Rope bridge question

Maybe I am out of the loop but can someone send me a link with some information on a reported dyneema failure? I have heard of the ropebridge failures, but i was not of the understanding that they were dyneema. Maybe we should start a dyneema thread and invite some engineering folks to comment and share their expertise.

I find it incredibly hard to believe that multiple multinational companies, with manufacturing presence in at least 3 continents and close to ten countries (including the USA) produce products using dyneema/spectra for a wide range of recreational and industrial applications where human life, protection of property and other serious issues are concerned if it is as frail as some people would have us believe.

Dyneema/spectra is strong and safe period.
 
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I have seen that. It doesnt apply to what we do in the least. Thats a discusion of fall factors in relation to anchoring directly through dyneema to a completely static point and then using it in a matter that it was never intended.

The systems we use involve rope. Rope has stretch. Stretch dissipates force. unless you clip your dyneema runners or rope bridge directly to the tree and then go above them and then hurl yourself straight down into open space you wont have to much of a problem.

from the friction saver thread... and heading to the new dyneema thread i have a feeling

bonner1040 said:
Sure, but that is talking about factor 2 falls on a completely static system. Fall factor is determined by dividing the distance of a fall into the amount of rope in a system. ie you tie into a branch pay out 20' of rope and let go, falling 20' on 20' of rope = factor 1 fall.

It is nearly impossible to generate a factor 2 fall in a friction saver setup. A factor two fall implies a distance of fall = to twice the amount of rope/cord in the system. i.e a 4' fall on a two foot sling. unless you climbed above your friction saver connected into it, with no rope, and then fell you cant do it and even then the amount of cord wrapped around the tree makes a factor 2 impossible.

Even if it was possible i would bet taking a similar factor 2 fall with an 80kg weight on 1/2 steel cable would snap it too, and it will most likely snap any arb rope or light to med rope you can name. further, if you use weights that fall close to SWF, say 1/2 SWF and drop them factor 2, whether its 2' on 1' or 20' on 10' it will break even the burliest of ropes/rigging materials such as larger bull ropes etc.

This is something that is discussed at length in rock forums / research as factor 2 falls are more possible in those situations, specifically multi pitch.

In any case a DDRT system always has far more rope out than the distance of possible falls as an inherent necessity of the system. I.E even if free climbing above the anchor/TIP 20' and you fall 40' there is still 40 feet of rope out guaranteed to allow you to travel the 20' above.

the point of the video was basically to tell you not to use dyneema and other low stretch items as anchor slings as people do when cleaning rock routes and setting for rappel and then climb above them because if you climb 2 feet up on a 2 foot sling and fall 4 feet, SNAP your dead..
Click to expand...
 
Treemagineers are never going to officially approve another rope for replacement bridges on the TM, and why should they? Every rope would have to be tested and CE certified for that purpose in order for them to be able to officially approve it. As it is they get to sell plenty of original spec replacement bridges, which aren't that expensive, so everyone wins.

That being said, there is clearly nothing special about that particular green doublebraid, and replacing it with a similar spec material is no big deal imo.
 
pete mctree said:
http://dmmclimbing.com/knowledge/how-to-break-nylon-dyneema-slings/

Here ya go. Opens your eyes for sure
Click to expand...



Nylon is more absorbent of a load, dyneema is more abrasion resistant......

while the testing in the vid is interesting, a harness bridge will not see those same loads applied. I stand by my orig thoughts. A triple layered and stitched dyneema sling (used as a bridge) is plenty strong, alot stronger than a piece of rope. Which btw, is not designed for that use at all. The warpspeed bridge IS designed for that use and is rock solid.
 
I am going to call DMM and ask them for further clarification, i will also contack Kolin Powick of Black Diamond who does all sorts of testing on similar matters and ak him for his opinion.
 
tophopper said:
Nylon is more absorbent of a load, dyneema is more abrasion resistant......

.
Click to expand...

I'm probably wrong since this is not my field of expertice, but I thought one of the issues about Dyneema was that it was NOT abrasion resistant.

