DMM Techincal Video on Slings at Anchors
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- เผยแพร่เมื่อ 3 ต.ค. 2013
- Ben Bransby from DMM tests a variety of slings at anchors.
This informative video is from the web link below.
dmmclimbing.com/knowledge/slin...
DMM climbing equipment is available at www.staffordoutdoor.com
In a previous video we compared the impact forces generated using nylon and Dyneema® slings with a dynamic load. It clearly highlighted the importance of ensuring there is no slack in a system using slings. As an example, a 85 kg mass free-falling just 60 cm on to a 60 cm Dyneema sling (fall-factor 1), with an overhand knot in it, generated enough force to break the sling.
Extending this previous theme we've looked at using nylon and Dyneema® slings in four different belay set-ups:
Equalised with an overhand knot at the balance point.
What is commonly known as 'self-equalising' or sliding X.
Clove hitch at anchor and clip-in points.
Overhand at anchor and clip-in points.
In addition, we simulated a marginal placement ripping by using 2 mm cord at one of the anchor points. In this scenario the 'self-equalising' arrangement placed the greatest shock-loading on the remaining anchor point and isn't advised with natural or hand-placed anchors for that reason.
Carrying out a final test replacing the slings with 8.2 mm rope for a worst-case scenario with a fall-factor two clearly showed -- as expected -- that utilising the shock absorbing properties of your rope dramatically lessens the impact forces on the anchors and is the best option. This could be by either clipping the anchors directly with the rope or into a central point in the system. For a full explanation and examination of the results watch the video. - กีฬา
this is a video that every climber should see...
Great video, thanks a lot!! A climbing instructor in France, after seeing me use a sling to tie into belays, told me to buy a piece of climbing rope and use that because of the possibility of a factor 2 fall when faffing about at a belay.
I always wondered how correct he was and now after seeing your video am really happy that I have been using this ever since. thanks!!!
I been using the Clove hitch setup for 22 years just for this reason. That and I was required to learn to make it with one hand.
Great video, thanks for the research and the info!
I'd love to see more of these, for example comparing the sliding 'magic x' (used in this video), to a magic x with a pair of limiter knots, and to using a figure-8 to create a redundant master point.
Wow. Def getting a nylon PAS vs dyneema although I would never climb above my anchor.
Great vid. You can still easily make an easily escapable belay from rope, but it's good to know the limitations of both to have more info when making decisions about which to use. After all, both are safe enough for the situations we find ourselves climbing in, just some give us different margins for error in particular instances. Ben Bransby too!
Nice video! Dyneema is good for individual protections because it's lighter and less bulky. But I'm a nylon fan for the anchors. Also nice to confirm the danger of the sliding X. Just miss a comparative of the loads for these same configurations but using nylon cords instead of slings. Cheers!
Very informative! Especially about knot absorbing the energy. But I wish I heard about the knots weakening the system as well.
Very educational! Great contribution!
Really informative video, nicely done!
Very informative film. Thank you.
Super educational!
very interesting. I was surprised with some of the results
Great video reminds me why I got into engineering. I miss this kind of stuff.
Thanks for the comment. Yes it is a great video!
Great job👍 thank you
Anyone else notice how much force DMM's test rack absorbs? When one point fails, the rack is immediately impacted and swings quite a bit, absorbing a lot of the shock that the other components would've taken instead...Seems like in a real-world setting there would be more failures in their test setups?
@Tammy Gueterman , I agree. I would rather the anchor points be rigidly attached like a actual rock.
@@KillroyX99 The rig is attached to a force meter so that they can obtain all the data that he was discussing. If you attached the anchor points to a static point like a climbing wall you wouldn't be able to measure the force introduced to the system.
