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Figure 3-2.–Safe work areas.
5. Do not mix lines of different materials or
constructions. This is an unsafe practice because
unequal stretch results in unequal loading.
6. Shiphandlers and linehandlers should be made
aware the new aramid line is a low-stretch line and that
it does not neck down appreciably when put under a
strain. The strain should be carefully controlled to avoid
excessive tension. This is best accomplished by having
linehandlers check the line frequently until they have the
feel of it.
7. As with all other lines, it is recommended you
use chafing gear where aramid lines pass through
chocks. If the cover of any strand of the aramid line is
abraded to the extent that the inner fibers are visible but
not damaged, the strand or entire line may be served with
marline or synthetic cord. If the inner fibers are
damaged, you must cut out that section of the line and
re-splice it.
The three following safety rules for line-handling
must be heeded regardless of the line fiber material:
1. Never stand in the bight of a line or in the direct
line of pull when the line is being pulled or under
tension. See figure 3-2 for an example of bight areas.
2. Never continue to increase the load on a line
after the rigs have been two-blocked or tightened. Many
injuries and fatalities have occurred when operators
have not observed this rule.
3. Remember: A safety observer is a must in every
case where lines are being worked.
Before using new three-strand synthetic fiber line,
it should be faked down on deck and allowed to relax
for 24 hours. The shorter the line, the less time the
relaxing process takes; for example, a length of less
than 50 feet will relax in 1 hour.
When wet, synthetic line shrinks slightly but does
not swell or stiffen. When the line is tensioned, the
water squeezes out; and under working loads, it appears
as vapor. Because line under tension develops friction
and, thus, heat, the water has a beneficial cooling effect.
Nylon differs from natural fiber line in that it
stretches under load, yet recovers to its normal size
when tension is removed. With plain-laid and cable-laid
nylon, a stretch of one-third of its length is normal under
safe working loads. A stretch of 40-percent of its length
is the critical point, and it parts at 50-percent stretch.
With double braided nylon, the critical point is reached
when the line is stretched 27 percent; it parts when the
stretch is 30 percent. This elongation at times may be a
disadvantage, but it can be reduced by doubling up the
lines by passing bight. Nylon line can stand repeated
stretching with no serious effect.
Sharp, cracking noises, caused by readjustment of
the strands, are heard when applying a load to new
cable-laid hawsers. Nylon line that has been under
3-5
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