As previously discussed in Chapter 2.3.1 , tensioned ropes which are deflected under load place high magnitudes of force at either anchor . In both setups on the previous page , unacceptably high forces are being placed on the top anchors , applied perpendicular to the arm of the tree in a direction in which timber is particularly weak .
The image below shows two essential improvements .
1 . By lowering the floating anchor to the minimum useable height above the casualty , deflection forces are significantly reduced . The included angle of the floating anchor ropes should be less than 120 °. 2 . By securing each end of the anchor line to a suitable ground anchor in the same plane as the line ( instead of directly to the tree ) the forces applied to each suspension point are both reduced in magnitude and improved in direction .
Whilst this setup might be time-consuming to install , the end result will be a useable top anchor positioned directly over the casualty , allowing safe access to even a heavilycompromised tree .
© Arboriculture Australia 2022 - 173 -