@@eagle191, thanks for your comment. The test rig could be riddgidly attached and the force meter could be added at any point that they want to measure. This would be just fine tuning the "Design Of Experiment". As mentioned before, the change that would add the most realism is a falling dummy that acts like a falling climber (rigid mass vs compliant body)
Ha ha ha we once used Carabiners to try & tow a 7.5 ton truck from a 9 ton truck. The DMM was the only one that held enough to get the 7.5 toner moving. It broke after about 100 yards. Thats a huge amount of weight though.
this video made me sweat, not many things are more worrying than seeing your anchor start falling apart
Nice work, congratulations. Could I have a kind of report including all these important information about the tests for a better understanding?
Thanks.
The test I would really like to see in addition to the others in this fine video are the forced involved when there is a short amount of rope (ie 1 foot) tied into the anchoring slings then drop tested. This would produce ie a 5 foot fall with one foot of rope out. I think we might be very surprised at the forces generated?
For me the most interesting point is the effect of knots and slippage into the system. Everyone mentions that knots weaken slings, but these tests emphasize that slippage of the knot adds a dynamic element to the system that lowers the peak force.
Not mentioned in the video is the effects of these forces on the human body... I am not sure what happens to a climber who absorbs >12kN of force from a fall. I imagine serious injury....
So your right that he mentioned the knots add a dynamic element, but they also reduce the total strength by half, so the knotted ones ended up breaking while the unknotted one did not break.
The biggest weakening in these examples is when they clove hitced to the anchor points with a sling. Then they got only one strand of the sling loaded and that will break it a lot easier.
Very interesting video, thank you for posting. I think the real world takeaways for this are:
1) Avoid using dyneema runners in an anchor system; use nylon or the rope instead.
2) Avoid using the sliding X unless you use limiter knots to minimize extension.
3) Don't be a f**king idiot and climb above your anchor when only attached to it with a dyneema runner!
4) Shout out to Black Diamond, DMM, Metolius, Petzl: Why is it that you tech wizards cannot manufacture a runner with more stretchy, dynamic qualities, when doing so appears to clearly minimize impact forces on rock protection? I'm talking about something like a really strong bungee cord is the core of a nylon runner. Any company that can figure this out could revolutionize climbing.
yep would be great if they actually brought out something like that
That's called a climbing rope... stretchy, dynamic and reduces the impact force on the climber and the anchor
@@duxforddude yeah, but you can't go tying your rope into the pro you're placing as you move up the route.
@@eagle191 It's just about the anchors and also only the persons directly connected to the anchor. With the pieces along the route (or your seconding climber) there's always the rope in the system, softening a fall.
@@ketzaston true
Great video and very well-made. I was wondering if the overhand knot method is common practice. The way I have seen it done before is an overhand on a bight(also making sure to not over-tighten the knot as to allow it to absorb some impact) tied at the master point, instead of just an overhand directly on the sling. Is there an advantage to either one of these methods? Does one of them weaken the sling more than the other? I appreciate your response.
One advantage of the simple overhand (a SWAMP, shelf without a master point) is that the knot is not cinched up very much under load, making it easier to untie, and it uses up very little of the length of the sling.
that's the last time I go sketching above my partner in crampons, linked to a crap belay by Dyneema, to try to find a decent anchor. what an ironic death!
I am curious, I often use a 120mm sling with a clove hitch around a master beener (very similar to the overhand knot example). I was surprised to see your clove hitch example using only one strand of sling down to the master point.
8
I've used the primary rope as much as feasible, with clove hitches or my all-time favorite, Butterfly knots, at anchors for over fifty years, and I find the modern sling-heavy systems to be "guide friendly," quicker to set up especially at fixed anchors, easier to swap the clients and then continue, the guide always leading. But, the extra complications, significantly weaker shock accommodation, and such I find troubling. The beauty of clove and Butterflys are they are rapidly adjustable while still tied in, and the BK is as strong across the loop as it is into the loop; it allows a lot of flexibility in opposing or combining directional elements, equalizing without extra slack added in a partial failure, and overall a far cleaner less cluttered look. On trad routes, as long as you have adequate rope per pitch, sling systems are far less versatile than good old lead rope tie-ins.
thanks for your comment, i realise it was a while ago but i have often wondered about using alpine butterflys in belay as it seems very elegant, do you have any suggestions on how to do this or reading material?
