# Cobra system



## Gopher (Mar 28, 2004)

Now that all of you have given me an earful of knowledge I don't have, I would like a little information on the cost to installa Cobra system in a mature sugar maple.

It is a three-pronged one, that has been slated for removal, and I agree that it should unless cabled. I believe this would ad the necessary few years to allow the owner to plant replacement trees nearby and get them growing.

Anyway, the distance bewtween the stems, I would guess, is about 15 feet two-thirds the way up the canopy. Also, would all three be cabled together, or just two of the three legs of the triangle?

If the cost is significantly higher for Cobra, then I would go with the oft-used steel. As I said, the tree won't be there for, at most another four or five years.

I will also try and put a picture in, but my staff technology person (better known as Lynn - my wife) is sleeping! And I am here talking to you smart fellers (but ugly!) I'm the one that needs to be examined!

Gopher


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## John Paul Sanborn (Mar 28, 2004)

Material cost is a little higher, but the labor cost is lower with the cobra. No drills and the splice is simple.

With Cobra each leg is seperate (Libra you can do triangle W/O cutting the line. But i don't know of anyone who carries it).

Fresco's Guardian system is cheaper then cobra and uses a simple Brummel splice and does not have the inserts that Cobra has, so even less time involved. 

I would say i could do it in 1.5 hours while showing you if you dont need to pull the tree together.

How long do you expect to keep the tree?


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## Gopher (Mar 29, 2004)

*HOw long?*

I will find out on April 6th if we can keep it - I would say in the neighborhood of 3 to 5 years, probably not much more.

It is a terrace tree - it needs to be there to help keep another tree that is very narrow due to close proximity while growing.

I'll keep you posted - as I am sure they will have me do it if it can stay.

Gopher


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## Kneejerk Bombas (Mar 29, 2004)

What is the reason the tree needs support? Is there a crack?


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## Nathan Wreyford (Jul 13, 2004)

This poor little thread was abandoned 

Thought I would resurect it to ask if anyone does any DYNAMIC cabling??

I am assuming most knowledge here is limited to an ad in the sherrill catalog, etc since I see so little posted here.

I install, on average, 4 systems a week.

Any thoughts?

http://www.cobranet.de/en/index1.htm


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## ORclimber (Jul 13, 2004)

Not nearly as many as you, maybe a dozen a year. Cobra is so easy to install. TreeSave gives me fits though, milking the fid through the center of the rope major PITA. Anyone have any tips to make it easier? If not, that gear will probably end up for sale.


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## bushman (Jul 13, 2004)

DO you think installing cobra cabling is better for the tree, then drilling into the tree and installing eyebolts. i was told that the cobra had to be ajusted alot , meaning a year or two.


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## MasterBlaster (Jul 13, 2004)

The Cobra system is superior. Just more costly.


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## Greg (Jul 14, 2004)

What do you guys charge to install cable? Around here $500 per cable(steel) is pretty much what everyone charges. 
I always have a hard time in my head justifying the application and don't sell cables unless some one really wants it. I think if a tree can not stand on it's own safely then it should be removed, if it is a hazard. Never installed cobra, but a friend I work with did and he loves it, very easy on the climber compared to steel.
Greg


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## Nathan Wreyford (Jul 14, 2004)

> _Originally posted by bushman _
> *DO you think installing cobra cabling is better for the tree, then drilling into the tree and installing eyebolts. i was told that the cobra had to be ajusted alot , meaning a year or two. *



By the time it needs adjusting for girth, it needs to be moved. Same as steel cables. Just a whole lot harder to install steel.

Plus steel frequently causes failures.


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## NebClimber (Jul 15, 2004)

I'v got a question:

Cobra is designed to expand as the tree grows. Each loop encircling a limb has a "growth leg" - an extra length of material that feeds into and expands the loop as the tree grows.

How does this work? I mean, why is it that the growth leg feeds into the loop as the tree grows, but does not feed into the loop during during the tension of high winds?

Steven


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## Nathan Wreyford (Jul 15, 2004)

Good question, but obvious if you use it.

1st, lets start with the *FACT* no cabling system can be left alone. They *ALL* require maintenance and check ups.

So, the extra material feeds in and expands the loop when you climb up there and milk it through.  

I find that pointless. These sytems are so cheap and quik, we just reinstall if they are very old. Plus their strength does degrade over time.

