"Dynamic" rope for specific SRT uses in relevance to anchor safety

Lupin_IV

Member
Location
St Paul
Sorry if I'm beating a dead horse here, I searched and didnt find anything too specific.

I'm a huge fan of redundancy and am always looking for ways to increase my safety barrier while climbing. Especially since I am mostly self teaching SRT in my work.

Now, I was wondering if any of you scholarly tree folk could speak to the safety of arb specific static and dynamic ropes on an anchor point (i.e 1.4% elongation vs something like 4%). I was climbing a burr oak the other day with no obvious main lead, there were about 4 or 5 vertical leads about 10 degrees off-center all of the same height. I trusted the anchor because I know the species enough but this got me thinking about situations like this with more brittle species that I am less familiar with. Normally I would just immediately set redirects to share the load a bit but if that's not possible, I'm just wondering if a more dynamic rope would increase the safety net on my anchor a noticeable amount. There are infinite situations in tree work of course, and if I see something I don't trust I'm not climbing the fuckin thing and I'm okay with walking away from stuff. But there are just so many situations where confidence may be there but some dark side of you thinks about the what if. I'd just like to know I'm doing everything I can. I can suffer thru a climb on some rubber band shit rope if its gonna add a level of safety :b

Excuse the longwinded thing and it might be day one stuff, but I get alot out of hearing from you all that have more experience than I.
 

Jehinten

Well-Known Member
Location
Evansville
I don't personally have a lot of knowledge on dynamic rope forces on anchor points, but if you are looking for a safety factor then perhaps adding a screamer would be beneficial? They can be found at Wesspur, I do not personally use one but in the case of a fall it should mitigate some of the force on your anchor point.

If you haven't seen it, @Mark Chisholm did a video on srt ascents on an enforcer, to measure the amount of force put on the tie in point. This info may be of use
 

Tuebor

Well-Known Member
Location
Here
When you're nearing the top of your ascent, will you be regretting using rope with 3.9% elongation instead of one with 5.7%? I mean, where do you draw the line?
 

Lupin_IV

Member
Location
St Paul
When you're nearing the top of your ascent, will you be regretting using rope with 3.9% elongation instead of one with 5.7%? I mean, where do you draw the line?
True lol. I'm trying to figure out the minimum amount of elongation I may be able to introduce to get a decent extra margin of safety in certain situations.Stretchy rope makes me more uncomfortable at height. If it does not increase safety that much and this isnt something people ever consider out in the field, I will just keep on keeping on as is. But if someone out there with more experience knows otherwise, I would heed their words. I will have to search around for this video, It may be the exact info I'm looking for.
 
A buncha other factors come to mind about this stuff. (Edit: In whatever rope discipline you're practising - are you climbing the rope (arb, caving, industrial access) or are you climbing something else with the rope as a safety (rock and ice). How much dynamic rope are you going to have in the system to absorb load, the fact that arb harnesses are not designed for fall arrest but for work positioning, that there have been lots of negative comments about the old USFS pine cone collecting system of running belays to the tree as a climb progresses, the fact that an ATC belay on an alpine or ice climb is actually kinda dynamic rather than a static attachment as in SRS, etc. etc. Best advice is "Don't fall". UK arb video cited elsewhere today about twin climbing lines cites some other interesting facts - only a 500 mm (~19 inch) fall "allowable" for arb systems and the necessity of a harness with dorsal attachment if you're going to use a sliding fall arrest type device on second climbing line rather than complete second climbing system (as these harnesses are rated for a fall). Screamers were around in my day about when we didn't have modern ChromeMoly ice screws (no not those $5 Russian titanium bendable ones!) and climbed using electrical conduit for ice belays. Intent was for it to spread out the peak forces on the anchor (still true) together with copious prayer and promises to your Maker to never do that again . . . .
For whatever it's worth, just my 2 cents this afternoon.
Stay safe out there.

