I just finished a top rope management class to learn the basics of setting up my own anchors. We used 6mm cord to set the anchors, which seems fine to me, but after reading some of the posts on this board I'm starting to wonder...

I just bought 3 lengths of 50ft 6mm cord from REI; sales guy said this was fine for setting anchors. What do you guys think? OK for basic top rope anchor setting, or did I make a mistake?

Thanks!

try to find an old guy tapping a flask between moments of his partner's progress on toprope. you want the guy that drinks with his non-brake hand.

(holy crap that's long), you can just double or triple them up for a bomber anchor.

Jeezum Crow! 6 mm?

6mm accessory cord has a breaking strength of about 2,000 lbs. With a standard 10:1 safety factor, that means you shouldn't have more than a 200 lb working load. A short fall and you're putting maybe double that on the rope and doubling that force at the anchor.

Jeezum Crow! 6 mm?

What happened to 1" tubular webbing, or short lengths of 7/16" static line?

6mm accessory cord has a breaking strength of about 2,000 lbs. With a standard 10:1 safety factor, that means you shouldn't have more than a 200 lb working load. A short fall and you're putting maybe double that on the rope and doubling that force at the anchor.

Also, a 6mm cord has a lot fewer fibers to cut or wear through if abraded over an edge or a sharp-crystalled rock.

What's your life worth to you?

Thanks for the advice everyone. To elaborate, I'm using the cord to clove-hitch to natural objects (trees/rocks), equalize two strands, and then setup on the master point.

We learned using two strands for redundancy; I've seen some people suggest three redundancies. When I asked, I was told 3 redundancies for placed gear, two is fine for fixed top rope points.

As an aside, about the 50ft lengths, I figured it would make it easier setting up using natural objects that are a bit back from the cliff. Since 6mm is pretty thin/light, 3 lengths isn't much to carry.

Thanks again!

Jeezum Crow! 6 mm?

What happened to 1" tubular webbing, or short lengths of 7/16" static line?

6mm accessory cord has a breaking strength of about 2,000 lbs. With a standard 10:1 safety factor, that means you shouldn't have more than a 200 lb working load. A short fall and you're putting maybe double that on the rope and doubling that force at the anchor.

Also, a 6mm cord has a lot fewer fibers to cut or wear through if abraded over an edge or a sharp-crystalled rock.

What's your life worth to you?

Since when is a 10:1 safety factor "standard" for top ropes? That's rescue talk...If that were the "standard", nobody could climb on gear.

The three 6mm cords that he owns when used together...would provide far more abrasion resistance than a single strand made from a comparable amount of material, and certainly moreso than a 7/16" static line.

he just needs to rig with redundancy.

6mm cord...

-If it's set up as a "Quad" you're bomber.

-If it's set up as a 3-point cordelette, you're good.

-If it's set up as a 2-point cordelette or equalette you're pushing it a bit.

Jeezum Crow! 6 mm?

What happened to 1" tubular webbing, or short lengths of 7/16" static line?

6mm accessory cord has a breaking strength of about 2,000 lbs. With a standard 10:1 safety factor, that means you shouldn't have more than a 200 lb working load. A short fall and you're putting maybe double that on the rope and doubling that force at the anchor.

Also, a 6mm cord has a lot fewer fibers to cut or wear through if abraded over an edge or a sharp-crystalled rock.

What's your life worth to you?

Is 6mil strong enough? Doubled, set on redundant anchor points and free from sharp edges. Yes.
Would I use 6mil for my toprope set ups? Maybe, if I had 150 feet of it!

I use 6mm for top rope set ups pretty often. If you need to extend waaay back to trees or other features it is a great light weight low bulk set up.

With that said I prefer 1" tubular for normal set ups, mostly because of the abrasion issue that rescueman stated.

I just finished a top rope management class to learn the basics of setting up my own anchors. We used 6mm cord to set the anchors, which seems fine to me, but after reading some of the posts on this board I'm starting to wonder...

I just bought 3 lengths of 50ft 6mm cord from REI; sales guy said this was fine for setting anchors. What do you guys think? OK for basic top rope anchor setting, or did I make a mistake?

Thanks!

Thanks for all the useful comments. To clarify, I've attached a picture of what I'm doing.

Basically, I've got two clove hitches for the legs with two overhands to create independent redundancy for the master point. The 6mm cord is doubled.

Does this look safe to the experienced folks in the crowd? (I know the angle is wide in the picture... it's just for demonstration.)

[image]http://swatyy.webs.com/photo.jpg[/image]

Thanks!

