, but certain alkalis, acids, and bleaches can cause degradation, especially in high concentrations. For the high-angle technician, the source of most damaging acids is batteries, including lead acid and so-called “sealed” or “dry-cell” batteries. Users must scrupulously protect ropes from direct contact with batteries and from exposure to acid fumes or residues that might be found in vehicle storage compartments, trunks, and garage floors. Industrial users should take special storage and handling precautions because of chemicals used in their rescue environments.

Dynamic Kernmantle Rope

A well-designed dynamic rope that is intended to absorb the shock load of a fall will also be very stretchy, with as much as 30% elongation at 10% of minimum breaking strength. Thus, a dynamic kernmantle rope would be very difficult to use effectively for positioning heavy loads (e.g., a rescue load), contending with changing loads (e.g., loading a patient mid face on a rock wall), or rigging into a haul system (i.e., where energy would be wasted with each pull because of the inherent elongation). This type of rope would also be very difficult to use effectively under high tension (e.g., as a highline).

Dynamic ropes also tend to have a lower tensile strength than do static or low-stretch kernmantle ropes because of the same design characteristics that allow it to stretch. Furthermore, dynamic kernmantle designs are often softer and have a lower percentage of sheath than do static kernmantle ropes, making them more susceptible to abrasion and wear (Figure 95-1).

FIGURE 95-1 Dynamic kernmantle rope.

Static Kernmantle Rope

A static kernmantle rope is designed to be very strong and to have minimal stretch (i.e., as little as 3% to 6% at 10% minimum breaking strength). For consistent strength, inner bundles run continuously and unbroken throughout the length of the rope, usually in a near-parallel manner to reduce stretch and spin (Figure 95-2). This load-carrying core is protected from dirt, abrasion, and cutting by a tightly braided outer sheath. Static kernmantle ropes are ideal for lowering and raising heavy loads (e.g., during rescue), work positioning, and fall protection. Static ropes should not be subjected to a fall factor of more than 0.25 unless additional force-absorption provisions are made in the system.

FIGURE 95-2 Static kernmantle rope.

Low-Stretch Kernmantle Rope

Low-stretch kernmantle ropes elongate 6% to 10% at 10% breaking strength, fulfilling the needs not met by highly dynamic climbing ropes or very stable static kernmantle designs. This is achieved using a different core construction and a better sheath–core relationship, which typically gives such ropes a softer profile than that of static lines. However, these same characteristics decrease abrasion resistance and make this type of rope less desirable for positioning. Low-stretch ropes are often used for belaying heavy loads, especially where there exists low fall factor potential.

Stopper Knots

A stopper knot is often used in rappelling. Before an end of the rope is thrown down for the rappel, a stopper knot is tied into the end to prevent the rappeller from rappelling off the end should the rope not reach the ground. Stopper knots are also used as part of other applications to perform a similar function.

The most common stopper knot is a figure-8 knot (Figure 95-4). When two ropes are used in tandem, the stopper knot should be tied into both lines together. A simple overhand knot (Figure 95-5) may also be used for this purpose, but its relatively low bulk makes it less desirable than a figure-8 knot.

FIGURE 95-4 Figure-8 knot.

FIGURE 95-5 Overhand knot.

Stopper knots such as the figure-8 and overhand knots—basic although they may be—are the foundations of many of the other knots one learns for wilderness use. It is important to learn these before progressing further.

End-of-Line Knots

Perhaps the most common use of a knot is to make a loop in the end of a rope to anchor, tie in, or attach the rope to something. Bowline knots have been borrowed from mariners, and have been used by mountaineers for years. However, this knot can “capsize” into a slipknot quite easily when the tail is pulled; therefore, the high-strength bowline knot (Figure 95-6) is often preferred for life-safety applications. Other variations on the bowline knot that include added safety for live loads are the simple bowline with safety (Figure 95-7) and the bowline with Yosemite safety (Figure 95-8).

FIGURE 95-6 High-strength bowline or double bowline.

FIGURE 95-7 Bowline with safety.

FIGURE 95-8 Bowline with Yosemite safety.

A handy way to tie a mainline and backup line together for attachment to a live load like a litter with patient and attendant is the interlocking long-tail bowlines (Figure 95-9), which consist of two simple bowlines with small loops tied to interlock, while leaving long tails for additional attachment to the litter and attendant.

FIGURE 95-9 Interlocking long-tail bowlines.

Another interesting bowline variation is the bowline on a coil (Figure 95-10). With its several large loops, the bowline on a coil can be used creatively. For example, this knot is sometimes used to attach a person to a belay line if a harness is not available or to create a load-distributing anchor.

