Manufactured ropes or cordage have been a part of human history for a very long time, with existing samples from 15,000 years ago; and archeological evidence of rope use and manufacture from 27,000 years ago. Humans have probably been using ropes, or something rope-like such as vines or creepers, even longer than that to tie, secure, pull and accomplish the same wide variety of tasks that take place every day on the work site of a modern tree care operation.
The art of splicing developed along with the ropes — needing to repair broken ones, make longer ones or even provide a more useful termination in the end of one. Thus, when a modern climbing arborist takes tools in hand to create an eye in the end of the climbing line or to construct a rope tool, they are but the latest example of splicers, modern representatives of an art that stretches back beyond the days of sailing ships and even the building of the pyramids.
Tools and materials may have changed somewhat over the centuries, sometimes quite radically, particularly in regard to rope fibers, and surprising little in other cases, such as in the case of some of the splicing hand tools. However, the basic principles and ideas of splicing have remained the same from the time of the ancients to the present: to create something out of the rope that is useful, strong and easier to use. The wide variety of materials, methods and splices make an in-depth discussion beyond the scope of this column, but an understanding of the basics can help interested tree care professionals begin to explore this ancient art and help all climbers better understand how the spliced products they use daily work.
Efficiency and strength
While knots or hitches can obviously be created much more quickly than the initial time it takes to create a spliced termination or eye in a climbing line, in the end they are much weaker than their spliced brethren. In addition, once an eye is spliced correctly into the end of a climbing line, the time taken to “clip” in is significantly less than the time required to tie any knot or hitch. This quickness, or efficiency in clipping in, can be seen in the accompanying table showing average time required to tie various hitches, with the additional benefit of never being incorrectly tied or “backed-up.”
Bends in the fibers of rope or cordage create strength loss, as is the case when creating knots and hitches, some greater and some lesser, depending on their construction. However, no knot or hitch yet developed is as strong or, put another way, reduces rope strength as little as does a properly spliced eye. A properly carried out splice will bend the fibers of the material being spliced the minimum amount possible, resulting in very little strength loss, especially in comparison to common knots and hitches. This can be seen in the accompanying table showing breaking tests with .5-inch climbing lines attached to carabiners.
How splices work
At their most basic level, splices work using the same principle as knots and hitches: friction. A properly created splice will, if pulled on harder, grab more through friction, making it even less likely to let go. This principle will vary somewhat with materials and construction, but holds true in general.
As an example of materials, many modern “super” cordages that have a great deal of strength and/or heat resistance are often slippery, thus the amount of friction the splicer needs to create is greater than an equivalent polyester or nylon cordage. The construction of the rope also will affect how the splicer employs their friend friction. Friction is created when splicing a three-strand rope by passing the individual strands back through one another in a particular pattern a specific number of times, typically five. Ropes of hollow braid construction, those often used in the creation of rigging slings and eye and eye Prusiks for climbing hitches, are simply buried back within themselves to create the required friction, but, once again, the distance they must be buried to be secure is quite specific.
There is often a misconception that lock stitches play some role in the strength of the splice – this is not the case. The strength of a splice is created by the friction generated by the proper bury and/or tuck technique, and lock stitches play no direct role in this friction generation. However, the existence of lock stitches is quite important in keeping the splice secure when it is not under a load, particularly in straight bury splices in hollow braids or climbing lines where no special splicing techniques have been used to secure the eye. These straight bury splices can be teased apart when not under load, and the lock stitches prevent this unlikely event from occurring.
One of the most common special splicing techniques mentioned previously to secure the eye of a splice is the locking brummel. This method is most often used with hollow braid ropes, and basically consists of passing the rope back through itself to create a lock for the eye so it remains fixed. Lock stitches should still be used to ensure that the final bury stays secure within the rope when not under load. There are a variety of ways to create a locking brummel, but when possible, one of the easiest is to simply pass the short end of the line through the long end, then the long end through the short end, and finish with the final bury and lock stitching.
One of the strongest and most useful rope tools available to climbers and riggers is the loopie sling. Interestingly enough, the loopie is also one of the easiest rope tools to create. The splicer should decide how large a loopie they wish to create and cut an appropriate amount of hollow braid cordage, keeping in mind that during the splicing process the length will decrease. Both ends of the length should be tapered, a process in which alternate strands are pulled to create a gradual “point” of sorts on the end of the line. To grab correctly, a loopie should have one and a half to two total fid lengths for the given diameter of rope buried inside. The accompanying table that illustrates fid length is useful in all splicing operations, though the rough field expedient method is to multiply the rope diameter by 21. Marks are made for the appropriate bury, and one end of the cordage is passed in from one mark and out from the other. Both of the tapered ends are now back spliced to provide a nice finishing touch and lock stitched simply to prevent ragged ends later. The finished product, if done correctly, provides an easily adjusted, extremely secure and very strong endless loop sling whose applications are only limited by the user’s imagination.
Would-be splicers must always remember that someone’s life will literally hang in the balance with the finished product. Splicing is an art that demands attention to detail, precision and focus; and while a beautiful art, it involves much more information and knowledge than the brief introduction presented here. However, there are a great many resources, classes and hands-on instruction available for those who are interested. Rope manufacturers, such as Samson, Yale and New England Ropes, all of whom have their own in-house splicing staffs, have splicing information on their websites and in some cases sell or offer splicing kits and splice testing/evaluation. Individuals and organizations that offer tree care industry specific splicing classes and hands-on instruction include Brion Toss Yacht Riggers, Arboriculture Canada Training and Education and North American Training Solutions.
Read more: Splicing 101