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Climb-spec vs. military-spec knotability
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shoo


Oct 27, 2008, 8:01 AM
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Registered: Dec 22, 2006
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Climb-spec vs. military-spec knotability
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I'm curious if anyone knows of any research concerning the ability of 1" climb spec webbing vs. military spec webbing to hold a water knot. Specifically, do they both need the same amount of tail?

My rough guess would be that military spec would slip slightly less than climb-spec for two reasons. The first is that it's just in general less slippery feeling. The second is that there are more pronounced horizontal grooves in military spec, which would, catch each other and make slippage more difficult.

A test would be difficult, as there are a number of variables you have to deal with, such as how well dressed and set the knots are, how quickly you load the knot, etc.


majid_sabet


Nov 1, 2008, 12:01 AM
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Re: [shoo] Climb-spec vs. military-spec knotability [In reply to]
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I have done some test on breaking water knot with almost no tail and I do not think,it makes that much of difference between same size/type webbing. the non-mil sepc commercial webbing were made based on mil-spec which rated to 4000-4400 lbs.

1-inch Tubular Nylon

NOMENCLATURE: TUBULAR NYLON, 1-IN, 4,000-LB.

DESCRIPTION:
A narrow fabric, woven or knitted. It is 1.00-inch wide, 0.120-inch thick, weighs 1.70 oz./yd., has a minimum breaking strength of 4,000 lb. and is identified with one black thread (dyed) in the center.

NSN: 8305-00-268-2455
PART NUMBER: (none)
APPLICABLE MILITARY SPECIFICATION/STANDARD: MIL-W-5625


knudenoggin


Nov 1, 2008, 9:26 AM
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Re: [shoo] Climb-spec vs. military-spec knotability [In reply to]
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shoo wrote:
... research concerning the ability of 1" climb spec webbing vs. military spec webbing to hold a water knot. Specifically, do they both need the same amount of tail?
What has been at issue re Water Knots is an incremental slippage
on repeated LOW loading; what happens is that the exterior end will
gradually be ratcheted through the knot--in SOME tapes.
You can learn more about this at Tom Moyer's site,
http://www.xmission.com/~tmoyer/testing/
(there's a pdf file about 3 down in left column of blocks).
N.B.: this is NOT of 1" tubular, but a smaller size, nylon.
There was similar testing done in which 1" tubular showed no such
slippage, but 3/4"? solid, and some size of Spectra webbing did
slip, on low-load cyclical loading--and NOT on higher loading.
(re "exterior": if you tie a white tape to a blue tape and the knot
looks white, the white end "lies exterior" (my terms))
In reply to:
... general less slippery feeling.
Which might not be indicative of knot holding.
Recently, I tested (moderate loading--500#?) an odd mid-line
loopknot in 12-strand, quite-slippery-feeling Spectra, and was
surprised that it held (on end-2-end tension, eye slack);
but the same knot did NOT hold in some 6mm kernmantle!?
--something to do with the compressible vs. firmer cross sections.

*kN*


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