Mass Dampening, rigging and leaving some brush....

[Matt Follett]

Just from another thread, got thinking about climbing on cleaned spars, and also rigging on them.

I try very hard to ensure I have a bit of brush below my tie in point left on the tree when doing a removal, and when "taking the top out"

I find it makes things far less shaky, and I'm am less worried (rightly or not) about total tree failure.

 

[MasterBlaster]

The more brush you leave on the tree, the less of a ride you take. The trick is not hanging the limbs yur roping up on the limbs you leave. Ya gotta cut a proper descent pathway, and have a good person running yur rope.

 

[Frans]

I dont know the technical answer to the question of "does leaving brush add to, to take away from, the strength of a tree"?
When brushing out a tree and I am nearing the top I check for the amount of flex in the trunk. This is done really from the moment I leave the ground. By how the branches hinge, bark flakes off etc.
My thought is: if a tree is under load, it cannot bounce. When this happens I imagine a rubber band stretched to it's limit. At that point the rubber band stops stretching and stops. The next moment it will break.
So, if a tree is not flexing because of whatever reason I suspect it's strength.
On the other hand rigging out a top without any lateral branches on the main stem makes it bounce alot. This bounce I know can set up an effect of slinging the trunk about which can cause it to break.
I still prefer rigging out of a stem without any branches because I believe it is stronger.
Frans

 

[John Stewart]

Never really thought about that point Matt but the bigger the hinge the bigger the ride! or not sure depends on my mood
If you got the balls keep cutting as the top hinges over and the ride and failure in my opinion will be less
What do you guys feel about my opinion on the failure part because it is absolutely true on the ride part!
Later
John

 

[Matt Follett]

Yeah John, I think cutting through the hinge at the end can reduce the convertable effect, perhaps due to the reduction in the top pulling on the stem before the face closes, or as it closes, this would be one for Spydie to discuss...

I tend not to though, as I think... in the deep recesses of the abyss I call my head... that that pulling force is energy being wasted on crusing and tearing the fibres apart, and better wasted there then in heat in the rope (= increase in momentum and therefore higher loading). Although this is probably some infintisimal (spelling?) amount and I would be better of letting the piece go clean... The lesser ride suggests that the clean sweep method reduces the loading, unless we could determine if it is a compounding effect (load the stem, release, caught in rigging, load stem again effect)

Do you find a difference depending on the the size of gob (opps thats the english getting out, blasted Lorraine) I mean notch, with regards to ride effect... ie more acute notch=bigger ride?

 

[John Stewart]

Hey Matt
When I am blowing a top out I always use a open face cut so the hinge doesn't load up on me and take me for a convertiable
I can't say I think about the frition on the riggin! Especially since I pretty much always use a block. If I was natural crotchin more, I think that might be a issue and even then, I would still use the same method but I would switch to a 3 strand lowering rope to reduce the melting factor!
Let me know what you think as this is just observations that I have made and nothing in writing to support these thoughts.
Later
John

 

[Matt Follett]

John

Was thinking about block and porty/brake lowering, still have to loose that energy somewhere.. heat in the porty... You should see the burn on our old stable braid from a big top this spring on the GOODS drum! yikes! I'll lend it to you some day ( he he the rope that is)

 

[Matt Follett]

This again brings up another thought on natural rigging verses blocks and brakes... This fall rigging out a really hollow, really dead, really scary big old oak.. I natural crotched the top in the thought of reducing the load on the spar (the doubling effect at the block with a brake)... And I got me once again thinking of all the crazy stuff we have, and the increasing unkown... the tree! Might sell all the rigging, and buy some old Manila!

 

[John Stewart]

Ah you got me all horney for a moment
I got a scary arse one coming up maybe we could play!
Can you ice pack that sucker or is it just as it is?
Is it worth the bucks?
Later
John

 

[John Stewart]

It does make you pause but I think we are on the right track

 

[Matt Follett]

Yeah you can ice the drum... did on a big poplar job this spring, not sure if it made any diff though

Ah I think I'm hi jacking my own thread!

