Two Tension System Overview
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- เผยแพร่เมื่อ 2 ก.ค. 2014
- Here is a quick overview of a Two Tension System with an artificial high directional. Two tension systems can be used on a low directional edge as well (without a high directional) but the belay is kept hand tight with only the main line under tension until the rescuer is over the edge. Once over the edge and in good control, both lines share tension.
OK, I will get this started by saying that my goal here is to point to the fact that the traditional non-tensioned belay like the tandem prusik belay can give you some significant downward movement before you are arrested. We have all been using tandem prusiks for decades now and they are safe. The reality is that they may not be the safest thing.
Maybe it would be better to say that we may not be using them in the safest way. I mean, how many times have you observed some not so awesome belaying.
Two tension systems and the MPD also have drawbacks but they are worth looking at.
It should be noted that many teams do actively add tension to their belay line to remove rope stretch and slack. This is probably more common with teams who do lowers in the 300 foot or greater range. I am just not sure how common that is or if the need to do so is well known.
I would like to hear your thoughts and if your team uses two tension systems or if you use a technique to add tension to your tandem prusik belay.
Thanks in advance for your voice.
Nice video Tom.
I'm a huge fan of Two/Twin Tensioned Rope Systems (TTRS).
From my tests and observations I feel that such systems truly offer the best protection to the rescue load. I have seen many belays offered with the best of intentions however I am not convinced that (before TTRS) these have been so effective.
My thoughts:
- operation of the business end of any such system is the job for the most experienced operators on the team
- operators must be well practiced and aware of the potential for human error
- where possible, get the attendant out of the system so that the load is reduced. This could be for the entire operation with the attendant ascending/descending on their own ropes next to the litter OR just getting the attendant out of the system for edge transitions.
Richard
Richard Delaney I have to say that this process and the great discussion just gets me thinking about more aspects of our rescue culture that need a bit of an update. I really liked you ideas about the whistle test or hands off test. I mean tens of thousands are killed every year in motor vehicle accidents and we have no sort of hands off test philosophy for drivers. Something as simple as having the assistant to the device operator formally act as the backup could really improve safety in a way that the hands off philosophy does not.
Thanks for your comments and the great testing that you do.
Tom
If you lower only one of the tandem ropes you are negating one of the systems intended safety purposes. By doing this you are making one rope longer then the other so if the high directional were to topple, one rope would be under more tension than the other which sets to back to a mainline and belay line system. I would suggest lowering both rope simultaneously.
Dude with black Petzl harness has a twist in the back of the harness. Buddy check system should be done. Goode video tho.