PHOTOS BY MICHAEL (HOUSE) TAIN.
 

A clove hitch being used in a rigging situation, appropriately secured with two half-hitches. Marls or half-hitches could be added beneath the halter for additional security.

A cow hitch with a better half-hitch used to secure an eye sling to a tree. The remaining tail can be tucked back into the sling to clear it from the rigging system.

Tree care rigging operations require some method of attaching ropes, slings and rope tools safely and securely to a tree or various parts of it. The variety of knots and hitches available to modern climbing arborists can be overwhelming, but a few basic ones should be part of every professional’s mental toolbox. It is important that not only the personnel aloft—climbers and aerial lift operators—know how to tie appropriate knots and hitches effectively, but also the ground personnel, as there are many occasions where it will not only be their responsibility to untie a given knot, but to choose an appropriate one and tie it unsupervised in complex rigging systems or situations. All knots, hitches and attachment methods used in tree care operations, whether for rigging or climbing, should be evaluated with an eye toward three basic criteria: safety or strength loss/retention, security and ease of use. The safety of a particular knot or hitch is a fairly obvious concern. All knots create some strength loss in a rope, so knots that minimize the amount of strength loss, or conversely, maximize the amount of strength retention will be the best choices in rigging scenarios experiencing high loads and forces. Security is quite simply how well or poorly the chosen knot or hitch
maintains the desired position without slipping, moving, releasing or losing its grip on the piece, branch or tree. Ease of use is the criteria that describes how easy or difficult the knot is to use, how complex it is and whether it takes a great deal of time to tie, whether it binds so tightly after loading that it is difficult to untie, and if it requires constant attention and a multitude of backups to remain secure, etc. All knots are not created equal, and some are incredibly secure, yet require immense time and energy to tie and untie, while others detract from the rope’s strength minimally, yet are as slippery as a greased minnow. The proper choice of knot or hitch is a balancing act of compromise, in which the climbing arborist ends up with a knot or hitch that offers the best possible of all three criteria for the given situation.

 

A half-hitch used to provide additional security when used with a running bowline, clove hitch, halter hitch or other appropriate rigging knot.

Eye slings

The traditional hitch used to attach the spliced rope tool called an eye sling to a tree has been the timber hitch. Eye slings are typically used to hang/attach blocks or lowering devices, such as the Port-a-Wrap III, in various rigging systems. This hitch is formed by passing the sling around the tree, capturing the eye with the tail of the sling and then taking multiple turns or twists with the tail around the body/standing part of the sling. No less than five turns/twists should be taken; they should be spread out evenly around the diameter of the tree as much as possible, covering at least half of the diameter if not more. Care must be taken to always load the timber hitch into the bight formed around the eye, not doing so can lead to failure with possibly catastrophic results. Additionally, the timber hitch should be inspected after each dynamic load if it is being subjected to multiple loads, as the turns/twists can creep or be pustitle together, lessening the hitch’s effectiveness.

 

A halter hitch being used in a rigging situation, marls or half-hitches could be added beneath the halter for additional security

Another option, and, in some ways, a more secure one requiring less monitoring and maintenance than the timber hitch, for attaching an eye sling is the cow hitch with a better half. This hitch is formed by passing the sling around the tree, once again capturing the eye with the tail of the sling, but then passing the tail all around the tree once again and passing it through the same bight the eye is through, creating a type of girth hitch around the tree. The hitch is then finistitle and secured by tying a half-hitch around the eye, with the tail of the sling exiting back toward the direction from which it entered the bight. Any excess or remaining tail can then be tucked under the tied sling to get it out of the way for rigging operations. The cow hitch with a better half obviously requires a longer sling than the timber hitch, as it goes all around the tree twice, yet this slight disadvantage may be outweigtitle in the eyes of many users by the facts that it requires less maintenance, and, once practiced, is easily tied and untied after loading.

A marl used to provide additional security when used with a running bowline, clove hitch, halter hitch or other appropriate rigging knot. Note the similarity in appearance between the marl and half-hitch, however the marl will result in an overhand knot in the line when the piece or branch is removed.

Running bowline with half-hitches or marls

The running bowline is commonly used to attach a rigging line to branches or pieces of wood; and half-hitches or marls are often added to increase security. Users should be aware that research on rope strength in rigging situations has shown that a running bowline by itself has less strength loss than one in which a half-hitch or marl is used, but the need in a given scenario for security may require sacrificing some strength in favor of security. The running bowline is simply a bowline tied around the standing part of the line, while the half-hitch or marl is formed beneath it on the piece. The half-hitch is formed by passing the working end of the rigging line around the piece then up beneath the standing part of the line, while a marl is formed by crossing the working end over the top of the standing part of the line, then up beneath it. On the ground, a half-hitch will collapse and disappear once the piece is removed from it, while a marl, which will look much like an overhand knot, will have to be untied. The running bowline, as mentioned previously, is typically tied above the marl or half-hitch, and is formed by passing the working end of the line around the piece, making a loop, passing the working end around the standing part of the line, in effect capturing it, then feeding the tail up through the loop around the standing part of the line and back down through the loop. This creates a bowline tied around the standing part of the line which will cinch or choke up against the piece or branch.

Clove hitch with two half-hitches

A running bowline being used in a rigging situation, marls or half-hitches could be added beneath the running bowline for additional security.

The clove hitch, a traditional method to secure branches or pieces of wood in rigging situations, is an effective knot, but requires more rope to tie than some other hitch choices and should be backed up with two half-hitches to ensure security. It is formed by passing the working end of the line around the piece or branch, capturing the standing part of the line, going once again around the piece or branch, and exiting beneath the loop formed by the first turn around the piece. If tied correctly, the line should exit from opposite sides of the hitch, with a bar of sorts crossing diagonally over the middle. The clove hitch, which can have a tendency to “roll” out, should then be secured with two half-hitches tied around the standing part of the line.

A timber hitch used to secure an eye sling to a tree. Note that the sling is long enough to carry out turns almost all the way around the tree, an excellent idea when using this particular hitch.

Halter hitch

The halter hitch, introduced to me by Wenda Li and Mark Cooke of Ontario, is a cinching or choking hitch that can be used to tie off branches or pieces of wood, yet is fairly easy for ground personnel to untie. The strength lond practiced, is quite simple to tie. This hitch is formed by passing the working end of the linss created by this hitch has not been tested yet, but it seems quite secure, and once learned ae around the piece, creating a loop, passing the working end over the standing part of the line. A bight is then formed in the working end of the line and passed beneath both parts of line through the loop. The hitch is then finistitle by passing the working end of the line or tail over the top of both parts of line and through the bight. It can be easily released by removing the tail from the bight and giving a firm pull.

Michael (House) Tain is a contract climber, splicer, educator and writer associated with North American Training Solutions/Arbor Canada Training and Education, currently located in Lancaster, Ky.