The cross-sectional area (or amount of fiber) of an 11mm cord is almost 13.5 times that of a 6mm cord. It would require more than thirteeen 6mm cords to resist the same amount of abrasion or cutting as one 11mm.

I should add that there are two issues here: not only is 6mm much quicker to abrade or cut than a larger diameter cord, but it will also have a lot more stretch - even multiple strands - and, if it's extended over an edge, there will be a lot more sawing action.

In trad climbing, it's reasonable to use lightweight gear for anchoring and make up for it with redundancy. In top-roping, there's no excuse not to use heavier anchor cordage on stronger anchors with as little stretch as possible when extending over an edge.

You leave a trad belay anchor and move on. In top-roping, you might climb for hours on one anchor setup and it's going to see a lot more abuse.

when in doubt, go stout.

How exactly did you arrive at that figure?

By my calculation it's more like 3.4X as much cross-sectional area.

I don't like your non-standard usage. I think your knot system is inconvenient, and maybe risky.

I don't understand why you choose clove hitches at the top. If you are tying the two anchors to bolts or slings, it's easier and safer to tie overhands or eights, and clip the carabiners. If you are tying to a boulder, it's easier and safer to tie a bow-line.

You don't need two overhands for the power-point. The cross-over is not useful, and you must equalize the knots after you equalize the clove-hitches. So you should tie only one single knot there, and equalize the two anchor legs while tying.

I know the 6 mm cord is "strong enough" but why scrimp? Get some 7 mm and relieve my worry.

What kind of loads do you expect to see on your TR setups?

By my calculation it's more like 3.4X as much cross-sectional area.

Still, I don't like it.

Actually, that is very close to what the AMGA teaches (only they use static line, not 6mm cord)

If we're talking hanging anchors over edges, I wouldn't use cord at all, but big beefy static and pad the edges, where appropriate.

In a top-rope anchor, it's not the maximum loads that matter but the abrasion and cutting on the rock.

A rope with body weight hanging on it cuts like butter on a sharp edge. A sawing motion can quickly bring a small cord to failure.

Webbing cuts much faster than rope, but it's also much more static and will experience less extension and abrasion.

Basically, I've got two clove hitches for the legs

(pi * 6.5 *6.5) / (pi * 3 * 3) = 4.7

Seems like the issue then would not be the cord itself but rather the overall situation. Maybe recommending some carpet scarps to the OP would be in order since he already has the cord purchased and fondled with.

This is the standard now taught by the AMGA, so that the power point is redundant (although the chance of a power point that's hanging over an edge cutting is close to nil). They either teach 2 independent 8's or an overhand on a bight with the extra loop clipped to the PP.

I will notify the AMGA immediately.

Josh

Thanks for all the useful comments. To clarify, I've attached a picture of what I'm doing.

Basically, I've got two clove hitches for the legs with two overhands to create independent redundancy for the master point. The 6mm cord is doubled.

Does this look safe to the experienced folks in the crowd? (I know the angle is wide in the picture... it's just for demonstration.)

[image]http://swatyy.webs.com/photo.jpg[/image]

Thanks!

The AMGA operates in a foreign country

So what I'm going to do is get some 10.5mm static, and the setup will be a figure eight on one leg and clove hitch on the other for easy adjustment. I'm still going to keep the two overhand loops for master-point redundancy, as it makes me feel both happy and safer.

When you link two ropes together, like I described above, could you link a figure eight on one rope with clove hitch on the second second rope? Or would you put a 'biner in between to prevent rope friction/pinching?

I'm still going to keep the two overhand loops for master-point redundancy, as it makes me feel both happy and safer.

And feeling safer is not the same as being safer. That double-eye master point is likely to triple load your biners. It adds nothing to the security of the anchor, particularly with 11mm static line.

tri-axis loading is not a concern here at all.

OK Josh but you don't have to do that.

The AMGA operates in a foreign country, with its own unique geography, climate, and culture. The community they serve have their peculiar notions about how gear and methods are invented and evolve, and about the role of education and culture.

On the other hand, the ACMG (Association of Canadian Mountain Guides) is responsible for how Guides are trained, not how climbers handle their gear.

I disagree.


The two double eyes have vectors about 60° apart and the one on the left is exerting its force very close to the gate hinge rather than the spine, which is what the carabiner is designed for.

If the carabiner should flip around with the wide end toward the anchor eyes, the triple-loading would be increased.

Give me a break, Pedro. We're talking about an extra figure 8. Do you have that little faith in humanity that you think that will complicate things too much.

Like I said in my original post, the chances of a PP hanging over the edge cutting is very slim, but adding that extra figure 8 is simple and does not complicate things in the least.

