in chapter 613 of the Naval Ships' Technical Manual
the lay and inspect the fibers. White powdery
(NSTM), but the more important precautions you should
residue indicates internal wear.
observe are as follows:
Do not drag a line over sharp or rough objects;
Because of the lower coefficient of friction of
doing so can cut or break the outer fibers. When
synthetic-fiber line, you must exercise extreme
line is dragged on the ground, dirt and other
care when you pay a line out or ease it from
particles are picked up and eventually work into
securing devices (bitts, capstans, cleats, gypsy
the line, cutting the inner strands.
heads, etc.). For control in easing out, take no
more than two round turns on cleats or bitts. For
The strength of line exposed to the atmosphere
checking a line under strain, take two round turns
deteriorates about 30 percent in 2 years from
followed by no more than two figure-eight
bends. Any more than this will present a danger
to personnel and cause difficulty in handling the
Line loaded in excess of 75 percent of its
breaking strength will be damaged permanently.
Inspect the inside threads to see if all or a portion
To minimize the hazard of pulling a line handler
of the fibers in the threads are broken.
into a securing device when a line suddenly
surges, have safety observers ensure that all the
Keep bitts, chocks, and cleats in smooth
line handlers stand as far as possible from the
condition to minimize abrasion.
device, with a minimum distance of at least 6 feet
Use chafing gear on rough, hard surfaces and
from the securing device being tended or
sharp metal edges.
worked. Note that this is particularly critical in
Apply loads slowly and carefully.
Since a snap-back action inevitably occurs when
a line parts under tension, never allow personnel
The synthetic fibers currently in use for making line
to stand in the direct-line-of-pull of the line when
are (in descending order of strength) nylon, aramid,
it is being pulled or when it is under tension. A
polyester (Dacron), polypropylene, and polyethylene.
synthetic line parting under tension will snap
back at near the speed of sound, and there will be
The characteristics of synthetic line differ from
no time to clear the area. Where possible,
those of manila line. This causes the safety precautions
position line handlers a minimum of 90 from the
for synthetic-fiber line to be more exacting than those
for manila line. A complete list of precautions is given
Figure 4-7.--Safe working area.