UKC

http://www.climerware.com/f8x.shtml does anybody use this as opposed to tying off a normal figure of 8 with a double stop knot? What do you think of it as opposed to using the double stop knot?

Dave

In reply to Dave Ogof:
Looks like a decent option, I'm pretty sure it would be safe. Might try it sometime, see whether it's true that it's easier to untie after falling on it.

In reply to Luke90: I've seen people use it abroad. It can be easier to untie than a normal fig-8 but it does still tighten right up if it's fallen on repeatedly. Use a Bowline!

In reply to Dave Ogof:

It's also called a Yosemite figure eight. It is much easier to untie after falling on it and very safe. I have been questioned about its use at some climbing walls saying its not safe yet no one could ever explain or show me why.

In reply to Dave Ogof:
I use it, as well as being easier to untie after loading, it also keeps the loose end out of the way, eliminating the (slim) chance of clipping the loose end instead of the live rope.

In reply to petrophile: I wonder why some say it is unsafe? I dont think it would come undone easily during use would it? It has a smaller profile and the the loose end is neatly tucked away I thought.

In reply to petrophile:

In a climbing wall situation it is safe, but in some trad climbing situations it is very dangerous.

If you set up a belay by clipping the first anchor like a runner, then bring the rope back to a clove hitch on a karabiner on the knot loop, then the effect of loading the anchors through a belay brake clipped to the knot loop can be to make this form of figure of eight knot roll undone.

In reply to Dave Ogof: It's not unsafe but many think that it is partially undone by the way it looks. I have fallen on this knot hundreds of times - I'm fine so far ;¬)

In reply to Oceanic:
Is that a real risk, or a theoretical one? I was taught the technique by a very experienced and safe climber (an Alpine guide FWIW).

In reply to Oceanic: How would it "roll undone" any different from a standard f8?

In reply to Dave Ogof:

The closest infomation I have as to whether or not this could happen in practice is the information on testing figure of eight knots for joining abseil ropes which is on the Needlesports site.

http://www.needlesports.com/advice/abseilknots.htm

I'm not aware of any tests being done on the knot mentioned in the OP. My personal decision is that I would be happy to sports climb on the knot described (although I don't) but there seems to be a big enough question mark in my mind for me to not risk belaying from it in the way described in the earlier post. Unless another f/m can provide details of a study, I guess we'll have to make our own minds up (I have to admit that I can't remember where I first heard about the knot unrolling).

In reply to Oceanic:

>then the effect of loading the anchors through a belay brake clipped to the knot loop can be to make this form of figure of eight knot roll undone.

bollox, engage brain and think it through.

In reply to Oceanic: F8's can flip over and over and come undone but not very likely if they are dressed properly. I have found that a standard f8 flips easier than the Yosemite version. (not an official study mind you, just me in my chair and a rope on my pants) Oooh, now that sounds dangerous ;¬)

In reply to Toreador:

There is a real risk when your tied into the rope for long periods. Alpine style climbs or Welsh VDiff type climbs when you can be tied in for a several hours at a time. There can be enough flex in the knot in use for it to work undone over the course of a day. In a climbing wall situation where you are retying every 10 mins its fine.

In reply to Toreador:

BTW the risk I mentioned is totaly seperate from what Oceanic is talking about and his reasoning stinks like a midden on dairy farm.

In reply to davidwright:

That's OK then, I make a point of checking my knot before leading each pitch, so I'd notice if anything were working loose.

If you're doing what Walls ask you not to do, tying a knot and clipping it in with a screwgate, then look at picture 3. During repeated use the 'loose' end can work back out of the knot leaving two loops. If you then mistakenly clip into the wrong loop..whooops

In reply to Dave Ogof:

Been using this knot for about 20 years to tie on, very neat.

In reply to Dave Ogof:

I coppied this off the Fish Cimbing Equipment web site.

Subject: Test Report - Fig 8 Tie In Knot
From: ratagonia@zdnetmail.com
Newsgroups: rec.climbing
Date: Fri, 22 Jan 1999 23:02:50 GMT

I tested a figure 8 as a tie in knot using the test machine at Black Diamond.
This was to see how strong the 'belay loop' formed by your tie in knot is.

Rope: slightly used 9.7mm single rope
Knot: follow through figure 8 like when tieing in
Date: Dec 16, 1998

Setup: pulled at 4"/minute. Pulled as a loop with the knot in the center of
one of the strands. Used 1" pins both ends.

Results: Knot loads steadily and tightens up to 2200 lbf. At this point, the
knot starts to roll, and the force drops to 1500 lbf. Then the stiff end of
the rope where it is taped started to get sucked into the knot, and the
rolling action stops. Load increased steadily to 4050 lbf, where the sheath
on the non-knot side broke. Force drops to 3400 lbf. Load increased steadily
to 4050 lbf, where the sheath on the knot side, upper strand broke. Force
drops to 3750 lbf. Load increased steadily to 4884 lbf, where the core broke
at the knot, breaking the loop.

Conclusions: Figure 8 knot can roll in this loading configuration ( belay
loop on harness or when used as quick rappel knot ) at a load on the order of
1500 - 2000 lbs. It will continue to roll until some mechanism stops it. A
backup knot on a figure 8 in a pulled-apart loading configuration actual does
something. I will use these from now on when rappelling. Ultimate strength of
loop is > 16kN belay loop strength.

Additional Comments:
One data sample only gives you a general idea of what is going on. Loads for
rolling and for breaking can be expected to vary quite a bit with rope size,
surface conditions and loading sequence. Having one side jammed up against a
chain or rappel ring may also effect this. Take this with a grain of salt,
please.

Opinions expressed are my own, and may or may not be shared by my employer.

In reply to Oceanic:
Did you look at the completed knot in the sequence it starts as a fig 8 and turns into a 'fig 8 with a second pass' that is what we are talking about here?

In reply to Dave Ogof:

Was taught this as an alternative to double stop knot, have used it from time to time ( usually due to leaving tail too short ), always worked fine for me but I actually find it harder to untie than the standard knot.