Remember, the AMGA is all about making things as safe as possible to eliminate as much risk as they can. It's all about institutional climbing. It makes sense for them to have a standard of care. In our recreational climbing, we can make our own decision, cut corners, do whatever we want to do and still know that we can keep ourselves relatively safe.

Josh

Rescueman, static available only in 11 and 13? Huh? I myself have hung off static ropes from 8 to 13 with cores and sheaths of varying construction. I know you've had training in rescue and probably know a lot I don't, but dude, step outside your box once an a while.

I disagree.

[image]http://swatyy.webs.com/photo.jpg[/image]

The two double eyes have vectors about 60° apart and the one on the left is exerting its force very close to the gate hinge rather than the spine, which is what the carabiner is designed for.

If the carabiner should flip around with the wide end toward the anchor eyes, the triple-loading would be increased.

Yeah, and a top-rope situation would still never generate enough force to make this even remotely a concern.

I think you missed my point as well, but it seems to me that we are arguing about something that neither one of thinks is a big deal.

Josh

Using equipment outside the parameters of the manufacturer's design, and specifically in violation of written warnings that accompany such hardware, should always be a reason for concern.

Biners are stamped with a minor axis strength number, and this particular example would not exceed the parameters of that design.

But I totally agree with you in that I wouldn't rig it this way, because its just uselessly silly.

Biners are stamped with a minor axis strength number, and this particular example would not exceed the parameters of that design.

Actually it's you who live in a foreign country and have a funny accent. The earth revolves around the US of A, don't ya know?

an unsupervised anchor "should" have 2 opposed biners

... the setup wont kill you on TR

Tri-axial loading is very different from minor axis loading (which is typically about 7 kN or a third of major axis strength).

3-way loading of a 'biner is the inverse equivalent of the American Death Triangle. For this reason, no 'biner is stamped with a rated strength for 3-way loading, which is specifically forbidden (and not by lawyers, as surfstar cynically and stupidly asserts, but by design engineers).

The AMGA operates in a country that not metric.
They wouldn't know what 6mm looks like.

The earth revolves around US ...... Aye.

I disagree. A single locking carabiner is not ok in my book for a TR anchor. An unattended locker can come unlocked and you'd be left with a single unlocked biner. I have personally seen unattended lockers come unlocked, most commonly in hauling/jugging situations, but also on a TR master-point. I'll still take two non-locking biners or a single locker with a non-locking biner.

And the forces in TR still would not be enough to cause any concern whatsoever.

I disagree. A single locking carabiner is not ok in my book for a TR anchor. An unattended locker can come unlocked and you'd be left with a single unlocked biner. I have personally seen unattended lockers come unlocked, most commonly in hauling/jugging situations, but also on a TR master-point. I'll still take two non-locking biners or a single locker with a non-locking biner.

You forgot to add "to me" at the end of that sentence.

But that's not the point of this discussion. This thread is about "top rope management" or professional/institutional rigging, not what is the minimum system that any one of us is comfortable with for our own use.

[
So it would be hard to get much outside of my "box" when it's so all-encompassing already.

[
I'm glad you put "should" in quotes, since that's pure bullshit (and pretty funny coming from a guy who thinks we "shouldn't" be giving other people advice).

We used opposite and opposed biners before lockers were available to prevent accidental gate opening. The reason we have locking gates is also to prevent accidental gate opening, so there's no need to carry on an old habit with new gear that serves the same purpose.

Also, as I have already pointed out, placing locking gates in opposition often puts one gate against the rock which can damage it. If you're using doubled 'biners for a wider rope bend radius in top-roping, then the safest way to use lockers is with both spines against the rock and the gates out in space.

No, not "to me", to anyone who is cabable of doing math.

guess rock climbing anchors 2nd edition is less relevant than the advice i get on the rc intrawebs ...

Except you haven't offered any math - merely your subjective determination of what is acceptable.

Here's some math:

According the the British Mountaineering Council,typical dynamic belay loads are 2 to 2.5 kN, and the load at the change of direction can be as high as 7.5kN, with a potential force of up to 12 kN with a non-dymanic belay such as a GriGri.

Using the typical minor axis strength of 7 kN, it seems that a decent top rope fall can potentially break a single carabiner, perhaps more so with 3-way loading.

Nothing you've said makes a scientific or "by the math" case for violating the design standards of climbing equipment. That's a purely subjective judgement about how far out on a limb you're comfortable walking.

