Felling a large tree using the CRAFT GTB (Greater Than the Bar) technique.
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Felling a large tree using the CRAFT GTB (Greater Than the Bar) technique.
1 844 просмотра · 4 дн. назад
B L
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1 844 просмотра · 4 дн. назад
Historically trees with a diameter larger than the bar of the chainsaw being used to fell it, have been felled by making a notch and then boring into the left side of the tree (if standing behind the tree), establishing the hinge on that side of the tree and then circling around the tree (while adding felling wedges if required) until reaching the far side of the tree and establishing the hinge on that side.
While this may result in the felling of the tree, there are several inherent issues or problems with this technigue.
These issues are:
1. With the bar "buried" in the tree, it is possible to accidentally remove a large portion of the hinge while circling the tree.
2. As the saw is circling the tree and before reaching the final position, a strong wind or heavy lean of the tree could cause the tree to start to fall prematurely while the hinge is too large and "pie" shaped. This could cause the tree to be pulled to the left of the target location and worse case senario, result in a "barber chair" where the tree splits and falls out of control (a potentially disastrous scenario). This means that the faller is unsure when the tree will actually start its fall.
3. The size of the tree being cut with this method, is limited to twice the length of the chainsaw bar.
The CRAFT (Controlled Release Accurate Felling Technique) GTB method illustrated in this video, show the following:
1. A tree with a diameter up to THREE times the length of the saw bar can be felled safely. Boring through the notch effectively creates a hollow tree which can be felled safely as long as there is a proper hinge in each side of the notch. Just as a door does not require a "piano" hinge to open and close properly, felling a tree safely does not require a hinge across the entire length of the notch.
2. A proper hinge is established BEFORE the tree starts to fall. The faller, not the wind nor the lean of the tree determines when the tree will begin to fall. This step is critical to ensure that no one has entered the felling zone before the tree falls!
3. As there is no need to have the tip of the bar near the hinge area, the risk of accidentally removing the hinge has been eliminated.
4. Boring from both sides of the tree permits the establishment of a "tab" (otherwise known by such terms as a strap or trigger, etc.), an uncut portion of the tree, opposite the hinge, that holds the tree in place until it is removed once the faller determines that it is SAFE TO DO SO - that is (1) no one has entered the danger zone, (2) a proper escape route for the faller to use to get away from the tree as it falls, has been established and (3) there is enough fuel in the saw to remove the tab!
Participation in training sessions over the years, has shown, that with the right coaching and guidance, even people with limited chainsaw experience, with properly-sharpened chainsaws can safely fell large trees using this felling method.