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How would you join two dyneema cords together?

Original Post
Fortuna Wolf · · Durham, NC · Joined Mar 2016 · Points: 20

Normally I'll do a water knot for joining cords, or two strangle hitches.
In dyneema what's a secure nonslipping way to join two rope ends? I'd like it to not loosen when unloaded and minimize bulk if possible (I usually don't do two strangle hitches because they're bulkier than a water knot.
Should I use a doubled water knot (like a double overhand)?

Highlander · · Ouray, CO · Joined Apr 2008 · Points: 256

Not the a good idea use hitches at all with dyneema. Knots are generally a bad idea as well especially with the thinner stuff, with the wider dyneema tests show triple fishermans knot has the highest breaking strength. I personally have done away with knotting and hitching dyneema all together unless I have no other choice in a certain situation, better to use nylon materials when available for those applications.

http://dmmclimbing.com/knowledge/knotting-dyneema-vid/

Greg Twombly · · Conifer, CO · Joined Nov 2007 · Points: 275

I think it depends on the dyneema. If it's a blend, or double braid (dyneema core, polyester or nylon sheath) then it holds knots well; if its braided tape ("webbing") then it might hold knots; if its a 8 or 12 strand single braid, then it doesn't hold any knots reliably. For sailing, even really high load critical applications, we splice single braids rather than knot them, and use rope protectant (like RP11) to improve durability. For climbing I agree with Highlander, better use nylon if there is any question.

simplyput . · · Unknown Hometown · Joined Nov 2013 · Points: 60

I wouldn't. Double fishermans slip, hitches often cause friction and dyneema has a low melting point.
Knots significantly weaken dyneema.
Just get some perlon instead.

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 252

For cord, triple fisherman's, with long tails. Are you sure it's not nylon?

Xam · · Boulder, Co · Joined Dec 2011 · Points: 76

The OP said cord, not tape, which is not the same as in the DMM video. I assume the OP means some kind of UHMWPE tech cord similar to Titan Cord. Bluewater clearly recommends two triple fishermans. Not really different than two strangle hitches with an extra loop each...just a strange way of putting it in the OP. This is common for reslinging hexes.

Fortuna Wolf · · Durham, NC · Joined Mar 2016 · Points: 20

Xam's got it. I'm thinking about picking up some titan cord for building anchors. Its light and low bulk and plenty strong. Just want to know how to securely tie it. I can do a triple fisherman's but would like to know what all the nonslipping knots are.

Greg Twombly · · Conifer, CO · Joined Nov 2007 · Points: 275

Not too stray too far off topic, but there are better choices for high strength lightweight cordage. Newer versions of dyneema like DSK99, prestretched dyneema, tecnora and vectran are fibers used in combinations that have the weight, strength, and low stretch advantages of dyneema without the knotting disadvantages. These are all available in double braid similar to Bluewater Titan.

nathanael · · Riverside, CA · Joined May 2011 · Points: 525
Greg Twombly wrote:Not too stray too far off topic, but there are better choices for high strength lightweight cordage. Newer versions of dyneema like DSK99, prestretched dyneema, tecnora and vectran are fibers used in combinations that have the weight, strength, and low stretch advantages of dyneema without the knotting disadvantages. These are all available in double braid similar to Bluewater Titan.
Examples of products using these blends?
Fortuna Wolf · · Durham, NC · Joined Mar 2016 · Points: 20

please tell me more

Jake C · · Salt Lake City, UT · Joined Dec 2015 · Points: 10

If it is dyneema, I hear that knots significantly weaken the cord. I'd reccomend load each of them through a carabiner. You maintain the strength of each sling and also are not attaching soft goods to soft goods. It will take an extra piece of gear but I'd certainly consider it safer.

Anonymous · · Unknown Hometown · Joined unknown · Points: 0

Basically just don't do that or you'll die.

Greg Twombly · · Conifer, CO · Joined Nov 2007 · Points: 275

Cordage manufacturers (FSE, Marlow, Yale, Samson, Maffioli, and New England Ropes (Maxim climbing rope and tech cord))produce many high tech double braids similar to Titan, but with other core materials.

Tech Cord is a good example of a Tecnora cored double braid: teufelberger.com/en/product…)

APS Ltd has a good selection and a fiber guide table:
apsltd.com/line-resources#f…

I used 1/8" single braid vectran spliced to make a lifting harness for a 5,000 lb sailboat. We crane lifted the boat for an entire season with no issues.

In addition to the stretch, UV sensitivity, melting point, knotting, and abrasion resistance of these high tech double braids, adding a little cordura or polyester to the sheath changes the handling characteristics to make them softer or stiffer depending on desired feel.

Fortuna Wolf · · Durham, NC · Joined Mar 2016 · Points: 20

greg, how do you feel about using a dyneema braid end spliced to make a loop as a long sling for building anchors with? or just end splicing it in general versus knotting.

Greg Twombly · · Conifer, CO · Joined Nov 2007 · Points: 275
youtube.com/watch?v=bLZUfPZ…
neropes.com/Resources/sail_…

Splices are stronger than knots, usually 30-50% stronger (see references above). Loops are difficult to splice, so I use a straight cord with eye splices at both ends. With double braid this means stripping the sheath, splicing the core, then pulling the sheath back to the neck of the eye splice and stitching it down. I then use RP-11 to stop the sheath from creeping back. I have never had a splice fail or come apart. I have had small diameter cord fail under load while sailing, though not at the splice.

Did that answer the question?
Will S · · Joshua Tree · Joined Nov 2006 · Points: 1,061

Triple fisherman.

Fortuna Wolf · · Durham, NC · Joined Mar 2016 · Points: 20

Greg, if I'm splicing and don't need to worry about having a polyester sheath for knots what do you think about using a single 12 braid cord as an anchor? A loop of 5mm dyneema cord is rated to something like 50kn...

Greg Twombly · · Conifer, CO · Joined Nov 2007 · Points: 275

I keep an eye spliced leash and sewn spectra runners with me for anchors and to clip in direct. They each have different benefits and uses. I make the spliced leashes and buy the sewn runners (loops). I have spliced leashes made from double braid with dyneema, vectran, and technora cores and different covers, either nylon or nylon-poly blends. Straight dyneema braid gets fuzzy with use and the fibers snag on stuff, so I like a cover, and the poly-nylon blend has both a good feel, abrasion resistance and doesn't melt as easily from friction. Splicing is easy. It takes practice and a few minimal tools, but the result is really cool.

David Coley · · UK · Joined Oct 2013 · Points: 70

Triple fisherman's

20 kN · · Unknown Hometown · Joined Feb 2009 · Points: 1,346

You could use the standard inline figure eight. I know a lot of people dont like it to join cord because it's bulky, but it's extremely secure, even more so than the tipple fishermans. Admittedly though, I dont know how it would impact the strength of the material compared to the tripple fishermans.

bearbreeder · · Unknown Hometown · Joined Mar 2009 · Points: 3,065

maxim says a double fishy is fine on their techcord ...

thats whuddah i use

;)

Guideline #1: Don't be a jerk.

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