Comparison of butt block redirect systems
System |
Redirected main line . |
Main line set through floating anchor |
|
|
above casualty . |
Advantages May be quicker and simpler to install , particularly if redirect pulley location is easy to access for rescue climber .
Requires less equipment . Reduces force applied to redirect point .
May be easier to install , particularly if redirect point is hard to access or if anchor line can be set with throwline .
May be possible to install from the ground .
Increases efficiency of system ( fewer pulleys ).
Disadvantages
May be significantly harder to install , if multiple redirects must be placed or if the redirect points are hard for the rescue climber to access .
Each redirect point decreases the efficiency of the system : more force must be applied to lift the casualty .
Requires more equipment ( anchor line ).
Increases force applied to redirect point .
May be more complicated to install , particularly if rescue climber is accessing casualty anyway .
Options for casualty belay
1 . Top-belayed on a separate line by the rescue climber who ascended the tree to install the lowering pulley .
2 . Twin-tensioned system ( mirror of the above ).
Skills that may be required : |
Technique |
Description |
Evaluating tree anchors |
Chap . 2.3 |
Floating anchors |
Pg . 170 |
Redirects |
Pg . 110 |
Butt block |
Pg . 46 |
3 . Connected via textile sling or adjustable lanyard to the attachment point on the rescuer ’ s harness . Rescuer to descend with casualty to assist with avoiding obstacles , support etc .
© Arboriculture Australia 2022 - 49 -