I am left with way more questions than answers
Can you show more detail (perhaps on your website) of where the failures happened on the slings?
For instance, static testing has shown that knots in rope reduce strength ~50%, yet in these test it looks like the failure was not always right at the knot. If the failure happens at the knot and the not comes undone, there is not redundancy. YIKES!
what if the dynamic rope is attached to the sling anchor?
Sile H adding a dynamic component to the system is going to reduce the forces substantially every time.
thank you very much!
It makes me wonder if a smaller, lighter nylon sling is better to climb with than a Dyneema sling even if the static strength is stronger.
We climbers don't put large static forces on slings, we put large dynamic forces. Dynamic force matters!
If you're putting large dynamic forces on your slings you're doing something wrong.
DMM make great gear (and I've got loads of their stuff) however, they are hopeless at answering customer inquiries, especially ones that concern cracks in pulley axels.
Hello, can you provide the loadings for the 3x clove hitch set up without the 2mm weak point please, thanks
I believe he talks about this around the 8:00 mark, and mentions the force was "just above 5kn".
And yet with all the knowledge and instructional material out there. Here we are in 2021 and THE widely accepted and prefered anchor buding material for the common outdoor climber is.......... 240cm Dynema sling.
Dyneema slings are perfectly safe to use as an anchor IF you have a dynamic rope in the system. It is almost common knowledge now that you cannot use a sling by itself as it's static and not good at taking shockloaded impacts.
@@sanchoviesfan6971 Go read the intructions that come with ANY Dyneema sling "DYNEEMA SHOULD NOT BE KNOTTED".
Same consensus from every reputable climbing equipment manufacturer.
Case and point!
@@Max-ik9qb The warning exists to tell you not to tie a dyneema sling back together if it was snapped or cut as it risks slipping. Using overhands or a figure 8 to make a master point in a non compromised dyneema is not an issue. A knotted dyneema sling will still be stronger than the 3 nut traditional anchors they are attached to.
@@sanchoviesfan6971 you are wrong! go troll mountain project.
@@Max-ik9qb I almost exclusively top rope from 11mm nylon slings or 8mm dyneema slings tied exactly like I said above. The exception is using cordalette or static rope when I need to extend my anchor beyond a lip. What material do you build your anchors from?
Your neighbors downstairs must love you.
Do the forces change because the bolted anchor actual moves?
The movement of the anchor requires energy, so there must be some (probably small) reduction in impact forces...
Was that rope static or dynamic?
And what size was it?
+Jimmy Carroll Its a dynamic rope. You can see it stretching during the fall, which suggests that it is dynamic. It would also be representative of a rope used for this sort of scenario hence why its moved. Looks like a 10.5 or 11mm single rope.
+happynotnormal He says at the start its an 8.2 1/2 rope
Everyone should know that static ropes still stretch a significant amount, but stretch very roughly 1/2 as much as a "dynamic rope"
What I don't understand is these slings are typically rated to 22kN and in this video they are failing at 4 and 5kN, what gives?
Knots, while they can reduce the force exerted on the rope/sling, can also weaken the rope/sling.
I think the failures at 4kN were the 2mm gear cord links....
Its Prof Brian Cox twin brother !
Good thing I'm not a solid chunk of metal using a static rope. A human wearing a harness, falling on a dynamic rope helps cushion shock, our bodies are bags of liquid & a harness & rope has a lot of give, HowNOTtoHIGHLINE has a number of videos on why shock loading is generally a myth & with dynamic rope + a harness + human... a human will never go over 5kn of force on even the hardest fall. Interesting test though.
You describe a very different situation that is not tested here. Whats tested here is a situation at a belay anchor, where you often have no dynamic rope in the system. Also in these situations factor 2 falls on static lanyards/slings are possible. And in these situations shockloading is not a myth, bc there is no dynamic rope in the system that absorbes the shock.
