Let me say this first to reemphasize my ever-important stand on the use of the hinge in felling and bucking. You must understand how a hinge should be considered or established in these discussed operations to see their effectiveness and safety. Sounds complicated? It is, unless you can first define it - The hinge is a predetermined section of wood, that connects the stump to the falling trunk stem or a log or limb section to another. Predetermined means you have a clear thought in your mind as to how much hinge you want to leave attaching the two parts. You just don't simply cut, you plan it.
The hinge dimension (rule of thumb) is approximately 10% of the diameter in width and 80% of the diameter in length. The diameter is a measured cross section of the tree or wood/log section. This calculation gives you a very predictable place to start in establishing a successful controlling hinge.
Now to our issue's of burned or rotted trees.
The planning process remains the same as with every tree to cut- establish the five steps - 1. hazards, 2. leans, 3. escape, 4. hinge dimensions and 5. how to cut, selecting tools and kerfs (back to front or bore cut).
Broken hanging limbs and tops (widow makers).
Rotted or severely burned tops or large limbs that may break loose during movement.
Cracks or channels that have occurred in the trunk from stress or rot.
Noticed splits, cracks or wear areas on the trunk or limbs.
Vines that attach to limbs or other adjacent tree tops.
Root systems that may be burned out causing unstable lean potential.
Obstacles, power lines, cables, structures, adjacent trees.
Ground hazards and terrain issues.
Odd shapes or missing fiber from rot or burn in the desired notch and hinge area.
Chimney effect burns. Forest Fire damage from the inside out on some burned trees.
Fiber that is hard and dry from burn exposure.
Fiber that is powdery, rotted or just weak from rot.
Be aware that rot or fire damage can cause a trunk or limb to be unstable several feet up. This can result in a tree folding back toward an operator when it begins to fall or strikes another obstacle.
Face notch's should be open for travel until the trunk is virtually parallel to the ground and should have no bypass or Dutchman in the apex of the notch. These things can cause a shaking action to the trunk that can snap out tops or unstable limbs.
Regarding initial techniques used to cut the tree or log; after your plan is established, burned or rotted fiber is usually found in the tree in a couple scenarios. On burned or rotted surfaces of the tree the outside wood needed for a hinge may be soft and offer little or no usable hinge material. Other trees may be hollow, limited the placement depth of the hinge into the tree. With either of these scenarios, the sawyer must look at the available wood or the lack of and make sure there is enough for a sufficient hinge to be established. A hinge may be sectioned or open in the middle, similar to hinges of a tall door however and still offer steering control and safety. On larger trees especially, two hinges can be formed, one at each side of the notch. If the tree is hollow and the notch extends back into the hollow, the two hinges located on the sides will still be successful to direct and support a tree as long as there is not too much side lean. Hollow trees, if you can establish a working hinge in the good fiber it only means you have less to cut.
Trees with rot in the hinge area, rotted or unstable fiber cannot be felled from the ground with complete confidence and control. Without hinge control, safety is a questionable issue. If a tree has lean in a favorable direction you may be able to notch and back or bore cut to fall the tree safely. If the plan information has obstacles or hazard situations that can affect the fall, you must decide to leave the tree. It will have to be taken down from the top by bucket, crane or a climber that can suspend from another adjacent tree or structure. If the tree base is unstable it's not safe to support a climber either. Leaving a tree in the woods you can't safely plan to cut means you have to mark off the area - at least the height of the tree or as is usually suggested, two tree heights so no one enters the area. In a residential area mark the area well, especially any walkways, until the tree can be removed. Don't leave a situation for another unsuspecting person or animal to enter the zone and be surprised by the tree falling on them.
The commonly used Definition of a Hazardous Tree is one with a Target. If the tree shows any sign of instability and there's a chance of people or property damage, it's a Hazard Tree! Stabilize it or remove it as soon as possible.
Practice your saw cuts and become proficient in making notches and hinges on practice blocks or stumps before ever attempting to work in rot or burned situations. Your chainsaw must be sharp and in perfect running order. Read your owners manual and be familiar with its content. Wear your PPE and if you are not comfortable with the plan you are able to devise... Call someone who is.
The ForestApps eBook, "The Complete Guide to Chain Saw Safety and Directional Felling" is available from our website and downloadable from www.BarnesandNoble.com . We have recently completed filming some very good video footage that we hope to have out in the next month or so regarding a few storm damage situations. So stay in touch with our website or by ChainPoint.
(c) Copyright 2010 Forest Applications Training, Inc.