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rschap


Mar 16, 2009, 5:04 PM
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Pull my anchor
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Hey Adatesman, I have some 7year old cordalet that has had double fisherman knots tied in them the whole time. Any interest in pulling them? I know youíre busy right now but maybe after things calm down. I donít remember the name but they were prepackaged 21í lengths 7mm nylon (I think) and one 5mm Kevlar. Theyíve never seen a fall (well other then short top rope falls) but Iíve been using them for TR and multi pitch anchors all this time. Well the last three years I havenít done a lot of climbing but the first 4-5 years I was out almost every week end on them. I decided to retire them and Iím curious to see how theyíll hold up.


Partner philbox
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Mar 17, 2009, 12:17 AM
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Re: [rschap] Pull my anchor [In reply to]
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I'd be interested in seeing how those knots stand up as well. My understanding is that knots become stronger over time as they cinch down tight.


rockforlife


Mar 17, 2009, 2:04 AM
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Re: [philbox] Pull my anchor [In reply to]
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philbox wrote:
I'd be interested in seeing how those knots stand up as well. My understanding is that knots become stronger over time as they cinch down tight.

Really?

Do you mean stronger as in less slipping...

or

Stronger and as in it will hold more with out breaking than when it was first tied?

I'm most likely wrong i just thought that knots were the week points.

So over time they would just stay the same or get worse because of things like wear and dirt and what not.


boymeetsrock


Mar 17, 2009, 6:45 AM
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Re: [rschap] Pull my anchor [In reply to]
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I have an old Tech-cord cordalet you could test as well.

You'll have to meet me at the Gap for some climbing so I can give it to you though!! Wink


Partner philbox
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Mar 17, 2009, 11:41 PM
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Re: [rockforlife] Pull my anchor [In reply to]
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rockforlife wrote:
philbox wrote:
I'd be interested in seeing how those knots stand up as well. My understanding is that knots become stronger over time as they cinch down tight.

Really?

Do you mean stronger as in less slipping...

or

Stronger and as in it will hold more with out breaking than when it was first tied?

I'm most likely wrong i just thought that knots were the week points.

So over time they would just stay the same or get worse because of things like wear and dirt and what not.

I mean as in stronger because the knot becomes stronger. What occurs is that the potential friction contained within the knot is gradually removed over time by way of cyclical loading. Thus the heat build up within the knot under high load conditions is not as high as what would occur within a newly tied knot. Note that the above statement is not a statement of fact but more statement of what I have been led to believe. I would like to see that either confirmed or otherwise by way of definitive tests.

I do know that nylon rope has a memory and knots are better to stay tied rather than continually untied and then retied. Of course that is not always possible. Let's look at a prussik loop, leave that tied, it is better to stay tied. Your tie in point of course will naturally have to be retied.


gunkiemike


Mar 19, 2009, 4:23 PM
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Re: [philbox] Pull my anchor [In reply to]
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Old knot vs. new knot should be easy to test. Just cut these old cordelettes 2 feet on either side of the current knot and re-tie into a (much smaller) loop with the same type of knot. Aric can't pull a full cordelette to failure anyway.


knudenoggin


Mar 23, 2009, 10:34 PM
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Re: [gunkiemike] Pull my anchor [In reply to]
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gunkiemike wrote:
Old knot vs. new knot should be easy to test. Just cut these old cordelettes 2 feet on either side of the current knot and re-tie into a (much smaller) loop with the same type of knot. Aric can't pull a full cordelette to failure anyway.
I've been lured by this specious reasoning; it's not easy to see:
in this case, it could well give just the opposite result,
as the newly tied knot, noting PhilBox's conjecture as to
the mechanics of new vs. old, will yield relatively much
material upon tension-compression, while the well-worn old
knot has done all it can in its history of useage; so at
any given overall force of the puller, the old knot's side
of the loop will have higher tension, and be likely to fail.
(Whether, on dynamic loading, that compression-yield could
produce heat sufficient to weaken that knot to fail first
is maybe a race condition sort of gamble.)

Beware generalizing, also: what might be true for one knot
might be false for another--where the cinching isn't all so
tight, and the usage thus has a chafing weakening effect.

In any case, I had just the same idea, and had found some
old longline with (single) Fisherman's knots very well set
in them. These can be tested against knots just manually
set, and also ones newly tied but more forcefully set.

*kN*


bandycoot


Mar 30, 2009, 7:45 PM
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I've got a pair of equalettes that I've been using for a couple of years that I'd like pull tested, also. They're made of 4' mammut dyneema slings and I have an overhand on each leg about 1/3 of the way in. I'd love to see how strong the things are after 2 or so years of use with knots it in. I'm going to see if a friend of mine can pull test them in the next week or two.


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