Rope Materials, Construction

MATERIALS

There are a few natural fiber ropes still out there, but most fire departments use synthetic or polypropylene to get the job done. This transition has taken place because natural fiber ropes are weakened by age, and absorb water well (which means they mildew and deteriorate). If natural fiber ropes are used, they'll be for utility use only.

Nine times out of ten you'll be working with synthetic rope (usually nylon) for a few reasons; the fibers are able to run the full length of a rope (which provides strength), they don't rot or mildew, they handle extreme temperatures better, and they absorb less water than natural fiber ropes. Heck, they're also smaller and easier to handle. On the down side, synthetic rope will be damaged by everyday UV rays and shouldn't be left out in the sun. They don't stand up to strong acids or bases well either, but what does?

Polypropylene is a common material used to create ropes for water rescue. It floats and doesn't absorb water, which makes it useful in this particular instance. It doesn't stand up to Nylon for strength and ease of use, though.

CONSTRUCTION

When a person pictures a rope, they'll usually think of a twisted rope. These are made by twisting small strands together to make a larger strand, then twisting the larger strands together and repeating that process until the rope is thick enough for the job. This method for making rope has existed since the dark ages (literally) and exposes every strand at some point along the rope, making abrasion a concern.

Another common construction is called braided rope. This method is more modern and usually only used for synthetic rope, but still exposes every strand at some point and thus still creates an abrasion concern. This type of rope will typically stretch, but it won't twist easily.

Kernmantle rope is awesome. It's thin, flexible, and incredibly strong. It consists of two separate entities... The kern and the mantle (stop me if I'm moving too fast). The mantle of the rope is the braided sheath we see on the outside, and only provides about 30% of the overall strength of the rope. The kern is at the core of the rope, which provides 70% of the strength and will remain protected by the mantle, which eliminates abrasion concerns.

All ropes will fall under one of two categories: dynamic and static. Dynamic rope is designed to stretch under a load, while static rope will resist it. They each have their applications, but that's more of a TRT topic and we'll leave that subject up to them. It may be noteworthy to remember that life safety ropes perform best when they are of static kernmantle construction (perfect for lowering someone).