Send me your tired, your ugly hitch cords...

Tobe_Sherrill

Tobe_Sherrill

New member
Location
North Carolina, USA
...I'd like to break em.

With limited research I've found pretty significant strength loss in (old, used) eye to eye tails used as friction hitch cords (not alarming, just measurable). So far I've only tested technora and would like to test more... of everything. No fear in knowing. For those interested in playing a part please send me used SherrillTree spliced eye to eye cords (cause we know material origin and start strength) and we'll pull to break and publish results when done. For your trouble I'd like to offer replacements for half price until we hit about 100 samples (we'll credit/note your personal account). Nearing that time I'll revisit this thread and notify readers that project is complete and take anything shipped up to that date.

Hope this forum isn't considered a poor place to run such a test. Not into rude. If it proves positive I hope to do similar in the future.

Send your Sherrill made eye to eye tails to;

SherrillTree
Tail Busta
200 Seneca Rd.
Greensboro, NC 27406

...and please include name, address & phone number
 
Great idea. Look forward to hearing the results. This type of testing furthers the knowledge and thus safety within the industry.
 
Great idea, Tobe! I've been breaking my own used stuff over the years and have always been happy with what I've found.

I bet the hemorrhaged HRC breaks at a good strength!

love
nick
 
Results were as follows (only 8 entries!);

(3) Yale 8mm Bee line (aramid/poly jacket, aramid core, doublebraid) average break strength 2,394 lbs.

(2) Samson 10mm Ice (Aramid solidbraid) average break strength 4,465 lbs.

(2) New England HRC (Aramid/poly doublebraid) abs 3,600 lbs.

(1) Tenex abs 3,890 lbs.

Anyone cares to try again on a bigger scale count me in for help.

B safe
 
[ QUOTE ]
Anyone cares to try again on a bigger scale count me in for help.

[/ QUOTE ]

I think this needs to happen.

Question is how? Even a large non-scientific study would be a boon.

Those results only raise more questions :)

Good work and thanks, btw.
 
Just read an article in Climbing (rock climbing pub) titled dirty little rope secret (or something like that) showing prusik cord lost 40% strength after soiling with dirt and water. Research was performed by Search and Rescue Assoc. Pretty alarming deterioration IMO especially considering the condition i've seen MANY arb ropes.

These break numbers seem to reflect that.

To date though i've heard of no prusik/rope failures due to reasonable climbing use.
 
Thanks Tobe, I sent in the tenex. It got sticky with use which I used on my lanyard. It wasn't so much the wear. The splice started pop out of the cover just on the end (don't think that was a problem)so I opted for a piece of ice to replace it. After seeing the results from the test it looks as if I chose well. And the ice is still doing a fine job on the lanyard. Thanks again for your effort and the 50% off.
 
So, even the low end 2,400 for the 8 ml beeline comes out to 4,800 lbs when used in hitch formation and would begin to slide well before that point. In dDRT, the hitch would need to be involved in a 9,600 lbs force scenario. This would make breakage of a hitch in a climbing scenario basically impossible. These figures make me more comfortable with my hitch only climbing style. However, I will no longer use eye to eye beeline as an end to end connection. I used to use it as a bridge extension (like an anchor bridge)

This is an interesting bit I found while researching hitches and how safe they are used in SRT. This was in a climbers corner in the 1990's regarding tests done by Frederick Mathias who was one of the ones that brought us modern hitches as well as one of the co-inovators of the ring to ring cambium saver.

"Tests have been done on the Machard tresse, the Blake and the 3-laps Prusik. Frederic Mathias has worked on those tests with "Cousin", a French rope company, with the following results. The climbing line used for the tests was 1/2 inch High Vee Blue from New England ropes. The Blake was made out of the same rope. The 3-laps Prusik was made out of a 10mm diameter dynamic kernmantel rope (mountaineering rope).

Two tests were done. A static test was performed by pulling on the friction knot straight down on a single rope. When breakage appeared it was the climbing line that was broken first where it was constricted by the friction knot. The tensile strength with the Blake was 1987 daN at the breaking point, for the Prusik it was 2054 daN. The result with the Machard was particular. This knot started slipping at 600 daN, then catch, then slip again and so on. The double advantage being that it doesn't break the climbing rope and would have the capacity to keep an eventual shock load lower than 600 daN. So in case of a fall, a part of the energy would be absorbed by the knot which would keep the shock load to a safe level for body.

The dynamic test reproduced actual working conditions. A 80 kg mass was dropped in a factor 2 fall (distance of fall equals twice the length of the rope). None of the three knots failed to stop the fall but the Machard tresse slipped about 10 inches before stopping. The dynamic test showed again that the Machard tresse is able to absorb energy. Thus this knot is not potentially dangerous on a tensile strength point of view, even with a relative small diameter. To the contrary it shows very interesting and unique features."
 
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