'SWL/WLL'.....am starting to think this isn't a proper approach to rigging-lines (v. "where's the bounce?" :) )

JeffGu

Well-Known Member
Suggesting that its good to Dynamically load static ropes on trees...
You need to work on your reading comprehension skills, Bubba. @theatertech87 never said or suggested that dynamic rigging was a good thing to do on static ropes... he said that we can get away with it, which is pretty much true. Nearly ALL rigging in tree work is dynamic. The loads are moving, dropping and swinging. He never mentioned negative rigging, which you seem to believe is the definition of dynamic loading.

Additionally, there is the fact that I am free to "like" a single sentence in a post if I so desire, even if the rest of the post was gibberish. @theatertech87 was trying to help the OP out, not trying to be a dick, unlike the bulk of your content.

You've proven once again that everytime you open your mouth or start typing, you prove your own ignorance.
 

Daniel

Well-Known Member
Let's just get this straight. @rico @JeffGu
Are you "liking" the statement?:
Our trees bend and flex, unlike structural steel or rock faces, so where other industries need rope stretch, we can get away with dynamicaly loading our elastic anchors (relatively speaking) using static ropes.
 

rico

Well-Known Member
Let's just get this straight. @rico @JeffGu
Are you "liking" the statement?:
Our trees bend and flex, unlike structural steel or rock faces, so where other industries need rope stretch, we can get away with dynamicaly loading our elastic anchors (relatively speaking) using static ropes.
I can only speak for myself, but I particularly "like" this part...

"A couple other locations where highly static lines can be desirable are...
-ziplines, where stretch causes unwanted drop.
-Any instance where you're not negatively rigging, high rigging point and tip tying is a great example; wherein you have substantially less dynamic load
- any time you are lifting a load (grcs, ropejack crane etc) where again there is limited dynamic load and type stretch becomes an inconvenience rather than a benefit
."

Surely you don't have a problem with the above statement Daniel?
 
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Daniel

Well-Known Member
I can only speak for myself, but I particularly "like" this part...
-Any instance where you're not negatively rigging, high rigging point and tip tying is a great example; wherein you have substantially less dynamic load
Surely you don't have a problem with the above statement Daniel?
NOT ANY rigging instance other than negative rigging... there are many scenarios where the stretch in the line offers rigging advantages. A little stretch allows the load to transfer slowly onto the line as the piece swings down into the rigging, which has the benefit of both slower controlled movement and keeping the piece moving down and away from the climber. SO, for example, there are many situations where I don't worry about how the piece could move after the cut, because I know the stretch in the line ensures the piece will move below me where it is harmless, no matter how it rotates or swings after separation.

For Zip lines and lifting loads a static line works, but there are a few scenrios where stretch in the line helps there too: for example when lifting a load with equipment or even equipment on a pull line, the stretch in the line allows the line to be loaded more slowly, thus allowing a little more control and less chance for accidentally overloading the line. I've made a good living for the past 13 years pulling trees over with a high pull line and skid steer and will rarely use bull lines or static lines. Now maybe the fact that we're used to using true blue has resulted in a familiarity that helps with the pre-tensioning etc. Sometimes the stretch in the line combines with a little bend in the tree to ensure that the tree will move a little farther towards the lay, (when just pre-tensioned), than you would get with a static line. These are fairly subtle distinctions that won't matter much in the vast majority of falling scenarios, but are valid considerations that can help get the job done on occasion.
 

rico

Well-Known Member
This certainly isn't a one size fits all occupation, and if I were to have done something as silly as rely on True Blue for all my rigging needs I would have been run out for town a very long time ago. Any well equipped pro should have both fairly static and dynamic rigging lines. Simply grab the right rope for a given situation......

Negative rigging, or need a piece to be pre-sprung... Grab something with a some stretch like Polydyne or Atlas.

Speedlining, pulling over big back leaning trees, swinging logs near a roof line, ect.
Grab something a little more static like some Stable Braid or Esterlon...
 

*useless info*

Well-Known Member
Proper tool for proper job;
Static for non-dynamic to limit motion not already there, like lifting cable,
but , dynamic, elasticity to absorb existing dynamic force as reverse strategy mechanix against reverse mechanix shituation .
.
Any dynamic contains opposing extremes to dial into also.
 

*useless info*

Well-Known Member
Would not look to do monster loads then;
my longest lasting in most premium condition would be True Blue 12strand.
Safety Blue 16strand HyVee Safety Orange for perhaps more flexibility.
Both kinda olds-cool now i suspect.
 

eyehearttrees

Active Member
I can only speak for myself, but I particularly "like" this part...

