Page 211 - J. C. Turner - History and Science of Knots

200 History and Science of Knots

15, a `Right-handed' (Direct) Sheetbend (#1431) after 22, a Double Sheet-
bend (#1434) after 36, a Carrick Bend (ends on the same side, #1428) after
20, a Carrick Bend (ends opposite, #1439) after 70, an Overhand Bend (right-
handed in left-handed yarn, #1558) after 23, or (left-handed in left-handed
yarn, #1557) after 33, a Fisherman's Knot (#1414) after 43; a Ring Bend
(#1412) withstood at least 100 cycles. Ashley called attention to the effects
of handedness of knot and lay in the Overhand Bend and how the ends lead
out in the Carrick Bend. He claimed that the security of a knot seemed to
depend solely on the nip of the knot, the spot within a knot where the end is
gripped and thereby made secure, and used as a major argument the behaviour
of the Direct and Oblique Sheetbends. He said that the Direct Sheetbend has
a good nip and does not slip easily, while the Oblique has a poor nip and
is unreliable. Yet the one slipped at 22 cycles and the other at 15, which I
should have thought not all that very different, and not all that good; and I
can recognise no real difference in the nips of the two knots.
Both Ashley [5, p. 16] and Day [16] denied what they called a common
misconception, that to be secure, adjacent parts of a knot should tend to move
under load in opposite directions. This does apply to a Reef Knot (not very
secure) but not to many other, more secure, knots.
Day [16] in the course of standard strength tests found the Oblique Sheet-
bend insecure when tied in manila rope, but Chisnall [14], using a variety of
more or less improvised tests, found that the Oblique form was more secure
than the Direct when tied in Kernmantle and some braided ropes. He also [15]
found that, using right-hand-laid rope, a Reef Knot tied with the first Half
Knot left-handed ('left over right') was more secure than when the first Half
Knot was right-handed.
An interesting example of insecurity is found in the Figure Eight Bend
(as [5, #1410], but using a Figure Eight Knot, [5, #524]). When subjected
to a heavy load, the knot flypes, that is, turns `inside-out', perhaps several
times if the working ends are long enough, before reaching the breaking point
[6]. Because the knot is so little liable to jam in cracks or under ledges when
the knotted rope is drawn over rock, some [6] think the knot has valuable
applications; others [12] disagree, finding inadequate security.
In many fields, natural fibres have been largely replaced by synthetics for
rope. But many knots are less secure when tied with the synthetics; this has
often necessitated the introduction of modified or new knots (see, for example,
the climbers' knots discussed in Chapter 9). Monofilament nylon fishing lines
are more slippery than gut; anglers have often met the problem by increasing
the number of twists or turns in the knot. Thus the Blood Knot had 11 turns
in gut [5, #2951 but 41 turns in nylon [11, p. 88]; the Water Knot and the
Fisherman's Knot used single Overhands in gut [5, #296, 293] but multiple