Double bowline
The double bowline is a secure loop knot that creates a fixed eye at the end of a rope by incorporating two initial loops—or a round turn—around the standing part, followed by the standard bowline structure of passing the working end through the loops and around the standing part before tucking it back.[1] This variation enhances the knot's stability and resistance to capsizing compared to the single bowline, making it suitable for applications requiring reliability under load.[2] Also known as the round-turn bowline, it is documented as entry #1013 in The Ashley Book of Knots (1944), where author Clifford W. Ashley notes its improved security for rough or heavy-duty use.[3] Historically, the double bowline builds on the ancient bowline knot, which dates back to at least the Age of Sail for securing sails and rigging, but the double version gained prominence in modern contexts like climbing and mountaineering.[3] Pioneering climbers such as Royal Robbins, Tom Frost, and Warren Harding employed it as a primary tie-in knot for harnesses in the mid-20th century, valuing its ease of untying even after significant falls.[3] It reduces rope strength by approximately 25-30%, similar to other loop knots, and is favored in arborist work for anchoring to trees or posts, as well as in sailing for heavy rigging.[3][2] Key advantages include its simplicity in tying, minimal jamming under tension, and quick release post-loading, though it requires careful dressing to prevent loosening.[1][2] In climbing, it is often finished with a Yosemite tie-off or backed by a half-fisherman's knot to mitigate risks of inadvertent untying if not fully cinched.[2][3] While less common today than the figure-eight follow-through due to visual inspection ease, the double bowline remains a versatile option in scenarios demanding rapid adjustment and untying, provided users verify its integrity through partner checks and load testing.[3]Description
Structure and Components
The double bowline is a loop knot tied at the end of a rope, distinguished by its use of a round turn—consisting of two wraps around the standing part—in place of the single turn found in the standard bowline, which enhances its grip on slippery or stiff materials.[4] This variation forms a secure, fixed eye while maintaining the bowline's characteristic ease of untying after loading.[5] The knot's primary components are the eye, a stable loop at the rope's end designed for attachment; the round turn, consisting of two wraps around the standing part for reinforced hold; and the working end, which passes through the bight formed by the round turn, around the standing part, and back through the bight to lock the structure.[5] These elements interlock such that the two wraps of the round turn increase friction against the standing part, distributing tension evenly and reducing the risk of slippage under load.[4] The double bowline is cataloged as knot #1013 in The Ashley Book of Knots.[4] This structural design yields an efficiency of 70-75% of the rope's tensile strength, as the additional wraps help mitigate localized stress by spreading forces across broader contact areas with the standing part. In contrast to the standard bowline's single wrap, the added turn provides extra security without significantly compromising the knot's overall simplicity.[5]Security and Strength
The double bowline enhances security over the single bowline through the incorporation of a round turn, which generates additional friction to resist slippage, particularly under dynamic or cyclic loads.[3] This extra wrap around the standing part creates a more stable nipping structure, reducing the risk of the knot rolling or loosening in applications involving intermittent tension.[2] In terms of strength retention, the double bowline typically preserves approximately 70-75% of the rope's tensile strength, comparable to the standard bowline but with improved reliability due to the additional wrap of the round turn that minimizes capstan-like slippage failures.[3] This efficiency arises from the knot's balanced load distribution, where the round turn and loops help equalize forces across the rope fibers. Testing in controlled studies, such as those conducted by the Professional Association of Climbing Instructors, has shown the double bowline achieving 63-64% efficiency on 8 mm polyester ropes (three-strand and braid-on-braid constructions), with no statistically significant difference from the single bowline (p > 0.34).[6] In climbing contexts using nylon ropes, broader knot efficiency assessments align with the 70-75% range, though values can vary based on rope diameter and construction; for instance, similar loop knots on 10.5 mm static nylon exhibit around 60% efficiency under standard tensile testing at 180 mm/min.[7] These results underscore the knot's adequacy for load-bearing uses, though it generally underperforms the figure-of-eight loop (76-84% efficiency in comparable tests).