"A couple other locations where highly static lines can be desirable are...
-ziplines, where stretch causes unwanted drop.
-Any instance where you're not negatively rigging, high rigging point and tip tying is a great example; wherein you have substantially less dynamic load
- any time you are lifting a load (grcs, ropejack crane etc) where again there is limited dynamic load and type stretch becomes an inconvenience rather than a benefit
."

Surely you don't have a problem with the above statement Daniel?

Whoa things really heated up quick here huh!?

I like how you put that (and good to see a thumbs-up from @Tom Dunlap who I've only recently learned of & am happy to see around - thanks for all those boss youtubes you've made!!), am going to add-to it though:

- The entirety of your special-cases wherein dynamic-strength isn't of benefit constitute a VERY small % of total-arboricultural-rigging. (I don't disagree w/ using Amsteel/Dyneema where-applicable, what drives me nuts is the "dual-purpose" usage of bull-ropes wherein someone is getting cordage to double-duty as both a dynamic-rigging line & their "pull line" and they choose cordage w/ attributes 'somewhere in the middle' when in reality there is a chasm between an optimal static line and an optimal "bull rope for regular-rigging", get Amsteel or Stable Braid for lifting, winching etc but keep it away from blocking!)

- The differences that 0.5%, 1.0% elasticity make to dynamic-strength are exponential (you can snub much more than 2X as much with a 10k, 2% line than you could w/ a 10k, 1% line), and it's only at the price of:

- Stretch-in-rope isn't "bouncy" as many(not necessarily in this thread) imply, all sub-10% rope is considered 'static' to every industry except arboriculture, if you go from a 1% line to a 1.5% line you get significant increases in dynamic-capacity of the cordage, but "stretch"? Picture a "regular" job, dismantling a ~40' Oak, you're rigging a 35' drop when topping it and you're going to push your ropes to 10%ABS, by going up to 1.5% your log, if snubbed, will land a whole 2.2" lower than it'd have landed with a 1% line, if snubbed.
I'm sorry but that is a VERY tiny elongation difference in the ranges we're considering here, if instead of 0.5% increase you did a 2% increase, IE the difference between *most* bull-rope and my Polydyne(3.5%), it'd be an 8.8" difference on a 35' fall when snubbing to 10% of the rope's fail-strength, I mean c'mon that is nothing nobody is snubbing above roofs in a situation wherein inches is making/breaking success of an operation!

So yeah there's absolutely use for super static ropes, and Amsteel is awesome for that. But for routine rigging, where dynamic forces are expected, increased elasticity is a massive load-increaser(or safety-increase if using same loads) and ropes should be judged as such, there's certainly zero harm in saying "I want crisp picks from a high-tied anchor so I'm getting some amsteel", but there's immense potential-harm in saying "I need a new bull-rope, for negative rigging, but also want it to be static for when I need that, so I'm choosing a 1% rope" Again I know 1% lines aren't breaking all over the place but #'s don't lie, also ropes degrade over time in relation to the %ABS forces they're hit with, so if speaking in dynamic-terms then your 1% rope will stiffen faster than a more elastic rope (hate having to phrase it as "more elastic" because when discussing sub-5% ropes they're *ALL* static, blows my mind that it's generally agreed that Amsteel isn't suitable for anything dynamic, yet 1.1% lines *are*....I think Sterling's release of 4.5% Atlas is going to be a game-changer for rigging but I guess we'll see, Atlas *is* the 1st product for arb-rigging that's *both* dynamic(kinda, <5% isn't really 'dynamic' to anyone but us) and available in proper diameters, am betting that if it'd been released a decade ago that Samson & Yale would both have more-elastic bull ropes on the market by now(and bet that that *will* happen in time, heck there's a reason Sherrill chooses Polydyne, not Double Esterlon, or Nystron, not Stable Braid, as their go-to bull rope ;) )
 

eyehearttrees

Active Member
Interestingly enough, on this topic I realized something interesting...My 7/16 climb line, Mercury, is FAR more suitable for negative rigging than:
1/2" Stable Braid,
1/2" Sirius

Yet I'd swear I see those ^ types of super-static lines used almost interchangeably with stuff like Polydyne/Atlas(and kinda Nystron, its 2.4% makes it a far 3rd-place here, although have heard whispers Samson is redeveloping it, wish they'd just release a new line instead of redeveloping one but hey if it leads to stronger bull rope I'm all for it!)

