Other line-throwing devices
The Big Shot can be used to achieve shots over 50m , but to do so requires careful setup and the use of non-traditional modifications , such as an open-faced fishing reel and monofilament line . If the rescue team may be called to tree accidents in trees which regularly exceed 50m , the Big Shot may not be the most useful method of accessing the tree .
Depending on the equipment that the rescue team has available for use in other environments , it may be worthwhile exploring the utility of other line-throwing devices . Shoreto-boat and boat-to-boat line-throwing devices can be easily modified to use in tall trees .
Arborists who specialise in tall tree access sometimes use modified crossbows as a mechanism to reliably set lines above 60m . Modern crossbows are extremely powerful and must be prepared and tuned in advance to operate in this manner . Crossbows are prohibited weapons in many states and require a permit to be owned or used .
A range of dedicated air cannons are produced for use in tree access . These are usually constructed so that standard-sized throw bags will fit down a length of tube which is separated by a pipe valve . The arborist closes the valve and uses a hand or powered pump to pressurise the rear part of the tube . The throwbag is loaded into the end of the tube and the cannon is aimed above the target union . When ready , the arborist opens the valve handle , and the released air pressure throws the bag over the target .
Rescue teams who frequently access tall trees may wish to consider the use of an air cannon . Depending on the model purchased , charts are available specifying the correct pressure needed to achieve a given height with a given weight .
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