Splicing Double Braid Dyneema

[Dockhead]

I've got to make an eye splice in a Dyneema sheet (Marlowe Racing Dyneema SK78).

I've become proficient at splicing single braid Dyneema, but double braid is a different story.

What do we think about this method, not using the cover?

https://www.youtube.com/watch?v=Vl8FBnBEZYM

Any other tips?

[SVNeko]

That's pretty neat. Its basically a Brummel splice with the core tucked away neatly. Since a core dependent rope utilizes the core for its strength, I wouldn't see why it should be a problem as long as one is OK with the core being exposed. Let's see what the experts say.

[Stumble]

There are other options, but it's pretty reasonable.

I tend towards just tapering the last few feet of the line then putting an eye splice in the core.

This is really just a core eye splice with the cover back spliced. With the loop thru the eye keeping it from slipping. All in all I am a fan, even if it is a little more fixedly than a tapered eye.


The one issue I can see is the line right before the eye splice is going to bulk up a good bit... so long as the hardware is ok with it I am.

[SF Bay Dude]

A bit off topic, but is there ever a need for whipping? I saw on a vlog where the splice slipped (pretty sure it was dyneema) while raising an engine. I've read that if you have the proper length spliced it shouldn't be a problem, but it gave me cause to ask.

[Alan Mighty]

Originally Posted by SF Bay Dude

A bit off topic, but is there ever a need for whipping? I saw on a vlog where the splice slipped (pretty sure it was dyneema) while raising an engine. I've read that if you have the proper length spliced it shouldn't be a problem, but it gave me cause to ask.

You could do worse than to browse through the research projects done by the engineering students supervised by Dr Andy McLaren at Strathclyde University.


I particularly recommend you read:


* Mark McKay's research paper, which directly addresses the need and placement of whipping at two locations on a splice using rope with a Dyneema core and a braided polyester jacket. See: http://personal.strath.ac.uk/andrew....McKay_2006.pdf


* Douglas Young's research paper on the strength of whippings and seizings is also a ball of fun to read. See: http://personal.strath.ac.uk/andrew....Young_2008.pdf


* William Diamond's research paper is not too shabby either. See: http://personal.strath.ac.uk/andrew....amond_2007.pdf

[SF Bay Dude]

Originally Posted by Alan Mighty

You could do worse than to browse through the research projects done by the engineering students supervised by Dr Andy McLaren at Strathclyde University.


I particularly recommend you read:


* Mark McKay's research paper, which directly addresses the need and placement of whipping at two locations on a splice using rope with a Dyneema core and a braided polyester jacket. See: http://personal.strath.ac.uk/andrew....McKay_2006.pdf


* Douglas Young's research paper on the strength of whippings and seizings is also a ball of fun to read. See: http://personal.strath.ac.uk/andrew....Young_2008.pdf


* William Diamond's research paper is not too shabby either. See: http://personal.strath.ac.uk/andrew....amond_2007.pdf

"Another reason for the low efficiencies could be down to the large change in cross section where the feed length ends. A schematic of this can be seen on the left of Figure 10 below. When the specimens were spliced, the rope end was simply cut and end sealed, which left a rather flat end on it. When the splice was completed, there was a noticeable change in the cross sectional area of the rope where the feed length ended. This has been highlighted on the schematic below. This sudden change in cross section will have caused a stress concentration to exist which will have reduced the load carrying abilities of the fibres, which in turn caused the rope to fail at this location as the fibres had been pre-stressed."

The third example didn't splice correctly, as they didn't taper the end. First was fine. Middle… meh. Oh the days of thick academic verbiage, abstract, etc. I called my professor from a payphone in old Vallarta and told him to move ahead with my thesis. I was done (literally and figuratively) especially after a faculty change that left me with a new guy that wanted to change a bunch of stuff around.

I'll go with my gut and throw a whip into my new halyards

[NahanniV]

Is the core of double braid dyneema UV resistant ?

[UNCIVILIZED]

Originally Posted by NahanniV

Is the core of double braid dyneema UV resistant ?

If you mean the Dyneema itself, then yes, very much so. There's more of it out there in use uncovered, than covered. Including as mooring lines on commercial vessels, instead of wire cables in cranes, etc. And of course all over the place on boats, racers especially.

