Which knot is commonly used as a backup knot to secure rope lines in climbing systems?

• A. Double Overhand
• B. Double Loop Figure Eight
• C. Water Knot
• D. Bowline

Answer: (A)

In climbing systems, a backup knot is added to prevent the main knot from loosening or the rope tail from slipping through under load. The double overhand works best as a backup because it’s a small, reliable stopper knot that sits snugly on the rope end, resists loosening under dynamic loading, and is easy to untie after it’s been loaded if you leave a bit of tail. It effectively locks the end so the primary knot stays secure.

The other options serve different roles: a double loop figure-eight is typically a main knot or a more complex variation rather than a simple backup; the water knot is meant for joining webbing, not rope lines; and a bowline creates a fixed loop that can work in some contexts but isn’t as dependable as a stopper backup knot for preventing slippage under load.