Physics in Rope Rescue? Absolutely!

When it comes to rigging, the laws of physics reign supreme. Small systems (e.g., a single knot) and large systems (e.g., a back-tied, elevated anchor supporting a horizontal line across a ravine) will only function effectively if they reflect an understanding of basic principles.

Rigging Physics

Advanced use of the TerrAdapter over an edge.

Which physical principles are we talking about?
Static and dynamic friction, mechanical advantage, vectors, fall forces, static loads, and many others determine whether our systems will be safe, be merely adequate, or are likely to fail.

What’s the best way to learn about these physical principles?
One option is attending our Rigging Physics course in Tempe, Arizona on June 8 and 9, 2017. This class combines classroom instruction (day one) with a second day of hands-on testing and demonstrations at a nearby UL Testing Facility operated by UltraSafe, a Phoenix-based manufacturer of fall protection and rigging equipment.

Why study rigging physics?
NFPA 1670 mandates that rescue personnel performing at the technician level have a working knowledge of force multipliers in rope systems. In other words, we must be able to manage critical angles, compression and tension, friction, and most important, gravity.

This class will help you answer critical questions such as:

  • How can we use an understanding of force vectors to predict how our systems will perform?
  • What are the effects of friction in raising and lowering?
  • What forces will the anchor have to withstand and what is the possible mode of failure?
  • What is the role of compression and tension in anchor systems?
  • What is the difference between a theoretical mechanical advantage and a practical mechanical advantage?
  • What is the capstan equation and how can we use it?

To answer these questions a basic knowledge of angles, components, and resultants is needed.

Another key component to our rigging physic courses is the cause and effect of shock force. The minimal distance of only a few inches of a free fall is profoundly misunderstood among rope rescue technicians. This phenomenon is magnified in bad belay practices and many other belay system misconceptions that are commonly practiced throughout much of the rescue community.

As rope rescue practitioners, the more we understand the physics of rigging, the more efficient we become, and ultimately, the safer we perform.

Pat Rhodes April 12, 2017

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