 

[John Stewart]

Ya but that is cool at least this thread has a point
OOPPS did I say that out loud!:blush:
Sorry
Tee Hee
Later
John

 

[Nickrosis]

Originally posted by Frans
I dont know the technical answer to the question of "does leaving brush add to, to take away from, the strength of a tree"?

Not picking on you, but you brought it up.

Limbs have a dampening effect by absorbing the wave motion created by knocking the top out. As that side-to-side motion is created at the top, it moves throughout the tree and is dispersed.

With limbs on the tree, a quiver and the energy is absorbed as every little leaf or needle shakes and absorbs the energy. Without limbs, the whole spar must sway to absorb the energy and eventually gets it passed off through friction in the air and, most importantly the ground and fibers in the trunk.

We also know that guying a tree will help. These guy lines are taking much of the force (if taut) and passing it to their anchors as well.

The limit of this arrives when the trunk cannot sustain the force of a top being dropped. So, even with all the limbs on a tree, knocking the top out could bring the whole tree to the ground if a compromised root system exists (has happened in Chicago). There, you have to consider other factors because the tree is about to fall over on its own weight.

In such a case, I believe leaving limbs will help but that guy lines and/or a crane is necessary. Leaving limbs allows parts other than the compromised trunk and roots to absorb the energy.

This has been researched lightly in our field.

 

[NeTree]

I like to leave some brush up if I can. After all, a convertible can be fun sometimes, but it gets old.

 

[Treeman14]

Sun hot.

Shade good. :angel:

 

[NeTree]

Originally posted by Treeman14
Sun hot.

Shade good. :angel:

Good point.

 

[Frans]

O.K. take a tree with a lean. The branches and top all work together to weight the main stem to its limit of elasticity so the main stem no longer flexes. When I am climbing such a tree I think cutting the limbs off make the main stem stronger because when I do so the main stem moves back up and begins to flex back and forth again. In this case I believe cutting the limbs off make the main stem stronger.
Also popping the top off and then using the main spar as a rigging point for other rigging needs is good even tho the spar now flexes alot. Leaving the top and branches spaced out along the main stem may achieve the 'dampening' effect but can also lessen the total amount of weight that the spar can carry.
I am aware that without some sort of dampening effect the spar can fail from excessive loads but allowing the load to run provides alot of dampening in and of itself.

I think it really is a case by case scenerio and a climber really should not just mandate that leaving branches and the top is always safer.
Frans

 

[TheTreeSpyder]

i try to pattern the unloading of the pulls destabilizing pull agianst lean to best advantage, sometimes bracing agianst lean or to opposing sides to stabilize more. Releivieng weight makes stronger in sense you can now carry more weight on same member, but there is more shake. If you took a large tent; and braced back against the lean to center to keep tent high; you would set line brace to equate loading to other side from weight, opposing brace etc.; no more no less dialed in just right. For if you take some of the opposing bracing or weight off or loosen present brace; the system may be able to take more pulls tensile wise; but wil be 'unsprung', sloppy etc.; less mechanically sound etc.

i think that the 'feathers'/leaves can dampen stalk shake as well as the falling force of the piece. Lower CG is more stable and less leveraged. By inertia, the increased weight, would be more dififcult for the forces to change direction and speed of. So if it is heavier, and sitting still; there is a componenet that says it is less likely to move at all.

i think that leaving weight below the CG stabilizes and keeps CG low. Taking low weight off raises the CG leverage point from the ground, and gives less low carried weight as wide as possible type stability to compound the effect; especially when altering width part of 'formulae' isn't an option.

When topping and not catching i try to get it to lean and pitch off of me quickly before getting very angled and push/pulls come across 'stump' rather than down it at tearoff; kinda a feel when it will be most neutral re-lease.

 

[Lumberjack]

If I am working from the bottom up then I dont leave limbs. If I am working top down, I will only remove the limbs that are big enough to change the direction of the top.

Creating the friction at the top of the spar will cut the load in half (approx.) as opposed to using a block.

 

[Scars2prove-it]

Originally posted by Frans
but allowing the load to run provides alot of dampening in and of itself.
Frans

I agree. As long as you can get the groundman to consistently let it run. I think we should make the groundman that holds the load go up the next tree and see how he likes it. I always expect the load not to run and quickly snap my saw and hold on for the ride.