Addenda, after a bit more thought (28-Nov-2020):
Reg Coates' latest video has some thoughts on climbing a dead hemlock - he carefully sounds out the stem wood on the way up - might be worth a look and also ClimbingArborist has a podcast discussion about a climber who got whacked by a part of a limb failure during a rigging operation (fatal). Maybe some perspective on having dead or questionable tree bits above you somewhere.
 
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CjM

Well-Known Member
Location
Elk Grove, CA
Personally, I like a really static rope for tree work. In what scenario are you imagining a fall? Agree with the above that screamers often increase fall forces, and that our gear and systems are for work positioning, not catching falls like rock climbing. Keeping good working positions, using your lanyard(s), keeping slack out of your system, tying around the main stem instead of limbs, canopy anchors, and being smooth on the ascent are all better for anchor integrity than a dynamic rope. I find tachyon to be a bungee cord of a rope at 2.2% elongation- most dynamic ropes stretch ~8-10% with static loads, and over 30% with dynamic loads.

There's also a lot of dynamic movement going on all over if you were to fall with slack in your system, the limb you're tied into will move, it's branches will help provide ballast, your hitch will move some, ect. Keeping your rope angles towards vertical will also drastically reduce forces in a fall, regardless of rope construction.

If you're worried about it, don't climb on it, and stick to ropes/redirects made primarily with nylon, which stretches more than polyester or dyneema.
 

Tony

Well-Known Member
Location
Lancaster, PA
I think we need to agree on some terminology. As climbers we do not use ”dynamic” rope. If you ask cordage manufacturers their definition they won’ t use the term dynamic until elongation is over 30% at low weight compared to breaking strength.

While it might seem to be splitting hairs all arborist lines are static because Rope elongation is a matter of two factors: How much stretch (precent) and at what weight (load).

We want low elongation (as stated above our system are not fall arrest) at low loads (the body can only handle so much)

True dynamic ropes will never be appropriate for our high angle work due more to the prevalence of hazards below which can be struck while the rope “stretches“ Than system limitations. Certainly a whipper would be better tolerated in an arborist harness than a rock harness. The problem would be like the old quip, its not the fall, but the landing that hurts! Even if you could configure a “screamer” to work( difficult to do) the same issues apply.

The Z133 stipulates no more than 7% elongation at 10% mbs (540 lb.) These numbers relate directly to Arbplex 1/2” which was THE rope at the time the Z133 was written. Regardless of orgin it is our staring point.

There are of course addendums to this stating that a rope of not less the 7/16” that the manufacturer states is suitable for tree climbing is acceptable. (a bit of an oversimplification I admit, but close) The Z has modernized.

Now you have the history and we can agree that our ropes are all static due to design and use, there is a great deal of variance in “feel” “bounce”. Call it what you will. This is more a factor of elongation at low load as opposed to high elongation. This “feel” cannot be said to be more or less safe it is within the guidelines, except for in the climber’ mindset and attitude. This of course is important as well.

History and terminology aside; use a rope made for tree work that has a hand and bounce you like. As stated a few times above in other posts, climb smart, position yourself well, select good anchors and suspension points and let procedure and technique be your redundancy.

Tony
 

Crimsonking

Well-Known Member
Tony nailed it.

Specific tools that may add peace of mind along the way-

Tachyon or imori- tachyon has plenty of elongation, a firm hand, and is 11.5mm. Imori is 12mm, has a softer hand, and comparable elongation to tachyon.

ART Snaketail- the Snaketail has stitched eyes that are designed to give way under enough force to dissipate energy in the event of a fall. As stated above, work on positioning more than relying on these things, but this has some built in oops factor.

Lastly, and I hesitate here, certain mechanical climbing devices- again, please don’t ever climb in a way to need your gear to catch you, and don’t put misplaced faith in your device’s ability to protect you in a fall. In fact, I’m just going to skip listing devices with slip potential.

If you’re concerned about brittle structure, start with a lower anchor. Once aloft, if you need to go higher, do as you said and incorporate multiple anchors. If your rope is the determining factor in whether your anchor fails, you’ve chosen the wrong anchor point.
 

