While younger tree crew members may groan in disbelief when the subject arises, it wasn’t all that long ago that the rope choices available to arborists were severely limited, and as hard as it may be to imagine, groovy colors were not even an option! Imagine oh-so-recent climbers’ shame as they ascended on basically white rope, perhaps with a thin stripe of a pale color running through it, nothing matching or coordinating with their other gear. Of course, the rest of their gear was pretty basically colored also, thus negating any major fashion faux pas or color clashes.
All attempted humor aside, the rope choices available at this time, along with the constant evolution and development of new/reconfigured cordages, gives climbers and tree crews an amazing variety of ropes to choose from for whichever particular job situation they’re confronted with. Having lots of options can be an advantage, but it can also be confusing, even overwhelming. While the constant release and refinement of new fibers means that tree crews will always be confronted with new possibilities, a basic knowledge of rope construction, habits and capabilities will go a long way toward helping crews choose from the myriad of new cordage offerings to choose the right rope for the right place.
Most cordage can be broken down into one of six basic types, as can be seen in the accompanying table. The types of construction include three-strand, 12-strand solid-braid, 16-strand, 12-strand hollow-braid, kernmantle and double-braid. The individuals of these basic construction types, in turn, have specific or unique properties and abilities that make them better or worse for certain tree industry tasks.
However, many ropes, particularly of newer development, may combine some elements of construction, creating hybrids of a sort that are useful for specific features.
Three-strand line is a blast from the past in modern tree climbing, a direct descendent of the twisted construction natural fiber cordage that the human race has been producing and using effectively for thousands of years. While the construction of a hank of modern three-strand would certainly be familiar to one of the deckhands on Magellan’s sailing ship, the materials it is constructed of would not.
Modern three-strand line that is suitable for tree work uses exclusively synthetic fibers, increasing both the rope’s durability and strength. While one of a significant strength could certainly be used for climbing, climbing hitch use and performance can be a challenge, and a more appropriate use is lightweight rigging, particularly when using the structure of the tree, or natural crotches, as rigging points. This type of construction is easily spliced through the tuck splice technique for those climbers so inclined.
Twelve-strand solid braid
This “old” standard was the first type of “new” construction after the move from natural fiber and synthetic three-strand lines, and for a number of years it was the primary type of construction available. It is still one of the best-selling tree industry lines in the country for climbing and rigging, perhaps due to its budget-friendly price.
Twelve-strand solid braid can be used for climbing and rigging, and is particularly well suited to natural crotch rigging. While this rope is technically capable of being spliced through the use of a tuck splice like three-strand, the end result due to the tucking of 12 individual strands of line is less than aesthetically pleasing and reminds one of a blunt club-like weapon. A better option is an eye created through industrial stitching, available from a number of arborist retailers and manufacturers.
The 16-strand was the next step beyond the 12-strand solid, braid and is somewhat unique in that the vast majority of the rope’s strength is contained in the fibers of the cover, the inner core primarily existing to keep the line round and functional. This feature allows the user to readily view any broken, burned or frayed strands, and evaluate the associated loss in strength.
It is often used primarily for climbing, though some of the stronger lines make excellent rigging lines, especially if purchased in different colors from the ones used for climbing thereby preventing line cross-use between rigging and climbing, a recipe for disaster. While it can be used for natural crotch rigging, the attendant wear on the primary strength bearing member, the cover, might make it better suited to the use of blocks and pulleys for maximum rope life.
This line can be spliced or stitched to create eyes or other rope tools, though the splicing technique used on 16-strand differs, and is known as a bury splice.
This construction is one that for many years was only used in rigging lines, but the last decade has seen exponential growth in the use of double-braid constructions in a variety of climbing line and rope tool applications.
A double-braid rope is best thought of as a rope-within-a-rope, meaning that both cover and core are braided to provide the rope’s total strength. The amount of load each component bears will vary with the individual rope’s design and materials, thus it is important to know what the manufacturer intended for its use. The rope within a rope construction allows for unique combinations such as a heat-resistant cover over a strong-fibered core, and even features such as cut-resistance incorporated into lines.
It works well in rigging situations involving the use of blocks and pulleys, but natural crotch rigging should be avoided, as the cover ends up bearing most of the load due to the friction of the bark, negating the rope-within-a-rope strength this construction holds.
Double-braid can be both spliced or stitched into any number of useful rope tool configurations, but those new to splicing it should recognize that a bury splice of a rope within a rope can be more challenging and complex.
This construction migrated to the tree care industry from the worlds of alpine/recreational climbing and structural industrial applications. Basically, it consists of a “mantle,” or cover, over a “kern,” or core.
Originally the cover was intended simply to protect the core, the source of most of the rope’s strength, which consisted of multiple parallel strands of line. Kernmantle lines in the tree care industry have continued to evolve and develop and now include lines that are far beyond this original concept and construction. This type of construction can often provide required strength in a smaller diameter and is well suited to use in the variety of mechanical devices available.
Traditionally considered “un-spliceable” due to the design of the construction, there are tree industry-specific kernmantles that can be spliced; and, of course, industrial stitching is always an option for the creation of eyes or specific rope tools.
Users of kernmantle lines, or any construction of rope for that matter, should pay particular attention to the static or elastic nature of the individual rope. The use of kernmantle lines from other industries or recreational pursuits in tree care applications could lead to situations where a line is far too stretchy or not near stretchy enough.
This construction, available in a number of materials with a variety of capabilities, is one that produces a relatively “flat” line with no core and 12 individual strands that bear the load together. Its construction and ease of splicing make it the primary choice for the construction of a wide variety of rope tools, including such standbys as eye slings, whoopies, loopies, eye and eye Prusiks and many more.
The cost of this type of construction will vary greatly depending on the type of material it is made of, with the more exotic high-strength, heat-resistant fibers costing more. Users should ensure that they are choosing the 12-strand hollow-braid fiber that makes the most sense for their application.
Obviously, there is a great deal more to rope choices than space permits discussion of here, particularly as new materials and construction combinations become available. Just as the modern age has seen an explosion in information and access to it in the world at large, the smaller world of tree climbing and rigging has seen increased access and information about cordage and fiber than ever before. The beauty of this access is that progressive arborists are able to learn of and perhaps employ fibers and cordages they didn’t know about just a few years ago, but this also contains a kernel of danger. Every new rope, line or fiber should be examined and evaluated closely through the lens of safety prior to its use in the field. The tree care environment is one that is inherently challenging, not only for the people working in it, but also for the ropes they employ. Unlike many other situations, the tree care world is one in which poor resistance to abrasion or too little elongation can mean a crew member not going home at the end of the job. A basic knowledge of rope construction and the needs/requirements of cordage in tree work can help make this outcome less likely.