central maillon...

[Cave_Troll]

Sam : using a hand jammer as a 3rd cowstail at rebelays. usefull as you can clip in and stand up in it.

on a different note, does everyone else say you need 3 cowstails for traverses (on the whole 2 points of attachment reasoning) ?

 

[Stu]

Sam : using a hand jammer as a 3rd cowstail at rebelays. usefull as you can clip in and stand up in it.

on a different note, does everyone else say you need 3 cowstails for traverses (on the whole 2 points of attachment reasoning) ?

I found it useful in some of the pure aid techniques adopted whilst working in roped access. I now tend to lead with the safety strop which gives me something to stand in. Clip shorty into bolt and bring the longy to one bolt behind me. Advance with safety and repeat. If I slip I'm hanging in a V rather than straight down from one cord = bit nearer to the rope which to haul my ass out..

on the subject of the difference between static and dynamic rope. I was once told by a CIC that as soon as you cut dynamic rope its no longer dynamic.
by this reasoning, if i'm belaying someone using my climbing rope and someone cuts 1m off the tail thats coiled on the floor, my leader will die when he falls off coz he's now effectivley on a static rope!

What was it they actually said? In what context? Strange comment to make. I've heard it said that cowstails could be semi static for all the difference it makes.

 

[SamT]

So on the subject of Fall factors - Ive been climbing for about 15 years and caving for the past 3 - I know about fall factors. Im not saying you cant genrate high fall factors over a small amount of rope - what Im saying is that the cussioning effect of so called 'dynamic' rope over the short (say 60 cm) length of a jammer safety leash is practically nada. So therefore is it worth compromising not having a useful (nay essential for mid rope rescue and piece of self rescue equipment for the sake of having a dynamic leash thats not actually very dynamic.

The reason for having a crab not a mallion to attach your jammer is that in an emergency - you are going to want to get that bit of rope (should you need it) off your jammer quick smart - chances are a screw gate will undo more easily than a mallion.

As for standing in your footloop at rebelays - I do that all the time - my jammer is positioned on the lower rope snug just below the knot (not too close mind). Maybe' s your footloop is too long. If I need it shorter i.e to gain more height at the belay - a quick clove hitch round my foot gives enough purchase to stand higher. (with either my foot loop - or lower rope

anyhows - we're really starting to split hairs now.

My main beef is people who have split systems for their leash and footloop - without what I consider a good enough reason.

Like I said earlier - this is the world according to me, so its only an opinion.

:soapbox:

 

[Cave Ferret]

So on the subject of Fall factors - Ive been climbing for about 15 years and caving for the past 3 - I know about fall factors. Im not saying you cant genrate high fall factors over a small amount of rope - what Im saying is that the cussioning effect of so called 'dynamic' rope over the short (say 60 cm) length of a jammer safety leash is practically nada. So therefore is it worth compromising not having a useful (nay essential for mid rope rescue and piece of self rescue equipment for the sake of having a dynamic leash thats not actually very dynamic.

So would you consider using LSK for your cowstails then?

In the event of a Croll failure it would be possible to generate close to factor 2 fall - this is unacceptable on LSK. Caving rope is only designed to accomodate a factor 1 fall with an 80kg mass. It is not uncommon for LSK to fail after only one such load, particularly if its old and of thin diameter (i.e 9mm, as many peoples footloops often are). A fall factor over 1 on 9mm LSK would not be good.

And talking of stretch, if a climbing rope has a typical stretch of 20%, it doesn't matter how long it is - 1m will still stretch by 20% relative to its length.

Cave Ferret

 

[paul]

Isn't all this talk about fall factors/type of rope in the context of safety links/leashes rather academic (when used for the intended purpose of acting as a back-up to the chest jammer in case of accidental removal or failure) seeing as how one end is connected to a jammer rated at about 450Kg connected to a rope it has a high chance of being cutting through by the jammer in a severe fall onto the safety link?

I agree with SamT that one length of rope (ususally 8mm cord) combined as footloop and safely link is the best option.

Interestingly, if you look in "Alpine Speleology", and excellent book, they don't use a separate safety link at all but advise you to use your long cowstail for that purpose by clipping it to the top jammer while prussiking. This leaves it still available for use as a cowstail in all other cases. The main reason seems to be is to save weight.

 

[SamT]

Thanks paul. As I aluded to earlier - if your generating fall factor 1 falls on your jammer safety leash - you've got other things to worry about than the dynanasysm (is that a word) of your leash.

