Advantages and disadvantages
Modern, progressive, climbing arborists have a wide variety of attachment or termination methods available to them—as alluded to in the poorly rhymed title of this article—yet often the method chosen is based more on opinion or hearsay than practical field evaluations and scientific evidence. A closer examination of the attachment/termination methods available to tree care professionals through the lens of testing and field use cannot help but assist us in making better, safer, more efficient and well-informed choices. These attachment methods should be evaluated in three basic functions: safety, security and ease of use. Safety refers to the strength loss created by the chosen method; sharp bends in a rope decrease its strength, thus an attachment method requiring sharp bends will be inherently weaker, or less safe. Security refers to the attachment method’s interaction with the connecting link. Carabiners are strongest and meant to be loaded along the major axis, thus an attachment method that does not stay in place is less desirable, or secure, than one that does stay in place during the various movements of tree climbing. Snap hooks or snaps retain roughly the same amount of strength as long as the attachment method is through their captured eye, thus a method that is less secure might be acceptable when using them, as movement within the captured eye does not radically reduce a snap hook’s strength. Ease of use is simply the efficiency of a particular attachment method. How difficult and how long does it take to attach and detach with the chosen method? Methods that are more quickly attached to and detached from are obviously easier to use.
|Photos by Michael (House) Tain.|
|Left to right, True Blue, Safety Blue, Ocean, Beeline, and Ice with industrially stitched eyes from a variety of manufacturers. Note the plastic shield to prevent direct abrasion and wear of the stitch pattern.||Left to right, The Buntline hitch, Triple Fisherman’s/Scaffold knot, and Anchor hitch, all appropriate attachment knots/hitches that securely grip carabiners, but with some loss of rope strength.|
A variety of knots and hitches are used for attachment and personal support, whether it be the end of a climbing line, a split bridge/tail in a dynamic climbing system or to secure a connecting link to the end of a work-positioning lanyard. All of these knots and hitches will cause strength loss, due to the creation of bends in the rope, however, some will create more strength loss than others. Traditional choices for a termination or attachment knot at the end of the climbing line have been the clove hitch or the bowline, both of which should be backed up in some fashion, particularly when used in a split tail/bridge system. In a traditional system, in which the tail exiting the clove hitch or bowline forms the climbing hitch, a figure eight and the climbing hitch itself forms the backup. More recent attachment or termination knots and hitches include the Buntline hitch, the Anchor hitch and the Triple Fisherman’s or Scaffold knot. As mentioned, all of these knots or hitches will create some strength loss in whatever rope they are used in; and, in addition, the ones that cinch down on the connecting link securely, such as the Buntline or Scaffold, are a better choice when using carabiners, due to possible cross or side loading of the carabiner. As knots and hitches, all of these choices require more time than some other methods to attach and detach, necessitating the correct forming of the knot whenever it is necessary to move over or around a branch, or reset the tie-in point.
The method of hand splicing will vary with the construction of the rope being used, but all rely on friction to provide a fixed eye in the end of the line. This attachment/termination method is also used in a variety of personal support applications, including the ends of climbing lines, split bridge/tail systems and work-positioning lanyards. Hand-spliced eyes may either be small, tight eyes that grip the connecting link securely or larger ones in 16-strand lines that are girth-hitched around the connecting link for security. An absence of sharp bends in the rope makes a correctly formed hand-spliced eye much stronger than any knot or hitch; and the ease of attachment and detachment from carabiners increases efficiency. However, small, tight eyes hand-spliced through the captured eye of snap hooks will prevent their removal entirely. A larger eye that is girth-hitched through the captured eye would give the climber the option of detachment.
Industrially stitched eye
Relatively new to the tree care profession is the attachment/termination method of an industrially stitched eye in which the rope or cordage is sewn back to itself. This method reduces sharp bends in the rope immensely, and causes the least amount of strength loss of any method examined here. In addition, the eyes formed may be as small and tight as possible, allowing for secure and efficient placement on a connecting link such as a carabiner. As with hand-spliced eyes, industrially stitched eyes through the captured eyes of snap hooks will not be removable, thus reducing their ease of use with that particular connecting link. Unlike hand-spliced eyes, industrially stitched eyes are not commonly available in larger eyes for girth hitching due to the core remaining inside the rope in the stitching process, preventing a secure grip when girth-hitched onto the connecting link.
|A larger hand-spliced eye appropriately girth-hitched for security around a carabiner. Note: This eye is on a split tail/bridge for tying open climbing hitches, thus the lack of lock stitching. Large or small eyes in the end of climbing lines should always be lock-stitched for security when not under load.||Large and small hand-spliced eyes on 16-strand rope. Note: These eyes are on split tails/bridges for tying open climbing hitches, thus the lack of lock stitching. Large or small eyes in the end of climbing lines should always be lock-stitched for security when not under load.|
All attachment and termination methods have advantages and disadvantages, whether it is safety, security, ease of use or simply cost. The use of hand-spliced or industrially stitched eyes means trusting in the professionalism and knowledge of the manufacturers who produce them, much as climbers trust the manufacturers of their climbing lines, connecting links and harnesses to provide them with a safe, well-made product. The use of knots or hitches means the climber must trust themselves to have the knowledge, attention to detail and judgment to tie the proper attachment hitch or knot correctly on the appropriate connecting link, while accepting a certain amount of rope strength loss and additional time spent tying the knot or hitch. Whichever method is chosen should be based on an honest examination of its properties, capabilities, strengths and weaknesses—not on tradition, folklore and opinion.
Michael (House) Tain is a contract climber, splicer, educator and writer currently located in Lancaster, Ky.