Hand Jammer Krab

[Mike Hopley]

when referring to any recent manuals (especially French/European) you will notice that our overseas counterparts use ... different rigging styles (i.e. post-spit philosophy).

That's an interesting comment. Which things would you say stand out as different rigging styles, and how have they been influenced by changes in anchors?

The main thing I can think of is the use of Dyneema. Also some details I'd just consider "good practice", like double anchors at the start/end of a traverse -- I'd say there's less emphasis on that over here.

Maybe also the preferred methods of placing the rigging? Using a hand jammer to rig/de-rig traverses seems somewhat uncommon among UK cavers.

I guess you also have stuff like umbrellas, but those seem rather specialist.

 

[LarryFatcat]

Petzl Am'd twist lock is what I would use if I was rebuilding my SRT kit; I currently use a Petzl oval triact but it makes it more fiddly than it needs to be to use as a third cowstail. Am'd if you insist on massive carabiners (I have twistlock Am'd krabs as cowstails).

Agreed: not a fan of Triacts but Am'd TLs aren't much better either though as they are a mare in-cave with mud ingress/being fiddly etc.. Best left in the bin, imo.

Re: "3rd cowstail" - can you clarify whether you are referring to using a semi-static handjammer/footloop connection or an additional dynamic rope cowstail?

More generally, have you tried these (link below)? I like them very much and have lots and have used them for years. Petzl Vertigos are excellent too, btw; easy/quick to use but twice as costly as the Grivels.

https://www.youtube.com/watch?v=jkraPv-I_Bk

it looks like it might be a lot more fiddly to get out of a rope bight (the place you are supposed to attach for a rebelay)??

 

[LarryFatcat]

I imagine any number of CICs would gladly provide a day of coaching on the topic, if you wish

I'm sick of getting wet while doing SRT, could I have a training session on the drier aspects of SRT.

We've been offered https://www.alter-rock.co.uk/labyrinth-cave/ for SRT training and it even has a dry cave!!

 

[LarryFatcat]

One other thing to consider when choosing your hand jammer setup: will you use your jammer to rig traverses? Or even just for progression along a traverse line sometimes, such as when it's sloping upwards?

In these cases, the jammer can load badly during a fall -- potentially levering it off the rope. To prevent this, you can clip the rope through the safety-cord carabiner. This could matter a lot, if the jammer is your only point of attachment.

Let's say you have a maillon connecting your safety cord and jammer. How will you make the jammer load safely in these situations?

There was a good video of some "realistic" tests falling on caving equipment, but I can't find it now. I think it was French again, maybe Petzl or EFS. It was filmed in some climbing / rope access centre (Petzl Institute?). It had slow-motion footage of jammer detachment. Does anyone have the link?

fantastic point

 

[Brains]

On the snap / screw debate, I use screw gates for everything apart from my cow tails and breaking krab. I have seen on more than one occasion people that should have known better hanging from a screw gate cow tail tighten it up out of boredom and over zealous checking while carrying out a manoeuvre, only to find the gate is now jammed leaving them hung up, possibly under water. I have also seen screw gates jam both open and locked due to silt ingress. For a paying punter or groups of novices I can imagine the peace of mind screw gates give might out weigh these factors, but with well trained competent groups snaps are fine. Yes I know they can unclip in some circumstances, and knowing that I can avoid those situations. For preference a wire gate IMO is the best on a cow tail. As a climber I would be happy to take a lead fall on to a wire gate, so don't see an issue here (Ordinary snaps can vibrate open, but a wire will stay closed).

 

[LarryFatcat]

screwgates usually unjam with a little weight on them and did you
read Backstory 2:
http://welshrandomadventures.blogspot.com/2014/09/the-fall.html
from above?

though back to the point
I recommend an even loading (straight up and down like an oval or even D) lockable krab for the hand jammer attachment

 

[Fulk]

Backstory 2:

Food for thought there, Larry; thanks for posting the link.

 

[pwhole]

I use a maillon as a connector - lasts for years and cheap to replace. I have a cheap steel krab clipped in for passing sharp rebelay anchors - an ally screwgate would be far lighter, but they're easily damaged on anchor plates, and a steely makes it a handy 2:1 accessory if needed - and a spare cowstail as the safety link is dynamic.

 

[Mike Hopley]

I recommend an even loading (straight up and down like an oval or even D) lockable krab for the hand jammer attachment

Agreed. This is one of my two recommended options. The other one is "just clip your safety cord / long cowstail directly into the jammer".

a steely makes it a handy 2:1 accessory if needed

I assume you mean lifting someone with a 2:1 mechanical advantage? What is the advantage of a steel carabiner here?

 

[alastairgott]

It jingles more as he walks on the streets of Derbyshire    2 for 1, we can keep tabs.

 

[pwhole]

Or just climbing back up a bit on a nasty caving descender - it can help sometimes. I just find ally krabs aren't very durable for this sort of thing, especially rope-rub. I once had to use an ally snapgate as a braking krab on a SRT trip and it had a groove in it when I got back. I've never had to do a person-lift underground, but it always worth having the option.

 

[LarryFatcat]

a steely makes it a handy 2:1 accessory if needed

I assume you mean lifting someone with a 2:1 mechanical advantage? What is the advantage of a steel carabiner here?
[/quote]

perhaps he means a standard oval steel (like used on a Stop) which are great for use with a pulley