[6] Despite its strengths, the double bowline can jam under heavy, prolonged static loads if not properly dressed, as the wraps may tighten excessively, complicating untying.[8] Vulnerability also arises from improper dressing, where uneven tension can lead to uneven loading and potential failure points.[3] Several factors influence the double bowline's performance, including rope material—nylon ropes retain higher efficiency under dry conditions but can lose up to 20% strength when wet due to water absorption, while polyester maintains more consistent values across environments.[9] Wet conditions exacerbate slippage risks in both materials by reducing friction.[10] Load type further affects outcomes: the knot handles static loads well but may loosen under repeated dynamic cycling, necessitating backups for high-impact scenarios.[11]History and Naming
Etymology and Origins
The double bowline lacks documented ancient origins, unlike its foundational counterpart, the standard bowline, which traces back to at least the 16th century in maritime contexts and was explicitly described in 1627 as the "Boling knot" for securing sails on square-rigged ships during the Age of Sail.[12][13] As a variation featuring an additional round turn for enhanced security, the double bowline likely emerged from similar nautical demands for more reliable fixed loops in rigging and mooring, where heavier loads or variable conditions required greater resistance to slippage compared to the single bowline.[14] The knot's first explicit mentions appear in early 20th-century knot literature, reflecting its evolution as a specialized loop form influenced by other doubled structures, such as the double sheet bend—a secure joining knot with prehistoric roots in sailing and netting, adapted for ropes of differing diameters since medieval times.[15] Clifford Ashley cataloged the double bowline in 1944 as knot #1013 in The Ashley Book of Knots, highlighting it as a robust variation suitable for demanding applications.[4] In modern contexts, the double bowline gained recognition in climbing literature from the early 20th century, with Robert Underhill describing its use as a tie-in method in the 1931 Sierra Club Bulletin, aligning with evolving safety standards in mountaineering as nylon ropes and harnesses became prevalent post-World War II.[16]Terminology and Synonyms
The double bowline knot is most commonly referred to as the double bowline or round turn bowline, reflecting the additional wrapping turn around the standing part that distinguishes it from the standard bowline.[17][2] An alternative designation is the double-knotted bowline, emphasizing the doubled structure in the collar formation.[2] These names are standardized in authoritative references such as The Ashley Book of Knots (ABoK #1013) and publications from the International Guild of Knot Tyers (IGKT), which consistently use "double bowline" to describe the end-of-rope loop knot with enhanced security.[18][19] Significant nomenclature ambiguities arise, particularly with the bowline on a bight (ABoK #1080), a midline knot that forms a pair of loops and is sometimes mistakenly interchanged with the double bowline despite fundamental structural differences.[20][21] Further confusion occurs with the double bowline on a bight (ABoK #1083), a variation using doubled rope to create multiple loops, often leading to misidentification in non-specialist contexts.[22] In some climbing guides, the knot is termed the two-turn bowline to highlight the dual wraps in its initial setup, though this usage is less standardized outside specific instructional materials.[23] The terminology has evolved with an emphasis on "round turn" to underscore the extra circumferential wrap that provides greater grip and security compared to the single turn in the basic bowline, a distinction noted in early 20th-century knot literature.[2]Tying Methods
Step-by-Step Instructions
To tie the double bowline, begin with a rope of sufficient length, ensuring the working end measures at least 3-4 feet to allow for forming the knot and leaving an adequate tail.[23] The knot is formed through the following sequential steps, which assume basic familiarity with rope handling terms such as working end and standing part.[3]- Form a small loop, known as a bight, in the rope near the working end; this bight will serve as the eye through which the working end will later pass.
- Pass the working end around the standing part to create a round turn, wrapping it fully around the standing part to position it parallel and adjacent.[1]
- Bring the working end behind the standing part to form the collar structure.[24]
- Pass the working end back through the initial bight from inside to outside, ensuring it exits through the loop created by the round turn.[2]
- Dress the knot by pulling the standing part, the loop, and the working end simultaneously to tighten and align the components snugly.[25]