Forums: Climbing Information: The Lab: Double figure Eight with "Yosemite" finish test request: Edit Log




tugboat


Jul 29, 2011, 10:13 PM

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Registered: Jul 19, 2011
Posts: 106

Double figure Eight with "Yosemite" finish test request
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OK well... I botched this test a bit. So i will do it again in the next day or so.

Long story short... due to rope stretch and knot cinching.... i ended up running out of ram stroke. Pretty wild since i tried to make the test sample quite short,...knowing i would need all my ram length (4 feet). But i still ran out.

I also waffled about what my first test scenario would be. I ended wanting to know if a "short" Yosemite tail finish would be a problem due to knot slip; so i used a short yosemite finish on one end (two inches) and a long Yosemite finish on a figure eight on the other side of the sample.

Result: After running out of ram, i loaded up around 3100lbs. There was no problems in the knots. So i decided to rerig the same sample and bust it anyway. THe rope broke in the knot at the long Yosemite tail finish at 4500 lbs. Remember, though, this sample had already been prestressed to 3100 lbs...and then pulled again to destruction.

While the video footage does lend some info,...it doesn't reveal the answers to the 'requested' info, ie "does the "Yosemite finish" improve break strength?".

Looking back the next (better) test now will be; A regular eight at one end and a Yosemite finish eight at the other. Or does someone have a suggestion for the best setup?

Note: the rope used was 11mm dynamic rope from Rocca. It is all black,...so some might think it is static rope, but its not. I had the rope custom made for the film industry. It was woven to UIAA and EN 892 standards. While unused and well stored,...it is over ten years old.

Anyway,... i'll edit the video and put it up tonight. If anything, it shows the dynamics of the knot, even, with a short tail. And it probably shows how multiple high loading decreases break strength.

But i think a better setup/test is in order.



sorry.....had to edit first load numbers to 3100lbs after watching video...my apologies. Final number is correct though.


(This post was edited by tugboat on Jul 30, 2011, 12:30 AM)



Edit Log:
Post edited by tugboat () on Jul 29, 2011, 11:43 PM
Post edited by tugboat () on Jul 30, 2011, 12:30 AM


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