CMI AAS48HD Web Loop Runner Heavy Duty, 48"

SELECTING THE ROPE

Selecting a rope involves evaluating a combination of factors. Some of these factors are straight forward like comparing rope specifications. Others are less quantitative like a preference for a specific color or how a rope feels in your hand.

Fiber and construction being equal, a larger rope will outlast a smaller rope, because of the greater surface wear distribution. By the same token, a stronger rope will outlast a weaker one, because it will be used at a lower percentage of its break strength with less chance of overstressing.

Consider the opinion of professional climbers who may have more experience as to how well a rope performs. Consider also the reputation of the rope manufacturer. Are they involved with and supportive of the arborist industry? Do they stand behind their products with consistent quality and reliable service? Buying unproven ropes because they are a little less expensive is false economy and can lead to disaster.

Some things to consider when looking at ropes are:

Construction
Kernmantle rope consists of a central core (kern) of fibers that support most of the load on the rope (about 80 percent). A woven sheath (mantle) covers this core and supports less of the load (about 20 percent). The sheath’s tight weave protects the core fibers from abrasion, dirt, and sunlight. The resulting rope is strong and resists damage, yet is easy to handle.

In laid construction, small fiber bundles are twisted together and combined into larger bundles that are twisted around one another. The “lay” of the rope is the direction in which the strands are twisted. Most ropes are right-laid (strands spiral upward to the right when the rope is held vertically). The lay may be either hard or soft. Hard-lay construction creates a stiff rope in which knots are difficult to set and hard to untie after use. When under a load, these ropes resist abrasion and hold their shape better than soft-laid ropes. Soft-lay construction results in a flexible, easy-to-use rope, but one that unwinds easily and is not recommended for rappelling. All ropes of laid construction tend to untwist when loaded, causing spin and rope kinking. The amount laid ropes untwist when loaded depends on the strength of the lay. Because each fiber may appear at the rope’s surface in several places along its length, the load-bearing fibers are more susceptible to abrasion damage.

Braided ropes have gained popularity among tree climbers because of their excellent knot holding and handling characteristics. Common types include solid braid 12-strand and double braid mantle and core 16-strand. Both types of construction are used in life support climbing lines and in rigging ropes.

Strength
When given a choice between ropes, select the strongest of any given size. A load of 200 pounds represents 2% of the strength of a rope with a breaking strength of 10,000 pounds. The same load represents 4% of the strength of a rope that has a breaking strength of 5,000 pounds. The weaker rope is having to work harder and as a result will have to be retired sooner. Braided ropes are stronger than twisted ropes that are the same size and fiber type.

Ropes used for safety lines, safety straps, lanyards, and climbing lines should have an abrasion resistance and a melting point that is equal to or greater than nylon rope and a minimum breaking strength of 5,400 pounds (24kN). Climbing lines that are UIAA approved and meet the standard for single-rope use are suitable. Smaller diameter rope of less than 5,400-pounds breaking strength may be used to construct slings and prusik loops if the finished product meets or exceeds 5,400-pounds breaking strength. However, the margin of safety will be lower because the smaller diameter rope will have less resistance to friction wear for these purposes.

Elongation
It is well accepted that ropes with lower elongation under load will give you better load control, a big help at complicated job sites. However, ropes with lower elongation that are shock loaded, like a lowering line, can fail without warning even though it appears to be in good shape. Low elongating ropes should be selected with the highest possible strength. Both twisted ropes and braided ropes are suitable for rigging. Twisted rope has lower strength and more stretch. Braided rope has higher strength and lower stretch.

A static rope has less than 20-percent elongation at the breaking strength and less than 2 percent elongation at a working load of 500 pounds. As a rule, these ropes are stiffer than dynamic ropes, which can make knot tying more difficult. Generally, static ropes are more resistant to abrasion and dirt penetration. Principal uses for static ropes include haul lines, lanyards, safety straps or slings, SRT ropes, and rappel ropes. Never use static ropes in situations where a fall could occur, such as with the 4-inch tie-in system, or as a safety line for a belayed ascent. 

