One must remember the term “static line” is often a misnomer, typically it’s any line if kernmantle construction is called “static”. This comes from sport climbing when dynamic lines are in the 20-30% stretch range. Their static lines can be .5% to 10% stretch at WLL.
In our industry it’s a very different set of criteria. For climbing any rope over 3% is kinda bouncy, for rigging lines in the 5-10% are dynamic.. I can’t really even recall if there are rigging lines beyond 10% at WLL.
I'd say it's more a descriptor than a misnomer I mean dyneema stretching, what, 1 entire inch for every 30' when hit w/ a 10%ABS loading (in practical terms, going over 2500lbs on your 3/4 TEC, which I maintain you shouldn't really be doing IE you should be setting a 2nd anchor once you're at the point of hitting it w/ >10%ABS levels, it's not just 'safety/redundancy' it's cordage longevity the ropes wear at
percent-ABS-usage so if you and I were always rigging identical situations, and used the same model of rope, just using 5/8 instead of 1/2 would mean my rope would retain its elasticity(and thusly its dynamic-capacity) far longer / would degrade far slower under identical loading....but this is also true if using 1/2 lines but switching to a more-elastic line, if you had two 1/2" bull ropes, both with 10k tensile ABS and one being 1% stretch the other being 3% and you did a cycles-til-failure test by repeating a 500lbs peak-force, your 3% sample would last many MANY cycles longer (non-linear which is why the most-acute stuff, say the 1% and belows or even low-1%'s, always blow my mind but thankfully most just use stuff like dyneema for winching although Sherrill's rigging section's Whoopie offerings are in TEC and Amsteel so.....and that's
for an anchor, length of rope-in-system is part of the equation, if you're shortening the rope you up its strength and/or elasticity, ideally both, couldn't imagine using an amsteel whoopie for say snubbing something it seems pointlessly static like using steel cabling in fact cabling must have
some give I'll have to google that
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The 'kernmantle=static' marketing logic is complete and utter nonsense, whose 'the offenders' you speak of here? I feel like Bartlett's & maybe Sherrill are unclear and/or conflate kernmantle/static/cover-thread-count, all are....worth knowing....but cover-threading is a hard data-point, and tells me something specific (higher thread-count,
smoother rope performance), 'kernmantle' is also an objective fact I mean it's still a double-braid or rather cover-over-core rope but it's not so useful w/o knowing what % of the cord's strength is from the kern% and mantle%, w/o knowing that 'kernmantle' is objective but of little use, I mean I climb Mercury it's got I think 16 strands of nylon as kern and is 3.5% at 10%ABS, the "kerns/3-strands are stiff" thinking doesn't really hold up, elasticity is in tightness of construction and materials of construction....but "static" is an utterly useless term in arb-rigging, I guess it's not wrong to say "amsteel is especially static" but all our ropes are static (as you say a rec climber would call all ropes under 10%-stretch 'static rope')
As mentioned I think Atlas, if it conforms to spec (as high an ABS per-diameter, or nearly, as Nystron and Polydyne like almost 20k for 5/8 and mid-20k's for 3/4, but instead of 2.4% or 3.5%, respectively, elasticity it's got 4.5% which if you did the math is a very serious boost in dynamic-capacity like as-big an improvement on Polydyne as Polydyne is on Stable Braid, for neg.rig/blocking/shocking), if it conforms to spec which I can't imagine it wouldn't it will be a game changer, I know elasticity could be problematic for guys topping 100' conifers but for lil tree crews that are limbing half the time and doing basic dismantlings (say, 40' Oaks w/ real targets below), the complaint of stretch is almost silly I did the math in another post but, for our 40' Oak, if we're topping him and rigging from 30' anchor-height, then a 0.5% difference in elasticity creates a mere
2.2" of extra elongation on a 30' drop (that's if&when you're hitting it at 10%ABS, mind you!) so really if you can add 2% elongation for the "cost" of an extra ~10" of drop on a 30' load
when you're hitting it @10% then you get massive increases in dynamic-capacity, I think people picture it being "like an elastic", 'bouncey', but it's not you DO NOT feel it in general/routine operations as being anything 'stretchy', if I had to put a word to it it's "cushion", hell if you've cut a 200lbs load and a guy's on the ground tasked to control its descent, using a more-elastic line reduces the peak forces the groundie must generate(or that the tree's anchor-points must withstand!) and it feels IMO just like using friction devices IE smooth&consistent, it's not like your guy starts decelerating a 200lbs log and it 'bounces up' the elasticity just feels like some cushion, some 'brakes in the system' just like adding another ring & pulling the line for friction does in fact it's funny how similar it felt going from 1.5%, 1/2" bull to 3.5%, 5/8" bull rope was like using a 2nd ring (or using another hole on the Safebloc) in terms of reducing peak-force.