FIGURE 95-10 Bowline on a coil.

Many people prefer to use forms of the figure-8 knot for multiple applications, perhaps because this way they have to learn only one knot. One advantage is that the figure-8 knot may be tied directly onto a bight (Figure 95-11), or it may be tied as a retrace (Figure 95-12). Although the versatile nature of the figure-8 knot is indeed attractive, it should be noted that learning only one knot may prove limiting. Some people feel that the figure-8 knot is easier to tie and check than other knots. In truth, the redundant nature of the figure-8 retrace can make it deceiving on visual inspection, and this factor has resulted in accidents.

FIGURE 95-11 Figure-8 on a bight.

FIGURE 95-12 Retrace figure-8 on a bight.

Midline Knots

Knots are often used to form loops in the middle of a rope, for clipping into, for grasping, or for bypassing a piece of damaged rope. Perhaps the easiest and most common method of throwing such a loop is with a simple overhand on a bight (Figure 95-13). Alternatively, a figure-8 on a bight (see Figure 95-11) may be used for this purpose. Either of these options works well as long as the load is attached to the bight. However, both these loops are susceptible to deformation when not loaded. Perhaps more important, if the rope below the knot is loaded, the knot deforms and weakens.

FIGURE 95-13 Overhand on a bight.

More preferable by far is the butterfly knot (Figure 95-14), particularly if the loop and the line beneath it will be placed under significant load. The butterfly can be pulled effectively either from the loop or from below the knot without negative effect. Caution must be taken with this knot, because if the loop is not big enough and not loaded, it can pull out under tension.

FIGURE 95-14 Butterfly knot.

For a quick and versatile solution to creating twin loops in the middle of a rope, a bowline can be tied on a bight of rope. The bowline on a bight (Figure 95-15) results in two relatively symmetric loops that can be used to make an emergency boatswains chair, hand loops, or towing bridle.

FIGURE 95-15 Bowline on a bight.

Another midline knot is the inline figure-8 knot (Figure 95-16). As the name implies, it is tied with its loop in line with the direction of pull on the rope. It is possible to make a nice foot-and-hand loop ladder out of a single piece of rope using this knot, but it should not be used if multidirectional loading of the loop and the rope’s ends is anticipated. The butterfly knot is much better suited for such multidirectional loading applications.

FIGURE 95-16 Inline figure-8 knot.

To quickly create two loops for multiple anchor points that need to be equalized to share a load, the double figure-8 (bunny ears) knot (Figure 95-17) can be tied midline or as an end line knot. The loops or “ears” can be elongated or shortened to equalize the load between the two anchor points.

FIGURE 95-17 Double figure-8 loop or “bunny ears.”

Knots That Join Two Ropes

Tying a knot that will not untie itself is very important when joining two ropes, particularly because the knotted ends are unlikely to be in a place where they can be constantly monitored.

Most people, by about the age of 3 years, have learned to tie a square knot (Figure 95-18) for the purpose of joining rope ends. Although well known and easy to tie, this knot is far from being a secure or reliable tie. It can easily untie itself, either by pulling through when tightened or by shaking apart when loose. In short, the square knot should be avoided for all but decorative purposes.

FIGURE 95-18 Square knot.

The overhand bend (Figure 95-19) is proclaimed by many in the climbing community to be the preferred choice for joining two ropes. However, this knot may untie while in use and is not deemed secure enough for rescue purposes. Instead, the more secure double fisherman’s bend (Figure 95-20) should be used. This bend is very effective for joining ropes of relatively equal diameter. Care should be taken to ensure that the two halves of the bend nestle against each other and that there is enough tail protruding from the knot to keep the knot from unraveling. This knot is also used to join two ends of a short length of cordage for use as a Prusik hitch (see Hitches, later).

FIGURE 95-19 Overhand bend.

FIGURE 95-20 Double fisherman’s bend, grapevine bend, or double-overhand bend.

When ropes of unequal diameter are joined, the double-sheet bend (Figure 95-21) is a more effective tie. This is a bulkier alternative that is perhaps not quite as strong, but can be easier to untie and and is preferred for joining ropes of different diameters.

FIGURE 95-21 Double-sheet bend.