CjM

Well-Known Member
Location
Elk Grove, CA
Lastly, and I hesitate here, certain mechanical climbing devices- again, please don’t ever climb in a way to need your gear to catch you, and don’t put misplaced faith in your device’s ability to protect you in a fall. In fact, I’m just going to skip listing devices with slip potential.
I had this same thought.

I might have skewed this conversation with the idea of catching falls. I read dynamic rope and I went straight to catching falls in my mind. I would like to add that in the above video, the loads are dramatically reduced by anchor configuration using the same rope.

True dynamic ropes will never be appropriate for our high angle work due more to the prevalence of hazards below which can be struck while the rope “stretches“
This is a good point, I've hit the ground on several occasions over the years rock climbing because of rope stretch.
 

Lupin_IV

Member
Location
St Paul
I think we need to agree on some terminology. As climbers we do not use ”dynamic” rope. If you ask cordage manufacturers their definition they won’ t use the term dynamic until elongation is over 30% at low weight compared to breaking strength.

While it might seem to be splitting hairs all arborist lines are static because Rope elongation is a matter of two factors: How much stretch (precent) and at what weight (load).

We want low elongation (as stated above our system are not fall arrest) at low loads (the body can only handle so much)

True dynamic ropes will never be appropriate for our high angle work due more to the prevalence of hazards below which can be struck while the rope “stretches“ Than system limitations. Certainly a whipper would be better tolerated in an arborist harness than a rock harness. The problem would be like the old quip, its not the fall, but the landing that hurts! Even if you could configure a “screamer” to work( difficult to do) the same issues apply.

The Z133 stipulates no more than 7% elongation at 10% mbs (540 lb.) These numbers relate directly to Arbplex 1/2” which was THE rope at the time the Z133 was written. Regardless of orgin it is our staring point.

There are of course addendums to this stating that a rope of not less the 7/16” that the manufacturer states is suitable for tree climbing is acceptable. (a bit of an oversimplification I admit, but close) The Z has modernized.

Now you have the history and we can agree that our ropes are all static due to design and use, there is a great deal of variance in “feel” “bounce”. Call it what you will. This is more a factor of elongation at low load as opposed to high elongation. This “feel” cannot be said to be more or less safe it is within the guidelines, except for in the climber’ mindset and attitude. This of course is important as well.

History and terminology aside; use a rope made for tree work that has a hand and bounce you like. As stated a few times above in other posts, climb smart, position yourself well, select good anchors and suspension points and let procedure and technique be your redundancy.

Tony
I should have clarified. By the quotation marks around "dynamic" in my title I meant a couple percentage points higher elongation that what I normally use (marlow vega at 1.2% and hyperclimb). More stretchy arborist ropes may have been more proper :b You kinda hit the nail on the head I suppose, it seems the feel and comfort level of the rope is gonna be the greatest safety enhancement which for me would be the lowest elongation possible. You guys know alot and I just wanted to make sure I wasnt missing something.

Personally, I like a really static rope for tree work. In what scenario are you imagining a fall? Agree with the above that screamers often increase fall forces, and that our gear and systems are for work positioning, not catching falls like rock climbing. Keeping good working positions, using your lanyard(s), keeping slack out of your system, tying around the main stem instead of limbs, canopy anchors, and being smooth on the ascent are all better for anchor integrity than a dynamic rope. I find tachyon to be a bungee cord of a rope at 2.2% elongation- most dynamic ropes stretch ~8-10% with static loads, and over 30% with dynamic loads.

There's also a lot of dynamic movement going on all over if you were to fall with slack in your system, the limb you're tied into will move, it's branches will help provide ballast, your hitch will move some, ect. Keeping your rope angles towards vertical will also drastically reduce forces in a fall, regardless of rope construction.

If you're worried about it, don't climb on it, and stick to ropes/redirects made primarily with nylon, which stretches more than polyester or dyneema.

