Types of Rope
Half inch Static Kernmantle Rope is the manufactured rope of choice used by the American Fire Service and one-half inch diameter is the workhorse for most basic Rope Rescue Operations. Kernmantle rope comes in many colors and ranges in size from 3mm cordage all the way up to 15mm or 5/8 inch for some rigging theories. The design basics can be read in every ligament rope book written and even out of the Firefighters Essentials Book used by almost every fire department in this nation. As a quick review, the core is used for the majority of the strength and the mantle as a small percentage of strength — but its major role is protection.
Rope for Fire Service Rescue has three basic designs for its sheath “mantle”: 16-strand, 32-strand or 48-strand. This option is offered by many upper end rope manufactures. Many rope “technicians” have never even heard of this option. This is a major concern for some departments. Do you need a rope that needs more “sheath” protection from consistent use or rough use in high abrasive environments, or is the 16-strand design what you need? If your department does not run many rope rescue calls or if budget constraints limit your options, then your needs are geared to the 32-strand designed rope. The 48-strand “mantle” rope is designed for recreational/sport climbing, but in larger and more Rope Rescue savvy departments, this rope has found a home and use for Lead Climbing/Urban Rescue Operations.
These urban rescue calls are becoming more pronounced as more and more cell towers, water towers and even tower crane rescue operations arise. Some even call these “bottom up” rope rescues and formal training references these classes as Rope Rescue IV. There are other types of rope for special needs such as, water rescues, high temperature rope for bailout systems and this just names a few. Again this article is for the one-half Static Kernmantle designed rope.
Pulling on a rope in a straight line until it breaks gives us the TENSILE STRENGTH of the rope. If bends in the rope (knots) are incorporated into the line it weakens that area of the rope. The sharper the bends in the knot, the weaker the rope becomes. Knots are a combination of bends. Rescuers try to use knots that have the largest possible bends, but that are still manageable to tie and use in a rescue operation. KNOT EFFICIENCY is measured by the percentage of rope strength that remains after a knot is tied in the rope. For example, if a particular knot is tied in a rope that has a tensile strength of 100 pounds, and the rope breaks when subjected to an 80-pound load, that knot is said to have an 80 percent knot efficiency rating.
It is important to use knots that are simple to tie and simple to inspect and to ensure that they are tied correctly. Many of the knots used in a department’s Rope Rescue System belongs to the FIGURE EIGHT family of knots. Using only a small number of knots, and becoming familiar with those knots through training and practice will ensure safer and more efficient operations. Knowing which knot to look for in a given position, on a given system, also makes it easier to safely inspect the system.
The following knots can be used with one-half inch Kernmantel rescue rope systems. These knots have been chosen because of their STRENGTH, SIMPLICITY and ABILITY to recognize they are tied correctly, along with ease of untying after the knot has been loaded.
Family of Eight Knots
- Figure 8
- Figure 8 on a Bight
- Figure 8 Bend
- Figure 8 Follow Through
- Inline Figure 8
- Double Looped and Triple Looped Figure 8
- Butterfly/Inline 8 Knot
- Figure of 9 knot
- Overhand knot
- Double Fisherman’s knot
- Long Tail Bowline
- Bowline with Yosemite (designed by the U.S. Park Service, Rope Division)
Some students are taught not to use the Bowline knots as life holding knots. As with any knot, if it is not tied right, checked, and used in the proper place of a rope system it should not be used. Again, education and practice will help remove most of these human errors.
It has been asked in many rope classes — what is the difference between a knot and a hitch? Two scientific reasons give us these answers. One is that the hitch in most cases is a constrictor and the other is that if you drop or set a knot down it stays a knot. In many cases the hitch will come undone. And as always, check both knots and hitches at least twice, by two different sets of eyes before employing either in a rope system.
Types of Hitches
- Clove Hitch
- Half Hitch
- Girth Hitch
- Munter Hitch
- Tensionless Hitch
All fire departments will strive for the safest system that they can afford. N.F.P.A. 1983/2012 states that rope systems will be built to a 15 to one Safety System Factor (SSF) with a maximum load of 600 pounds. This means that you will need to use one-half Static Kernmantel rope, which will have a minimum strength of 9000 pounds. The above N.F.P.A. statement does not take knots into account in a rescue system. The scientific problem with this is; as soon as the rope makes a bend/turn over an edge or around an object it loses it 100 percent strength because the rope now has the fibers in a physical state of hyper tension (outer) side of bend or turn and then in a type of compression or lack of use on the (inner) side of the bend or turn. This also holds true for all knots. This is where, in some cases, hitches are used to help increase the rope system’s strength. And no matter what, the rope will be downgraded to training or cut up after 10 years after its made — N.F.P.A. certified rope will have a tracker tape inside the center of the core.
Something else that is discussed in tremendous depth — does a knot need to have a safety on it? Understand that there has not been a documented case of a properly tied knot coming untied, but in the same breath, this is not an advanced rope class by no means, nor is it to chance to fight about SOPs on rope operations. The American Fire Service strives for the strongest rope systems in the world, by many they seem to be over built. Even the biggest city in the world or the busiest rope rescue team in the world does not go to rope rescues every day. So who uses rope every day? Tree surgeons are one example, with both high abrasive and high shock impacts on their rope. Marine operations use rope in a salty, wet environment. Window washers are another example. Most window operations employ a five to one safety standard and are not even regulated to wear helmets. All of these mentioned are not regulated by many standards, if any at all. The only other professional service that has a complete standard and is regulated, is rope access workers. Their standards use 9/16 Static Kernmantle rope, a 5000 pound anchor system and they strive for a Safety System Factor (SSF) of 10 to one.
Inspection and Storage of Life Safety Ropes
All ropes should be inspected before use and after use — whether it’s training or after a real call. Things to look for are glass, dirt, frays, deformities and soft spots, just to name a few. In general, if it feels or looks different than when it was new, it might be time to cut it up. Before you cut it up, ask someone else to check it and then send it up the chain of command for the final answer.
To get the most use and life out of a rope it must be stored in a place where it is protected from harm. Rope can be damaged if it is left:
- In sunlight
- Exposed to vehicle exhaust or fumes or residues from batteries
- On the floor (Concrete floors contain damaging acids. Stepping on the rope grinds in dirt).
- Wet or damp areas (This will promote the growth of mold and mildew)
- In areas of high heat (Prolonged exposure to temperatures higher than 90 degrees can cause degradation of rope)
Advantages of Using a Bag
One of the most convenient ways of storing, transporting and protecting the rope is in a bag.
- The rope can be flaked into the bag faster than it can be coiled.
- The bag helps protect the rope from damage while keeping it clean.
- The bag has 2 shoulder straps, which makes it easier to carry.
- A bagged rope is easy to deploy.
Remember, all rope systems have and use a backup/Belay system. This system uses the same type of rope — ½ Static Kernmantle rope. In most cases the Belay system uses a different color rope, mainly for identification purposes.