The versatile figure-8 knot deserves honorable mention here. Retracing a figure-8 knot in the opposing direction with a second rope results in what is commonly referred to as a figure-8 bend, an effective means of joining rope ends (Figure 95-22). Care must be taken with this method to ensure that the rope ends exit from opposite ends of the bend. If tied simply as a figure-8 knot, this bend has a tendency to deform and pull itself apart (Figure 95-23). Most knots work best in cordage or rope that has a rounded surface. Flat webbing and similar materials perform differently under tension. The preferred bend for joining webbing ends is known as the ring bend, sometimes also called the tape knot (Figure 95-24). This is most useful for forming webbing slings into a loop, but can also be used for lashing.

FIGURE 95-22 Figure-8 bend.

FIGURE 95-23 Incorrectly tied and loaded figure-8 bend.

FIGURE 95-24 Ring bend or tape knot.

Hitches

Hitching is a method of tying a rope around itself or an object in such a way that the object is integral to the support of the hitch. Hitches are seldom used in rescue and should be considered for use only by a skilled technician, because there are severe consequences when a hitch comes untied or does not perform as intended. Specifically, disintegration of a hitch results in immediate release of whatever load it is holding.

One of the most commonly used hitches is the Prusik hitch (Figure 95-25). A Prusik hitch is a sliding hitch by which a cord can be attached to a rope and slid up and down the rope for positioning. However, under tension, the hitch will not slide. A Prusik hitch is created by tying a length of cordage into a loop by means of a double fisherman’s bend. Wrapping the loop around the main rope and through its own loop two or three times and then pulling it tight forms the hitch.

FIGURE 95-25 Prusik hitch. A to C, Tying sequence for the Prusik hitch. D, Two-wrap Prusik hitch. E, Three-wrap Prusik hitch.

Another fairly common hitch used in climbing and rescue applications is the clove hitch (Figure 95-26). This hitch can be useful when trying to shorten the distance between two objects, such as the climber’s belay and the climber or the litter rail and the rescuer. It is also useful in some lashing techniques, but can have a tendency to roll loose.

FIGURE 95-26 A and B, Clove hitch. C, Clove hitch with a draw loop for temporary attachment.

Another type of hitch, called the Münter hitch or Italian hitch (Figure 95-27), can be used around a carabiner or pole to add friction to a system, as in a belay. This hitch is particularly useful in that it effectively adds friction regardless of which direction the rope is moving. However, care should be taken when using the hitch around a carabiner, because there can be a tendency for the moving rope to slip through the gate of the carabiner, rendering the hitch useless.

FIGURE 95-27 Münter hitch.

A very handy hitch known as a trucker’s hitch is useful for pulling cord or webbing tight across something (e.g., a load in the bed of a pickup truck [hence the name]) or securing a patient snugly into a litter (Figure 95-28).

FIGURE 95-28 Trucker’s hitch.

The handcuff hitch (Figure 95-29), which is not in common use, is possibly useful for combative patients or pulling gently on the arms of someone stuck in a tight spot. Care must be taken to not pull hard enough to rip off hands or arms. A little force applied in the right direction may provide the key to moving a trapped caver or similarly stuck patient.

FIGURE 95-29 Handcuff hitch.

No discussion of knots would be complete without mention of the girth hitch (Figure 95-30), useful for a quick, although not too secure, attachment of a sling or rope to almost anything.

FIGURE 95-30 Girth hitch.

Lashing

The term lashing refers generally to the process of binding items together, such as poles for a shelter or drag. One basic technique used when starting or finishing a lashing involves the round turn with two half hitches (Figure 95-31). This is a more secure but bulkier solution for lashing than the aforementioned clove hitch. There are several variations on the concept of lashing, including square lashing (Figure 95-32) for arranging the poles to create a corner, diagonal lashing (Figure 95-33) for joining poles to create a triangular shape, and sheer lashing (Figure 95-34) for joining poles side by side. Lashings can be extremely useful tools for creating conveniences at camp as well as for emergency use in creating tripods and other mechanical aids.

FIGURE 95-31 Round turn and two half hitches.

FIGURE 95-32 Square lash.

FIGURE 95-33 Diagonal lash.

FIGURE 95-34 Sheer lash.

Emergency Harness

The ability to quickly make an emergency harness out of rope or webbing is a key skill for anyone traveling into the wilderness, whether for climbing a damaged mast or belaying someone up an unexpected cliff. One of the simplest and easiest harnesses to tie is the hasty diaper harness (Figure 95-35). A simple loop of webbing is made by tying a ring bend (see Figure 95-24) in the ends of a length of webbing; alternatively, a loop of rope is made by tying a double fisherman’s bend in the ends of a length of rope. The loop goes on like a diaper and closes in the front with a carabiner.

FIGURE 95-35 Hasty diaper harness.