Tie-in fail

Ther was no working it back into the crotch...his rope was in a crotch, and it failed 4' below it (1' above the crotch below)
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"Kiss My Axe"
Associate degree in forestry from PSU Mont Alto
Certified Arborist
Owner/operator of Climb High Tree Service established in 2002
www.climbhightree.com
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yoyoman said:
This certainly is not about SRT vs. DdRT or even DSRT
It is about picking TIPs and then what system you will use to access the tree with that and the MANY ways to make it work.
Every tree is different and each one may require something different.
I think I'm going to take the ATCC climbing club thru the woods and look at MANY trees and talk about how each one could be set up, including SRT with multiple anchors or back ups etc. talk about forces, species, angles etc.
Maybe that would be a good training session in the work place so that this "engineering" the tree thing can be learned.
My laser pointer is going to get a work out.
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Exactly.

Never never get stuck in one approach, climbing system, or even setup system.

It is why I still teach new cl8mb er old school methods of climbing and line advancement.

"Kiss My Axe"
Associate degree in forestry from PSU Mont Alto
Certified Arborist
Owner/operator of Climb High Tree Service established in 2002
www.climbhightree.com
https://m.facebook.com/ClimbHighTreeService
https://www.youtube.com/user/climbhightree
https://www.youtube.com/user/2treekiller2
 
macswan said:
I think you wind up loading branches just as heavily on ddrt ascent as base anchor. When you exert the 2 to 1 pulling yourself up.
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I don't think so.

ddrt or being 'cinched' in would only have presented 1/2 of the load on the limb that failed. As the climber made in over half way up I predict that the limb would have held using ddrt or being cinched in. The doubled forces generated by a base tie was likely a critical factor. That and a poor choice of tie in points.

I'm so glad he made out as well as he did and wish him a full and speedy recovery.
 
Most of the time I base tie for SRT. If my rope goes over a branch for the TIP I'm diligent about wrapping the down leg around the trunk on the way to the ground. The friction gained from the wrap and also a slight redirection of the load, around the trunk, dissipates some of the shear load.

At every branch union there is a trunk/branch relationship. Wrapping over the branch puts all of the load on the branch collar. Getting the rope around the trunk takes a load off the branch collar.

Without a better 'map' of the tree showing the angles of the branches and dimensions it would be really hard to conclude what happened.

From what I can see and guess it looks like the TIP was in smaller diameter wood than I would have used. It also looks like the branch broke because of the levering forces.

Something else I'm seeing in the butt of the broken branches is what looks like odd faces on the ends. They seem a bit too blocky rather than long angular fibers like I expect to see in a solid ash. When I've seen blocky ends like that it reminds me of what looks like early white rot. Might the tree be in decline? EAB stress is possible.
 
I don't want to start a jihad here, but I don't think there is a mechanical advantage (and the concurrent multiplication of force at the anchor) in Ddrt. There is no moving block in Ddrt; it's exactly the same as a change of direction single pulley set up, except the input is anchored to the load. That means the load is shared by both legs, which is what makes it easier to pull than a choked SRT line. If you hung your friction saver or a pulley off of a load cell, I am certain you would be see body weight, unless you were actively pulling (read: humping like a horny but injured hipo) or you had some of your weight on the trunk or a union. This is an important distinction in the current discussion.

When I heard about this accident, I had just come down from deadwooding a white ash, which I accessed via a base tied SRT system. The throwline was installed by a coworker before I arrived, and was 70'. The combined weight of me and the other climber in the company is over 525 lbs, more or less evenly distributed.

Please send my best wishes to your guy.
 
TreeCo said:
I'd just like to repeat what has been mentioned, that there is no good reason to be in a crotch that far from the trunk on a limb that size. Take the time to re-shoot.
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Other than it was the highest most central crotch in the tree. I can see why he shot for it, just should have had it backed up more...and/or worked his way into that crotch from one a bit lower and bigger.

PS - I don't think he is currently a member of this forum, but I did send him a link to this thread...so he has/is reading it.

"Kiss My Axe"
Associate degree in forestry from PSU Mont Alto
Certified Arborist
Owner/operator of Climb High Tree Service established in 2002
www.climbhightree.com
https://m.facebook.com/ClimbHighTreeService
https://www.youtube.com/user/climbhightree
https://www.youtube.com/user/2treekiller2
 
climbhightree said:
Other than it was the highest most central crotch in the tree. I can see why he shot for it, just should have had it backed up more...and/or worked his way into that crotch from one a bit lower and bigger.