Hard to remove or install a steel sytem without damage. Not to mention a tree becomes dependent on a steel sytem do to the lack of reaction wood caused by the sytem.

A dynamic sytem allows a tree to build reaction wood.

.02


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## nod (Jul 17, 2004)

Hi Nathan

You wrote, 
"Hard to remove or install a steel sytem without damage. Not to mention a tree becomes dependent on a steel sytem do to the lack of reaction wood caused by the sytem."

Could you expand on this as I'm a little confused by what you're saying.

I worked in Sweden 10years ago & installed far too many bracing systems, there also seems to be a good generated income in Germany for unecessary rope & cable systems! What do you feel about this?

Cheers Nod


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## Nathan Wreyford (Jul 18, 2004)

Hey Nod!! Good to hear from you.

I was merely referencing that steel systems prohibit a tree from moving naturally with the wind, thus inhibiting the growth of reaction wood. So you end up with a stem no longer making reaction wood and quite possible failing due to the karate from a static sytem.



> there also seems to be a good generated income in Germany for unnecessary rope & cable systems! What do you feel about this?



I couldn't agree more. But hey, in tree work much of what we do is for people not for trees. To make them feel "more safe". Or we nit pick half inch and smaller dead wood out so the trees "look better" or "healthier" (live oaks come to mind here). Some clients need a psychiatrist, not an arborist. Bottom line is the only 100% safe tree is the one that is chipped and at the dump. 


I do mainly city contracts. We cable about anything with included bark. Especially if it bulges where they meet. I quickly get to the point where I think, "If it is so dangerous, why not just remove it?" I am not referencing specimen trees when I say that. I mean 18"dbh maples with terminal defects.

Unnecessary, yes, I agree. Fear is always a popular product to sell and "tree professionals" often capitalize on this.

As for me cabling so much when ordered to - I am very much just a monkey right now. A bit stuck in a rut at the whim of other "professionals". I never stay stuck in a rut too long. I always get out though I may have to sling mud or burn rubber to do so


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## Gopher (Jul 18, 2004)

*The rut may deepen...*

Good points, Nathan. Do not let your experience in the tree be overshadowed by beaurocracy on the ground. Be politically savvy and help determine the outcome.

I have not done too many cable jobs, and have only assisted on one cobra system (a multiple attachment in a large tree.) 

I still go back to the "Wye Oak", which outsmarted us all for about 460 years (1540 to 2002). There was something like 3200 feet of cable in that tree, and I'd like to think the arborists that cared for this tree gave us a few more years over doing nothing.

I still am looking for someone to get me some information regarding the soil type, and any information on who cared for the tree as well as cabled it.

Thank you.

Gopher


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## Guy Meilleur (Jul 18, 2004)

"If it is so dangerous, why not just remove it?" I mean 18"dbh maples with terminal defects."

What kind of defects are terminal? I use that term too, but very cautiously, given the many ways trees can have their useful lives extended. How long does it take to grow another 18" maple? I'm not that young; would rather preserve if at all economically feasible. And a hard look at the numbers will show that preservation often makes $en$e.

But I know what you mean about over-supporting; we put on a workshop here a few years ago and invited a large company with yellow trucks to demo cabling and bracing. They looked at all the Ulmus parvifolia and said they all need hardware to reliably stay together.  I said subordinate, subordinate...

"I still go back to the "Wye Oak", which outsmarted us all for about 460 years (1540 to 2002). There was something like 3200 feet of cable in that tree, and I'd like to think the arborists that cared for this tree gave us a few more years over doing nothing."

Dave, I wonder if that tree would still be outsmarting us if it had been reduced instead of strung together with all that metal. Rumor has it that some Europeans said early on, "Why not shorten it, it'll last much longer", but were outvoted by the drillers.
 

I believe everything Nathan said about static systems and karate whipping. Better a smaller, safer, longer-lived tree. Us Americans have a lot to learn about pruning for the tree's own good.


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## Gopher (Jul 19, 2004)

*The survey says...*

Well, the maples are gone. The City decided to start there on their removal process based on their inventory, which was a good one, but they will more than likely not get to all of the trees this year (40 - no money) , so I was trying to be practical and save these trees for the end of the list. It made sense to me, but there I go again, thinking...