Honestly I think Yale's lil article&vid from my signature is all that needs to be known on this, it's hard to wrap my head around the idea of using a 1% for negative rigging and, if I were constantly winching/lifting stuff, I wouldn't want my polydyne *or* 1.5% Sirius I would want Amsteel....right product for the right job, we (rightly) keep a separate kit for rigging climbing-setups than our kit for rigging dismantling-setups, seems silly to knee-cap your dismantling kit so it's more "lift-friendly" or "mech.advantage-friendly", just buy a super-static line for those circumstances IF those inches of extra elongation bother you so much but just please do not go and choose a line that's 50% as strong, dynamically, so you've got a crisper lift from the line when the line is used 95% of the time for dynamic cases....actually am surprised retailers don't try to push this IE "you don't need A rigging line, you need a dismantling/blocking line and you need a static pull/advantage/lifting line" lol
 

eyehearttrees

Active Member
Wow so the sheer "dynamic-illiteracy" evidenced just generally in rigging is amazing, yesterday I wanted to do maths to show how far you could drop a 100lbs log with Mercury versus those ^ 1/2" lines to show how big elasticity is when at the acutely-static end of the spectrum of ropes ie all arborists' ropes, and found the most misleading framing of dynamic-loading (not arb-specific just a general-rigging retailer)
Under their "What is Shock Load?" article they frame it as such:
For instance, let’s say you are lowering a heavy piece of equipment weighing ¾ of a ton, and all the components of your rigging system have a working load of 1 ton. Since working load denotes how much the equipment can lift without any fear of failure, you might think that you are more than covered in this situation. But, if there is slack in the line which allows the equipment to free-fall for 10 feet, the rapid deceleration when the object is caught by the rigging system applies an extreme shock, which could vastly exceed the working load. Thus, the shock load could break your system and send the object hurling towards the ground.
They're talking about a 1T system with 1500lbs on it (75%ABS load), then their described dynamic event is free-falling for 10 feet, free-falling a 75% load for 10 INCHES would smash that system hell 10mm may be enough for a 75%ABS load to shatter a system depending how static the equipment is..... Have to imagine I wasn't alone when, just learning to climb to height, I did those free-fall calculators, seeing how far a fall my line could catch, it is astounding how fast an object picks up 'weight'(dynamic-force) in a free-fall, from a proper article:
Write down the equation to determine shock load in pounds: shock load = load x [1 + (1 + (2 x FD x A x E)/(load x L))^1/2].

Plug in the values in the following example: load = 200 pounds, falling distance = 12 inches, area factor = 0.472, diameter of rope = 0.25 inches, metallic area = 0.0295 inches^2, modulus of elasticity = 15,000,000 pounds per square inch, and length of cord = 10 feet (120 inches). Therefore, in this example, shock load = 200 x [1 + (1 + (2 x 12 x 0.0295 x 15,000,000)/(200 x 120))^1/2].
Calculate the numerator then the denominator separately, as per the order of operations. So in this example, the equation simplifies to shock load = 200 x [1 + (1 + (10,620,000)/(24,000))^1/2].

Divide the numerator by the denominator, as per the order of operations. So now you have shock load = 200 x [1 + (1 + 442.5)^1/2]. Add 442.5 to 1 within the parentheses to get shock load = 200 x [1 + (443.5)^1/2].

Take the square root of 443.5 and then add 1 to perform the calculations within the brackets and get shock load = 200 x 22.059.

Multiply for the final result: shock load = 4,411.88 pounds.
^200lbs load, *1* foot drop, over 2 ton dynamic hit... Now to be clear that's a literal free-fall with a clean snub which isn't something you'll achieve in arb-rigging your piece is almost never going to be dead-in-line with the rope and even a few degrees off-alignment makes a difference, the rigging points(limbs/etc) take-up dynamic energy when the load hits etc etc so no your average 1' rig of a 200lbs log isn't generating 2T you'd need to be using a platform-drop to try a perfectly-vertical drop but it still illustrrates the potential forces that can accumulate so damn quickly, I've heard generalities of (seriously) just multiplying feetXweight for peak-dynamic (ie as-if it were linear and not exponential, when it is very much the latter)
 
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evo

Well-Known Member
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.
 

