Which size Cobra?

[welwell]

Hello all, over the years we've installed quite a few cobra kits, but we have a large lime to brace soon, its about 28-30metres tall with x2 co-dominant stems that fork at about 3metres. These stems are approx. 80cm at the fork. we have reduced the tree -30% crown volume (at the most) but there are existing braces that have failed and so the client wants them reinstalled.

 

We have always used the 2 tonne kit in the past, but I think this is not going to be man enough.......question is go for 4 or 8 tonne kit?

 

Thinking 8 tonne kit........is this over kill?

[Andrew Gale]

I recently installed an 8tn cobra system in a Cedrus libani and although I thought it overkill, it has achieved the 'belt and braces' the client wanted.

 

The Lime does sound a beast and going by your description I'd say an 8tn would be ok.

 

As this sounds quiet a tricky one I'd also suggest you keep your justification in terms of bracing selection - see BS3998:2010 section 10.3 (2nd para last sentence); just in case........

 

Hope it helps..

[JaySmith]

The largest I've fitted is the 4ton have seen some 8ton and its a beast! It's hard to say without seeing the tree but also remember the 8ton has a lower service life than the 4ton

[Darrin Turnbull]

Maybe this can help.

 

http://www.cobranet.de/en/datenblatt/cobra_manual_US_20080829.PDF