Yes, Guy, the reduction would have been the answer, if the impetus would have been there to keep them for a couple of more years. It was not. they are gone. Next question now!

Have a good one.

Gopher


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## Nathan Wreyford (Jul 21, 2004)

*Bump!!*

Since I installed 5 cables today just thought I would bump.

2 in a linden and a triangle in a psudoplatanae

Ok Guy, terminal defects..... they exist. Let me just say tree has zero chance of reaching maturity or a mature tree that won't see the next decade. Nothing as simple or petty as included bark, etc.

I like cables even when unneccessary because I prefer that to an unneccessary limb/stem removal.

Subordinate? Sweet music to my ears. My coworkers tend to reduce an entire crown. I subordinate growth ala Gilman style. I wish more people practice subordination over pure reduction. For example, in a classic double leader included bark senario, I lean towards subordinating one leader over reducing both (with or w/out cable).




> And a hard look at the numbers will show that preservation often makes $en$e.



Agreed, but sometimes, as Gilman says, a tree is in jail after 20 yrs of neglect. In some cases it makes more $ense to remove and start over. (redistribute the growth potential to a new tree ) I don't like ringing the cash register on anyone. I like to lay options out to a client and let them spend their money. Sometimes it is worth it to them to have a few more years with a beloved tree even if it is in a terminal situation.

.02

I'll take cable pics soon.


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## Gopher (Jul 23, 2004)

*I like you style...*

Nathan, I like your style. 

There are no absolutes in nature.

We can preach all we want about virtues, butwill they keep a client happy for a return visit?

Often times we talk about, "Is it the best for the tree?" Is it best for the tree/tree owner relationship?

I worked on a very old suger maple tree last year; it may be close to 200 years. Anyway, someone many years ago had placed tin over a couple of holes in it. I removed one piece (about 15 cm square - it almost fell off) and the other has grown into the tree. Under the one that came off was the nicest sealed healthy looking scar tissue. The whole tree looks good. 

Would we have laughed at the person for putting the tin on? Was it an experiment? No, I don't condone the use of cement in cavaties!

Anything else on this summer evening?

I have a tall black locust to cable and do a stem reduction on tomorrow. Yes, I did let it be known that I recommmend removal, but at least for the forseeable future, it just ain't going to happen. I believe I have expressed all of the concerns I have, but we could remove just about every tree due to something, couldn't we?

Have a good Friday, all.

Gopher


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## NebClimber (Jul 24, 2004)

Someone please answer me this question:

If I install a Cobra system, and the stem being supported completely fails, will the Cobra hold the stem from falling (assuming the Cobra would otherwise be strong enough to hold the stem), or will the Cobra "self-adjust", pulling its tail thru its "growth loop" until it completely pulls apart?

Sounds like a dumb question, but the Cobra advertises itself as "self-adjusting", and I find this a bit confusting.

Steven


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## Kneejerk Bombas (Jul 24, 2004)

Once there is presure on the rope, it no longer adjusts. That's how splices work, the more load on the rope, the tighter it holds the end. 
In normal rope splices you need to whip the tail to keep it from pulling apart when it's not loaded.


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## NebClimber (Jul 24, 2004)

OK Mike, I guess I understand that the splice on the Cobra system acts like a Chinese finger trap, but then how does the Cobra "self adjust"?

My assumption is that, because the tree grows slowly, it will slowly pay out line thru the splice without tensioning the line, thus allowing the tree to adjust the line as circumference of the tree increases.

Sound right?

Steven


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## John Paul Sanborn (Jul 24, 2004)

> _Originally posted by NebClimber _
> *
> 
> My assumption is that, because the tree grows slowly, it will slowly pay out line thru the splice without tensioning the line, thus allowing the tree to adjust the line as circumference of the tree increases.
> ...



In theory it is. Sometimes it needs a little encoragement.

this is why we are to install it slightly slack.

To paraphrase Nate, once we modify the tree with a support system, we need to monitor that system, no matter what is is constructed of. A good buisness man will contractually put the responsability for schedulling the inspections on the property owner. The make file notes to call to set an apointment at a determined interval. 

This may be a 1 month then 1 year the every 3 years after that, or mor or less depending on the nature of the defect being supported, and the vitality of the tree.

If the property owner is a client, then the company will be on site with enough frequancy that inspection will be a matter of course.


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