Difficult or impossible to untie after loading. Uses more material than double fisherman's
The fisherman's knot is a bend, in other words a knot for joining two lines. The double fisherman's knot and triple fisherman's knot versions of the knot are variations used in climbing, arboriculture, and search and rescue. The difference between the three variations is the number of turns in the overhand knots that form the completed bend.
The bend consists of two overhand knots in their strangle knot form, each tied around the standing end of the other. For the double fisherman's variation a double overhand knot is used, while the triple variation adds a third turn. The knot is known for its strength and reliability when used correctly.[1]
The (single) fisherman's knot is also known as the angler's knot, English knot, halibut knot, waterman's knot, and true lover's knot.[2] The double fisherman's knot is also known as a grapevine knot.
History
There is evidence of the fisherman's knot and its variations being indigenous to many cultures.[3] The knot was described by Heraklas in the first century as part of an essay on knots for surgical and orthopedic uses.[4]
Multiple turn variants of the fisherman's knot would have been relevant for Inuit peoples fishing with fishing lines made of baleen due to the monofilament nature of the material, which could cause slippage similar to modern nylon materials. Triple fisherman's knots made in baleen found near in Nuuk have been carbon dated to 1700.[3]
In 1865 the Alpine Club Journal reported on tests conducted on knots in a manila rope. They found that while all knots weaken ropes, the fisherman's knot did so least of all the knots tested.[5]
Properties
All variations of the fisherman's knot jam when tightened. However, the bend can slip or come undone when using lines or ropes made of more slippery materials such as HMPE (also known as dyneema) or nylon monofilament. In general, increasing the number of turns in the overhand knots increases the security of the completed bend.[1][6][7]
The fisherman's knot can be difficult to untie especially after being well tightened or weighted.[8] It is generally easier to untie a bend with fewer turns. The selection of the number of turns in the overhand knots needs to balance the security of the bend against the ease of untieing it.[9]
Uses
All variations of the fisherman's knot are used in fishing, particularly the single overhand variant. Other knots sometimes provide superior performance for this application when using nylon lines, such as the blood knot.[10]
The double and triple variants of the bend are common in climbing when tied using appropriate ropes or cord. A primary use of the knot in this context is creating closed loops (cordelette) by connecting the ends of a piece of rope to each other.[11] The triple fisherman's knot is recommended when using HMPE or aramid ropes.[12][13]
The double fisherman's knot is not recommended for joining ropes where the ropes need to be pulled down and might get snagged in the terrain, such as canyoning.[14]
This knot can be used to join the ends of a necklace cord. The two strangle knots are left separated so that the length of the necklace can be adjusted without cutting or untying the cord.[15]
Security
The technique used in tying the knot is important to determining the behavior of the knot under load. When pulled until failure the failure mode of the fisherman's knot (either by the rope breaking or by a topological change) is dictated by a combination of the coefficientof friction between the rope strands, elastic stiffness, and the initial geometry. The balance of friction and elasticity determines how the knot tightens and whether it will slip or jam firmly. The extent to which the overhand knots are tightened before use is crucial in determining the coefficient of friction.[1]
Testing has shown that a failure mode exists at high loads (generally higher than 15 kN) with the fisherman's knot in ropes using Spectra and Technora cores. The sheath of the rope separates at the knot, and the high-lubricity core slips through the fisherman's knot. This failure occurs at a slightly higher load in the triple fisherman's knot leading to the recommendation to use the triple fisherman's knot in these materials.[13]
↑Ashley, Clifford W.; Budworth, Geoffrey (1993). The Ashley book of knots: with amendments (Reprinted.). New York: Doubleday. ISBN978-0-385-04025-9.
12Turner, John Christopher; Van de Griend, Pieter (1996). History and science of knots. Series on knots and everything. Singapore New Jersey London [etc.]: World Scientific. ISBN978-981-02-2469-1.
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