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Tech Tip: Question Shrinkage (ropes, canyoneering)

Discussion in 'Tech Tips and Gear' started by ratagonia, Jul 22, 2016.

  1. Bootboy

    Bootboy Atwood Gear

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    Yes actually :D


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  2. jcaffclu

    jcaffclu

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    Very interesting topic. Recent trip to Moab (Sunseed)--last rap 200' nominal (per beta)--we had 220' for the rap side and 200' Blue Water, new, just cut in Moab for pull. Apple suggested I pre-rig pull side with webbing attached to bag. I love it when a woman makes a suggestion! Last to rap, it was an awkward start and the rain and wind didn't help--I clipped the bag and the horse tail was very reassuring--200' Blue water was short about 15', but the horse tail made the difference. Back in SD, I measured all my ropes--Sterling C-Tech (200') and C-IV (165') have shrunk about 1.5-2.0%--I measured them when purchased, they've seen wet and dry canyons. Need super accuracy? Let me know and I'll re-measure. Have Imlay C-Fire, but didn't measure it when I received it-- a gift--I never look a horse in the mouth. Except when I'm buying.
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  3. delenius

    delenius

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    @hobo_climber looks like all those Kordas ropes are semi-static (3-4% stretch). Seems sub-optimal...
  4. hobo_climber

    hobo_climber

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    Quite the opposite actually. Our canyons (in NZ) are more akin to europe with moderate to high water levels being the norm. This combined with a distinct lack of "keeper potholes" means that we don't do a whole lot of ascending if we can avoid it.
    It also means we are sometimes climbing out of the flow in order to reach anchors hence the requirement for 'some' dynamic properties to our ropes... protecting that rare fall! Also makes our numerous traverse/access lines that little bit safer.
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  5. hlscowboy

    hlscowboy

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    Which kordas do you recommend and where do you buy it? I'm finding limited inventory online.
  6. hobo_climber

    hobo_climber

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    Location:
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    We are lucky enough to have a direct importer in NZ (a rare occurrence). A friend of mine Pete who runs accessgear.net

    He also makes pretty sweet canyon packs and associated gear if you are serious about proper "wet" canyoning. Definitely ships stateside, just drop him an email.

    Recommendation: Dana 9mm for main cord, Speleo 8.6mm for handlines and backup...
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  7. Bootboy

    Bootboy Atwood Gear

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    New Hykon Olympic 1450. [​IMG]

    Just measured a lightly used nominally 200’ Canyon fire. Now at 193’5”

    I noticed as I was pulling it through that the rope was still somewhat wavy having been left in the bag for a few weeks. Maybe I’ll wet it and run it through a pretensioner of some sort, like a figure 8 or the like.

    Also measured a very well loved , 3 year old BW canyon Extreme. Measured as a remnant by bluewater at 80’. Now 77’3”.

    With my fancy new cord counter, I’ll be tracking shrinkage on all my personal ropes and perhaps account for shrinkage when selling rope.
    Last edited: Nov 19, 2017
  8. ratagonia

    ratagonia

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    How did the calibration go on that?

    The somebody's-workshop-sold-on-ebay rope measurer I bought a couple years ago was off by 2.5%. That one looks a lot better, but... no way to know until it is calibrated.

    It is also possible for the device to give different readings on different ropes, thickness or slickness might be a factor. My rope factory mostly makes FAT ropes, and had a bit of trouble at the beginning delivering consistent-to-length spools of my skinny ropes, until they got it sorted out.

    Tom
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  9. Bootboy

    Bootboy Atwood Gear

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    Guaranteed to within 2% underregistration and 1% overregistratiom.

    Will calibrate with 50’ tape measure to be sure for my specific ropes.
  10. tom_brennan

    tom_brennan

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    I measure all of my ropes intermittently. Here's a few data points for you. Unfortunately I didn't (or wasn't able to) measure them all before use, so in some cases it's measuring vs nominal length, so not directly comparable. But I would say that on a small sample size, Imlay Ropes hold up well in the shrinkage stakes.

