Highlights

• 100% Polyester
• 12 Strand Braided, cannot be spliced
• Cover: Polyester (12 strand braided)
• Core:Polyester (4 strand parallel)
• Works as a tree climbing line or as a rigging line
• 12-strand braid holds together when rigging without blocks or pulleys
• Sizes Available: 3/4" diameter
• 3/4" Breaking Strength: 18,000 lbs (for comparison)

Description

Versatile Rope: AllGear’s 12-strand Forestry Pro works great as a tree climbing line or rigging line. This rope can be used in a knotless rigging system. AllGear's knotless rigging systems allow for multiple branches to be cut and lowered simultaneously, saving you time and energy.

Handling and Performance: The Forestry Pro is a 12-strand braided polyester rope over a 4-strand polyester parallel rope core. The 12-strand braid holds together when rigging without blocks or pulleys and retains 100% strength when wet. Excellent tensile strength compared to a polyester over polypropylene.

Specifications

• Material: polyester over polyester
• Exterior: 12-Strand polyester braided
• Interior: 4-Strand polyester parallel
• Weight at 150': ½ inch (9.15 lbs); ⅝ inch (17.8 lbs); ¾ inch (32 lbs)
• Average Tensile Strength: 
• ½ inch (7,300 lbs)
• ⅝ inch (11,000 lbs)
• ¾ inch (18,000 lbs)
• Working Load Limit: ½” (608 - 1460); ⅝” (916 - 2200); ¾” (1500 - 3600)

More Options: Watch our 2 minute video for more guidance on how to choose the right rigging rope for your tree work.

Important Safety Tip

We recommend a 5:1 safety factor to determine the rated capacity or working load limit. To find the working load limit, divide the tensile strength by 5 for the diameter you choose. See specifications for tensile strength and working load limits (WLL). Do NOT exceed the working load limit. 

Breaking Strength vs. Safe Working Load Limit

One of the most important parts of rope safety is understanding the difference between tensile strength and working load limit. The Breaking Strength, or tensile strength, is the force needed to break a new piece of rope under perfect conditions. Safe Working Load Limit, on the other hand, is the safe amount of weight the rope can handle during real-world use, without sustaining damage. If you stay at or under the SWLL you have a much lower chance of a break, which means a much lower chance of an accident.

Typically your SWLL (or WLL) will be the Breaking Strength of the rope divided by 5. This is called the safety factor, and the more dangerous the use case for the rope, or the less ideal the use of the rope, the higher the safety factor should be. For example, a 1 inch piece of HMPE rope has a breaking strength of 110,000 lbs., but for a low-danger operation its Safe Working Load Limit is up to 22,000 lbs (110,000 divided by 5).

For operations where a rope failure would be catastrophic, such as causing certain injury or death, a safety factor of 12 should be used. For this high risk operation, the same piece of HMPE now has a SWLL of 9,166 lbs (110,000 divided by 12). Finally, that same piece of HMPE being used for a low-risk operation but with a figure-eight knot on a bight (non-ideal use of the rope) should have a safety factor of more like 7, putting SWLL at 15,700 lbs.

Knowing how to calculate your safety factor and SWLL takes some experience, the ability to recognize real-world physics, and the history of your rope. Read on to learn more situations that may weaken your rope.

A final important thing to remember about SWLL is that exceeding the SWLL may weaken or damage the rope, often in ways that are not immediately obvious. The more often you exceed the SWLL, the easier it will be to break the rope. Respecting the working load limit is one of the most reliable ways to avoid accidents and get the most our of your gear.

How Knots and Splices Affect Rope Strength

Many rope users don’t realize that knots reduce rope strength significantly. A bowline or clove hitch can reduce breaking strength by about 40%. Certain knots can reduce strength by up to 60%! Knots create sharp bends and friction points that concentrate stress on the rope fibers. Some knots slip under load, and others can jam so tightly that they damage the rope permanently. The best knot you can use is a figure-eight knot, which only reduces the strength of the rope by about 25%. Make sure if you are using any knots that you factor that in to your SWLL, increasing the safety factor by a representative amount.

In heavy rigging, lifting, and towing, splices are much safer because they preserve most of the rope’s original strength. A well-made eye splice maintains eighty-five to ninety-five percent of the rope’s strength, especially when paired with a thimble to maintain proper bend radius. Rope safety means knowing which knots to use, when a splice is the better option, and how different tying methods affect load capacity. If you have doubts about your ability to calculate the proper SWLL, speak with a seasoned professional, and err on the side of caution.