By Michael “House” Tain
A whoopie sling girth hitched to a Port-a-Wrap in place around the base of a tree for lowering in rigging operations.
A hollow-braid eye sling providing an anchor point for a block tied with a Cow Hitch with a Better Half.
All photos by Michael “House” TainTree crews use rope and cordage in many different ways, and in multiple situations. In fact, there are very few days or even individual jobs in which climbing arborists do not use at least one form of rope. Previous Arbor Age columns have examined topics such as rope choices and construction, knots and hitches, splicing and even the general subject of rope tools itself, but this column will focus specifically on rope tools for rigging, their safe use and applicability, and how they can add safety and efficiency to tree care rigging.
A rope tool is simply a piece of cordage that has been fashioned or formed into a useful device, or tool, through any number of ways. They may be spliced, stitched on an industrial sewing machine, or even formed just through the use of a particular knot or hitch. Although the use of knots may be the simplest and quickest — not to mention cheapest — way to create a rope tool, it certainly has limitations; and may end up being more expensive through catastrophic failures and associated damage in the long run. Knots inherently weaken a rope through their creation of bends in the fibers — thus rope tools created by knots or hitches are going to be much weaker than those that are spliced or stitched. Also, the use of knots necessarily limits the complexity of the rope tool being created, and should be limited to simple rope tools like an endless loop, but always with the knot-created strength loss kept in mind.
Climbing versus rigging
Rope tools used in rigging operations should never be used in climbing operations due to the greater loads and forces experienced during their rigging use. No one is saving time or money if a rope tool fails in climbing operations and someone is injured or worse.
The endless loop, as mentioned previously, is one of the simplest of rope tools, and can easily be created by attaching a length of rope back to itself with an appropriate knot or hitch, although they are also easily spliced or available in stitched form from arborist retailers with much less strength loss than in their knotted form. Rigging almost always means that there is going to be more force than an individual could handle or control on their own put upon the various components of the rigging system, thus the importance of paying attention to items such as the lessened strength of knotted endless loops. An endless loop of appropriate strength can certainly be used as the primary anchor point in spar pole rigging, although its set length, i.e. lack of adjustability, will often result in it being too short or longer than is desired. Endless loops are extremely useful as floating anchor points on rigging lines formed into appropriate hitches, in simple balancing systems to balance a horizontally oriented limb, or in knotless rigging where multiple branches/pieces are being attached to a load line. The use of rope/cordage slings and systems in crane operations, also allows the creative and imaginative climbing arborist to find applications for the endless loop.
Eye slings are typically spliced or stitched from double braid or hollow braid rope constructions; and are probably one of the most commonly known rope tools in the tree care industry. These tools have a large eye in one end, and can be used in a wide variety of ways in rigging operations. Although an eye sling can be created out of a length of rope with a knot or hitch tied to create the eye, this practice is extremely dangerous due to rope strength loss and should be avoided if at all possible (being used only in situations where it is clear and dependable that the knotted eye sling will experience very minimal loads and forces regardless of what happens with the rest of the rigging system). Eye slings are often very useful in establishing anchor points within the tree’s canopy or on its trunk for other devices such as blocks, pulleys or lowering devices. The use of connecting links should be avoided with eye slings, particularly in dynamic rigging situations due to possible cross or side loading of the connecting link. And, whenever feasible the large eye of the sling attached directly to the device, such as around the bushing of a block or girth hitched onto a Port-a-Wrap. Eye slings can provide an excellent anchor point for the primary rigging block in a wide variety of rigging situations/scenarios such as spar pole rigging, lifting, balancing, or even the multiple points needed in a drift system. One of the better hitch choices to attach an eye sling to a tree is the Cow Hitch with a Better Half. This knot is, with practice and experience, easily and quickly tied and untied — even after heavy loads — remains secure, and requires less care and attention during multiple load rigging operations. Eye slings can also certainly be used for multiple lighter static loads often small branches — in crane operations or knotless rigging, where the eye is placed on the hook or rigging snap, and the end of the sling attached to the load with an appropriate knot. But, once again, tree crews should keep in mind the rope strength being lost in attaching the sling to the load with a knot, and adjust the load size accordingly.
