Can Dyneema cut Nylon?

Hey folks, question for the community at large here. I've always been under the impression since I started climbing that you should not girth-hitch a Dyneema sling to nylon, like a belay loop(s). The reasoning I was given when I began climbing 10 or so years ago, was that the Dyneema can cut  the nylon, cause fraying in the nylon, which can cause failure down the road. Does this argument hold any water? 

Any fabric to fabric girth hitch is going to cause wear.   I imagine dyneema to nylon cause the nylon to take the brunt of the wear rather than it being shared more with like fabrics.   People have died from wearing through belay loops with a girth hitched pas, but it occurred due to jugging 1000s of feet and a possibly already worn harness.   Sport cleaning use wouldn't cause this.  

As for outright cutting in a fall type secenario, I have no idea.

> People have died from wearing through belay loops with a girth hitched pas, but it occurred due to jugging 1000s of feet and a possibly already worn harness

singular person, Todd Skinner. write-up. it would take an insane level of blindness for it to happen again.

Yea, he must have been pretty negligent with checking his gear.  Apparently he even knew his loop was wearing through per that write up.

Chris Blatchley wrote:

I thought the big "no-no" was girth hitching two Dyneema slings together. Something about large forces being able to generate enough energy at the knot to fail,...???by partial melting?? 

Dyneema will cut nylon at high loads (think 12kN+) but I wouldn't worry much about that because you have bigger problems if you're generating those loads, like rupturing your internal organs. In other words, those kinds of loads probably aren't happening, otherwise you'd probably be dead.

As for prolonged wear and tear from a girth hitched sling, you'd have to not inspect it for a very long time. As long as you're not leaving it girth hitched to your belay loop for long periods of time, you'll be fine.

If you want to keep a tether on your harness permanently, it's better to girth hitch to your tie-ins on the very small off chance that you forget to inspect your belay loop for a year or 2. We all know humans makes mistakes, so IMO it's better to just keep a permanent tether on your tie-in points. 

Robert Hall wrote:

I thought the big "no-no" was girth hitching two Dyneema slings together. Something about large forces being able to generate enough energy at the knot to fail,...???by partial melting?? 

In order to generate enough energy to melt it and/or cause breaking or cutting, you'd have to be taking high factor falls directly on the dyneema without any dynamic rope in the system. The only other way you could melt dyneema would be falling onto a friction hitch tied with dyneema, which is highly unlikely unless you're using one to toprope solo. And even then, you would probably cause glazing, as opposed to melting the sling all the way through. 

girth hitched dynema has cut through  itself on a TR anchor. 

Nick Goldsmith wrote:

girth hitched dynema has cut through  itself on a TR anchor. 

Any write-up on this?   

Chris Blatchley wrote:

> People have died from wearing through belay loops with a girth hitched pas, but it occurred due to jugging 1000s of feet and a possibly already worn harness

singular person, Todd Skinner. write-up. it would take an insane level of blindness for it to happen again.

You'd have to somehow put miles and miles on the harness while simultaneously never letting another climber see your girth hitched sins.

Everett wrote: girth hitched sins

I believe nothing until King Tut weighs in.

Please read:

https://www.blackdiamondequipment.com/en_US/experience-story?cid=qc-lab-connecting-two-slings-together

Thanks curt!  Good read.   

Tim Young wrote:

Hey folks, question for the community at large here. I've always been under the impression since I started climbing that you should not girth-hitch a Dyneema sling to nylon, like a belay loop(s). The reasoning I was given when I began climbing 10 or so years ago, was that the Dyneema can cut  the nylon, cause fraying in the nylon, which can cause failure down the road. Does this argument hold any water? 

Most people climbing el cap will have a pair of daisies attached to their harness. Often these will be dyneema. Many will attach them to their (nylon) belay loop. Some will then fall onto said daisies. This will be a painful high factor fall. I have never hear of this being a problem for the dyneema-nylon interface.

David Coley wrote:

Most people climbing el cap will have a pair of daisies attached to their harness. Often these will be dyneema. Many will attach them to their (nylon) belay loop. Some will then fall onto said daisies. This will be a painful high factor fall. I have never hear of this being a problem for the dyneema-nylon interface.

They are connected via a carabiner, not directly hitched together...

How would you manage a high factor fall on a daisy chain?

Russ Keane wrote:

How would you manage a high factor fall on a daisy chain?

> FF1 is high for non-dynamic materials.

You could also have some sort of via ferrata > FF2 rig, where the daisy chain's on a biner and the biner is allowed to slide along something -- or even more absurd setups.

Russ Keane wrote:

How would you manage a high factor fall on a daisy chain?

Quite easily and quite commonly in aid climbing. It's typically user error and it's preventable, but it happens regularly. I've belayed people who have whipped hard onto a daisy. Basically, you clip the top piece, shift your weight over onto the top piece and then before disconnecting the lower piece the top piece blows and you fall directly onto the lower piece.

Russ Keane wrote:

How would you manage a high factor fall on a daisy chain?

Daisy fall on aid, or messing around and biffing it with your hips at or above an anchor in a free climbing situation with a PAS.