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Frost Knot info...?

Discussion in 'Tech Tips and Gear' started by Disruptive_Rescue, Dec 27, 2017.

  1. Disruptive_Rescue

    Disruptive_Rescue

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    Canyon Collective Community -

    I am very new as a member here - although I have been reading it for years (commitment issues?) - I am not sure if this is the correct place to post this, or if I am breaking etiquette by posting a thread, but I have a question. Does anyone have any break data on the Frost Knot when used in tubular webbing? I have been using the frost knot in various configurations for awhile, we switched to it back in 2007 for a couple reasons for military / federal teams...with good success. Recently a friend of mine who is an up and coming climbing guide called asking me for the break strength data for the frost knot. The guide group he is interning with let him go through their "canyon" course. In it they were using the water knot for their webbing anchors, and he brought up and showed them the Frost knot - but they won't let him use it unless he can show the break data. So... I tried some preliminary searches, to no avail, and went down to a testing facility with a new spool of Sterling Tech Tape / Climb Spec 1" tubular and did about 10 breaks each in a couple different configurations. Obviously 10 breaks in a couple different configurations is not a big "n", but I just needed a starting point. All of the breaks I did was utilizing the bight portion of the Frost, and did not do any within the shelf...

    So, does anyone have any additional data on the frost knot? If so, could you share it with me? Thanks in advance. Also if anyone has any opinions "pro" or "con" on the frost knot, that would be valuable.
  2. Disruptive_Rescue

    Disruptive_Rescue

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    Here is the data I got on the first round of breaking... It was a slow pull test, with a 2" bollard. This is the data for the Frost Knot in a loop configuration. All new webbing. Break strength of webbing is listed as 4,200 lbs. Same person tied all of the Knots - I have to check my notes but I believe we tied with 3' of webbing, and had 3" tails. There was zero slippage of any of the tails...Also, I realize there are a bunch of variables not accounted for in this testing data. On the right - first column is Lbs, second is kN's.
    Screen Shot 2017-12-27 at 7.06.05 PM.

    Here is the data for the Basket Hitch configuration... same spool of webbing as above, non of the breaks occurred in the bight formed by the frost knot, all breaks were in the "non frost knot bight"... also prior to beginning the slow pull, the were separated around the bollard, so there were no compressed wraps around anchor...just fyi.
    Screen Shot 2017-12-27 at 7.06.18 PM.
  3. ratagonia

    ratagonia

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    Hi DR.

    Thanks for posting this question.

    I am a Mechanical Engineering BS holder - too long ago to honestly call myself a 'Mechanical Engineer' - and have an interest in the community both climbing and canyoneering developing test information that actually means something, so I appreciate that you recognize that your low sample size may not be meaningful. But it might be the best available data to date, especially if you wrote up a Test Doc on it. I have a question, though:

    You list your sample webbing as 'Sterling Tech Tape / Climb Spec 1" tubular'. I see that Sterling makes a 1" tubular product they call Tech Tape. And BlueWater makes several products that they call "Climb Spec". But the 1" Tech Tape and the 1" BW Climb Spec appear to not be similar. Which product are you testing?

    Tom
  4. Rapterman

    Rapterman

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    IF the web in question is the most current stock,
    Both the Sterling and the Bluewater goods are likely from the same mill (some recent consolidation in the web industry). Climb Spec and Tech Tape do refer to the same weave, but
    testing is only useful if it is apples to apples...even differences in finish (stiff vs. soft) from lot to lot could? make a difference in how a knot behaves
    :)
  5. Disruptive_Rescue

    Disruptive_Rescue

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    It is the Sterling Tech Tape. It has a has a different weave than the mil-spec (pics attached). The Tan is the Tech Tape, Green is the mil-spec. Sterling lists the MBS as 4000 now on their website, but the insert with the spool had it at 4,200. I have seen some varying MBS with Sterling, with website changes, and what comes with the spools of various products. Talked to them about it a year or two ago and they weren't sure where the discrepancies came from. They thought maybe one was a 3-sigma mean and one may be a 3-sigma minimum... maybe one was 3-sigma using STD Dev and the other using Mean Average Deviation... not sure. The Tech Tape and climbing spec are supposed to be manufactured using the same loom technique - I will say my knowledge is pretty limited concerning webbing manufacturing techniques.
    IMG_5278.

