Replacing my cordelette with a 240cm dyneema sling?


Original Post
Toad · · Unknown Hometown · Joined Oct 2015 · Points: 0

Just looking to reduce the bulk of my anchor system; 7mm cordelettes are sort of bulky on the harness along with all that other gear.

Any compelling reasons NOT to use a 240cm dyneema sling in its place? I'd pretty much be using it for quad anchors on bolts (overhand knots), or typical 3-piece anchor with a figure-eight masterpoint.

I've read all about the lack of stretch, melting point, etc., but I'm mostly concerned with the tendency of the knots to slip on a dyneema sling.

Thoughts? I'm gonna die?

Firestone · · California · Joined Nov 2015 · Points: 449

A dynema sling is sewn together, the knots in a quad wont slip. You are thinking about what happens when you use a water knot to tie a dynema sling. The biggest thing I can think of is that a 7mm cordelette can be used for bailing easily. You can also tie a cordelette rabbit runner style with a figure eight on either end of the cord and get out of reach placements easier.

Sam Stephens · · Unknown Hometown · Joined Jan 2010 · Points: 740

I do it, I have a dyneema one, but I don't like to knot it. I called Misty Mountain and had them sew me two made of 11/16 webbing.

I love it. Quick, simple, robust and compact.

t.farrell · · New York, NY · Joined Aug 2016 · Points: 0

The biggest drawback you'll probably encounter is lack of elasticity in dyneema. You increase the chances of shock loading your pieces, so it's up to you to determine whether or not you have a system that is dynamic enough for you to be comfortable on.

The second biggest drawback will be the amount of people on here telling you that you're wrong and need to adopt their method for anchoring.

Ernest W · · Camarillo, CA · Joined Aug 2009 · Points: 0

Quite a few of the self-rescue techniques use that cordalette, and you won't be able to use a dyneema sling for that. Not a big deal if you're doing single pitch stuff, but for long multi-pitch trad....

Having said that, I didn't like the bulkiness of the 7 mil either, so I shifted to 5 mil tech cord many years back and find it to be, for me, a decent compromise between bulkiness and useability.

Barrett Pauer · · Brevard, NC · Joined Apr 2013 · Points: 225

I have a 240 I can sell if you're interested

Todd Anderson · · Seattle, WA · Joined Jun 2011 · Points: 0

I use 240cm dyneema slings a lot for quads. If you're climbing a long route with bolt anchors it's pretty awesome to have two pre-tied quads on the rack that aren't much bulkier than normal double-length slings.

Brace yourself for the "just use the rope" comments....

Nick Sweeney · · Spokane, WA · Joined Jun 2013 · Points: 615
t.farrell wrote:You increase the chances of shock loading your pieces, so it's up to you to determine whether or not you have a system that is dynamic enough for you to be comfortable on.
I don't understand this line of thinking. Since when does your anchor material need to be dynamic? Nylon stretches, sure, but the small amount you use to construct an anchor with is not going to be enough to make much of a difference when it comes to shock loading gear. The dynamic part of your system is the rope.

I don't see anything wrong with using a 240cm dyneema sling as anchor material, but you lose a lot of versatility using one versus a cordalette. I prefer to keep my cordalette untied because I use it quite frequently to connect gear that is spaced somewhat far apart on Cascades rock climbs. Additionally, cordalettes are useful for self-rescue situations. If you want to reduce bulk, check out 5.5mm titan cord.
BrokenChairs · · Seattle · Joined Feb 2015 · Points: 182

I generally only take a 240 dyneema sling unless I know that there is a reason to take cord. It works well for a clean fast three point anchor. If there is bolted anchors or out of reach placements I will generally use the climbing rope to build the anchor. Again saves the bulk of cord and accomplishes the same thing. Also note that if it's a longer route and I'm carrying a backpack I will throw 30' of 6mm cord in there for any oddities that may come. I have experienced no issues with knotting it in a quad or three point set up. But really this is up to you but that's my 0.02. Good luck.

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 45

Well, to be fair, if you're trying to reduce bulk...

But, anyways...you'll be fine. People have made a big deal about knots significantly weakening dyneema, which is true, but it's still plenty strong that your pieces/the rock will blow way before the dyneema could possibly fail, especially on something as overbuilt as a quad.

Xam · · Boulder, Co · Joined Dec 2011 · Points: 8
Ernest W wrote:Quite a few of the self-rescue techniques use that cordalette, and you won't be able to use a dyneema sling for that. Not a big deal if you're doing single pitch stuff, but for long multi-pitch trad....
Could you please expand on this?
J. Albers · · Colorado · Joined Jul 2008 · Points: 1,228
Ted Pinson wrote:Well, to be fair, if you're trying to reduce bulk... But, anyways...you'll be fine. People have made a big deal about knots significantly weakening dyneema, which is true, but it's still plenty strong that your pieces/the rock will blow way before the dyneema could possibly fail, especially on something as overbuilt as a quad.
You bring up a question that has been on my mind recently. That is, exactly how much does tying a figure eight or overhand knot weaken the dyneema when employed in an anchor? Its pretty well publicized that a girth hitch can lead to dyneema cutting through itself like a knife through hot butter, but clearly a belay anchor knot is different.