And no nothing near 10%, Nystron is from the 1950's and Polydyne IIRC is oldAF too, they re-design them but couldn't tell you what that means...Sterling seems like they're fighting to make a hit, innovative product going on like 20yrs now and they're more from a sport-climbers' market aren't they (ie fall-prevention, high-elasticity climbing bouncey-dynamic lines, etc) Yale's 3.5%(polydyne) was the stretchiest (Samson's Nystron is 2nd place with a distant 2.4%), these were the most-dynamic cordage that was "in popular use" (better stuff is made, even by Samson & Yale, but it's not what's most-popular) that you could get in sizes over 1/2 or 5/8 if lucky, then Sterling drops Atlas with 4.5% a huge increase 50% increase over Polydyne, time will tell how prone-to-disfiguration the line will be but I've heard mostly(entirely?) good anecdotes and, on-paper, if you're talking about how much weight a system can rig for a dismantling/negative rigging you're gonna see the best choice is the appropriate-diameter of Atlas, would bet anything we'll see a marked upward increase in elasticity, industry-wide, for bull ropes over the next decade (would be nice to see Samson move TEC to a 2%, am honestly just too-lazy but want to find a hollow 12-strand of nylon, something like TEC but nylon instead of poly, am surprised Samson doesn't promote it that way I mean on short length anchor cordage elasticity would be more-important, again I know it's kinda unnecessary beefing-up past what TEC offers but, all things being equal, I just don't get the choice to use poly over nylon (both with TEC, and in-general)
And totally disagree Re "for climbing, over 3% is bouncey", am sure it matters how heavy you are & how high you climb, I'm rarely over 40' and I'm a small guy *but* I was given free Mercury (3.5%, 7/16" kernmantle climb rope) and in climbing I've noticed zilch, and in rigging it was as expected ie comparable to my 1/2 polydyne meaning it feels a bit skinny in the hands but doesn't lose 'the cushion' of that elasticity (no did anything ever feel 'stretchy', doing it in-practice feels simply like a touch more 'cushion' and if anything it was more pronounced w/ Mercury although it's a weaker line than 1/2 p.dyne so, despite an equal 3.5% elasticity, Mercury would start its stretching at lower weights of course.
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) I would use a 2nd line w/ a 2nd anchor in most cases where I'm moving anything over say 300lbs I have seen *far* too many times dumbass groundies (yup, myself included) get carried away by hits that seemed in-line with the 10 logs before but one just hits the right way (and maybe groundie doesn't nail initial catch/lets it pick up too much on deceleration), when I switched from static 1/2" to a 5/8", 3.5% "heavy duty" system there was a marked drop in peak-forces (a ring-based system), for instance using a Porty or Safebloc(yay!) as terminal is something I'm surprised isn't more 'default' (and no I'm not saying "A safebloc can handle all your needs!" I'm saying "Use 2 Safeblocs when 1 isn't enough", @LawrenceSchultz3000 - his youtube handle am hoping his handles are homogeneous!- his youtube shows some of the most elegant rigging systems I've seen IE two Safeblocs at the terminal position along with a Safebloc on the log for double-whip configuration rigging, would love to see @thexmanjdd dave driver using a load-cell to show just how much you can reduce a peak shock-force by using a 3 Safebloc setup ie 2 as anchor / 1 on log for double-whip configuration, with that much extra rope going into the setup & friction being taken up it wouldn't surprise me to see 50% loading on the groundie's end, max, compared to just using a block.
