By Michael Tain
The use of multiple lines in rigging operations can provide tree care professionals with several advantages. The secondary lines can provide additional support for the load, perhaps distributing its weight more evenly among several anchor points. They can also direct, move or drift the load to a different, yet desired, location as line is fed out on the original load line and taken in on the secondary or drift line. As the load nears the drift line’s anchor point, that rope becomes the load line. Secondary lines may also be used in situations where the rigging plan and obstacles prevent any radical or sudden movement on the part of the tree or branch being removed, thus the additional line(s) act as supports and stabilizers. Although there are many advantages to using multiple lines, their use can be quite time and gear intensive, and requires suitable anchor points within the tree(s) for employment. Therefore, they are best used only in situations where they will truly make the rigging operation safer and more efficient.
One of the most basic scenarios in which the use of multiple lines would be advantageous is a tree with either immovable high-value obstacles beneath it or an extremely restricted drop zone, such as a small fenced yard. Both of these situations could probably be overcome with a simple rigging system, but the need to take very small pieces and then maneuver them around the obstacles safely — or manually remove them from the fenced yard — would make this process quite time consuming, less than efficient, and possibly unsafe. If a second anchor point exists — either a large lead within the existing tree or another tree off to the side of the existing tree — the use of a drift line could make the rigging operation much more efficient. A secondary anchor point is established within the second tree, usually at the same height or higher than the primary anchor point, and typically with an appropriate rigging sling and block to minimize friction. A retrievable false crotch may be installed and retrieved from the ground, providing the same advantages without the need to climb the tree for installation. The practice of “hanging” a rigging line over a branch or attachment point with a block attached to the end of it should be avoided, because this multiplies the forces at the secondary anchor point exponentially and could lead to catastrophic failure. The piece to be removed is now secured with lines from both anchor points, one from the existing tree and one from the secondary point, though the secondary one should remain slack unless the individual scenario dictates otherwise. The tree crew will need to have mechanical advantage of some sort at the secondary anchor point (through a system they assembled themselves with a Port-a-Wrap for control, a set of fiddle blocks with a Port-a-Wrap for control, or through a ratcheting device such as the Hobbs or the Good Rigging Control System). This advantage will be necessary when the piece or branch is being moved or pulled to the secondary anchor point. Additionally, some form of lowering device, such as a Port-a-Wrap or GRCS, should be used at the primary anchor point in order to feed out the load line smoothly and under control.
A basic load and drift line rigging system has now been assembled and put into place. The piece to be removed is cut and caught by the rigging system at the primary anchor point. Although users would typically wish to decelerate the piece gradually to minimize forces at the anchor point, in this scenario the piece should be caught with the minimum of downward movement possible. And, quite often, due to obstacles beneath, the piece will be “snubbed” off within the safety parameters of the system and tree. The downward movement or lowering of the piece is minimized to not only avoid the obstacles beneath, but to lessen the amount of movement required and forces experienced by moving the piece with the drift line. Once the piece has been safely caught and stabilized, tension is applied on the drift line with whatever mechanical advantage system is being used. As the drift line grows taut, the piece will begin to move toward the secondary anchor point. As the process continues, line should be fed or paid out at the primary anchor point, gradually transferring the load to the secondary anchor point as the piece moves toward it. Communication should continue among all crew members throughout the process, with the climber usually being in the best position to monitor progress and give instructions. With good communication and a proper set-up, the piece can be gently placed in the desired location — even on the waiting feed tray of the chipper — smoothly and efficiently.
The use of multiple lines has many applications within tree care rigging operations. It can be a technique that will increase the safety and efficiency of various scenarios, but, as with any tool, it must be applied properly and only when necessary. The addition of multiple rigging lines, anchor points, lowering devices and attending crew members obviously complicates an operation. Thus, the benefits of this complication must clearly be an advantage to justify their use. Although not a technique that will be necessary — or even justified — in every situation, an ability to design, assemble, and employ load and drift lines in rigging operations is an excellent skill to have available.
Michael (House) Tain is a contract climber, splicer, educator and writer associated with North American Training Solutions www.northamericantrainingsolutions.com and Arbor Canada Training and Education www.arborcanada.com. He is currently located in Lancaster, Ky., and can be reached via e-mail at firstname.lastname@example.org