    3/8" (9.5mm) BlueWaterII Non-Dry (Nylon) [purchased Sep 2003] - shrinkage = 11.6%
    measured Mar 2009 55.7m
    measured Oct 2005 56.4m
    measured Aug 2005 55.6m
    measured new Sep 2003 63.0m

    9mm Edelrid Non-Dry (Nylon) [purchased Jan 2010] - shrinkage = 12.9%
    measured Nov 2016 54.0m
    measured Oct 2013 54.1m
    measured Dec 2011 54.1m
    measured Mar 2010 58.4m
    measured new Jan 2010 62.0m

    9mm Tendon Static (Nylon) [purchased Aug 2011] - shrinkage = 10.7%
    weight: 3.93kg (62.0g/m)
    measured Nov 2016 63.4m
    measured Oct 2013 65.6m
    measured Dec 2011 67.7m
    measured new Aug 2011 71.0m

    8.3mm Imlay Canyon Fire Yellow (Polyester) 8.3mm 120'/36.6m [purchased Aug 2012] - shrinkage = 0.6%* (vs nominal)
    weight: 2.23kg (61.2g/m)
    measured Nov 2016 36.4m
    first measured Oct 2013 37.1m (already used)

    8.3mm Imlay Canyon Fire Red (Polyester) 8.3mm 120'/36.6m [purchased Aug 2012] - shrinkage = -1.0%* (vs nominal)
    weight: 2.26kg (61g/m)
    measured Nov 2016 37.0m
    first measured Oct 2013 37.8m (already used)

    9mm Sterling CanyonTech (Technora/Nylon) 200'/61m [purchased Sep 2013] - shrinkage = 8.0%* (vs nominal)
    weight: 3.99kg (71.1g/m)
    measured Nov 2016 56.1m
    measured Jan 2015 57.3m
    first measured Oct 2013 57.6m (already used)

    9mm Imlay Canyonero Blue (Polyester) 9.2mm 200'/61m [purchased Oct 2013] - shrinkage = 1.6%
    weight: 4.06kg (67.7g/m)
    measured Jan 2015 60.0m
    measured new Oct 2013 61.5m

    ** Edit: added rope material, rope diameter
    Last edited: Nov 22, 2017
  11. Bootboy

    Bootboy Atwood Gear

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    Kind of apples and oranges there. Some of those are ropes that are either dynamic, contain nylon, not intended for canyoneering or all of the above. Their stretch makes the specific shrinkage much less important.

    In my experience, nylon shrinks much more predictably and dramatically than polyester.

    The half way mark on nylon climbing ropes won’t remain accurate for very long, especially if it gets wet.
  12. Rapterman

    Rapterman

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    I have an olympic cord meter and have found it useful for cutting the SAME (model and diameter) new rope in volume (apples to apples).
    It has Not been accurate on different ropes, of different ages.
    Tape measure, I am afraid :meh:
  13. tom_brennan

    tom_brennan

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    None are dynamic. They are all low stretch ropes intended for abseiling - and mostly used for canyoning.

    But yes, they are a mix of materials. I have edited in the missing materials (Sheath/Core). Where only one material is listed it is for both sheath and core (to the best of my knowledge)

    Measuring process has generally been to measure a 10m length of rope using a metal tape measure, use the 10m rope to measure the longer ropes to the nearest multiple of 10m, and then measure the excess/shortfall with the tape measure.
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  14. Rapterman

    Rapterman

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    Another trick we have used in our shop which is 50 feet wide (variation of tom-brennan's)
    Have a couple of old rescue pulleys bolted at the base of opposite walls then run the rope back and forth then measure the remainder with tape.
    Works pretty fast...
  15. ratagonia

    ratagonia

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    Basically what we do here, but outside.

