2 Piece Alpine Anchors

Nice video Josh. And very helpful.

1. as the angle increases between the pieces does the force increase exponentially? Doesn't it increase as sin(theta)?
2. if instead of tying an overhand as the powerpoint you tie and alpine butterfly the whole undoing-thing-after-loading goes away. This is slightly harder with gloves one, but no harder when without.

...and

I wasn't sure if the bolts were used just as a demo, but if you are talking bolts, I would have included a banshee with just the rope. Or possibly an overhand and a clove with just the rope.

But anyhow something with just the rope would have been good as you might well have run out of slings.

David Coley wrote:2. if instead of tying an overhand as the powerpoint you tie and alpine butterfly the whole undoing-thing-after-loading goes away. This is slightly harder with gloves one, but no harder when without.

David, do you have any pictures of this tied with two strands? I've never seen an alpine butterfly powerpoint and it has peaked my interest.

James T wrote: David, do you have any pictures of this tied with two strands? I've never seen an alpine butterfly powerpoint and it has peaked my interest.

I'd like to see it as well

Well David is probably off on an adventure but it's raining here, so I took a stab at it:

Timely or beautiful - no. But that would just take practice I think. My main concern is that it's harder for me to visually check that the knot looks right. Maybe a better looking knot would help.

James T wrote:Well David is probably off on an adventure but it's raining here, so I took a stab at it: Timely or beautiful - no. But that would just take practice I think. My main concern is that it's harder for me to visually check that the knot looks right. Maybe a better looking knot would help.

Perfect! The knot is real easy to check, and so fast to tie. Welcome to the modern world. :)

By the way, the knot is tied around a finger and is quicker to form than an overhand.

Here are some more images of all things belay:

people.bath.ac.uk/dac33/hig…

Being that the alpine butterfly is my most used and favorite knot. I love the idea of the double butterfly at the master point, however, wouldn't a figure eight on a bite be a better knot? Simply because a butterfly's strands are meant to be pulled perpendicular to the loop as where the eight's are pulled parallel? Granted a master point really pulls at an angle, but it should be less than 45 degrees, meaning it is closer to parallel than perpendicular. Thus eight on a bite?

Thoughts?

David - thanks! And concerning the act of tying, I normally use the hand wrap to tie an alpine butterfly but the angle of the anchor strands seems to make the twist and flip method the natural choice, but again maybe I need practice.

Nick - I would guess the fact that you're loading the knot in a direction closer to parallel is what makes it easier to untie than a figure 8.

Yo Josh,

Nice video... very clear presentation.

I have 1 minor issue and 1 less-minor issue with the video.

Minor: The summary screen for the SWAMP lists a con as "no shelf" when the name is shelf w/o a masterpoint. Confusing.

Less minor: I'm on-board with the STRADS order emphasizing the priority. That's cool. But I'm against including "shock loads". Anchor extension (the term I'll use for the masterpoint's movement when a piece blows) doesn't magically multiply force like some people seem to believe. 6" of anchor extension is no different for the climber than a 6" fall.

Here's a thought experiment: Energy to be absorbed in a fall = mass * g (acceleration due to gravity) * height of fall.
Suppose a following climber is hanging on the rope when a piece in your anchor blows. Your sliding X extends 6". Energy is climber weight * g * 6".
Now suppose a following climber takes a top rope fall on a sliding X anchor with 2 good pieces with 6" of slack in the system. Energy is still climber weight * g * 6".

Now, is there any difference in where or how fast the energy is absorbed?
Answer: Nope. Still absorbed primarily in the climbing rope in both cases and at the same rate.

It's still mildly useful to think about extension in an anchor though. For instance, perhaps the extension would result in the masterpoint extending beyond a sharp rock edge and now the anchor material is being abraded.

Cheers,
Dan

Nick Turtura wrote:Being that the alpine butterfly is my most used and favorite knot. I love the idea of the double butterfly at the master point, however, wouldn't a figure eight on a bite be a better knot? Simply because a butterfly's strands are meant to be pulled perpendicular to the loop as where the eight's are pulled parallel? Granted a master point really pulls at an angle, but it should be less than 45 degrees, meaning it is closer to parallel than perpendicular. Thus eight on a bite? Thoughts?

