Clove hitches on traverse lines

[JJ]

Can anyone shed any light on why cavers generally don't use clove hitches as the knot of choice when rigging traverse lines.

I can see quite a lot of advantages and only a few disadvantages or is it just tradition?

 

[dunc]

I've never seen anyone using a clove hitch in a rigging situation, so I just learnt from others and used apline butterflies.. Might have to give it a try next time and see how it goes!

 

[Fulk]

In Alpine Caving Techniques it states that:

Clove hitch: this knot is also suitable for traverse lines but, while it makes it easier to regulate tension, this knot is hard to tighten down when used with stiff rope. In this case a butterfly is better.

 

[Ship-badger]

An alpine butterfly does give a nice loop to attach a cows-tail to. Clove hitches should not, I think, be tied around something smaller than the rope diameter; so an 8mm maillon would not be recommended. Clove hitches can also be difficult to undo if tightened excessively.

 

[damian]

I've seen them used in France, but never in the UK.

For me I prefer butterflys for two reasons: firstly clove hitches don't work very well on the traditional 7mm long-oval rigging maillon (and I'm traditional!) and secondly it is harder to protect yourself well when rigging and derigging because you can't clip into the knot itself.

 

[Fulk]

Quote from Damian:

firstly clove hitches don't work very well on the traditional 7mm long-oval rigging maillon

Good point; I suppose it would be OK if you were rigging with krabs?

 

[Bob Mehew]

I quote from a report, see page 16 / 17 at http://www.hse.gov.uk/research/crr_pdf/2001/crr01364.pdf

"On most of the tests with low-stretch rope, the clove hitches slipped without breaking, at widely varying forces only partly dependent on the manufacturing process. Interestingly, with the dynamic rope the knots broke on every test at forces comparable with the overhand knot."

I have never tested them, another potential job!

 

[cap n chris]

When rigging with karabiners (something which is becoming more frequent nowadays) using clove hitches, depending on the situation, seems reasonable enough.

 

[JasonC]

I quote from a report, see page 16 / 17 at http://www.hse.gov.uk/research/crr_pdf/2001/crr01364.pdf ...

I hadn't seen that before.  Most interesting, thanks for the link 

 

[JJ]

Thanks for all your comments so far.

Bob - thanks for that report I had also not previously seen it. Can't really decide that the knot possibly slipping with static rope and a dynamic load if this is a good or bad thing in this situation - shock absorption etc.

From my perspective regarding clove hitches mid points on traverse lines

Advantages

Easy to tie mid traverse, so speed
Can be easy adjusted (tightened) once tied without unclipping
Uses  less rope
Keeps the traverse line higher which is especially useful for self rescue
Knots largely untie themselves when unclipped

Disadvantages

Only suitable with crabs
No knots to clip into
Lack of test data on knot slippage
Not suitable for an end anchor

 

[Fulk]

quote from JJ:

Keeps the traverse line higher which is especially useful for self rescue

Just as a matter of interest, has anyone out there ever had to do a 'full-blown' self rescue from rope of someone who was totally incapacitated?
A couple of times I have prusiked down to or up past someone stuck at a rebelay to help sort them out ? but it's obviously a totally different situation when they're compos mentis and able to help themselves.

 

[Mark Walker]

I never use clove hitches on travese lines as I feel that the potential load on the connector in a traverse set up is incorrect. If either side of the rope are loaded simultaniously it twists the connector and in-turn puts incorrect loading on  the hanger. Also for most connectors that I use it would cause them to be overloaded. The alpine butterfly reigns supreme.

 

[Fulk]

Mark Walker:

Also for most connectors that I use it would cause them to be overloaded.

I'm sorry, but I  don't really understand this remark. If by connector you mean karabiner, then how can you 'overload' ('exceed its safe working load of around 2 tonnes +'?) by merely hanging on a rope tied to it?

 

[Mark Walker]

Depending on the thickness of the rope a clove hitch on some karabiners (most of mine) does not load it along its major axis particulary when in a travese situation this is "overloading" overloading does also mean too much weight, but the former is what I meant.

Also FYI karabiners have a breaking load stamped on them eg. 24kn <> this means the krab will break at 24kn on its major axis. A "working load" is not given on karabiners but is stamped on maillons eg. 20kn <> this means the maillon can take a force of up to 20k "comfortably".

 

[hrock]

most maillons are marked with braking load like crabs but some are maked with  WLL (working load limit) this has a safety factor of about 5 times for something like a maillon.

the problems with clove hiches is that in alot of caving situations they are too short and mean the rope rubs on the rock worse than with long knots. but each situation is different and to try and rig with one knot all the way will always give you problems use the right knot in the right place. 

 

[Fulk]

Mark Walker

Depending on the thickness of the rope a clove hitch on some karabiners (most of mine) does not load it along its major axis particulary when in a travese situation

So if I understand this correctly, you have found that in practice, if you rig a traverse line using krabs and clove hitches, the krabs orient themselves under load such that they are loaded across the short axis?

 

[potholer]

I guess with a stiffer connection between rope and crab if using a clove hitch, it may be easier to end up with the crab being manipulated by rope movements into odd attitudes relative to the hanger than when there was a knot loop of any size involved.

 

[Mark Walker]

Exactly, get a krab put a clove hitch on it and pull either side and see what happens the krab will twist and the hitch will load the krab incorrectly, this won't happen with an alpine butterfly.

 

[potholer]

Presumably some nasty orientations are possible with normal knots, just maybe rather less likely (though I guess a normal knot might have the possibility of a true crosswise loading if the rope slips round the crab in a way that a clove hitch might not be able to do).

I suppose a lot comes down to just how much flexibility there is in the system.

I'm reminded of the old 'Oh my god, you can't hang a Stop on a 10mm long maillon - look, it's so easy to get accidental opening!' comment from someone demonstrating by manipulating Stop and maillon in their hands, with complete control over position, twist, torque, etc, whereas trying to do the same thing even just with the maillon attached to their harness is rather harder, let alone by duplicating the kinds of forces that a rope and/or cave wall might conceivably place on a Stop, due to the freedoms of movement in the system and the limitation of extent of manipulation that introduces.

If someone *was* going to use clove hitches, how much difference would the tautness of the lines make to the risk of misoriented crabs?
My first guess would be that even if people were moving along the lines in a pessimal way, there'd be some threshold of slackness below which misorientation would be much less likely to happen.

 

[paull]

just had a play with this idea on a training board , the hitch works OK (ish) on the krab the problem is when tention is placed on the rope between the krabs.
the krabs try and rotate and jam tight against the p-hangers  :-\  surely this cant be good