Rescue Rope Specifications and Webbing Overview

Written By: Lance Piatt

Previous Articles on Rescue Rope

Rope Diameter

The rope diameter is the width of the rope. The rope diameter is measured in either inches or millimeters. American rope manufacturers typically use inches, while European rope manufacturers use millimeters. The current test method to determine the rope diameter can be found in the Cordage Institute’s Standard CI-1800. NFPA 1983 uses metric sizing for all ropes and rounds up to the next half millimeter.

The rope diameter is an important factor to consider when choosing a rope for your needs. Larger diameter ropes are stronger and can provide more friction for a slower rappel, while smaller diameter ropes are less expensive and lighter in weight. Choose the rope that best suits your needs based on the factors that are most important to you.

Sheath Construction

The number of sheath strands also affects the rope’s torque, which is the tendency of a rope to rotate around its axis when subjected to loads. A higher strand count sheath will have less torque than a lower strand count sheath. The sheath design is also a factor in the rope’s flexibility. A 16-strand sheath rope will be more flexible than a 48-strand sheath rope. However, the higher strand count sheath ropes are less likely to kink, which can be an important consideration when using the rope in applications where kinking could be problematic. Knotability is also affected by sheath design. A 16-strand sheath rope is more likely to jam in a knot than a 48-strand sheathrope. In general, the higher the strand count, the better the knotability.

One issue that can occur with kernmantle rope is sheath slippage. This is when the sheath slides past the core, typically at the end of the rope. While this can be fixed with a hot cutter, it can cause problems if the sheath slippage causes the rope to increase in diameter. This could create a jam when the rope is passed through a pulley or a prusik hitch. To avoid this, it is important to choose a rope with a well-constructed sheath that will not slip.

Abrasion Resistance

Rope rescue is a critical life saving technique, and the abrasion resistance of the rescue rope is a key factor in its performance. There are many different fibers that can be used in rescue ropes, and each has its own advantages and disadvantages in terms of abrasion resistance.

Abrasion resistance is a measure of a material’s ability to resist wear and tear. It is an important consideration in the selection of rescue rope, as the rope will be subject to a great deal of friction and abrasion during use.

There are several factors which affect the abrasion resistance of rescue rope, such as fiber content and properties, yarn structure, fabric structure and weight, and various chemical and mechanical treatments during processing.  The most abrasion-resistant rescue ropes are made from high-strength synthetic fibers such as polyester or nylon. These fibers have a smooth surface which helps to resist wear, and they are also highly resistant to UV damage and chemicals.

Nylon is a synthetic polymer that is made from long chain polymers of amino acids. It is a strong and durable fiber that is resistant to abrasion.

Polyester is another synthetic polymer, made from long chain polymers of esters. It is also a strong and durable fiber, but it is not as resistant to abrasion as nylon.

Kevlar® is a high-strength synthetic fiber that is made from long chain polymers of aromatic amines. It is much stronger than nylon or polyester, and is also highly resistant to abrasion.

The yarn structure of the rescue rope also affects its abrasion resistance. A rope made with a twisted yarn will be more resistant to abrasion than a rope made with a braided yarn.

The fabric structure of the rescue rope also affects its abrasion resistance. A tightly woven fabric will be more resistant to abrasion than a loosely woven fabric.

Finally, various chemical and mechanical treatments can be used to improve the abrasion resistance of rescue rope. These treatments can include impregnating the rope with lubricants or waxes, coating the rope with polymers, or adding abrasion-resistant fibers to the rope.


Rope elongation, or stretch, is an important factor to consider when technical rope rescue is required. Measuring elongation is done by taking the percentage of increase in rope length under a given load. For static rope, the ideal range for elongation is 6-10% under a 10% MBS (Minimum Breaking Strength) load.  For dynamic rope, a higher elongation range is acceptable due to the nature of the rope.  It is important to use the correct type of rope for the application, as static rope is not meant for dynamic loads and vice versa. Understanding elongation and choosing the right rope can help ensure a successful technical rescue.

When the person on rappel or the litter tender transfers the weight from the ground to the rope, the load will descend some distance based on the elongation of the rope and the mass involved.

There are two types of rope typically used in technical rope rescue – static and dynamic. Static rope has very little elongation and is designed for use where minimal give is desired, such as when setting anchors. Dynamic rope has more stretch and is designed for use where some give is desirable, such as in belay systems.

The amount of elongation that occurs when a load is applied to a rope depends on the type of rope, the amount of weight applied, and the length of the rope. In general, dynamic ropes will elongate more than static ropes, and longer ropes will elongate more than shorter ropes.

When technical rope rescue operations are being conducted, it is important to be aware of the amount of elongation that may occur so that proper safety precautions can be taken. For example, if a person is rappelling down a cliff face, the person holding the rope (the belayer) must be aware of how much the rope will stretch when the person on rappel reaches the bottom. If the belayer is not prepared for the additional slack in the rope, they may not be able to stop the person on rappel from falling.

Similarly, when a litter is being lowered from a helicopter or other high point, the litter tender must be aware of how much the rope will stretch when the load is transferred from the ground to the rope. If the litter tender is not prepared for the additional slack in the rope, they may not be able to control the descent of the litter.

Energy Absorption

Technical rope rescue is the use of ropes to stabilize, support and extract people or materials in a variety of situations. There are two main types of rope used in technical rope rescue: static and dynamic. Static rope is often used for Raise, lowering, anchoring and belaying, while dynamic rope is typically used for climbing.

Energy absorption is an important factor to consider when using technical rope rescue techniques. Static ropes are not designed to absorb energy, so if a person were to fall while on a static rope, the rope would not stretch and would not dissipate the energy of the fall. This could result in serious injury or even death. Dynamic ropes, on the other hand, are designed to stretch and absorb energy. This makes them much safer to use in technical rope rescue applications.

And Now Something on Webbing!!!!
Courtesy CMC

Flat webbing is often used in applications where it is important to be able to tie knots securely. The flat webbing has been specifically selected for the suppleness necessary to allow knots to be set securely. Flat web also tends to be easier to untie after a heavy load than the softer tubular web. While the flat web is bulkier than the tubular, it does provide a significantly higher strength.

Tubular Webbing

1″ webbing is frequently used in military applications because of its strength and durability. It is important to choose webbing that meets mil-spec standards in order to ensure that it will be able to withstand the rigors of use in a combat environment.

Mil-Spec webbing is webbing that has been tested to withstand extremely high levels of force. This webbing is made from a durable nylon 6-6 fiber and is used in a variety of tactical applications. This webbing is incredibly strong, with a breaking point of over 4,000lbs. When you need webbing that can stand up to the toughest conditions, choose Mil-Spec webbing.

1″ Work Spec Tubular Webbing 1″ Mil Spec Webbing 1″ Flat Webbing

Sewn Slings

There are several reasons why sewn webbing slings are commonly used for anchors. First, they’re extremely strong and can hold a lot of weight. Second, they’re relatively easy to adjust and attach to anchor points. And third, they’re relatively lightweight and easy to transport.

Sewn webbing slings are made from high-strength webbing that’s sewn together with heavy-duty thread. They’re typically rated for use up to 5,000 pounds (2,268 kilograms), but can exceed 100 kN MBS depending on the material and manufacturing design and process.

CMC Texora Sling CMC Texora Sling Sterling 1″ Flat Nylon Sling

Peace on your Days



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