Arranging Pull-through Descents

[nobrotson]

Biner block every time in a caving context, very simple and difficult to get stuck.

 

[Cantclimbtom]

Biner block every time in a caving context, very simple and difficult to get stuck.

I never used to, but I'm coming round to the idea of biner-block, here's an old pic of mine with an alpine butterfly and locking krab, but the knot started to bed into the chain and I remember it took a bit of a tug to start the retrieve, was wondering for a minute if I'd need to jug back up the chute. I can easily see how with a thinner rope or bigger chain links it might get stuck, maybe if you zoom on this pic you can see it's borderline going to happen here, someone fatter than me with big bounces might have got it stuck

Never heard "NOT the knot" before, that's a good saying! (although keeping the retrieve end in a bag and descend with the bag is also a good option when possible, that's also idiot-proof)

 

[rm128]

I'm a big fan of the retrieve end of the rope being kept in the bag for as long as possible. However, if the last person brings it down then there is no chance to ensure that the rope does indeed feed while there is still someone at the top. Fine, if you're sure your method precludes jamming, I suppose.

 

[nobrotson]

If using a biner block, its very simple to install redundancy as well: just clip the karabiner into the bolt using a sling and 2 karabiners, a chain of karabiners (not ideal) or (best case) a dedicated quickdraw (canyoners carry dedicated quickdraws with lockers on for this reason). Then there's no need to worry about which side gets loaded. Really basic canyoning technique which many cavers don't seem to know about.

Ian is correct, you really want to use a triact karabiner for biner blocks. Means there's no need to worry about anything coming undone.

Its still a good idea for the last person down to be experienced in pull-thrpough SRT; they can also supervise at the pitch head.

Of course its best practice for a pullthrough to be tested before the last person descends, and this is quite feasible if using a biner block as well, especially in caves as opposed to canyons where white water can cause ropes to get very twisted if both ends hang down the pitch. However if a biner block is used I would estimate you will have very few issues with stuck ropes in a caving context, I certainly never have. Every single stuck rope I have had in caves has been due to clipping a knot to the rope, which I stopped doing after learning some basic canyoning techniques in New Zealand and then in the Alps. Knot clipped to rope is an outdated technique which is unnecessary and has been shown to cause problems.

 

[cavemanmike]

Our club practice leaving the rope bag clipped into the p hanger . When the last (and experienced) person comes down he pulls the knot off the p hanger to make sure it’s knot (pun intended) stuck in the hanger so will pull down easier