heavy strain may develop glazed areas where it has
worked against bitt and chock surfaces. This condition
may be caused by paint or the fusing of the fibers. In
either condition, the effect on the line's strength is
New cable-laid nylon hawsers tend to be stiff and
difficult to handle. To alleviate this condition, put the
cables under tension for 20 minutes at 30 percent
extension; for example, 100 feet when under tension
would measure 130 feet.
Nylon line can hold a load even though a
considerable number of the yarns become abraded.
Where such a condition is excessive but localized, the
chafed section may be cut away and the ends spliced
together for satisfactory reuse.
When nylon lines become iced over in use, they
should be thawed carefully at moderate temperatures
and drained before stowing.
If a nylon line becomes slippery from contact with
oil or grease, it should be scrubbed down. Spots may be
removed by cleaning with light oils such as kerosene or
Do not stow nylon line in strong sunlight. Cover it
with paulins. In stowage, keep it away from heat and
Synthetic lines under stress are far more dangerous
than natural fiber lines. Remember synthetic line,
unlike natural fiber line, will not give you an audible
warning that it is under great strain and is in danger of
parting. You must rely on visual cues; the line begins to
smoke because of the heat generated by stretching, the
line diameter will get smaller and smaller as stretching
continues, and finally the tattletale cord will lay taut
against the line. A tattletale cord is a bight of six-thread
manila hanging from two measured points on the
working line. When tensioned to its safe working load
(SWL), the line will stretch to a certain percentage of its
length. When this point is reached, the six thread
becomes taut, warning that there is danger of exceeding
the line's SWL. Table 3-1 shows the dimensions for
NATURAL FIBER LINES
LEARNING OBJECTIVES: Describe natural
fiber lines. Describe the characteristics of
natural fiber lines.
When you have a new coil of natural fiber line to
open, remember that if you open it backwards, or from
the wrong end, you will have a kink for every turn in the
coil. Every kink must be unwound by walking it out the
entire length of the line. When you start to walk out a
kink from the middle, you turn into the next kink and
the next, until the line is one large tangle.
The end of a new coil to be drawn out first is
marked with a tag. Occasionally, it is tagged on the
wrong end. The only way you can be sure that you are
opening a coil properly is to know how to do it. The
inside of every new coil is in the form of a round tunnel.
At one end of the tunnel is the inside end of the line.
This inside end always comes out first, usually from the
bottom of the tunnel up through the tunnel. Reach
through the tunnel until you find the end, and determine
on which end to set the coil so the line will uncoil in a
counterclockwise direction. Reach in, draw the end up
through the tunnel, and the entire coil will run off
without a kink. The important point to bear in mind is
that when you pull on the inside end, the line must
uncoil in a counterclockwise direction.
Until the development of synthetics, manila was the
strongest line. It also was the most expensive. It was
natural to compare other ropes with manila, and it still
is convenient to do so. The following table gives the
comparative strengths of the various lines using manila
as a base strength of 1. (All synthetics are stronger than
Polyester (three strand)
When you are sent to the Bos'n locker for 5 fathoms
of line, you need not measure off exactly 360 inches
with a tape measure. Your two arms, spread as wide
apart as possible, will equal approximately 1 fathom (6
feet). With the end of the line in one hand, spread your
arms, grab the line where your other hand reaches, and
change hands until you have spread your arms five
In measuring a long line, such as a boat fall, it is
much easier and faster to measure a long stretch on deck
and fake your line back and forth until the desired length
is laid out.