    Tom
  16. Andrew J Farrow

    Andrew J Farrow

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    just my opinion . but :

    you get new rope - wash it [ to get rid of lubricants used in manufacturing an to pre-shrink it ] - then cut it to measured lengths with an ASSUMPTION that it will have 10% shrinkage " over lifetime " - and use it

    at intervals - you re-measure it and log the new length and re-label the rope

    dont ever even attempt to understand why a given rope = X% shorter than it was last time you measured it

    just accept that it is - and get on with life
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  17. ratagonia

    ratagonia

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    Bluewater denies that their ropes have lubricants used in manufacturing, and my ropes do not. I think it is just that the brand new fibers are kinda slick. So I would not say "wash it", I would say "soak it and dry it". Soaking and drying tends to tighten the sheath onto the core, and perhaps shrink the length just a bit. Tightening the sheath to the core usually prevents sheath slippage, which can be a problem especially with new ropes.

    I don't usually pre-shrink my personal ropes, but they usually get wet on their first usage, so same thing kinda sorta. But I do have a common(ish) complaint, that goes like this:

    A: I just got this rope, and it has a bad spot, and I don't know if I should be concerned.
    me: what does the bad spot look like.
    A: It is a section about 2 feet long that is really soft, like the core is too small.
    me: Have you used the rope?
    A: Just got it. Me and my friends went out to the local rock and did a couple rappels on it.
    me: Can you give me more details?
    A: it is a 200' rope, and the soft spot is about 50 feet from the end. We anchored the rope at the top and each rappelled a couple of times. The rap is 150 feet.
    me: And how many of you were there?
    (editors note: this is where Tom slips into obvious hyperbole)
    A: Just a few, like 10. My rappling buddies, about half of whom are over 200 lbs. No one did more than 5 laps.

    Well, it does not take that much 'abuse' to get a sheath bunching, which creates a soft section where it feels like the core does not fill the sheath, because the core does not fill the sheath. When you rappel on a rope, your device interacts with the sheath, and squeegies the sheath down the core. Sheath slippage is normal especially on a brand new rope. If 50 people rappel and stop at the same place on the rope, each person pulls the sheath down a little bit, and then leaves it at that specific point.

    Weaving ropes is an art as much as a science, and each batch/spool comes out slightly different. I think we get darn good consistency, but there is some variation. Whereas my ropes are on the stiff side, the ones that are somewhat softer tend to sheath-slip a bit more.

    Therefore, it is good to wet and dry your rope a couple times before first use, if convenient. Sheath slippage does not compromise strength, but it can make the rope harder to use. You can get rid of the soft spot by undoing what you did, usually. If not, I suggest cutting that section out, and now you have two ropes, though both shorter than the original.

    Tom
    Last edited: Nov 29, 2017
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  18. 2065toyota

    2065toyota

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    New ropes always feel skinny and fast until they have been through a few canyons and a few wet and dry sequences. Almost a full friction setting highter than normally used
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  19. tom_brennan

    tom_brennan

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    I disagree about just accepting it. It would be very useful to know before purchase how much a given rope is likely to shrink.

    One reason is from a cost point of view. If a rope shrinks very little, it may be better value for money than a rope that shrinks 10% (or more).

    It's also annoying to buy an Xm rope and find after a couple of uses that it's only 90% x Xm. To be fair I tend to buy ropes 10% longer as a result, but then some of my ropes have shrunk more than 10%, so still not optimal. As well, if you're buying pre-cut lengths, then you can't just buy 10% more.

    On my so far limited sample size (see stats above), the Imlay ropes I've used have barely shrunk, which makes their cost per metre (or feet) comparatively better value than some other brands. And my 200' (61.0m) Imlay Canyonero rope is still 60m, which is more than I can say for some of my other ropes.
  20. Bootboy

    Bootboy Atwood Gear

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    Hence the reason I will be selling my rope by the foot, measured and cut to order so you can build in the shrinkage factor.
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