Dyneema knot failures

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Mophead
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Dyneema knot failures

#1

Post by Mophead » Tue Jan 19, 2016 1:28 pm

Over at hammock forums there was a thread where some ideas of a knot base suspension with Amsteel- "becket hitch ideas and questions" or something like that. I know at least a couple of the participants from that thread post here as well.


Just curious if anyone can report any failures on what they've been tying? Be it crocks bend, sob bend, or something else.

I haven't been pushing the limits of the SOB bend much. Just using it like I normally do with some extra bouncing. Same set of Amsteel and loops still going strong. But i only have 7 or 8 nights plus lounging and testing through last season and I am hoping to get some icy conditions testing soon.



Ksbcrocks
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Re: Dyneema knot failures

#2

Post by Ksbcrocks » Wed Jan 20, 2016 5:56 am

No failures so far with mine!


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Mophead
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Re: Dyneema knot failures

#3

Post by Mophead » Wed Jan 20, 2016 8:57 am

Good to hear!

Mophead
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Re: Dyneema knot failures

#4

Post by Mophead » Wed Jan 20, 2016 11:29 pm

Just to add this to the discussion... I was trying to find some info to get an idea of the shock loads on the suspensions and ran across this document: http://tdt.usitt.org/GetPDF.aspx?PDF=49-2shockloads On page 4 there is a formula from New England Ropes for estimating shock loads on their lines using the percentage of stretch (0.96% I think for amsteel at 30% tensile strength). It's interesting to just give an idea of how the line will change based on the length of cord you use and height of the fall.

The numbers most often seem much larger than the forces we likely put on our hammocks or else I suspect we would have shredded our lines long ago. The best knots tested over at http://www.bethandevans.com/load.htm seem to come in around 45-55% tensile so i suspect ours do too. Estimating the shock load that we generally put on hammocks though is difficult, most of the formulas like above are for free fall scenarios. I just simply plan on running with it as long as it works.

Edit: also, while the lines have low elasticity I am usin a 1.1 RS nylon hammock which is very stretchy. Maybe some of the shock is absorbed by the hammok fabric which spares the lines some of the added tension?

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