principle of opposite twists must be observed. The
reason for this is to keep the line tight or stable and to
prevent the parts from inlaying when a load is
suspended on it. All Navy line 1 3/4 inches in
circumference or larger must be right laid. This
requirement is important because if a left-laid line and a
right-laid line were bent together, they would unlay
each other under strain.
Braided lines have certain advantages over twisted
lines. They will not kink or cockle (explained later), nor
will they flex open to admit dirt or abrasives. The
construction of some braids, however, makes it
impossible to inspect the inner yarns for damage. The
more common braided lines are hollow-braided,
stuffer-braided, solid-braided, and double-braided.
Hollow-braided lines usually consist of an even
number of parallel, tapelike groups of small yarns
braided into a hollow, tubelike cord. This type of
construction, formerly in cotton, was used for signal
halyards-a purpose now served largely by plaited
polyester. Other uses are parachute shroud lines and
shot lines for line-throwing guns.
Stuffer-braided lines are manufactured in a similar
manner except that the braid is formed around a highly
twisted yarn core, which rounds out and hardens the
Line 1 3/4 inches or less in circumference is called
line. This type of construction in cotton is used for sash
small stuff. Its size is designated by the number of
cord (heaving lines).
threads (or yarns) that make up each strand. You may
find anywhere from 6 to 24 thread, but the most
Solid-braided lines are fashioned in various ways.
commonly used sizes are from 9 to 21 thread. See figure
One familiar solid-braided line is the one used for lead
4-3. Some small stuff is designated by name. One type
lines, taffrail log lines, and the like. This braid is of large
is marline, a left-laid, two-strand, tarred hemp. Marline
yarns, either single or plied, tightly braided to form a
is mainly used for seizings. When you need something
hard, relatively stiff line that will not kink, snag, or swell
stronger than marline, use houseline, a left-laid, three-
strand, tarred hemp. Rope yarns can be used for
Double-braided line is, essentially, two hollow-
temporary whippings, seizings, and lashings. The yarns
braided ropes, one inside the other. The core is made of
are pulled from strands of old line that has outlived its
large single yarns in a slack, limp braid. The cover also
usefulness. Pull the yarn from the middle, away from
is made of large single yarns but in a tight braid that
the ends, or it will get fouled.
compresses and holds the core. This line is
manufactured only from synthetics, and 50 percent of
its strength is in the core. Double-braided line is used
for mooring ships, towlines, and many other purposes.
Plaited line is made of eight strands--four right-
twisted and four left-twisted. These strands are paired
and worked like a four-strand braid (fig. 4-2). Thus two
pairs of right-laid strands and two pairs of left-laid
strands are formed into a line that is more or less square.
Plaited line is used for towlines, ship mooring lines,
messengers, and many other applications. Plaited line is
available in nylon, polyester, and polypropylene.