Climber Down

[Mick Dempsey]

Don’t get it, sorry.

Edited September 25, 2020 by Mick Dempsey

[Paddy1000111]

1 minute ago, Mick Dempsey said:

Don’t get it, sorry.

It's basically because if you use a cambium saver you tie into the cambium saver and you hang off a branch so it is only your weight on the branch i.e a top anchor. In this format you're climbing with the same forces as a DDRT system, all of your weight only on the branch. If you base anchor then it's like having a pulley on the branch. Your weight of say 80kg is on one end of the line then the other end has to balance your weight so the anchor is basically weighing or pulling 80kg too. In total you have now loaded the branch with 160kg (your weight on one side of the line and the anchor pulling your weight again on the other acting as a 2:1 pulley system. 

 

Now, let's say you climb above your anchor point without using redirects. The "safety factor" when doing rigging if my mind is remembering correctly is 11x. You slip and fall 2/3 meters. Your shock loading (especially as you are using a static line) can be up to 880kg. Now, because of the basal anchor and the 2:1 system you have created your loading on the limb is now 1760kg of force in the worst case scenario.

[monkeybusiness]

33 minutes ago, Tommy_B said:

Because the other end is not anchored off statically. It is moving you

Correct in DDRT but not so in SRT (which was what was being referred to).

Great post Paddy, but I think you are confused (or I’ve interpreted it wrong) in saying that the cambium saver removes the double loading from the branch/anchor point. It doesn’t. 

[monkeybusiness]

Apologies, the post above mine came as I wrote.

If you tie a stopper knot into the cambium saver (which I now think you mean) then yes, you only load the branch with the climber’s weight. You can subsequently tie off a very long tail as a base anchor and that won’t apply any additional significant load into the cambium saver (and therefore anchor point) unless the anchor point fails and the ‘redundant’ tail then becomes hung up and catches the climber.

If (as I thought you meant) you simply base-tie your climbing rope after running it through a cambium saver you are in no way reducing the actual loading imposed on the anchor point - it will be double. 

[Paddy1000111]

Sorry, bad explanation on my behalf. I usually tie an alpine butterfly and stick a carabiner through it and pull that up onto the the small ring side of the cambium saver. The knot side which is now unloaded goes over other branches and gets basal tied, if my cambium saver branch snaps then the loading changes to the basal anchor and hopefully the branches below. Worst case scenario the top snapping branches on the way down would hopefully slow my decent a little ?

[Mick Dempsey]

Right, gotcha, not using a base anchor.

 

 

Edit. No, still don’t get it. 
 

if you’re using a base anchor then there’s the same pressure on your top anchor point when ascending, cambium saver or not. 

Edited September 25, 2020 by Mick Dempsey

[monkeybusiness]

5 minutes ago, Mick Dempsey said:

Right, gotcha, not using a base anchor.

 

 

Edit. No, still don’t get it. 
 

if you’re using a base anchor then there’s the same pressure on your top anchor point when ascending, cambium saver or not. 

The base anchor is tied but not loaded - the loading is taken up by a stopper-knot on the base-anchor side of the cambium saver. 
Clever system, I like that idea!

[Mick Dempsey]

Ok, the penny is dropping, I get it now.

[Paddy1000111]

Anyway, back on topic. I didn't mean this to be a "mines better than yours" "I'm better than you" thing...  Just explaining how I SRT when I'm unsure of anchor and how I feel it's safer than DDRT as we were discussing the dangers of srt. 

 

At least this seems like a clean cut case of climber error... 

[Khriss]

I prefer a base anchor and cambium saver+karabiner,   as I can advance up to next anchor point if needed. Bit of faff, but am naturally cautious. SRT is not easy easy as some portray it. Poor lad had a close one there K