/ Question about tying in..
I've done some climbing a few years ago but when looking online and in books to refresh my memory I've seen different ways of tying a rethreaded figure 8.. I'm aware that there may be more than one way to tie the same knot, but my confusion comes when the final knots do not look exactly the same. Surely there is a best/strongest way?
Some start by threading the rope from the right and finishing on the right, others starting on the right, finishing on the left and vice versa.
I seem to remember tying in like this: http://www.youtube.com/watch?feature=endscreen&NR=1&v=F2InKUWixwI ...leaving a nice, neat looking knot.
An example of another way is starting on the right and finishing on the right: http://www.youtube.com/watch?v=4PRVLSfJ3LE (This is the same way shown in freedom of the hills).
So, are both ways right? Or is one way more right than the other?
This is not a troll post, just a very basic question I'd appreciate clearing up from someone who knows!
And yes, when I do decide to start roped climbing, I will be going with a qualified instructor!
They're both right. Left-right/upside down doesn't make any difference. The only difference was the second one added a stopper knot which is a good idea, most people do
When you rethread, note that you can go in either side of the rope you're following. One side is "wide", the other is "narrow".
If you go in the wide side, make sure you leave the top by the narrow side at the top and vice versa. This will ensure that the knot is properly dressed.
Figure-of-eights are vastly more complicated than most people (even most climbing instructors) realise. However, before I start an in-depth discourse it is worth emphasising that even extremely untidy Figure-of-eight knots are still perfectly safe and are NOT significantly weaker.
Its forgiving nature is one of the main reasons why we use it.
[See the paragraph 'Myths about backup knots and neatness of knots' at the bottom of the third page of http://www.efclimbers.net/resources/Knot-and-cord-strength.pdf if you want some evidence about this.]
Even a basic single strand Fig-8 knot is chiral. Basically, you get right and left-handed versions that are mirror images but not identical.
The re-threaded version introduces an additional variable. This means that perfectly dressed re-threaded Figure-of-8s exist in FOUR distinct geometries. Therefore there are 4 non-identical ways of tying one neatly. [Add in the chirality of a stopper knot and you end up with 8 non-identical variations, so it is no surprise if you are slightly confused.]
So, in answer to your basic question:
The answer is NO. Testing by Lyon Equipment for the HSE has confirmed both of the potential re-threading geometries are equally strong. See 3.3.2 of http://www.hse.gov.uk/research/crr_pdf/2001/crr01364.pdf
However, in order to be neat and tidy, the knot needs to be both re-threaded correctly and then 'dressed' correctly. The re-threading process is crucial to whether the knot will end up 'well-formed' when it is finished. If you start re-threading on the outside of the rope you are following you need to maintain that for the 'first' turn and then re-thread on the inside for the 'second' turn (or vice-versa). You then need to tighten the knot such that the 'outer' loops end up towards the centre of the knot and the 'inner' loops are towards the ends of the knot.
So, looking at your links.
The first link is a poor demonstration and is guaranteed to lead to a badly dressed knot. The rope is re-threaded starting on the INSIDE of the existing rope, but the first turn is then made on the OUTSIDE, followed by the second turn on the inside.
The second link is initially a good demonstration of how to tie a tidy knot. They start re-threading on the outside, maintain that for the first turn and then re-thread on the inside for the the second turn. However they then fail to complete the dressing on the knots, both when using one rope and two ropes. The 'outer' loop at the top of the knot needs to be tightened so it ends up lower, towards the centre of the knot. That would then result in a well-formed neat and tidy knot.
The second video then messes things up completely when showing their so called 'finished product'. There is a massive continuity error as they show the stopper knot tied on an untidy and poorly-tied Fig-8 that is completely different in geometry from the one the demonstrated at the start of the clip.
Anyway hope all that helps.
> Its forgiving nature is one of the main reasons why we use it.
One of the advantages of it is that it needn't be, as a messily tied one is safe enough. Indeed (I've used this as a demo though not at any height) one only partly rethreaded (even only two "bits") will still catch most top rope falls.
Ideally, we do a better job. But the fact that it's still safe makes it a good knot for beginners to use, unlike a bowline which is not inherently safe in that way and must be tied correctly.
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