Or is that just when we compare it to steel, in hard rigging contexts?
 
tophopper said:
Nylon is more absorbent of a load, dyneema is more abrasion resistant......

while the testing in the vid is interesting, a harness bridge will not see those same loads applied. I stand by my orig thoughts. A triple layered and stitched dyneema sling (used as a bridge) is plenty strong, alot stronger than a piece of rope. Which btw, is not designed for that use at all. The warpspeed bridge IS designed for that use and is rock solid.
Click to expand...

I don't understand you statement. None of the 3 were designed for bridges on saddles. They were originally made for other reasons. The major bridge failures have involved Vectran and Technora fibers. The SK-75 whcih is the Dyneema in Warpspeed is not as self abrasive as the former 2. Also I believe the larger diameter of the core in Warpspeed is favorable for retaining strength.
 
wiley_p said:
I don't understand you statement. None of the 3 were designed for bridges on saddles. They were originally made for other reasons. The major bridge failures have involved Vectran and Technora fibers. The SK-75 whcih is the Dyneema in Warpspeed is not as self abrasive as the former 2. Also I believe the larger diameter of the core in Warpspeed is favorable for retaining strength.
Click to expand...


As pictured in post #9.......a dyneema(spectra webbing bridge) made designed for a harness bridge. A flat webbing sling triple layered and stitched, designed to be used a harness bridge. FYI, there is no core, its flat webbing, stitched together in layers.
 
Dyneema is stronger by weight than steel and more abrasion resistant than nylon and similar materials. Because of its high strength it has very low dynamic properties, meaning it doesnt stretch. When applied to high fall factor tests it broke at slightly lower forces than similar materials.
 
As "the Nothingness" is my witness, I shalt never badmouth dyneema again.


I like dyneema.

For pulling trees over.

I love that the days when I had to drag a frigging skidder winch wire up in a tree is over.

Just don't ask me to incorporate it into my climbing system!
 
I will use it for winch line and static loads, but it will never be in any of my life support rigging.

The buzz has a whole list of threads about failures, go do some searching and reading.
 
Already read it.

Think about it. A climbing system is built full of components that absorb impact loading. From a False crotch, to the climbing line itself. Do you really think a webbing bridge will see that kind of force, even in a fall factor 2? Maybe if you climb on chain or steel cable. All those failures at the buzz were guys using hitch cord for bridge material. Hitch cord and flat sewn webbing are completely different animals even if constructed from the same material. Those failures were also bridges that were neglected and in service for far too long.

Go back to TB and read some more........... the TM bridge has a dyneema core! and has been tested and CE approved!
 
So you are saying that Sherill, Wesspur, Treestuff, Petzl, Mammut, Black Diamond, Trango, MadRock, Camp Usa, Omega Pacific, Cypher, Stubai, Singing Rock, Bluewater, Edelweiss, Wild Country, Sterling, Grivel, The list continues ON AND ON. But what you are saying is that all these companies either manufacture, sell or both; a product specifically designed for implementation in climbing systems. Systems that people rely on for personal safety and life support? And that during this abhorrence of corporate responsibility there hasn't been one recall on dyneema product? Not one CNN story about the millions of dollars raked in by the irresponsible merchants of death?

You prepose that the mother freaking BUZZ is the authority here?? EVER HEAR OF OSHA????? There are tens of thousands of users here, casual, industrial and so forth and all these products are unsafe? What about the United States Patent office, you think Spectra holds a patent for use in aerial environments and it isn't safe?

I am getting really upset by the absurdity of all this. The buzz? are you out of your minds, the buzz could explode and i wouldn't believe dyneema wasn't safe.

And if someone even dares to quote the 2006 mammut incident Im really gonna go nuts...

The buzz has a whole list of threads... HA!
 
Tophopper, you beat me to it man! im going nuts over here... did you hear that its crazy to hang in trees and run chainsaws on rope? These people sound like homeowners! Totally uneducated.

The freaking BUZZ??? really, ill stick with ANZI and CE anyday over the damn buzz.

the buzz...
 
I hear that.

Would I use a system compleltey built from dyneema? Hell no.

Would I incorporate dyneema into a system that already has a multitude of shock absorbing components. Absofreakinglutley!
 
No more than you would use a whole system made out of wire core or steel cable. But you use a flipline made out of one wouldnt you? I bet if you submit the wirecore to the same misunderstood tests you get the same results, misguided sheep.
 
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