Anyone got any actual info on strength degradation with dyneema and anchor knots?
t.farrell · · New York, NY · Joined Aug 2016 · Points: 0
Nick Sweeney wrote: I don't understand this line of thinking. Since when does your anchor material need to be dynamic?
It definitely doesn't. Just something to keep in mind. It seems to come up in every anchor discussion.
matt c. · · Unknown Hometown · Joined Nov 2009 · Points: 10

I found that the draw-back of using a Dyneema is that the knot can be a real pain to get out after it's weighted. If you decide to do this, think about using a figure 9 instead of a figure 8 for master-point knot.

Also, for good measure:

' just use the rope'
' have you seen that dmm video?'
' you're going to dieeee'

BrokenChairs · · Seattle · Joined Feb 2015 · Points: 182

"Anyone got any actual info on strength degradation with dyneema and anchor knots"

I may remember wrong but I thought that my Mammut slings came with a table that showed the strength reduction for each common knot. I seem to remember that at most it was reduced by 50% so down to around 11kn breaking strength. (Still stronger than many SLCDs) Basically more than enough to work in a proper anchor set up.

Edit: mammut.ch/documents/Hardwar...

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 45

Yeah, beat me to it. :p I believe BD did tests as well, and their results were similar.

http://dmmclimbing.com/knowledge/how-to-break-nylon-dyneema-slings/

john strand · · southern colo · Joined May 2008 · Points: 1,575

Ya could use 2 120cm slings ? It's not gonna fail and you prolly have them already

as a preview,,don't gimme that shit about "low strength" ..you'll retire it long before

Fucking cordalette bs

J. Albers · · Colorado · Joined Jul 2008 · Points: 1,228
Ted Pinson wrote:Yeah, beat me to it. :p I believe BD did tests as well, and their results were similar. dmmclimbing.com/knowledge/h...
Thanks for posting that. I do recall that video now. The problem with their table is that they don't show any values for an 8mm sling with an overhand knot (at least amongst my partners, 8mm is kind of the standard sling thickness); instead they just put a 'dash' in for the value, which makes me suspicious that the sling simply broke. Even the 11mm sling was down to like 10 kN, which is a drop of over 50%. Yes, 10 kN is still pretty good, but its not exactly a heartwarming number.

On the hand, the data in the Mammut brochure (thanks for posting that BrokenChairs), appears to show that most anchor type knots introduce about a 50% reduction as well, which is ballpark in line with the DMM video. Again, not heartwarming, but probably not disastrous either (though who knows how that number changes with sling age).

In case anyone is interested, I posted some images from a study done on cordelette strength (see immediately below). The take away message is that bending cycles (i.e. tying and untying the knot) lead to drastic strength reductions in the fancier tech cords. This is why Sterling quit making Vectran, i.e. it was essentially worthless after a small number of bending cycles. 7mm nylon on the other hand is essentially impervious to bending cycle decay, which is why Sterling only makes cordelettes out of nylon these days.

http://www.mountainproject.com/v/106563580

john strand wrote: Fucking cordalette bs
Just for that little tirade, I am gonna use a cordelette for all situations now...clipping bolts, anchoring in...everything. That way I will maximize how much I plug up classic routes like that guide guy asked us to do :)
rgold · · Poughkeepsie, NY · Joined Feb 2008 · Points: 40
Toad wrote:Just looking to reduce the bulk of my anchor system
Todd Anderson wrote:Brace yourself for the "just use the rope" comments....
Silly folks, wanting to actually achieve what the OP was asking for.
Don Ferris · · Eldorado Springs · Joined Nov 2012 · Points: 0
Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 45

Ha!

J. Albers wrote: Thanks for posting that. I do recall that video now. The problem with their table is that they don't show any values for an 8mm sling with an overhand knot (at least amongst my partners, 8mm is kind of the standard sling thickness); instead they just put a 'dash' in for the value, which makes me suspicious that the sling simply broke. Even the 11mm sling was down to like 10 kN, which is a drop of over 50%. Yes, 10 kN is still pretty good, but its not exactly a heartwarming number. On the hand, the data in the Mammut brochure (thanks for posting that BrokenChairs), appears to show that most anchor type knots introduce about a 50% reduction as well, which is ballpark in line with the DMM video. Again, not heartwarming, but probably not disastrous either (though who knows how that number changes with sling age). In case anyone is interested, I posted some images from a study done on cordelette strength (see immediately below). The take away message is that bending cycles (i.e. tying and untying the knot) lead to drastic strength reductions in the fancier tech cords. This is why Sterling quit making Vectran, i.e. it was essentially worthless after a small number of bending cycles. 7mm nylon on the other hand is essentially impervious to bending cycle decay, which is why Sterling only makes cordelettes out of nylon these days. mountainproject.com/v/10656... Just for that little tirade, I am gonna use a cordelette for all situations now...clipping bolts, anchoring in...everything. That way I will maximize how much I plug up classic routes like that guide guy asked us to do :)

Yeah, it's not heartwarming, but again in the OP context of a quad on bolts, not something I'd worry too much about. The really big concern with dyneema are FF1 and FF2 falls directly onto them from clipping into an anchor on a multipitch or falling off a cliff. As long as the rope is in the system, I doubt even a knotted dyneema sling would break.
Guideline #1: Don't be a jerk.

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