eyehearttrees

Active Member
That last quote was from random site "sciencing" btw, link https://sciencing.com/calculate-shock-load-7255380.html , I'm not a 'math guy' but I spent a good amount of time "flipping-through" all the free-fall calculators online (battling initial fear-of-heights when starting) and the crazy high #'s were the norm, youtubes showing it clearly with marked weights as well, it's incredible how little room a 100lbs block needs to drop to generate 1k lbs of force and again I know our peak-forces are attenuated by "hitting at-an-angle" but sometimes (high rig points w/ short/tight angles nearly pure vertical) that won't offer you much help; I know they're attenuated by 'cushioning' from the rigging-structure(tree) itself, although sometimes your tie-in-point for rig-anchor may be strong enough it's providing almost zero 'cushion' (and sometimes a flexible limb takes half the force) Lastly, I know there's a massive difference in dynamic-capacity going from stiff-ass steel cabling to fibres-based cordage, a massive difference in dynamic-capacity going from the stiffest (amsteel 0.5%) of these cordage just to 1.5% (Stable Braid), and far more going to a still-static 3.5% (polydyne, mercury)

So yeah while drop-angles, rig-anchorage etc vary and may reduce forces, the 1 factor we really do control is 'the give', the cushion/elasticity of the system. I do use 1.5% TEC, solely because of how great it is in-use (ie practical/convenient/versatile) and because I'm never loading it past 10%ABS I always put at least a 2nd anchor when doing anything heavy anything 1 groundie can't easily control, if I had my way (when! :) ) 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.
 

eyehearttrees

Active Member
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 :p )

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.
 

eyehearttrees

Active Member
, for rigging lines in the 5-10% are dynamic..
W/ Atlas, at 4.5%, being such an outlier I'm intrigued to try it and do expect that when my 5/8 polydyne is too worn that its replacement will likely be Atlas, glad to have had Polydyne for more of 'baseline' (and stiffer 1/2" rope before) but the #'s for dynamic-capacity for Atlas are just astounding, if they remain an independent company (I've heard disconcerting things about sale/merger and hope I'm mistaking companies on that but don't believe I am, think Sherrill&Sterling have some future, united plans but can't recall where I read it :p) if they remain independent I'm guessing I'll try it and stay with it because I just don't do really tall trees where 1' of elongation hurts me, I do suburban stuff where a 1' cushion on a 30' drop helps me by cushioning and reducing peak-dynamic-forces :)

Would bet anything we'll see more-elastic bull rope from all major manufacturers over the next decade, #'s don't lie and it's just a matter of time before enough videos of crazy snubbed-loads w/ Atlas convince that 'critical mass' and it becomes a leader (sadly I imagine it'd be seen as "Atlas rules" and not "elasticity is part of calculating dynamic-strength" but if it leads to stronger rigging it's a good thing!)
 

eyehearttrees

Active Member

Re earlier forces talk, this is a good video of what I meant this guy's got a load-cell and a 220lbs steel test weight, generates over 2000lbs of force with tiny little drops, things pick up weight fast as hell in free-fall yikes!! That's why I chose to climb Mercury (3.5%) over Blue Moon (1.4%), I know I'm little but never noticed one iota of perceptible stretch while climbing and I'm not 'gentle' I mean I tend to be kind of crude/quick instead of graceful on ascent most of the time so would think I'd have felt something as I know just being jerkier on ascent can spike peak forces (and thus elongation) surprisingly high but I've not noticed, it's an 8.5k lbs ABS line so hitting the 10%ABS to get 3.5% stretch takes 850lbs so maybe just not heavy enough!
 

eyehearttrees

Active Member
And I promise I won't beat this horse again (here ;) ) but since I think I can put it in-thread, and since it's (by far) the best & most-relevant example, I present Yale using a 100kg(220lbs) load in a controlled-drop environment (6.5' drop) just like that ^ video above only using arborists' ropes instead of steel wiring, comparing their 20k ABS Ultrex to their 6k "XTC" climb line, they illustrate a comparison of these two cords using the same load and fall-height and get immediate failure of the 20k Ultrex line while the 6k XTC line takes the force 6 times:

link in my sig to their short article where they do a more fair comparison, this time between their two bull ropes Double Esterlon(2%) and Polydyne (3.5%) and they do the math showing just how much stronger polydyne is for anything dynamic (ie most of our concerns) so much so that it makes you wonder if they're trying to crush any reason to purchase Double Estelon! (and p.dyne & d.esterlon have comparable static ABS's, yet Yale shows clearly&simply they have vastly different dynamic ABS's, THIS is the epitome/crux of why I made this thread & of my frustration with the arb-industry(retail-specific I mean) for the praising & formalizing-around static/tensile strength when, climbing or rigging, your 'fears' your reason for checking specs is to ensure you'll survive a slip, or it'll catch a log, *all* inherently dynamic yet prevailing 'magazine&forum wisdom' is "take tensile/static ABS and use 1:5 or 1:10 and you're set" which couldn't be further from the truth.
 

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