Arborists often need to provide structural support for trees through the use of either fibre ropes or steel cables to secure the stability of the major elements of the tree.

There are several different approaches to bracing a tree but the Cobra System is one of the most popular and best. It is easy to install, will cater to many different types of defects and instabilities, does not require any specialist tools or training, and is completely non-invasive to the tree.

The Basics of Tree Bracing

Some trees can end up growing at a rate and in a direction that makes them unstable. Part of the tree or even the whole structure may be in danger of collapse. In other instances, damage can come about through storms, vandalism or interference from other elements. If a tree is unstable or damaged, this clearly presents a danger to the public and to other structures around the tree. Trees that have multiple trunks and trees with open canopies are most likely to be unstable.

Supporting a tree with cables and/or rods is referred to as tree bracing. In general, tree bracing is used to:

1. Prevent failure - reduce the chance of a healthy but weak tree structure becoming unstable
2. Restore damage - to extend the life of a tree
3. Mitigate a hazard - reduce the risk of damage to human health and life or property

It must be remembered that bracing is not an exact science and does not offer a guarantee of maintaining the tree structure, or indeed the life of the tree. When you are deciding whether to brace or not, you will need to weigh up the likelihood of it being successful, the risks of carrying it out, the aesthetics of the final result and conservation issues. A skilled and experienced arborist is best placed to make that assessment.

All about the Cobra Bracing System

The Cobra Bracing System has been scientifically developed to give the best support, shock absorbance and flexibility. Some of the specific benefits are:

• It’s lightweight - the Cobra rope is a monofilament polypropylene hollow cable which is much lighter than the steel cable alternative, making it strong and comfortable to handle.
• It’s aesthetically superior - there are no bracing rods which cause damage and can look unsightly. Once installed, Cobra systems are often very difficult to pick out at ground level, leaving the tree’s natural beauty uninhibited
• It can be used for several purposes - it is suitable for dynamic bracing (for sudden stresses) and load bracing.
• It absorbs shock - it significantly reduces impact forces
• It maintains strength - it loses only 2 percent of its strength per year which means that it will generally be 12 years before it will need to be replaced.
• It protects the tree - the system does not require rods to be placed inside the tree and uses hollow cables made out of monofilament polypropylene together with a quick splice instead. The expanding bands and anti-abrasion cover also help to minimise any friction damage between the cables and the bark.

System components

Cobra Bracing comprises:

• Hollow cables - made from woven monofilament polypropylene in 4 and 8-tonne strengths
• Expansion inserts - used to flatten the contact area and prevent girdling.
• Anti-abrasion hose - needed to prevent rope damage by making sure that the cable does not slide around the connection point.
• End caps - which are colour coded to quickly identify the year that the bracing was erected.
• Shock Absorbers - To reduce impact forces and hence cut down on damage.

Cobra bracing methods

There are three main types of bracing:

Dynamic braking / cabling:

For preventing breakage caused by oscillation-induced overstretching, install Cobra with a shock absorber. That way, the oscillations of the crown are not impeded, yet load peaks from strong gusts are softly dampened.

Static braking / cabling:

If damage is already present (i.e. formation of cracks), we recommend installing a Cobra 4 t or 8 t without a shock absorber. By immobilizing the critical spot, this type of cabling system prevents enlargement of the crack and helps prevent the branch from breaking off.

Load support cabling:

If, for reasons of traffic or pedestrian safety, a broken branch needs to be prevented from falling to the ground, install a static load/support cabling Cobra system without a shock absorber.  Bracing should be installed as vertically as possible so that, should the branch break, it will hang in the rope. The only acceleration will be from the rope extension hence there will be little or no shock loading. The rope and anchor point should be sufficiently strong for the weight of the branch.

Selecting the right Cobra system

There are three main system variants for you to choose from depending on the load that you need to support and the diameters of the branches involved - 2 tonne, 4 tonne or 8 tonne. 

The chart below gives guiding information on selecting the correct system for your job. For further details please refer here.