Extendable / Equalizing Anchor Sling

oldfart

oldfart

Participating member
Location
Asheville, NC
The Extendable/ Equalizing Anchor Sling builds on the TreeStuff Thunder Sling, but to different application and scale.


Guys, I’m not sure you’re going to see much utility in E/E Sling. A working pro can afford to have nice long, heavy bull ropes. He can’t afford not to. While I’ve got hundreds of feet of lighter stuff, my heavy lines could be an exhibit about New England parsimony. So, for me, the sling lets me do “what I can with what I got”.


Also, I like the equalization … it takes the suspense out of that moment when I’m watching to see which tree, exactly, is the one coming out of the ground.







Regardless of what you think of the device, if you like thinking geeky rigging thoughts, these videos will provide tons of entertainment value (yes, intended). And I’m hoping some of the concepts might be useful for the future.


Thanks to Nick for the design help and to Luke for the Stuff.



OF
 
These's something almost magical watching MA systems in action.

Love your work OF. The geek factor was very high and I loved watching the process and learning the outcomes... very very nice indeed. (y)
 
monkeylove said:
You are a sick man Tom, I love it. Very cool use of gear, and some imaginative thinking.
Click to expand...

Thanks, guys. Monkey, you’re so right … and it’s just getting worse. You say you’re always trying to learn? Every time I pick up one of those rigging rings, I learn something new.


Here are some follow-up comments to the proof test ..

tREX, 3/4-inch

You can see in the video but I didn’t mention it … the tREX broke in the single strand center section. That means the terminal ends were not compromised and the cord delivered its full measure of MBS.

Teuf says it’s good for 22,998 lbs breaking strength, on average.


Stablebraid, 1/2-inch

I found two (2) tiny, temporary flattened dimples where the mechanical munters were pinching. No sign of any distress, melting, slipping o anything that would compromise the rope.


7/8” tREX Main Line

The sling looks awesome, like it didn’t even have to get out of bed for this fight.



If you haven’t done it, turn up your audio around 5:30 min into the proof video. You can hear the tension in the line, the fibers ripping and the sheave of the big snatch spinning after the break. That beast left a 7-inch divot where it landed after flying 12 feet.


If you care to see it, my rigging inventory is online with pix and specs at

https://www.dropbox.com/sh/vdh5zrbnn5gjfvm/AACI1U4gs69-n_Jd0UUHV65ga?dl=0

I’m moving to Asheville soon and I’m going to lighten up on my kit. Many of the Homeowner Associations don’t allow dogs or rigging pulleys bigger than 100 pounds. PM or email me (Tom@Hoffmann.net) if you have interest in pieces.



OF
 
Cool sling OF.

I watched the videos and just wanted to know for what job you would actually need or use this for?

Innovation that you come up with is always interesting just not sure when I could use this?
 
The trees are on drugs or something...or maybe it's me, but those trees are moving...like, wiggling. Did anyone else see that?;)

And OF, you are amazing. B-R-I-lliant.
 
John, your cartoon is terrific! Love it!
That shimmy is an artifact of the Google/YouTube stabilization software. I shoot handheld and the software takes out a lot of the shake but, in some scenes, the distortions are mind-blowing.

OF
 
Kevin,

That is a perfectly fair question and I’m not sure I have an answer for you. Under my YouTube posting, I say that I do not consider the E/E Sling to be a candidate to be a commercial product. Rather, I’m publishing more as a “proof of concept” for what can be done with rigging rings.

For me, the sling works nicely but only because of a very specific combination of application and pre-existing circumstances. I rip stumps with a high MA set up. For that, I have a beautiful piece of Amsteel II, but I wish it were longer.! I try to keep as much of it within the pulley system as possible so I don’t reset so often. The E/E Sling lets me deploy a 250 foot bag of light stable braid that I use for shoreline work. For me, It’s the classic “necessity as the mother of invention”. But if I were a working pro setting up my kit from the start, I put the cost of the sling into additional rope length and save the time associated with lace up.

I do like the equalization feature, but, here again, there are cheaper and easier ways to do equalizing bridle.


So what are these concepts that could have some value? I’ll do some spitballing here…


Multi strand to single-strand

The rope manufacturers have been doing this for years: taking multiple weak strands and making up one big strong rope. The concept may be useful for arborist applications, particularly when you don’t want to permanently commit to one configuration or the other.


High strength knotless connection

I was impressed at how well the rings treated the stable braid. It’s not hard to imagine a device to facilitate a knotless connection between two ropes of equal or disparate sizes. Picture a sling with rings in both directions, no shackle. Two ropes could lace up past each other from opposite sides . A low-tension stopper knot could take advantage of the rings ability to resist sideloading. My guess is such a device would deliver a nearly 100% strength efficiency.



Mechanical Munter


I believe the principles embodied in the “Mechanical Munter” could be a patent-able idea: using an incline plane as a force multiplier to rope friction. Conceivably, this could lead to a line of light, cheap double-rope hand ascenders with no spikes that you could also descend on. Maybe one of the hardware manufacturers might run with it.


Who knows, I’m just throwing stuff out there. I’ll bet someone once told Norm Hall “hell, just wrap it around the trunk”. Out came the Portawrap. You never know.


Regardless, I think the sounds on the Proofing video are the sexiest since ScarJo did that computer thing…!


OF
 
"...there are lethal forces involved here..."
It made for compelling and enjoyable viewing, even if it seemed several nanolevels in complexity beyond any rigging I'll ever try. Thanks Tom!
 
RopeShield said:
Interesting stuff.
Probably should have wrapped those tree with something to keep the pressure dispersed from the loaded slings.
o_O
Click to expand...
Good eye, RopeShield. At that force level, it doesn't take much movement to start to saw into the bark. I took some pix afterward, posted below. Nothing anywhere near the cambium, certainly gone by next year, but still you are right on.
Untitled%201.jpg


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Keep some of the old moving blankets.
Happy and safe move to you:)
I use to have an old piece of 3"dbl braid for this purpose. Easy to weave around the sling and lotsa cushioning. Burlap/jute roll is good.
Horse blanket seatcovers get used a lot aerially.
 
Nice tip, Rope Shield. I tried the "weaving" and it works great.


Separately, I got a good question about my use of the phrase “application regime”. Wazzup with that?

Mostly it means more than just strength or “safe working load". There are many ways these two similar-looking devices operate very differently …

  • The Thunder Sling operates on dynamic (running) rope; the E/E is a static connection.
  • The TS can deliver variable friction; the E/E is for knotless lockoff friction.
  • The TS supports a single-ended connection to the load; the E/E is double ended.
  • The TS delivers its force to one (1) anchor; the E/E divides the force to two (2) anchors.

Surprising, when so much of the hardware is identical … !

I am a huge fan of the concept of an Aerial Friction Brake. It's just that the E/E Sling isn't one of them!

Reg Coats has a great vid out where he discusses the safety advantages: 1)aerial friction cuts the rigging load on the crotch and 2)it presents much less variability to the groundie. The whole operation gets safer for the crew. There's no doubt in my mind that this idea will evolve, the hardware will change and techniques will adapt. But, somehow, it's going to be the future.
 
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