2.2.2 Setting an anchor point from the ground using a throwline
The tree climbing industry uses many tools to set climbing ropes in trees , including throwlines , catapults , crossbows , drones and gas-powered line-throwing devices .
Setting an anchor point with a throwline can be a quick and efficient way to establish a tie-in-point high in the tree . In addition , the anchor point can be effectively load-tested from the ground , and a ground belay system can be installed to allow the rescuer to be lowered in the event of difficulties .
Accurate and efficient throwline use is a skill that can take years to master . If there are other climbing arborists on site , a safe use of their skills during the rescue process may be to ask them to set lines in the tree or in adjacent trees to install rescue ropes .
Equipment required : ! Throwline , including throw bags , or similar ! Access ropes ! Access equipment
Using a throwline
Proficient use of a throwline can make setting lines quick and easy .
Begin by attaching the throw weight to the line using a clove hitch , slippery clove hitch , or by tying a bowline with a large loop and girth hitching the bowline onto the bag .
Ensure that the person throwing the line , and all other crew members on site are wearing suitable PPE . Give a loud warning such as ‘ stand clear ’ or ‘ heads up ’ to warn crew members that you are throwing , as throw weights are heavy and can be very painful if they hit you from a height !
Choose one of the two methods shown : either the single-arm technique pictured above or the cradle-arm throw pictured on the right .
With both techniques , begin by swinging the throw bag back and forward in line with your target . The longer the length of cord between your hand and the bag , the further you will be able to throw ( ensure the throwline does not hit the ground ).
It may help to pull a bight of throwline through the eye of the throw bag as shown to the right , to give yourself something to hold .
Visualise the bag going through your target union - it may help to focus on a target higher in the canopy or further back , so that you are looking ‘ through ’ your target union .
- 72 - © Arboriculture Australia 2022