Ben Bransby from DMM tests a variety of slings at anchors.
This informative video is from the web link below.
https://dmmclimbing.com/knowledge/slings-at-anchors/
DMM climbing equipment is available at https://www.staffordoutdoor.com
In a previous video we compared the impact forces generated using nylon and Dyneema® slings with a dynamic load. It clearly highlighted the importance of ensuring there is no slack in a system using slings. As an example, a 85 kg mass free-falling just 60 cm on to a 60 cm Dyneema sling (fall-factor 1), with an overhand knot in it, generated enough force to break the sling.
Extending this previous theme we’ve looked at using nylon and Dyneema® slings in four different belay set-ups:
Equalised with an overhand knot at the balance point.
What is commonly known as ‘self-equalising’ or sliding X.
Clove hitch at anchor and clip-in points.
Overhand at anchor and clip-in points.
In addition, we simulated a marginal placement ripping by using 2 mm cord at one of the anchor points. In this scenario the ‘self-equalising’ arrangement placed the greatest shock-loading on the remaining anchor point and isn’t advised with natural or hand-placed anchors for that reason.
Carrying out a final test replacing the slings with 8.2 mm rope for a worst-case scenario with a fall-factor two clearly showed — as expected — that utilising the shock absorbing properties of your rope dramatically lessens the impact forces on the anchors and is the best option. This could be by either clipping the anchors directly with the rope or into a central point in the system. For a full explanation and examination of the results watch the video.