I'm not so much concerned about a fall specifically, but also maybe additional forces applied from movements in a branch that appears fine but is structurally weak. Theres an educated climber video that comes to mind where he climbs on an anchor for awhile, removes it and takes the branch he was climbing on and it breaks right where he was climbing, revealing rotten interior. Confident in my climbing ability just want to do everything I can to reduce chances of mishap. We dont have quantified data on the strength of every tree we climb. One just gets so much experience they know what's safe and what isnt. Agreed on the tachyon lol I climbed on drenaline even the other day and couldn't stand it anymore.

Lots of great food for thought here and other points to drill into my climbing style.
 

rope-a-dope

Well-Known Member
Location
Asheville
I think there is a repeatedly misplaced focus illuminated here. And in other threads as well, deep dives into the technology we use. Discussions about strengths, statistics, elongation, manufacturing.....
The gear you use is never going to do anything significant to improve the tree structure supporting all of it. There is nothing out there that will somehow block forces from reaching the wood that you are using to resist those forces!
In every situation I felt uneasy or suspicious about the integrity of an anchor point, I have used more anchor points or did something to expand or support that tree structure.
My all time favorite anchor is out of Fundamentals of General Treework. The climbers rope is cinched around a big bundle of bushy regrowth. Like 50 one inch sticks sucked together. So your instinct about redirects was a good one. Two awkward shitty tips are better than one!
 

Bart_

Active Member
Location
GTA
A different perspective is to point out that a properly isolated DRT tip, or a branch cinched SRT tip are 100% reliance, no backup methods, eggs all in one basket. Fail, fall, crunch.

A base tied SRT multiple tip, or because it can also be non-isolated (I refer to them as catch branches or crotches below) gets rid of the 100% eggs in one basket stress. It reduces tip load, lessens the shock if catching a fall (via extra rope stretch and via tree flex), and adds the ability to actually catch your fall - in the case of some tip failure.

Didn't seem hard to spot these advantages, technical analysis or not.

I have a standing gentlemanly beef with Mark showing how bouncing during a climb anchored on a pulley increases tip forces. Friction.! Somewhere between 1 1/2 and 2x load distributed correctly can certainly be provided for in tip(s) choice. If you're running that tight on margin of wood strength you should reconsider.

Friendly conversation, for thought.
 

rope-a-dope

Well-Known Member
Location
Asheville
rope-a-dope, I take exception this. A shit anchor is a shit anchor. If you and your crew are not CONFIDENT in your anchor selection, then why the fuck are you climbing on it?

Did I misconstrue your comment?

Tony
It certainly depends on what we mean by shitty! Every climb starts with a risk assessment, and there are a lot of things that can make a climber uncomfortable that arent seriously wondering if an anchor will fail.
Maybe I can elaborate. In my experience there is often a gray area of confidence in an anchor point. Like a situational restriction on how you might use a tip. Im thinking of an anchor that I'm confident will hold my mass while working, but I would not want to do a huge swing on, or deflect with a flat rope angle. Or an anchor that does not provide a comfortable rope angle by itself, but when combined with another less than ideal rope angle gives a boost in climbing security and confidence.

What do you think about KBingham describing a benefit he enjoys from two tips, selecting one that is higher and smaller than he would not normally be %100 confident climbing on? Balancing improved access and risk with a stronger lower anchor point.
 

Mark Chisholm

Administrator
Administrator
I will reply regarding the stretch in rope. I was under the impression that low elongation was king for ascending. I actually set a few world record foot lock times on these ropes. Then, I had to climb a redwood on TV and the host was on my kmiii max and all I had for me was Tachyon. Turns out the bounce helped my speed once I worked with it. It was incredible. It made me rethink. I will try to post a video.
 

rico

Well-Known Member
Location
redwoods
I will reply regarding the stretch in rope. I was under the impression that low elongation was king for ascending. I actually set a few world record foot lock times on these ropes. Then, I had to climb a redwood on TV and the host was on my kmiii max and all I had for me was Tachyon. Turns out the bounce helped my speed once I worked with it. It was incredible. It made me rethink. I will try to post a video.
No world records here, but I have also learned that on very long ascents (300 ft + of rope in system) a little bounce can help... If you get into a rhythm and use the bounce to you advantage it can make very long ascents easier on your body....
 

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