Bowline for Master Point Knot?

So, it occurred to me that I've never seen a book or diagram in which the master point of an anchor was made using a Bowline knot. Why is this?

It's a strong, dependable knot, and unties easily after being weighted. In an equalized anchor it's unlikely to work itself loose. I'm sure that I'm not the first person to think of this.

Why wouldn't it work?

Probably because it is so much simpler to grab a handful of cord or slings and tie it in a figure 8 any time, almost one handed if need be. Why mess with a bowline if you don't need to? Nothing beats the security and simplicity of a figure '8'.

Woodchuck ATC wrote:Probably because it is so much simpler.

That's the first thing that went through my mind.

I have used one before if I'm gonna be jugging on a rope a lot. It's basically as quick to tie as a figure eight on a bight. The only disadvantage I see is it wouldn't be as trustworthy if you wanted to clip in to the cordalette above the knot, instead of through the master point.

Maybe I'm missing something here. However, when I use cordelette to make an anchor I connect to the three points, make sure the anchor point is pointing to the direction of pull and THEN tie the figure 8. I don't see how you can tie a bowline for three connecting loops which might not be the same length easily or 'with one hand'.

Carl H. wrote:Maybe I'm missing something here. However, when I use cordelette to make an anchor I connect to the three points, make sure the anchor point is pointing to the direction of pull and THEN tie the figure 8. I don't see how you can tie a bowline for three connecting loops which might not be the same length easily or 'with one hand'.

I definitely can't tie it one-handed, but equalizing it across three points, even if they're not the same length, isn't any harder than tying a figure 8 or overhand with equalized strands. At least the way I tie it, it's just an overhand with an added step.

Behave that is an awesome master point.
I prefer the ACR for my anchor, but love the bowline at the sharp end.

If you climb with any other knot than the sacred eight,
the masses here will scorn you!

Which will lead you to the inevitable. .

Yer gunna die!

Also, you can fix the images by "edit photo" then "edit properties" then "rotate photo"

Terminology: its a bowline on a bight.

There's nothing the matter with it; it is as strong and as reliable as a figure eight and easier to untie when loaded. It is superior to the figure eight for tying into a harness too, where it would is called a rethreaded bowline (and sometimes, incorrectly a double bowline). There's nothing simpler or easier to tie about a figure-eight, it's just that most people are familiar with the figure-eight and and may not even know how to tie a bowline on a bight.

As mentioned, using the "shelf" clipping technique would be of unknown security. Probably not a problem because that application is really for body weight at most, but in any case totally avoidable; I never use the shelf configuration on the rare occasions when I use a cordelette and have never seen a real need for it when other people do it.

Another reason that jumps out to me is that a lot of people may not be able to easily tell if it is tied right. I feel like thats a major reason for the change between tying in with a Bowline vs. a Figure 8.

rgold wrote: As mentioned, using the "shelf" clipping technique would be of unknown security. Probably not a problem because that application is really for body weight at most, but in any case totally avoidable; I never use the shelf configuration on the rare occasions when I use a cordelette and have never seen a real need for it when other people do it.

Just curious where you got the idea that it's body weight only? I always thought it was just as strong (or nearly) as clipping the masterpoint, but if there's been research otherwise that you've seen I'd love to know about it.

What's wrong with the shelf? Just curious, I've seen very experienced (guides) teach it. Good to know if there is danger.

I'm surprised no one has mentioned yet that the BOAB as shown takes up much more material than a traditional overhand or Figure-8 would.

Sometimes a regularly sized cordelette is barely enough to clip three pieces in various placements and pull it together with a tiny master loop. Don't see how this is better, just different.

Panda Express wrote:What's wrong with the shelf? Just curious, I've seen very experienced (guides) teach it. Good to know if there is danger.

the shelf is perfectly fine and safe with an overhand or figure8 style knot at the masterpoint ... especially if there is a biner to prevent pull through

the main concern about clipping into the shelf is that in a wide angle anchor, it may place some unusual loading on the biner ... for most purposes this is a non issue

as to the anchors ... i just use a fig 9 ... easy to tie and untie ....

;)

This looks complicated. I typically anchor with a single #1 or #2 stopper, so a single length sling works fine.

From what I understand a figure 8 is a stronger knot than the bowline(this is the first thing I thought of), I don't know if this is true for figure 8 on a bite vs a bowline on a bite. Which, if true, may be the reason it's not in books.

Take an anchor building course from an AMGA certified guide and use what they recommend. Ask the guide for their thoughts on the BOAB for the anchor master point.

Abram Herman wrote: Just curious where you got the idea that it's body weight only? I always thought it was just as strong (or nearly) as clipping the masterpoint, but if there's been research otherwise that you've seen I'd love to know about it.

I didn't say it was rated for bodyweight only. My point was that in practice, it is rarely if ever called on to take more than body weight. Clipping the shelf is usually done as a temporary intermediate anchor position. The belayer, the person who might be subjected to a possibly high fall impact, is connected to the power point, not the shelf. So the shelf is typically not going to be weighted with much more than someone leaning back on it.

The main reason for clipping the shelf that I know of is to reduce clusters at the power point, but this can also be done by intelligent rope management.

There doesn't seem to be available test information on strength and/or stability of the standard figure-8 anchor rigging when the shelf is used rather than the power point. Adam Fox is supposed to have tested this in Materials testing of climbing equipment; debunking common myths and confirming truths, but I've never been able to find a copy. Fox's result is reported to have been that the shelf is fine.

The following video indicates that some nasty things can happen when a single arm of a bowline on a bight (noeud de chaise in French) is loaded in shelf-like fashion.

efs.ffspeleo.fr/techniques/…

The video addresses the use of the bowline on a bight to create "rabbit ears," each of which is clipped to a single anchor, to create a fixed single rappel line, and then loading one of the "ears," separately. This type of loading is completely different from the loading imposed by clipping the shelf of a bowline on a bight cordelette power point, but it might be enough to defer clipping that shelf until some testing proves it safe.

The other comments in my post were meant to suggest that losing the shelf is really no loss at all.

It's actually pretty easy to tie as a BOAB, but you get twice as many strands in the master point loop as if you did an 8 or overhand. To tie it, you basically tie an overhand and flip one of the loops of the knot around itself; I think Rgold put a link to it above. The same knot used on a bite if your climbing rope the BOAM a convenient anchor method for 2 bolt belays.

Allen Corneau wrote:I'm surprised no one has mentioned yet that the BOAB as shown takes up much more material than a traditional overhand or Figure-8 would.

The reason no one has mentioned it is because it isn't true. The two knots use about the same material; actually, slightly less for the bowline on a bight since it is based on an overhand rather than a figure eight.

Larry S wrote:To tie it, you basically tie an overhand and flip one of the loops of the knot around itself; I think Rgold put a link to it above.

The link I posted has nothing to do with tying the knot.

Sorry, RG, Was posting from my phone late and didn't actually view it.

rgold wrote: The main reason for clipping the shelf that I know of is to reduce clusters at the power point, but this can also be done by intelligent rope management.

I'm really confused by this statement. How does better rope management affect how many things are getting clipped to the master point?

I generally belay direct off the anchor using an atc in autoblock mode on the master point, and then I tie myself in with the rope using a locker on the shelf to keep the atc clear from obstructions so it can function properly. Why is this bad, and how could it be avoided through different/better techniques?