PS - I don't think he is currently a member of this forum, but I did send him a link to this thread...so he has/is reading it.
Click to expand...

I find myself quite often going for the ultimate crotch with my line toss from the ground, often taking more time and throws than I'd be happy paying someone else to take.

Lots of time when I get in the tree I see the crotch I wanted so badly is right in reach from the larger, stronger, easier to hit lower crotch that I settled for and can easily just move my climbing line once in the top of the crown.

It's great of you to have this discussion here.

......and to the injured fellow............................we love you man! :birra:
 
Please correct me if I'm wrong but I just want the comparison to be clear.

  • DdRT - 100% of climber load on TIP (both lines share 50% load summed at the TIP and the harness)
  • SRT Canopy anchor - 100% of climber load on the TIp
  • SRT Base anchor - 200% of climber load on the TIP. This is because the climber has 100% on the harness - which has to mirrored on the other leg, so there is 100%CL on the base anchor - and the sum at the TIP is 200%.

So if you're going to climb on something you are not really confident of especially where there are not "backup" crotches to catch a falling line, canopy anchor has be a strong contender - as it is the equal of DdRT in terms of TIP load.
 
Paul Hedderly said:
Please correct me if I'm wrong but I just want the comparison to be clear.

  • DdRT - 100% of climber load on TIP (both lines share 50% load summed at the TIP and the harness)
  • SRT Canopy anchor - 100% of climber load on the TIp
  • SRT Base anchor - 200% of climber load on the TIP. This is because the climber has 100% on the harness - which has to mirrored on the other leg, so there is 100%CL on the base anchor - and the sum at the TIP is 200%.

So if you're going to climb on something you are not really confident of especially where there are not "backup" crotches to catch a falling line, canopy anchor has be a strong contender - as it is the equal of DdRT in terms of TIP load.
Click to expand...

It depends on the angle of the rope going through the tree as to whether the load is doubled. Also friction at the anchor point can effect the load as well. This article has been posted here before but it is so good I'll post it again. towards the end is where it talks about rope angles.

http://vtio.org.au/Content/wp-content/uploads/2010/07/Single-Rope-Technique-i.pdf
 
Really appreciate Paul and treezy summing that up .. Saved me the typing..:birra:
To the climber who fell glad your not dead or or paralyzed for life or in worse shape than reported. Good luck with your recovery.
 
In a base anchor the 200% is ideal in a frictionless environment with the rope's two parts parallel to simplify the calculations. Rope angle then plays a part in the forces acting on the tip. If you think in terms of breaking down the force in terms of horizontal and vertical forces these vary with the angle while the force in the direction of the load remains constant. That is while it's not being accelerated, i.e., energy input into the system. As that angle increases from the vertical (as in your moving outward away from a direct downward force) the force acting horizontally on the TIP increases. Now you no longer have just compression but also moment, a force at a distance from some point where there is rotation. It's where that point is likely to be on the limb that becomes a major factor. We can assume it to be the branch collar but, it could be elsewhere if there is a defect reducing the strength of the limb at a point somewhere between the collar and the TIP.

Sudden acceleration, like thrusting your body upward increases that load depending on how quickly you accelerate your foot. All of this and some unseen internal defect such as in my case and in this one where with each spike in the force a few fibers fail until the critical point is reach and you have catastrophic failure. It was telling that he felt something wasn't quite right and was about to or in the process of making some sort of adjustment.

Physics is our best friend or worse nightmare....
 
macswan said:
I think you wind up loading branches just as heavily on ddrt ascent as base anchor. When you exert the 2 to 1 pulling yourself up.
Click to expand...
TreeCo said:
I don't think so.

ddrt or being 'cinched' in would only have presented 1/2 of the load on the limb that failed. As the climber made in over half way up I predict that the limb would have held using ddrt or being cinched in. The doubled forces generated by a base tie was likely a critical factor. That and a poor choice of tie in points.
Click to expand...

While in ddrt ascent you are definitely adding more than your weight,at least 1.5 times your weight on any given pull. Now add some friction into that and your bounce from the hip thrust ,you are probably approaching equal loads that a base tie will apply.

Im even inclined to suggest that the weight is 2x the load at the tip,while ascending ddrt. Someone tell me why it isn't,cause we know its that way with a static load and two legs,when you go for the thrust dynamics are definitely changing .
 
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