But don't sell your own recklessness as fact or an acceptable standard for someone who's trying to learn to be safe.

since when do you provide "dynamic" belays on top rope ???

methinks the BMC is talking about LEAD belaying

If there is any slippage of rope through the belayer's hand or through the device, or the belayer's body moves with the force, then the belay is dynamic. A static belay involves no slippage or movement.


Here's some more "fuzzy" math:

According to a test report by Stephen Attaway, PhD and J. Marc Beverly, "the maximum credible event for belay loads for new ropes…would be 9 kN for devices limited to fall factors of less than one (single pitch or top rope)."

That's at the belay device. At the top rope change of direction, the force would be approximately 1.67 times that.

http://www.caves.org/...ng_Em_High_Final.pdf

there is utterly no way you are seeing 9 kn at the belay device in a real world top rope situation with dynamic rope that i know off ...

btw ... i sure dont provide a "dynamic" belay when TRing ... as the word is commonly used

Except you haven't offered any math - merely your subjective determination of what is acceptable.

Here's some math:

According the the British Mountaineering Council, typical dynamic belay loads are 2 to 2.5 kN, and the load at the change of direction can be as high as 7.5kN, with a potential force of up to 12 kN with a non-dymanic belay such as a GriGri.

Using the typical minor axis strength of 7 kN, it seems that a decent top rope fall can potentially break a single carabiner, perhaps more so with 3-way loading.

Nothing you've said makes a scientific or "by the math" case for violating the design standards of climbing equipment. That's a purely subjective judgement about how far out on a limb you're comfortable walking.

But don't sell your own recklessness as fact or an acceptable standard for someone who's trying to learn to be safe.

Well, there's your answer: what you know is "off".


Unless the belay device is tied to a tree and there's a stopper knot behind it, it's a dynamic belay.

"Common usage" is commonly wrong.

Well, there's your answer: what you know is "off".

Wait, are you seriously saying that a TR fall can generate 9kn at the belay? What in the wide wide world of sports kind of crazy-ass things are you doing on top rope???

That was the sound of your entire argument evaporating

I'm not "seriously saying" it, I'm quoting from a study by one of the world's leading rope system physicists.

That was the "maximum credible event", while typical belay device forces would put up to 7.5kN at the master point carabiner.

I offered some credible numbers from a reliable source. You claim to base your argument on the math but have offered nothing to substantiate your judgement.

And the UIAA standard for harnesses is 15 kN, while the standard for anchors is 20 kN (not the <7 that you're advocating).

You can continue arguing with BearBreeder, since that seems to be his only joy in life. I'm done wasting my time on this one.

there is no REAL TEST data on TR falls from that source

you area (sic) aware that one of the most common petzl (sic) belay biners has a 7kn xloaded (sic) rating... but then petzl (sic) doesnt (sic) know what they are doing i (sic) guess

Data for top rope and gym climbing:
[image]http://tinyurl.com/3fyr7dr[/image]


Comes with every Petzl carabiner:
[image]http://tinyurl.com/425f8rx[/image]

Go back to your den. You're nothing but a troll.

I'm not "seriously saying" it, I'm quoting from a study by one of the world's leading rope system physicists.

That was the "maximum credible event", while typical belay device forces would put up to 7.5kN at the master point carabiner.

I offered some credible numbers from a reliable source. You claim to base your argument on the math but have offered nothing to substantiate your judgement.

Based on the above comparison, the maximum credible event (MCE) for belay loads with new ropes would be 12 kN for devices designed for all falls and 9 kN for devices limited to fall factors less than 1.0 (single pitch or top rope climbing).

And the UIAA standard for harnesses is 15 kN, while the standard for anchors is 20 kN (not the <7 that you're advocating).

In case you missed it, my argument is that it's not OK to tell people on a beginner's forum that a carabiner can be tri-axially loaded when every carabiner manufacturer says otherwise. That it can survive as long as loads are minimal and no unexpected event occurs is irrelevant.

As a former municipal emergency manager and as a 30-year emergency responder, the motto we live by is plan for the worst and hope for the best.

also if you had half a brain youd realize that a "factor 1" on TR means yr hitting the ground anyways ... ie you top belayed and took in no slack ... broken biners i suspect will be a non issue in this case

...
I never recommended a single 'biner for a TR master point, since that's too tight a bend radius for the rope. I recommended two locking 'biners both oriented with the spines toward the rock.

If the gate is not rubbing on the rock and a screw-gate is facing downward (so it can't "screw up"), then it should not unlock itself. In years of institutional top-roping, I've never seen a gate unlock itself in that configuration.

But it's true that no equipment or system can ever be made fool-proof, since there's always a fool who can screw it up.