*think about it*

And no - I wouldnt use Low Stretch Kernmantle (for those who dont know what is meant by LSK) for my cows tails. Why would I, what would be the point in that. I use nice 10.5 dynamic rope, incase I fall onto them.

 

[Cave Ferret]

And no - I wouldnt use Low Stretch Kernmantle (for those who dont know what is meant by LSK) for my cows tails. Why would I, what would be the point in that. I use nice 10.5 dynamic rope, incase I fall onto them.

But you just stated that a short length of dynamic has so little stretch it is no better than LSK. If there is no safety benefit why not choose the cheaper and harder wearing caving rope?

The answer is, as I am sure you know, that any rope that is used as PPE (Personal Protective Equipment) that has the *possibility* of taking a high fall factor, should be dynamic.

The possibility of severely damaging or cutting a rope when falling onto a jammer would be far greater using an LSK security link as less of the energy will be absorbed by the rope, transmitting more to the jammer.

Cave Ferret

 

[SamT]

I still stand by the fact that if you generate a high fall factor onto your jammer, your going to do some serious damage regardless of if you have a dynamic leash or not. Therefore in the whole sceanario of the slim chances of something unfortunate happening, you are better off having your emergency rope that you can use as necessary than you are if you have a 2 piece system.

A compromise would be to have a one piece dynamic system i.e. dynamic foot loop too.
Going on the "short length of dynamic aint very dynamic" theory then you shouldnt be too disadvantaged (efficiency wise).

Still, Im gonna stick with my static. If I ever find myself climbing my full leash height above my jammer - I'll make sure Im backed up with a cows tail or two.

As for the cowstails, I dont use LSK for them as there is no_good_reason to.
IMHO there is a good reason for using a one piece leash and footloop.

Each to their own. So long as you have your reasons. Thats all I ask.

 

[paul]

And no - I wouldnt use Low Stretch Kernmantle (for those who dont know what is meant by LSK) for my cows tails. Why would I, what would be the point in that. I use nice 10.5 dynamic rope, incase I fall onto them.

But you just stated that a short length of dynamic has so little stretch it is no better than LSK. If there is no safety benefit why not choose the cheaper and harder wearing caving rope?

The answer is, as I am sure you know, that any rope that is used as PPE (Personal Protective Equipment) that has the *possibility* of taking a high fall factor, should be dynamic.

The possibility of severely damaging or cutting a rope when falling onto a jammer would be far greater using an LSK security link as less of the energy will be absorbed by the rope, transmitting more to the jammer.

Cave Ferret

Really the safety link should only be used for one purpose: to provide a backup should your chest jammer come off the rope. The only time this should be able to happen is while prussiking when either the chest jammer fails, detaches from the rope or its attachment to the harness fails or disconnects. In this situation a severe fall is extremely unlikely. It would be more of a surprise as you sit down onto your chest jammer and find that you keep going until brought up short by the footloop jammer. The fall factor would be very small.

If on the other hand you are using your footloop jammer as a security attachment while manouvering where you may fall onto it for some distance, as you say, you could indeed have a significant fall factor introduced.

The point is that this is not what the safety link is intended for. This is the job for a cowstail which always uses dynamic rope. If you need to be attached to a rope where a slip could occur and a cowstail is unavailable then a descender with a knot tied a short distance below would be far safer.

This is my opinion - your mileage may vary.

 

[Stu]

In the event of a Croll failure it would be possible to generate close to factor 2 fall - this is unacceptable on LSK. Caving rope is only designed to accomodate a factor 1 fall with an 80kg mass. It is not uncommon for LSK to fail after only one such load, particularly if its old and of thin diameter (i.e 9mm, as many peoples footloops often are). A fall factor over 1 on 9mm LSK would not be good.

And talking of stretch, if a climbing rope has a typical stretch of 20%, it doesn't matter how long it is - 1m will still stretch by 20% relative to its length.

Cave Ferret

EN1891 Type A
Static Strength: 2400kg
Strength with fig.8 knot: 1700kg
FF1 100kg Falls: 6
Elongation @ 150kg: 4.4%
Shrinkage: 4%
Weight per meter: 62g

FF1 @ 100kg not 80kg and remember these figures are minimum, the averages are a lot higher. eg Static Strength is nearer 30kn

Still can't work out FF2 whilst jugging. I'd have to be a safety leash length above my foot jammer wouldn't I???