A dynamic rope has an elongation of 40 to 60 percent at the breaking strength and less than 10 percent elongation at a working load of 176 pounds. A dynamic rope absorbs the shock of a fall, giving the climber added protection. Principal uses for dynamic ropes include safety lines and 4-inch tie-in systems. Because of their versatility, dynamic ropes are suitable for lanyards and rappelling. They are NOT recommended for haul lines, SRT, and DRT because of their tendency to stretch. 
Semi-static/dynamic ropes fall into the elasticity range between fully static and fully dynamic. Ropes designed for use in DRT climbing systems are commonly in this elasticity range, i.e. from 3 to 4 percent elongation at working loads of 500 pounds.

Firmness
Select ropes that are firm and round and hold their shape during use. Soft or mushy ropes will snag easily and abrade quickly causing accelerated strength loss. Because the fibers are in a straighter line, which improves strength but compromises durability, loose or mushy rope will almost always have higher break strengths than a similar rope that is firm and holds its shape.

Stiffer ropes generally resist abrasion better than more flexible ropes. All ropes may be abraded from within by dirt particles rubbing against the fibers or from the outside by contact with rough or sharp surfaces.

RETIRING THE ROPE

One of the most frequently asked questions is “When should I retire my rope?” The most obvious answer is before it breaks. But, without a thorough understanding of how to inspect it and without knowing the load history, you are left making an educated guess. Unfortunately, there are no definitive rules nor industry guidelines to establish when a rope should be retired because there are so many variables that affect rope strength. Factors like load history, bending radius, abrasion, chemical exposure or some combination of those factors, make retirement decisions difficult. Inspecting your rope should be a continuous process of observation before, during and after each use. In synthetic fiber ropes the amount of strength loss due to abrasion and/or flexing is directly related to the amount of broken fiber in the rope’s cross section. After each use, look and feel along every inch of the rope length inspecting for damage as listed below:

Webbing for Arborists

Webbing is a form of flat cordage that comes in many different sizes and types. Wider webbing is generally stronger, but due to differences in construction and materials, width is not always a good indication of breaking strength. It is essential to know the breaking strength of any material used in tree climbing work. The climber is responsible for purchasing webbing that meets or exceeds approved safety standards.

Heavy-duty webbing that is 2 to 3 inches wide is available. Heavy-duty flat webbing may be difficult to handle or tie securely. Tubular webbing is usually stronger and more flexible than a similar width of flat webbing. Quality 1-inch tubular webbing usually has a breaking strength of about 4,000 pounds. This webbing will only meet life-support strength requirements when assembled and used as a loop sling.

Two types of construction are used for tubular webbing:

1. Spiral structure, also referred to as shuttle loom construction. This type of webbing is suitable for life support.
2. Chain structure, also referred to as edge-stitched or needle-loom construction. This type of webbing is NOT suitable for life support

Suitable Uses for Webbing

1. Safety straps for protection points in the 4-inch tie-in system
2. Safety straps for protection in belayed climbing
3. Step-up slings or etriers
4. Utility cordage for attaching and hauling equipment aloft
5. Tree-crotch lanyard/friction savers
6. Re-direct anchors in DRT climbing systems.
7. Light rigging work
8. Anchors

Care, Cleaning, and Storage of Webbing

1. Never wash, rinse, or soak new webbing before initial use. New webbing is naturally slippery, which makes it soft and supple. Washing new webbing tends to remove the natural slipperiness, causing it to become dry and brittle and shortening its life.
2. Dirt will damage webbing over time through abrasion. When necessary, wash dirty webbing in warm water with mild detergent to reduce the likelihood of abrasion.
3. Avoid heat and direct sunlight when drying webbing.
4. Before storing, remove knots if webbing is to be retied in different configurations in the future. If webbing is tied in a permanent configuration (such as safety straps and etriers), leave knots in place to help them “set.”
5. Store webbing in a cool, dark, dry place.
6. Never store webbing where it can be stepped on or have equipment piled on top of it; this can cause internal wear by grinding abrasive dirt into the fibers or direct damage by abrasion or cutting.
7. Examine fibers closely for wear. Retire webbing before the surface fibers are worn at any place along the webbing.
8. Keep webbing used for life support separated from utility cordage. Mark utility cordage so it can be distinguished from material used for life support.
9. Never use life-support webbing for vehicle towing or subject it to other such abuse.

