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TOPIC: 3:1 Systems (Z-Rigs) & 5:1 Systems

3:1 Systems (Z-Rigs) & 5:1 Systems 1 year 8 months ago #43717

  • KizzTW
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Some useful links with handy illustrations to cover what was learnt at the rescue training last night - 17/11/2022

3:1 - roperescuetraining.com/raising_3-to-1.php

5:1 - roperescuetraining.com/raising_5-to-1.php


Last Edit: 1 year 7 months ago by KizzTW.
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3:1 Systems (Z-Rigs) & 5:1 Systems 1 year 8 months ago #43731

  • Sweetie
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Thanks for posting the links Kieran. Anyone who is leading an SRT trip should have the knowledge of rigging a z-rig and should also be carrying enough gear to rig one (including enough rope - even if you keep it in the car). If you don't know how to rig one it would be a great idea to visit the links Kieran has posted above.

If you've ever been on an SRT trip with me, you'll have seen the roll of kit I always carry:


The systems shown in the diagrams are absolutely fine and will get you out of a bad situation, however there are a few things to consider. The hauling systems shown are aimed more for rope access rescue rather than cave rescue and while prusik knots work ok as a progress capture device, they don't allow you to lower the casualty in a controlled manner - something you may need to do in a confined space. You can see from my picture above that I carry a Petzl Grigri as a progress capture device - however a lot of rescue teams are now using the Petzl Rig.

Another thing to consider is the additional force you are putting on the anchor (it's not mentioned in the diagrams as anchors used for rope access on buildings and wind turbines are usually bomb proof).

In a confined space rescue, you often need a change of direction pully to allow a rope to be pulled along an adit level. The anchors we use as cavers are often drilled into questionable slate walls and terrible shattered rock (like all of the mines in the Gwydir Forest) adding a change of direction pulley will increase the force on the anchor by 33%. If the change of direction pulley is placed before the mechanical advantage, it increases the force on the anchor by 100%, so if your casualty weighs 90kg it's 180kg hanging off the anchor.

Happy caving everyone :sick: :blink: :woohoo:
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Last Edit: 1 year 8 months ago by Sweetie.
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