Hollow plaited rope for owl box

[openspaceman]

I am in a discussion about  mounting for more tawny owl boxes in a local park. The owl people specify mounting the boxes to the tree with a foam plastic sheet between the box and bark with four galvanised steel coach bolts securing the 12kg boxes to the tree.

 

This is a bit of an anathema to me so I was wondering about a cheaper than cobra bracing  with similar resistance to sunlight to give a 10+ year life.

 

I was thinking using it like the way we used hollow braid rope passed through itself to attach flying bollards, thoughts anyone?

[GarethM]

What's wrong with a A2/A4 stainless bolt into the tree, pretty cheap, personally I'd say two directly down the middle.

 

Anything galvanised is asking for trouble long term, firstly the zinc then the steel corroding.

 

Plus if it's oak you really need a non reactive metal such as stainless, or a building would be preferable.