Intro
Rigging rope is essential in the tree service world because without simple tasks would be very difficult if not impossible. It needs to be purchased from a reputable company. Any rope from your local hardware store will not work. Make sure you use a rope that has been rated for use in tree work.
SWL (Safe Working Limit), has been designated to allow safe usage of a rope without fear of it breaking. Typically the SWL of a rope will be 10% of the Minimum Breaking strength or MBS.
WLL (Working Load Limit), is another way to describe the limit allowed for using a rope. Typically the WLL rating of a rope will be 10% of the Minimum Breaking strength or MBS.
Rigging Ropes
Rope Sizes
The most common rope in the tree industry is the half-inch rope. Rope can commonly be purchased from as small as 3/16 to 1″ in diameter. I am sure you could get a specialty rope bigger but that is the most common range. Typically rigging ropes will be purchased in diameters of 1/2, 9/16, 5/8, 3/4.
Rope Materials
Twisted rope
3 strand, is commonly used when natural crotch rigging. This rope is the most effective rope when using a rope puller like this one here.
12 strand rope, is similar to 3 strands however it typically has a higher maximum breaking strength. It can also be used in a rope puller but not always as effective.
Braided Rope
Double Braid, is great when rigging as it has a higher maximum breaking strength than most strand rope. Some double braid rope can be used with natural crotch rigging but it is advised to use a device to help reduce wear and tear.
Positive Rigging
Positive rigging uses a tie in the point above the desired cut. This is the preferred method because it is easier to eliminate slack which is your enemy. Leaving slack in the rigging line can cause things to break if shock loaded too hard.
Negative Rigging
Negative rigging uses a tie in point below the desired cut. Often this is used when rigging chunks off of the main trunk to finish a job in a tight situation.
Rigging Points
Natural Crotch rigging is when you put your rope through a crotch or over a limb without any aerial friction devices, rigging blocks, or pulleys.
False Crotch Rigging is when you use an aerial friction device, rigging block, or pulley
Crane Rigging, is used when options are limited that put property and personal safety at risk. Tree companies will use cranes on dead trees, gigantic trees over the house, and blown over trees.
Rigging Attachment Points
Tip Tie, is when you tie onto the end of a branch or tree. This is used to prevent the tips of the tree from damaging property when it is cut. In certain cases, climbers will tip tie a branch and cut a notch facing up on the butt end. Then the rope will be pulled upright towards the tree. The benefit of this allows the branch or tree to be lowered in a controlled manner. Small branches could be pulled upright with just a rigging block and someone on the ground. Large branches may use specialty devices like the GRCS (Great Rigging Control System), Hobs Lowering device, or another form of mechanical advantage.
Butt Tie is one of the most common forms of rigging. This occurs when you tie the butt end of the branch or tree. This allows the end to fall first to then be lowered by the butt end of the branch. The advantage of this method is speed because the climber does not have to attach a rope further out on the limb. One must be careful when using a butt tie, as the tip may brush up against something as it falls.
Spider Legs, are not as common but come in handy when more control is necessary. Spider leg rigging is when 2 or more “legs” are attached to the same rigging ropes. This is used to balance the branch in order to keep the branch as level as possible while rigging it down.
Friction
Tree wraps, is the method of using a tree to add friction into the rigging line. The advantage of this method is it’s free, however, the friction it produces is less predictable than other friction devices. One wrap around a big tree will produce more friction than a wrap around a small tree. Also, different trees will produce different friction based on their bark composition. Another big disadvantage to tree wraps is the extra wear and tear on the rope.
Port-a-wrap, is one of the most common friction devices used in the tree industry. you will be hard-pressed to find an established tree company without one.
Aerial Friction Devices, are tools that produce friction in the tree. One advantage of this is the ability for the climber to lower a limb. Another less known advantage is the lower impact on the rigging point. Let us imagine there is a limb that weighs 100 lbs. The rope going from the limb to the rigging point is pulling on the rigging point with 100 lbs. At the same time, the rope going from the rigging point to the ground has 100 lbs of weight. Combine these two numbers and you have 200 lbs of weight, which does not include any extra weight from shock loading. An aerial friction device takes the 100 lbs of weight from the limb and reduces the weight being pulled between the device and the ground. This means you would have 100 lbs of weight from the limb to the device, and let’s say 30lbs of weight from the device to the ground. This leaves us with a total of 130 lbs of weight on the rigging point instead of 200.
Natural Crotch Rigging, is the use of a crotch or limb to lower a branch. There is friction produced when the rope moves across the crotch or branch.
Miscellaneous
Speed Line(s), also known as a zip line, are used to efficiently move branches or chunks of logs from the tree to the ground. The big advantage of this method is speed (No pun intended, haha). One does not have to wait for the rigging rope to be pulled back up to them. They can just cut one or a few limbs to send down to the ground. Another advantage of this method is overcoming obstacles that are close to the tree. Some people have been known to send branches over a house all the way to a chipper, which saves time dragging brush.
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