Double Bowline on a Bight for Rescue and Rigging
In rope rescue, where every connection point is a matter of trust, the Double Bowline on a Bight (DBoB) earns its place through redundancy, midline adaptability, and strength. It is especially valued in fire service and search and rescue (SAR) teams for creating two fixed loops without requiring access to rope ends—making it ideal when operating with long lengths of rope or within dynamic mechanical systems.
This knot builds upon the foundational bowline structure but doubles the loop and adds an extra twist, resulting in a symmetrical configuration. These loops provide multiple points of attachment, spreading load and adding critical backup in scenarios where failure is unacceptable. Its midline application sets it apart from more commonly known terminal knots and allows it to thrive in anchor, hauling, and load-transfer roles.
Why This Knot Matters in Rescue Contexts
What makes the DBoB unique is its combination of reliability, efficiency, and ease of release, even under heavy load. While figure-eight knots tend to cinch tight and jam, especially when weighted, the DBoB maintains accessibility without sacrificing integrity.
It’s not just about convenience. It’s about performance under pressure.
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Two load-bearing loops allow for dual-point anchoring or redundant patient attachment.
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High strength retention maintains rope integrity in life-safety applications.
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Non-jamming behavior ensures it can be untied even after repeated heavy loading.
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Redundancy by design: if one loop or carabiner point fails, the other remains active.
In critical scenarios like vertical rescue, confined space entries, or over-the-edge pick-offs, that kind of predictability matters.
Deployment in Rescue Systems
The DBoB finds practical application across nearly every major component of rope rescue systems.
In anchor systems, it shines as a midline solution where both loops can be clipped to independent anchor points. This balances the load, minimizes shock on any single anchor, and maintains system integrity even if terrain or anchor positions are asymmetric.
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Used in cliff rescues, vehicle anchors, structural offsets, and confined spaces.
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Ideal for semi-permanent midlines where rope ends are in service or inaccessible.
For load management, it enables direct, redundant connection to litters or patients during vertical raises or lowers. Whether used with a twin tension system or a main/belay approach, it ensures that movement remains stable and predictable.
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Each loop can hold its own carabiner to isolate connections.
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Works well in improvised patient tie-ins or hasty harness setups in the field.
In mechanical advantage systems, the knot provides a fixed attachment for progress capture pulleys or directional changes. Its midline nature makes it a versatile choice in dynamic systems like 3:1 or 5:1 configurations.
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Enables fast insertion into active hauling systems.
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Doesn’t require rerigging or untying rope ends, preserving system momentum.
Advantages Over Comparable Knots
While some teams default to the figure-eight on a bight, the DBoB offers meaningful operational benefits. The double bowline is easier to untie, even when heavily loaded, and is less prone to jamming—an important factor when converting or disassembling systems under time pressure.
It also addresses a well-documented limitation of the single-loop bowline: the potential for slippage under cyclic loading or when improperly backed. The DBoB’s dual loops inherently reduce this risk and give rescuers an added layer of safety.
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Figure-eight: Strong, but more difficult to untie post-load.
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Single bowline: Easier to tie but susceptible to slippage without proper backup.
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Double bowline on a bight: Midline capable, redundant, and easier to dress and inspect.
Best Practices for Field Use
As with any critical knot, the DBoB must be used with proper technique and oversight. A few field practices help ensure its performance:
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Use a backup knot. An overhand stopper behind the final twist of the bowline reinforces security and mitigates loosening.
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Dress the knot carefully. Loops should remain symmetrical and sit cleanly without crossing or twisting.
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Check materials. Ensure ropes or webbing used are rated for life-safety, ideally above 4,000 pounds minimum breaking strength.
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Inspect under load. Confirm the knot’s integrity during low-stress test loads before full deployment.
Visual inspection of the knot is critical. Poorly dressed DBoBs can collapse into asymmetry, reducing load efficiency or compromising system redundancy.
Conclusion
The Double Bowline on a Bight stands as a highly functional, field-proven knot—designed for situations where rigging must be fast, adaptable, and fail-safe. Its ability to deliver dual-loop redundancy without the need for rope ends makes it indispensable across modern rope rescue operations.
Whether used to build anchors, manage patient loads, or integrate into mechanical advantage systems, the DBoB is more than just a knot—it’s a safeguard against the unknown. And in the fire service or SAR world, that margin can mean everything.
Peace on your Days
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