Page 198 - J. C. Turner "History and Science of Knots"

188 History and Science of Knots

that is, with minimal torque within the cord, and the most direct transfer of
internal forces; it has been said [29] that neglecting this precaution may as
much as halve the knot strength. All the knot parts should also be optimally
packed, tightened to avoid any deformation when the load is applied; this is
usually best achieved by working round the knot tightening each emergent end
against the knot and repeating until no further motion occurs (complex knots
may need to have internal parts worked through to the end). However, care
should be taken with very light lines not to overtighten; one recommendation
[7, p. 297] was that the tightening tension on knots tied in anglers' line should
never exceed 60% of the line's breaking strength, or the line could be greatly
weakened. Many knots have asymmetric elements such as twists and turns,
which may be `right-handed' (or `Z-twisted') or `left-handed' (or `S-twisted');
`right-handed' follows conventional screw or bolt threads. This may be ex-
pected to have some effects on the behaviour of the knot, specially when using
rope that itself has a handedness, such as the lay. Most investigators ignore
this point, but there are exceptions. Day [16] found that a Fisherman's Knot
is 20% stronger when the Overhands are tied against the lay of the rope; on
the contrary, a Fisherman's Knot with both Overhands of the same handed-
ness was 15% stronger than when they differed [36]. Then Day [16] found
that the Sheetbend was equally strong and secure whether the turn was left-
or right-handed (this does not refer to what is sometimes called a Right- or
Left-handed Sheetbend, depending whether the ends came out on the same or
different sides; these may be better called Direct or Oblique knots). Chisnall
[15] made a number of comparative tests using improvised methods of loading
a light line containing two knots. Full details of these tests are not available,
but some results are interesting. Using right-handed line, a Reef Knot tied
with the first Half Knot left-handed ('left over right') was stronger than if it
was right-handed; a right- handed Ring Bend was stronger than a left-handed;
and Single and Double Fisherman's Knots were stronger if the Overhands were
left-handed, corroborating Day [16] above.
Fifty or a hundred years ago, mountaineers, specially from Britain, were
very emphatic about the value of tying their knots `with the lay', but appear
to have been in some doubt about what that term meant [36]. The most
comprehensive study of this topic [36] defined `right-hand lay rope' in the usual
way, twisting as in an ordinary screw, but defined making turns, hitches or
twists `with the lay' when they were made in the direction usually followed by
most right-handed people, which in the authors' case generally meant counter-
screwwise, called `left-handed' or `against the lay' by most knot tiers in the
nautical tradition. Most of the discussion is of the Bowline, arguing that it
should be tied `with the lay', defined as with the turn in the direction called
`left-handed' in the nautical tradition, the opposite direction to that found
after many tying methods. The authors justify their opinions purely by the