10), For best, average, or unfavorable conditions, the
following safety factors may often be suitable:
Best conditions (new line): 4;
Average conditions (line used, but in good
condition): 6; and
Unfavorable conditions (frequently used line,
such as running rigging): 8.
HANDLING AND CARE OF LINES
If you expect the fiber line you work with to give
safe and dependable service, make sure it is handled
and cared for properly.
Study the precautions and
procedures given here and carry them out properly.
Cleanliness is part of the care of fiber line. Never
drag a line over the deck or ground, or over rough or
dirty surfaces. The line can easily pick up sand and
grit, which will work into the strands and wear the
fibers. If a line does get dirty, use only water to clean
it. Do not use soap because it will remove oil from
the line, thereby weakening it.
Avoid pulling a line over sharp edges because the
strands may break.
When you encounter a sharp
edge, place chafing gear, such as a board, folded
cardboard or canvas, or part of a rubber tire between
the line and the sharp edge to prevent damaging the
Never cut a line unless you have to. When
possible, always use knots that can be untied easily.
Fiber line contracts, or shrinks, when it gets wet.
If there is not enough slack in a wet line to permit
shrinkage, the line is likely to become overstrained
and weakened. If a taut line is exposed to rain or
dampness, make sure the line, while still dry, is
slackened to allow for the shrinkage.
Line should be inspected carefully at regular
intervals to determine whether it is safe. The outside
of a line does not show the condition of the line on the
inside. Untwisting the strands slightly allows you to
check the condition of the line on the inside.
Mildewed line gives off a musty odor. Broken strands
or yarns usually can be spotted immediately by a
trained observer. You will want to look carefully to
ensure there is not dirt or sawdust-like material inside
the line. Dirt or other foreign matter inside reveals
possible damage to the internal structure of the line.
A smaller circumference of the line is usually a sure
sign that too much strain has been applied to the line.
For a thorough inspection, a line should be
examined at several places along its length. Only one
weak spotanywhere in a line-makes the entire
line weak. As a final check, pull out a couple of
fibers from the line and try to break them. Sound
fibers show a strong resistance to breakage.
If an inspection discloses any unsatisfactory
conditions in a line, make sure the line is destroyed or
cut up in small pieces as soon as possible. This
precaution prevents the defective line from being used
LEARNING OBJECTIVE: Upon completing
this section, you should be able to determine
the use, breaking strength, and care of wire
rope used for rigging.
During the course of a project, Seabees often need
to hoist or move heavy objects. Wire rope is used for
heavy-duty work. The characteristics, construction,
and usage of many types of wire rope are discussed in
the following paragraphs. We will also discuss the
safe working load, use of attachments and fittings,
and procedures for the care and handling of wire rope.
Wire rope consists of three parts: wires, strands,
and core (figure 4-5). In the manufacture of rope, a
number of wires are laid together to form the strand.
Then a number of strands are laid together around a
core to form the rope.
Figure 4-5.Parts of wire rope.