Eye and eye sling
These slings are exactly what their name suggests — a length of rope or cordage with spliced or stitched eyes on both ends. Although these are available in a variety of rope constructions for towing, boating and other applications, those most useful in tree care operations are typically made out of smaller-diameter hollow braid. Once again, a field-expedient eye and eye can certainly created by the use of knots on either end. And though this might be appropriate in many climbing applications, the higher forces and heavier loads of rigging operations make knotted eye and eye slings a very bad idea. These slings have enormous value in rigging operations, and tied with appropriate hitches such as the VT, Michoacán, Diestel or Schwabisch provide a floating anchor point or cordage grip on the rope wherever the user might desire it. Although the imagination of the tree crew is the only true limit to their use, eye and eye slings are often used in rigging operations requiring mechanical advantage, balancing, lifting or slide lines. The smaller the diameter of the eye and eye sling in relation to the line it forms a hitch around, the stronger it will grip. And though this may seem an advantage, it can quickly become negative — gripping so fiercely as to be hard to adjust or even remove without the use of sharp edged implements. A good guideline is that the eye and eye be 1/8-inch smaller in diameter than the rope it is encircling. This difference in diameter will provide good “gription” without becoming too fiercely tight. In addition, the hitches used should employ more wraps than they would in climbing applications, as more grip under extreme loads is the goal in these rigging applications.
Most often spliced from 12-strand hollow-braid ropes, whoopie slings have an adjustable eye on one end with a fixed eye on the other. They are available in various lengths and diameters from arborist retailers and are quite useful in providing an adjustable anchor point for different devices that will fit around a large number of differently sized trees. The device should be attached to the fixed eye — once again without connecting links if possible, particularly in dynamic rigging operations. The whoopie sling should be attached to the tree by passing the adjustable eye around the tree/trunk, and the fixed eye with or without device passed through the adjustable eye, using the sliding splice in the adjustable eye to make the sling the proper length. This sling can certainly be used to attach a block aloft in the canopy, but adjustability is often easier at ground level. So it is most often used for lowering devices in spar pole rigging operations or for redirects in mechanical advantage, lifting, slide lines, etc.
These rope tools — like their cousin, the whoopie — are usually spliced from 12-strand hollow-braid ropes, and are available in a variety of diameters and lengths. However, the loopie is an adjustable endless-loop sling, providing the ease of use of the simple endless loop, yet with a fair degree of adjustability. The sling is simply adjusted to the proper length for the diameter of wood it will pass around, then girth hitched around the trunk or branch with the unspliced portion passing through and over the spliced portion for additional security. The device, typically a block, is then attached to the unspliced portion — once again without connecting links in dynamic rigging situations. Tree industry rigging strength testing has shown loopie slings to be one of the strongest slings in appropriate rigging configurations, retaining more rope strength than other sling/rope combinations. This sling is best suited to attaching primary or secondary rigging points aloft for blocks or pulleys in spar pole rigging, lifting, balancing and slide line operations (although it is certainly appropriate anywhere a strong secure anchor point is needed or desired). Adjusting a loopie can be challenging for larger-diameter trunks/trees, as can be attaching a device such as a Port-a-Wrap, though it can certainly be done with some patience and experience. So often a loopie will be used aloft for the block and cousin whoopie at ground level for the lowering device.
Rope tools have an infinite variety of applications in rigging, many of which make the operations not only safer but more efficient. The brief introduction provided here should help tree crews better decide which rope tool would be best for that day’s rigging challenge, while opening their minds to the world of rope tool possibilities.
Michael “House” Tain is a contract climber, splicer, educator and writer associated with North American Training Solutions www.northamericantrainingsolutions.com and Arbor Canada Training and Education www.arborcanada.com. He is currently located in Lancaster, Ky., and can be reached via e-mail at firstname.lastname@example.org.