How to Break Nylon and Dyneema Slings

[@cambronsherman5904]

You would think that the force would be somewhat diminished by the force absorbed by the elasticity of the human body. Is this hypothesis correct? It seems that no force is absorbed by the 80kg mass, but some significant amount would be absorbed by the body. What are your thoughts?

[@vovkaclimber2511]

I agree. Load on the slink is getting low a lot on dynamic rope stretching, in case of tension on climbing harness or on belayer small upper yank. This video just demonstrates how sling hardness is getting low in such cases.

[@gumwap1]

Cambron Sherman Your intuition is correct. The force absorbed by your body can reduce forces by up to 50% for a factor 1 fall on a 120 sling. I the case of a lead fall, a soft catch by your belayer and the stretch of the rope combined can reduced forces by up to about 70%. These tests are conducted with worst-case-scenario setups that don’t account for all the variables mentioned above. When you factor in those variables, you get an idea of the margin of safety you’re dealing with in the real world.

[@DeShark88]

I've seen way too many people watch this video and decide that "dyneema isn't safe with a knot tied in it". The sling failed at 11kN, way more than any normal force you'd generate in a system with a significant amount of rope in it (indeed that's the whole point of the "max impact force" test done on UIAA ropes). The reason the dyneema failed and the nylon didn't is that dyneema is even less dynamic than nylon, it's not because dyneema is somehow weaker. I've heard people decide never to buy dyneema and only use nylon as a result of this video. That's not the point at all. The point is: don't take fall factor 2 falls into static slings. Dyneema is perfectly safe, when used correctly. It's lightweight, it's more chemical resistant, etc etc. But it's not suitable for taking falls on directly.

[@derdude261]

what are you talking about? this is not even a high fall in the test. when climbing alpine as a climber with 80kg this can happen any time. dyneema is bullshit for multipitch. but the mountaineers always want freaking lightweight stuff, not thinking about the dangerous disadvantages!

[@DeShark88]

@@derdude261 impact force isn't determined by fall distance. It's determined by fall distance divided by the amount of time the fall is caught over. Slower, more dynamic catch = lower peak impact force. That's why we talk about fall factor, not fall distance, and why it's important to have stretchy kernmantle ropes. I don't know how you can make the claim that dyneema is bullshit for miltipitch. What's your background in terms of experience?

[@DeShark88]

@The Dali Llama using dyneema as a tether is ok as long as you understand its limitations. Don't climb above your anchor point and it's fine. It's not great with abrasion so may be a bad idea to use in a top rope anchor if there's any chance of it being abraded across an edge (static rope is better but will still need some sort of protection from sharp edges). But Dyneema is fantastic for slings for extending protection when leading. Its strength to weight ratio really makes it worth the extra cost compared to nylon. It generally packs down more compact on a harness which means it gets in the way less and you can fit more slings on a gear loop. There's also no problem using dyneema to extend your gear placements up to (but not over) an edge if you're top roping. And it's also great as a prussic loop if needed. So it definitely has its uses, but like any safety equipment must be fully understood before use.

[@DeShark88]

@The Dali Llama yes, Via Ferrata is deceptive. This video is aimed at increasing understanding of dyneema for this reason, to avoid people misusing it. And it does that job well I think. However, it does present an absolute worst case. A fall factor two with zero give is unlikely (few people are made of solid concrete after all!) In all likelihood, your fall on Via Ferrata may have been caught fine, but there are better things to use for the job. Even an offcut of some dynamic climbing rope would be better. I think dyneema is a bad name for it - it's anything but dynamic! Staticeema maybe? I should also add that the instruction booklet that comes with the slings does caution against its use as a tether. If people don't read the instruction booklets of safety equipment then I don't have a huge amount of sympathy frankly.

[@z1522]

You're 'dead wrong.' The sling failed, because static slings have very little stretch, and the FF1 peak actually exceeded the rated breaking strength of the Dyneema. That impact force would cause serious internal injuries to a climber, if it did not rupture the harness tie point. Nylon absorbed half the force, closer to a tolerable impact for a body, but then even a 60 cm static sling in FF1 impacted nearly 17kN, and then broke with a knot tied - these combinations are routinely incorporated into all sorts of modern anchor systems, and the moment the dynamic rope is taken out of the equation, inadvertent shock loading is a real risk. THAT is the point. You're correct in saying Dyneema can be used safely, but their point is that most people cannot differentiate one from the other.

[@103troy]

Very interesting

[@benfox4784]

I'm willing to carry nylon. More my style. More abrasion resistant, a bit beefier, stretches a bit more for fat guys. I'm not that fast anyways. If being the fastest climber was my priority, I'd just skip those beers and stop eating wings after my sick 5.9 multipitch. But I like my wings and beer, nylon is cheap, and I'm not light anyways.

[@jozefcatlos1957]

11mm VS 16mm ??? Why you don't compare 11mm VS 11mm .?

[@landminze]

I believe it's because the 11mm Dyneema and 16mm nylon are rated for the same KN amount.

[@bamabiker]

i love how all the comments are exactly what he says in the video......apparently he used to many big words and it confused ppl

[@jokkes1595]

I think it's only Americans that are confused - as usual.

[@EdFudge]

I would argue the impact force on the nylon sling (compared to dyneema) is not from the overhand knot but it is reduced due to nylon's elongation properties. Dyneema (Spectra, UHMWP, etc.) has very poor elongation properties, thus underperforming. Adding an overhand knot to any rope will almost always reduce it's strength by 60-65%. Maybe they left the knot loose? I am sure the experts at DMM know what they're talking about but that claim seemed strange. Maybe I missed something?

[@Ghostman719]

He was comparing the measured forces on the untied nylon strap to the nylon strap for that section. So dynamic ability of the material would be the same. Likely a loose knot, yes.

[@bertsanford4987]

B

[@thomasbrooklyn1820]

Doesn't a 60cm sling fall 30 cm? Vovka seemed to be saying it falls 60cm.

[@ZapeZeam]

The fall in its entire lenght is 60 cm even though half of the sling is already hanging

[@jokkes1595]

Lol