5. Dynamic Ropes
What makes ropes dynamic? Dynamic ropes are designed with the intention of absorbing impact that may result from a lead climbing fall. When a climber falls, a well-balanced rope will stop the fall in the shortest distance, while also lessening the impact felt by the climber and reducing force on equipment. As mentioned in the construction section, dynamic ropes have much higher levels of twist in the sheath and core yarns creating mechanical elongation to act like a spring absorbing the energy created during a fall. A careful balance is needed in rope construction to create a rope that will catch the fall with minimal impact, yet not be so stretchy as to allow the climber to hit a ledge or ground.

5a. Testing / Standards for Dynamic Ropes
UIAA 101 is the standard to which all dynamic ropes are tested. There are five areas of testing: Construction, Sheath Slippage, Static Elongation, Impact Force on first fall, and Number of Falls Held. UIAA delineates dynamic ropes into three categories: Single Ropes, Twin Ropes and Half Ropes.

• Single Ropes: Dynamic climbing rope, capable of being used singly, as a link in the safety chain to arrest a person's fall. Usually found in diameters from 9.5mm to 11mm.
• Twin Ropes: Dynamic climbing rope, which is capable, when used in pairs and parallel in each piece of protection, of arresting a person's fall. These are generally smaller diameters from 7.5mm to 8.5mm. They have the added safety factor of a two-rope system and can be useful when doing long rappels.
• Half Ropes: Dynamic climbing rope, which is capable, when used in pairs, as a link in the safety chain, of arresting a person's fall. Generally smaller diameters from 8mm to 9mm, this system reduces rope drag, allows for longer rappels, offers better safety for the "second" and greater versatility in the field.

The basics of UIAA 101 testing requirements:

1. Construction: Kernmantle with core having a greater mass than the sheath.
2. Sheath Slippage: Must be less than 20mm over a 200mm sample or no more than 10%
3. Static Elongation: 80kg weight for single and twin ropes and a 55 kg weight for half ropes.
   Single and Twin ropes (using both strands): Must be less than 8% (possibly increased to 10%).
   Half Ropes: Must be less than 10% (soon to be 12%).
4. Impact Force: Tested during the first factor 1.8 fall (4.5 meter fall on 2.5 meters of rope).
   Single Ropes: Impact must be less 12 Kilonewtons (kN) using an 80 kilogram mass.
   Twin Ropes: Same as Single ropes, but using both strands during the test.
   Half Ropes: Impact must be less than 8kN, tested using a 55 kilogram mass.
5. Falls Held: Number of falls rope holds before breaking.
   Single Ropes: Must hold 5 falls of an 80kg mass.
   Twin: Must hold 12 falls of an 80kg mass.
   Half: Must hold 5 falls of a 55 kg mass.
   
   1 Kilonewton = @ 224.82 lbs/force
   1 kilogram = @ 2.2 lbs
   

Next time we will continue with the topic of Static Ropes in Rope Design and Construction.

Until next time, be safe and always dress your knots!

STERLING ROPE and AHS Rescue