That said, one "trick" is to paint it with a couple of coats of Maxi Jacket II, or RP25. It increases UV, & abrasion resistance on most any line you put it on. The stuff is similar to the shiny, slippery coatings that all new lines come with, which in addition to the above, helps to prevent individual fibers from getting snagged.

[Dockhead]

Originally Posted by SF Bay Dude

A bit off topic, but is there ever a need for whipping? I saw on a vlog where the splice slipped (pretty sure it was dyneema) while raising an engine. I've read that if you have the proper length spliced it shouldn't be a problem, but it gave me cause to ask.

In my actual experience -- single braid splices can come apart if subjected to a very light pull, or shaking. Because the splice itself needs tension to make the parts fit together.

Not based on scientific research, but I would not leave off the stitching.

[UNCIVILIZED]

Originally Posted by Dockhead

In my actual experience -- single braid splices can come apart if subjected to a very light pull, or shaking. Because the splice itself needs tension to make the parts fit together.

Not based on scientific research, but I would not leave off the stitching.

In the class I took from Brion Toss, he commented on this as well. That sometimes splices in Dyneema & other single braids would slip loose under low loads. Thus he had us lock stitch them by hand at the time. Don't know if he's still of the same philosophy, but likely so, as most reputable rigging shops lock stitch their splices via machine.

I can't see how whipping (seizing) a Dyneema splice would be a huge help, given how slippery the stuff is???

[Benz]

Another vote for lockstitching. I actually stitch my whippings on, thereby getting both at once. Sometimes the bury of a splice tries to sneak out just past the brummel, which is supposed to prevent that, so I usually put a stitched seizing there.
The only downside I can see of the OP's splice is that the eye now has no protective cover; if a soft shackle is put there they'll chafe on each other quicker. Though not that quick.
I have sometimes slipped a short piece of Dyneema anti-chafe sleeve over the uncovered portion in this scenario before splicing. The ends of the sleeve can be hidden tidily beneath the cover. But it does add a little bulk.
Ben
zartmancruising dot com

[Dockhead]

Originally Posted by UNCIVILIZED

In the class I took from Brion Toss, he commented on this as well. That sometimes splices in Dyneema & other single braids would slip loose under low loads. Thus he had us lock stitch them by hand at the time. Don't know if he's still of the same philosophy, but likely so, as most reputable rigging shops lock stitch their splices via machine.

I can't see how whipping (seizing) a Dyneema splice would be a huge help, given how slippery the stuff is???

Yes, I agree totally.

I wrote "stitching" -- and I meant lock stitching, not whipping.

I have always done this, but still I wonder -- does the stitching prevent the loads from going to the splice which are necessary to make it gather up?

Apparently not, since these splices work really well and hold tons of forces, but I still wonder hot it works . . .

[Kenomac]

We have two new jibs, what is the best way to attach the sheet ends? I've always just used bowlines, is there a better way?

[Dockhead]

Originally Posted by Kenomac

We have two new jibs, what is the best way to attach the sheet ends? I've always just used bowlines, is there a better way?

For polyester sheets, I always use bowlines, although eye splices and dyneema soft shackles are neater and easier to get on and off.

For dyneema sheets (like my new ones), you can't use a bowline.

[GrowleyMonster]

Have you tried using the instructions for sta-set in the New England Ropes splicing manual?

http://www.wesspur.com/images/pdfs/n...lice-guide.pdf

I am sure that the breaking strength of the eye is quite sufficient. The breaking strength of the core-only eye is nearly as great as doubled core, which is to say, greater than the standing part of the rope. However, I like the cover in place on any double braid rope, for chafe and UV protection. I think if you can manage either of the two methods in the above mentioned manual or the Samson's manual or the German "Schpleissebuch" (I probably butchered the spelling) and lock stitch the throat, maybe serve the splice as well, you will be good to go.

Now the disclaimer... I have not actually spliced Dyneema double braid. Single braid with a brummel type splice, yeah. Nylon double braid up to 12" Samson on ships, yup. Polyester double braid on sailboats, sure. But my opinion on how to splice Dyneema double braid is worth approximately what you paid for it.