I'm not sure I get the "meant to be pulled perpendicular" bit. A butterfly is good when pulled in this way (unlike an 8), but this doesn't mean it is bad or even not as good when pulled in any other way. The most common, weighted, use of a butterfly is in tying in a haul bag - then it is only pulled on one strand; ditto when using it for a fixed line.

An eight is not so good as it will be harder to untie. Probably uses more material too.

mtnmandan wrote: 6" of anchor extension is no different for the climber than a 6" fall.

Dan, spot on. Lots of people get this wrong.

However, just to point out that a system that extends if an arm fails can create bigger forces than a falling climber dropping the same distance.

If the belayer is pulled off the ledge, or dropped because it is an hanging belay, then this now gives the force of two falling climbers. As the belayer is on a shorter length of rope, the total force might be more than doubled. If the belayer is connected with a daisy then it might be much more than double.

Hopefully if the fall is only 6inches then all will be well. But without limiter knots and a 120 sling......

Cool video, the tip about keeping a biner in the knot is a good one.

David's point about 6" of extension in the anchor rigging deserves to be emphasized. In terms of anchor load, it could be vastly different than a 6" fall by a second if the leader is pulled off the stance. The reason is that the only material absorbing the belayer's fall is the belayer's tie-in. For instance, a belayer tied in with 1 foot of rope who falls 6" will be result in a factor 0.5 fall on the anchor with the weight of both climbers, plus any of the second's fall energy that hasn't been absorbed, and things will be a lot worse, as David says, if the belayer used relatively static slings rather than the rope to connect to the anchor.

I'm no doubt at the extreme end of the spectrum on this, but I don't care for any system that allows extension in belay anchors and only even consider sliding systems in my own rigging when there are two bomber bolts, in which case the advantage is ease of set-up rather than any hypothetical load distribution. The questionable ability of the various sliding anchors to equalize loads under a sudden dynamic impact (as opposed to slow pull testing) means that eschewing sliding systems gives up little, if anything, in terms of load distribution anyway.

The situation is different if a sliding-X or one of its competitors is used to equalize two protection points, in which case a relatively small amount of extension will have a negligible effect on the fall factor.

David Coley wrote: If the belayer is pulled off the ledge, or dropped because it is an hanging belay, then this now gives the force of two falling climbers. As the belayer is on a shorter length of rope, the total force might be more than doubled. If the belayer is connected with a daisy then it might be much more than double.

Quoted to emphasize the important bit for anyone following along.

Thanks for adding that David; you're absolutely right that that if the belayer is weighting the anchor and it extends, bad things will happen. The force on the anchor will be much greater, but it follows standard fall factor math as rgold pointed out. No Voodoo involved. I wouldn't want to be hanging off an anchor when it extends (especially on a PAS, ouch!).

All that said, I still disagree with Josh using the term in his video, especially without an explanation. For a video focused on alpine anchors, I think it's especially misleading. When was the last time you were on a hanging belay in the alpine? I can't remember myself.

Cheers,
Dan

It would be helpful, but probably too much to hope for, if the term "shock load" could be eliminated from climbing vocabulary. I don't think anyone knows what a shock load is and isn't---it has something to do with how fast the loading is. In climbing, "shock load" seems to mean a load imposed by a weight dropping some distance unimpeded. But this means every bit of pro is shock-loaded, and belay anchors are shock-loaded whenever fall impacts pull the belayer against the anchor.

mtnmandan wrote: When was the last time you were on a hanging belay in the alpine? I can't remember myself. Cheers, Dan

Climb harder routes and it will happen more often.

What a great vid, it's not that hard to follow and very much detailed, appreciate thanks

Hi Josh,

Really well made video! I like "STRADS" over SERENE and ERNEST and I think I'll start using it instead. Thanks!