boa bracing system?

[nod]

Hi Tony

 

Still interested in what folks use as a benchmark when deciding on what support system to use, but to answer. If you worked outside of our industry & required a contractor to install a support system for you exactly what meaningful information can be deduced from what the standard says apart from what materials to use?

 

Crown support is a complex & rarely straight forward operation that should be guided by an understanding of tree growth patterns, timber strengths & weaknesses, topography of the site & no doubt a whole host of other factors including physics, we're not dealing with architectural structures where tolerances can refined to the enth degree but we can go some way down that path. I just feel that our choice of system should be dictated by these factors & not by factors that are based on lack of information , convenience & the say so of those interested in making a buck out of the sale.

 

I've recently seen a 2ton polyproplene system with a shock absorber insert (cobra or boa) installed high in a Cedar of Lebanon where branch diameter is approx 40cm. My thoughts are, the weight below the installation point combined with small amounts of movements will more than likely snap that cord like it's a shoestring. The draft standards give no guidance & therefore no standard of what we should be installing only how we should install it. When push comes to shove & a court needs to refer to our BS standard, what is actually there of any worth? Then on the basis of 4.5:1 safety factor & the strength reduction of the system due to insertion of the shock absorber that system has a SWL of approx. 250kgs.

 

Maybe I'm being unecessarily sensitive!

 

Cheers

Nod

[Amelanchier]

Hi Tony

 

Still interested in what folks use as a benchmark when deciding on what support system to use, but to answer. If you worked outside of our industry & required a contractor to install a support system for you exactly what meaningful information can be deduced from what the standard says apart from what materials to use?

 

Crown support is a complex & rarely straight forward operation that should be guided by an understanding of tree growth patterns, timber strengths & weaknesses, topography of the site & no doubt a whole host of other factors including physics, we're not dealing with architectural structures where tolerances can refined to the enth degree but we can go some way down that path. I just feel that our choice of system should be dictated by these factors & not by factors that are based on lack of information , convenience & the say so of those interested in making a buck out of the sale.

 

I've recently seen a 2ton polyproplene system with a shock absorber insert (cobra or boa) installed high in a Cedar of Lebanon where branch diameter is approx 40cm. My thoughts are, the weight below the installation point combined with small amounts of movements will more than likely snap that cord like it's a shoestring. The draft standards give no guidance & therefore no standard of what we should be installing only how we should install it. When push comes to shove & a court needs to refer to our BS standard, what is actually there of any worth? Then on the basis of 4.5:1 safety factor & the strength reduction of the system due to insertion of the shock absorber that system has a SWL of approx. 250kgs.

 

Maybe I'm being unecessarily sensitive!

 

Cheers

Nod

 

No. I think on balance, you're probably not being unecessarily sensitive!

 

I think you're right in that there perhaps should be some guidelines for safety factors and tolerances. Is there perhaps an issue with attempting to give instructions or specifications that become over presciptive? Perhaps a seperate document would be needed?

 

I specify bracing here and there on the odd tree but mostly as a precaution to defend the retention of a high value tree. I defer the installation and specification to a specialist contractor who does his thing. Its certainly a bit of a mystical practice...

[MattyF]

Hi Tony

 

Still interested in what folks use as a benchmark when deciding on what support system to use, but to answer. If you worked outside of our industry & required a contractor to install a support system for you exactly what meaningful information can be deduced from what the standard says apart from what materials to use?

 

Crown support is a complex & rarely straight forward operation that should be guided by an understanding of tree growth patterns, timber strengths & weaknesses, topography of the site & no doubt a whole host of other factors including physics, we're not dealing with architectural structures where tolerances can refined to the enth degree but we can go some way down that path. I just feel that our choice of system should be dictated by these factors & not by factors that are based on lack of information , convenience & the say so of those interested in making a buck out of the sale.

 

I've recently seen a 2ton polyproplene system with a shock absorber insert (cobra or boa) installed high in a Cedar of Lebanon where branch diameter is approx 40cm. My thoughts are, the weight below the installation point combined with small amounts of movements will more than likely snap that cord like it's a shoestring. The draft standards give no guidance & therefore no standard of what we should be installing only how we should install it. When push comes to shove & a court needs to refer to our BS standard, what is actually there of any worth? Then on the basis of 4.5:1 safety factor & the strength reduction of the system due to insertion of the shock absorber that system has a SWL of approx. 250kgs.

 

Maybe I'm being unecessarily sensitive!

 

Cheers

Nod

 

what sort of system would you of recommened for the case of the ceder in question ???

I have not been sure about many of the cobra or boa systems ive installed would hold if put to the test but they would atleast steer the bulk of the failing limb away from the target!

 

I once saw a snow loaded steel cable braced cedar of lebanon limb that had snapped then catapulted back in to the remaining crown and hang up near the top! was in a church yard with loads of graves under it was a right pig to sort out but the bracing had held!I often wonder if it would of done the same with a different system installed.