what's the first mistake made in this rigging failure

A better placement of the sling would have helped make everything more controllable. But bottom line is the rope broke. If the piece remained attached to the rigging and had hit a target as a result, then the conversation would pertain to the sling setup.

So, too much of a shock load in combination with too big of a piece broke the rope. Looks like at the knot. Bigger rope plus not locking it off and it probably would have all been fine. Maybe the sling would have broke if the rope hadn't
 
Jack Valenti said:
A better placement of the sling would have helped make everything more controllable. But bottom line is the rope broke. If the piece remained attached to the rigging and had hit a target as a result, then the conversation would pertain to the sling setup.

So, too much of a shock load in combination with too big of a piece broke the rope. Looks like at the knot. Bigger rope plus not locking it off and it probably would have all been fine. Maybe the sling would have broke if the rope hadn't
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Jack for the win!
 
Looks like a candidate for the safe bloc. That slings gonna stretch no matter what although it could of been neater. I bet they were using that rope all day and were thinking of switching on the next cut
 
I could be completely off, but the first time I saw that I think it was said that the break was done as some type of gear failure demo for that particular method. Some type of teachable moment intentional accident? I don't remember for sure, go figure!:sorprendido3:
 
southsoundtree said:
Slung the block way too low, poorly dressed, and slack in sling.
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You're like the smartest kid in math class that spits the answer out before anyone else has a chance to figure it out...

Sling should have been above the cut limb... the piece drops 2' for every foot the block is below the notch. That extra drop gets the force multiplier WAY up there...... Lots of other possible improvements could have made a difference, as mentioned by others... even the knot... BUT IMO the first mistake is setting the block too low... He could have left a little stub on the limb to secure the sling.... heavier rope, more stretch in the rope, one less wrap etc...

I actually broke a rope a few weeks back. Funny thing is someone asked me if I had ever broke a rope the day before. I AM quite sure the rope would have made it if I had doubled the bowline, which I almost always do , but I spaced out on this one... Nothing damaged. I was just protecting the perennial shrubs in the bed, and the rope ended up swinging the piece into a nice drop zone before it broke...
 
I would argue the removal plan was flawed and thus the rigging plan was flawed. Why was a piece that large and that close to the ground being rigged in that manor? Certainly there should have been no expectation that the piece was going to be slowed safely to avoid a crater, so why rig it. If bouncing away is a concern, vertical speed line is a great option. Rig a smaller piece or chunk smaller pieces. All safer options.
There is a propensity in our industry to get sloppy when we get to wood. Probably because it’s the end of the day, we are tired and we have had enough. The eyes get bigger, we get braver and take bigger chances. “Go big or go home”, right?
 
Daniel said:
That piece seemed small to me.... guessing he had to keep it small to clear the ground.... I rig pieces that heavy on 1/2" true blue all the time..
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I agree that 1/2" is fine for wood that size.......when there is room to let it run. This looks like he purposely dropped it into a static system
 
RELATIONSHIPS!
Get you every time!
No singular consistent value is always right; everything is a perspective from a given benchmark...
So, even for pine, that rope just looks puny to the load.
i can't see all of kill zone, but kinda wonder why rigged?
>>If just so wouldn't run from stump, gives more options/less control needed.
Side chose to do facing, eliminates some choices i'd favor; but once again can't see kill zone fairly why dumping to that side
.
If 1 uHual runs into unyielding stone wall; it is like it is hitting it's own mirror force speed/weight/deforming reliefs
>>if uHaul_A weighs 2x uHaul_B (magically matching in all other aspects); square head on MATCHING SPEEDS uHaul_A walks thru uHaul_B
>>same scenario uHaul_A weighs 2x uHaul_B; but uHaul_B 2xSpeed of uHaul_A ; walks thru uHaul_A absolutely mecilessely with even more force than _A just tore _B up with; the speed value rules..
in the force formulae, weight is a multiplier but it is speed squared that rules
i would have tried for slower hinge over on such a short piece,where CoG reach wasn't as bad;perhaps opposing guy line to take force.
wider face, tilt over with rope, and semi-truck trailer tire spoon from rear to force stronger, slower hinge
i woulda then perhaps hung on the back side of tipping load perhaps stretching out as far as can as ballast of CoG on other side of hinge pivot to further slow on hinge
>>not that there needs to be,but i see no forward pull on spar on tip, more of a free fall on pivot than controlled hand off
>>i didn't inspect stem myself on way up, but if solid, and that much top already off stem; i GUARANTEE it can take some hit/windloaded much more in lifetime in daily exercise, jest sayin..
>> for softer hand off primary input into next stage of system...
strictly speaking CoG is behind hinge so is backleaner strategies to me
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But the next stage is to same point eventually: peak force into system produced and specifically what is handed off to next stage
The spread from the primary hitch on load to the block support on anchor to give so much impact from acceleration/drop trying to beat out at hinge previously
>>The CoG of target load distance from same block support on anchor point for another view..
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But, in the mr. Miagi sense, best way to win fight; is no be there; as Cain said somewhat too the grass that bends is the one that don't break...
Only parts of force resisted by friction control(?) loaded in rope.
even more elasticity might have helped mitigate.
Or run/free dump into softer matting of any deformable items that also spread out force
Also, am a great fan of pre-tightening; even if while also slow tipping!!
Also, i woulda gone over the top with a pull line for highest leveraged, most rotational force to place on hinge rotation.
If drop was longer, more line in system, more elastic respond mite work
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note:in somethings; especially longer / farther out CoG wouldn't chance the slow rotation due to CoG leverage
>>here think i'd consider, along with possibly opposing guy rope out other side as perpendicular to spar as possible.
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side note: for any BackHand based hitch (Cow, Timber, Muenter types etc.) i STRONGLY prefer not just a single, simple, deforming Turn around Standing Part that holds block etc. in hyperloading situations.
i preach Round Turn to not just deform('weaken') but re-firm(bolster some 'strength' back into deformity) Standing Part; and geometrically perhaps pull more along the rope device Standing Part by some gripping preserving more of the Pure Inline profile.
In any case best securing Nip is 180degrees from Standing Part pull on firm convex.
 
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I agree that it's obviously a test-to-failure. They should have put an enforcer in the system. If the block is up higher and/or above the knot, it might come over the top at the climber, so it's well-placed. The video is frustrating to watch until I understood what they were doing.
 
It might be a test to failure, but that's not what it says...
It says one of their clients gave them the video... They may have asked them to perform the task... does it say that somewhere...

If it was a test to failure, the climber looked safe enough... Probably better to do such things out of the bucket truck..
D
 
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