    IMG_5279.
  6. ratagonia

    ratagonia

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    Thanks for the clarification.

    All these products are made on a needle loom with a double lock stitch. Very standard loom these days. That tells us very little. The ORIGINAL Mil-Spec was made on a Shuttle Loom, because that is what the web manufacturers had at the beginning of WWII. It persisted as a shuttle loom requirement for several decades, because the US Factories were the only ones running Shuttle looms. Mil Spec has since been revised to allow the needle loom.

    Being made at the same plant does not mean it is the same webbing. Even if the Sterling Tech Tape and the BW Climb Spec look much the same, each company has sufficient volume to have the product adjusted to their requirements... However, I see that the BW 1" Climb Spec is now rated to 4000 lbs on their website - I remember it as rated at 5000 lbs but don't see that anywhere anymore. So maybe they are the same, since they have the same rating.

    Tom
  7. ratagonia

    ratagonia

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    The rating on any piece of equipment is a management decision, usually in the marketing department. Unlikely to change from batch to batch. Given the data available, the QA Engineer probably dictates what the highest possible rating is; but a lower rating may be more appropriate. On an item like the webbing, the variance batch to batch is likely VERY low, so a 3-sigma rating would be not much lower than the mean. And these variations of rating style you mention above are unlikely to be significantly different.

    My GUESS (only a guess) is that Sterling's requirement to the mill is quite a bit higher than their published rating. And what the mill actually produces is much higher than their requirement. And maybe the 4200 is Sterling's requirement of the mill, but someone noted that the standard requirement for this general kind of webbing (1" tubular) is 4000 lbs, and it is not clear that there is an advantage to having a 5% higher rating and ...

    All conjecture of course.

    Tom
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  8. Disruptive_Rescue

    Disruptive_Rescue

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    Okay, I am back... sorry for delay. Here are 2 pics showing the configurations of the frost knot loading for the above breaks.
    IMG_5280.

    This is the loop configuration -

    IMG_5281.

    Basket hitch configuration. This is what we sometimes use during RTEC - rough terrain evac course. This is just the releasable used for certain terrain where the rope is laid through the carabiner and screw link - the end coming out of the screw link is tied into the casualty, the rest of the rope is with the rescuer on the carabiner side, and attached to the rescuer DCD. You can either tether the rescuer to the casualty, or not - depending on environment. Casualty is put over edge transition - and rescuer can lower them from above - or until there is an obstacle - then weight the rope and go over and work casualty around friction point, or just continue down and belay casualty down. Then obviously tie a sloppy overhand knot in the end of the rescuer side of the rope and pull from the casualty side to retrieve anchor. We typically keep this configuration so if it is multi-pitch, the rescuer can secure themselves with a tether / purcell, and tie the casualty off with the rope - so casualty is not ever detached from system.

    This is not "the" way, but a way that has been pretty successful with limited organic resources - has been used off of a roll bar on a Hilux, to hotel balconies - to an add hoc waterfall rescue in western north carolina. The friction within the edge and 180 within the carabiner & screw link has made the weight difference between the rescuer and casualty inconsequential. Is there some carabiner bangin' on the release - sometimes - but if you have additional webbing, and equipment - or more people, other techniques would be used.

    All of that to say why we use the basket hitch frost knot - realizing it probably sent negative waves up many readers spines because of the rope grooves it will produce when pulling to release -
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  9. Disruptive_Rescue

    Disruptive_Rescue

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    That's interesting and sounds like that could be it... When talking with Sterling - it's interesting - their Canyon Tech and one of their Tactical ropes - are the same rope, except the Canyon Tech has a tracer. But when comparing - they list one as a 9.0mm, and the other as a 9.5mm - and they have 2 different MBS - when I asked, they weren't sure why, but that certifying agencies (NFPA) allow them to move the diameter up or down by .5mm.
    ratagonia likes this.
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