Table 4-4.--CID-A-A-50435 Aramid Rope Characteristics
Before you use a new three-strand synthetic-fiber
line, fake (coil) it down on deck and allow it to relax for
24 hours. The shorter the line, the less time the relaxing
CIRCUMFERENCE
BREAKING
process takes; for example, a length of less than 50 feet
(INCHES)
STRENGTH (POUNDS)
will relax in 1 hour.
3 3/8
50,000
When wet, synthetic line shrinks slightly and may
3 1/2
60,000
swell slightly. When the line is tensioned, the water
3 3/4
squeezes out; under working loads, it appears as vapor.
70,000
Because line under tension develops friction, and thus
4 1/8
96,000
heat, the water has a beneficial cooling effect.
4 3/4
135,000
However, nylon loses 15 percent of its strength from
water being absorbed by nylon molecules.
5 3/8
180,000
Nylon, aramid, and polyester lines exhibit almost
5 7/8
225,000
no decrease in strength due to sunlight, but
6 1/4
280,000
polypropylene does. Polypropylene line may lose as
much as 40 percent of its strength in 3 months when
7 5/8
350,000
exposed to tropical sunlight if the line is made without
8 3/16
420,000
ultraviolet inhibitors. Ultraviolet inhibitors can be
added to the line at the time of manufacture to reduce the
effects of sunlight. White polypropylene line has
Four-Strand Aramid Line
almost no inhibitors added, while black polypropylene
Four-strand aramid lines are designed to fail
has the most inhibitors added. However, just because a
sequentially, meaning that one of the four strands will
polypropylene is black does not mean that it has had
fail before the other strands. This line has been proven
ultraviolet inhibitors added. If a polypropylene line has
to work better than a three-strand mooring line, and less
had ultraviolet inhibitors added, it should meet military
line handlers are required due to the smaller size of line
specification MIL-R-24049. Line obtained through the
required to moor a ship. Table 4-4 shows the
Naval Supply System (stock system), meets the proper
characteristics of aramid rope.
specifications.
Aramid line is being phased into the Navy as a
Oil and grease do not cause synthetics to
substitute for three-strand nylon; table 4-5 compares
deteriorate, but they may make them slippery. When
equivalent sizes of lines, from three-strand nylon to
this happens, the line should be scrubbed down.
polyester double-braided line.
Table 4-5.--Aramid Rope Substitution
ARAMID
NYLON
NYLON
NYLON
POLYESTER
4-STRAND
3-STRAND
PLAITED
DOUBLE-
DOUBLE-
CID-A-A-50435
MIL-R-17343
MIL-R-24377
BRAIDED
BRAIDED
MIL-R-24050
MIL-R-24677
3 3/8
4 1/2
4
4
4
3 1/2
5
4 1/2
4 1/2
4 1/2
3 3/4
5
5
5
5 1/2
4 1/8
6
5 1/2
6
6
4 3/4
7
7 1/2
7
7
5 3/8
8
9
8
8
5 7/8
9
10
9
9
6 1/4
10
11
10
10
4-8