You could not be more mistaken; lost two friends around twenty years ago, when their anchors were ripped, probably from a short but FF2 past the belayer; they went about 800 feet to the base of Middle Cathedral in Yosemite. Impact forces of lead ropes are designed to stretch below the threshold of serious injury to a climber. Petzl's site shows real world measurements in belayed fall scenarios, where a belayer feels 2kN, the leader feels 4kN, and the top piece feels 6kN impact force. A long factor 2 fall requires many feet of stretch in a dynamic rope to spread the force over time, and the notion that a flexing bag of fluid can absorb such energy over a foot or two is absurd. The far more dangerous, yet intuitively underappreciated scenario is dropping a few feet, but onto static sling or chainlink anchors, where a climber commonly has little or no dynamic material in the connection. Clipping in to a one foot chain with 6" of lead rope, stepping above to rig something, and dropping down makes a fall of three feet, onto just 1 foot of dynamic material, and effective FF of 3. Replace the rope with a static sling, and you have an incalculable fall factor, with only the harness and body to absorb the impact. And there is not "a lot of give" in that situation.
So it is better if one of your anchor points fail :D
...
i weigh 95 kilos !!!! so none of this shit is safe lol
Wayne Diffin . So you have to loose weight my fat kid
A kilonewton is a dynamic force. Kilogram is static. They would easily hold 15 or 20 of you. However, If you took a fall above the anchor point and the sling had to absorb all the energy built up during acceleration, they might not make it.
Dyneema failed and Nylon didn't -- I would rather have Nylon
Dyneema's impact load was significantly more than Nylon -- I would rather have Nylon
Dyneema is less bulky than Nylon-- I would rather have Dyneema in this case
Wait a second, impact loads are much less in Nylon, why not decrease the bulk of Nylon?
Nylon is less expensive too, so it can be replaced more often if we are worried about abrasion and UV exposure.
And as a mountaineer I always use dyneema over nylon (that stuff stays in my sport climbing bag). Nylon will saturate and freeze at which point it loses significant strength, whereas dyneema sticks it out like a champ.
Not the point of the video I know. But close your eyes and climbing is being talked about by Proff Brian cox!
Up next let's watch a bicycle helmet get impacted going 300 miles per hour.
Technical! Not Techincal ;D
the video doesnt match the table!
Seems misleading. This test is taking the belayer and the dynamic rope out of the video. Outside of fall forces if built your anchor out of the climbing rope as suggest it would be difficult to escape the belay if you needed to rescue your climbing partner.
***** I think Greg G has summed it up perfectly. The tests are that just tests and it is never going to emulate the real world. In test the variables are controlled, however we believe it is a great effort at informing us climbers.
You can always cut it.
He's really only talking about messing around above an anchor while still attached to it, which you shouldn't do anyway
Miss informing* Again the test has nothing to do with real life situation. The static gear is not meant to be fallen on directly and that type of fall would have never happened in a real life situation.
This video refers to the forces at a belay station. Using your rope to tie into the anchor with clove hitches has been a long standing technique used by experienced multi-pitch climbers. Slings and cordelettes are used primarily for natural pro that needs equalization because of different heights in the anchor system. As for anchors placed on lead they are usually but not always single point, with no need of equalization and the forces on each anchor are considerably less because the climbers rope is dynamically applied in a fall as it slides through the quickdraw vs statically in a belay.
Windows Vista... Makes me vomit.
I hate this video, so many climbers see it and think "OMG, dyneema is death."
A steel weight is a poor model for the human body, especially at the lower end of the energy scale with small falls on static gear: skin sags and stretches, limbs/muscles extend, blood sloshes to the extremeties, etc; which all absorb quite a bit of energy and reduce peak loads. I understand that rigid steel weights are a cheap/practical way to get repeatable results, and the results extrapolate well to long falls on a rope (where the energy absorption of the body becomes a smaller component), but it gives unrealistic data for climbing anchor scenarios.
You are right and the video addressed the worst-case nature of the test.
maybe they should repeat the test with a pic carcass in a harness in place of the weight.... :)
Impossible combination for a foreigner, british dialect & this kind of mumbling voice... Does he have pebbles in his mouth?