Advantages of Webbing

1. Worn webbing is less expensive to replace than worn rope and is more convenient.
2. Webbing may be used to keep climbing rope away from points of wear and contamination.
3. Tubular webbing is extremely flexible, making it easy to handle. It is relatively resistant to breaking over rounded edges (such as carabiners and branches), and it generally withstands abrasion well.

Disadvantages of Webbing

1. Webbing does not have a protected core like a kernmantle rope, so the load-bearing elements are directly exposed to abrasion and ultraviolet deterioration.
2. Webbing is more vulnerable to cutting when exposed to sharp edges.
3. Webbing is not suitable for rappels.
4. Knots in webbing are difficult to untie once loaded.

LANYARDS

Always use lanyards that can be easily adjusted while climbing. Practice adjusting them while still on the ground. Before ascending a tree, master throwing and catching the lanyard around the bole as well as limb-over procedures. Always use the correct type and length of lanyard for the job.

Many types and styles of lanyards are suitable for tree climbing work. These can be divided into four categories:

1. Belt lanyards or lineman’s safety straps. Belt lanyards normally consist of a wide piece of nylon webbing with an adjustable buckle and a snap catch at both ends. Generally, these are not the best choice for tree climbing because they are awkward to adjust and come in just a few sizes.
2. Prusik lanyards may be equipped with a snap catch at one or both ends and are adjusted by means of either a prusik knot or other friction hitch. The lanyards come in a variety of sizes and styles that meet almost every climber’s needs. Some styles may be awkward to adjust, but most adjust quickly and easily. The addition of a slack-tending micro pulley to the adjustment system increases ease of use significantly. The versatility of this lanyard has made it the preferred “all purpose” lanyard for tree climbing. Never use these lanyards for primary support when cutting, trimming, or pruning trees because of the possibility that the lanyard might be cut.
3. Mechanical adjuster lanyards come with a snap catch at one end and a mechanical adjuster that can be moved along the lanyard and attached to the climber’s belt or harness. These rope or cable steel-core lanyards are the easiest to adjust as the adjustment takes place at the climber’s hip D-ring. Safety measures include placing an end splice or knot at the end of the rope to prevent the adjuster from going off the end and keeping the adjuster cam cleared of twigs and leaves.
4. Cut-resistant lanyards are typically made from cable core rope and are considered cut-resistant. Use of cut-resistant lanyards is recommended when spur climbing and required when cutting, trimming, or pruning in trees. Lanyards made from cable core rope have an eye spliced at one end of the rope that contains a snap catch. Always inspect the steel-cable core before use to ensure that the cable passes around the eye splice and is spliced or crimped back onto itself. The lanyard is snapped into a D-ring on one side of the climbing belt or safety harness and fastened to a D-ring on the opposite side with a Becket hitch, mechanical lanyard adjuster, or friction hitch. When using the lanyard for support, always maintain at least an 18-inch tail on the running end where the Becket hitch is tied.

Care of Lanyards

1. Fiber and synthetic lanyards
   1. Check knots, splices, and metal parts for defects.
   2. Inspect rope lanyards and retire them when the rope meets the criteria outlined in "When should I finally retire my rope?" above.
   3. Never store lanyards with sharp or abrasive objects.
2. Steel-core rope lanyards
   1. Remove sharp edges and protruding cable.
   2. Check for weaknesses in the steel core.
   3. Inspect the cable splice for defects.

CLIMBING ROPE VS. RIGGING ROPE

Your ropes are, of course, some of your most essential pieces of tree gear. To start from the beginning, it’s important to understand features and specific purpose:

• Climbing ropes are used to secure an arborist to the tree. These ropes will help you ascend and descend the tree, and are not designed for any other task.

Climbing ropes have a little bit of stretch, unlike lowering ropes which have next to no stretch. This feature is important for climbing, as it helps absorb the kinetic force of a sudden stop in the event of a climber’s fall, helping to prevent serious back injuries, but mustn’t be too great or it would absorb too much energy in the climbing process and cause premature fatigue.