as dirt, also abrade fibers. Unfortunately,
dirt and salt are found in abundance on the
sea bottom, which means that an older line,
even one that is healthy looking and supple,
may have already begun to weaken significantly. Fibers are also weakened by sunlight
and exposure to certain chemicals, including
acids and alkalis.
There are other ways that nylon rope
is affected by age. Repeatedly expanding
and contracting weakens the fibers; the
more times the line is used and heavily
stressed, the more likely it is weakened.
As they get older, nylon lines become stiff
as they shrink and fibers lose lubricant.
Better-quality nylon line is pre-shrunk but
it’s not possible to eliminate all shrinkage;
some is inevitable. The lubricant found on
better nylon line minimizes shrinkage by
keeping water from penetrating the fibers.
Lubricant has the considerable added benefit of reducing yarn-on-yarn friction, which
helps to reduce heat.
Two obvious indications that the line
is shot are stiffness and, when it’s under
load, “squeaking.” Nobody knows how
long an anchor line should be considered
dependable but any line that is used hard
and often is likely significantly weaker than
a new line.
More Than A Rode
Using larger and newer lines is a
good start but there are more choices yet
to be made. After Arsenault’s harrowing experience (the boat survived, albeit
with a bent rudder shaft), he replaced his
failed nylon braid-on-braid rode with nylon
three-strand. The reason, he said, was that
the three-strand line has greater elasticity
(more stretch) to absorb the violent loads.
The bow of his boat had been thrown high
into the air by waves in the open water
and the lack of elasticity in the anchor rode
(and perhaps its age) led to the failure.
Would three-strand or plait have survived?
It’s hard to say.
Owners must choose how much of a
trade-off in breaking strength they want to
make to get additional energy absorption.
Once again, nobody knows. It could be
boat; opting for increased breaking strength
(braid-on-braid or even polyester) might be
a better choice.
About polyester: Polyester is much
tougher and far more resistant to chafe,
both internal and external, and has the
capability of going to 50 percent to 60
percent of its breaking strength without
fatiguing, at least not quickly. Even when
wet, polyester line retains full strength;
nylon loses strength, although water is
necessary to cool the stressed fibers. One
rope manufacturer’s expert, who also owns
a boat, said he would consider using a combination of three-strand polyester rode with
a nylon rode in a hurricane. The two could
be looped eye-to-eye to avoid having a knot
in the line. (Knots weaken a line by as much
as 50 percent.) Polyester would be used
from the cleat through the chock, where the
line is likely determined by the size of the
cleat(s). Another obvious choice: A rode
(and storm anchor) that is used purely
for anchoring the boat in a storm should
be made up before the start of hurricane
season. The boat’s everyday working rode
should not be relied on; it probably isn’t
big enough and, if used routinely, has lost
its resiliency and breaking strength.
COMPARABLE AVERAGE BREAKING STRENGTHS
FOR DIFFERENT ROPE SIZES AND TYPES*
Diameter Braid-on-Braid Three-Strand Plait
1/2” 8,300 lbs. 6,100 lbs. 6,300 lbs.
5/8” 17,000 lbs. 9,350 lbs. 10,400 lbs.
3/4” 21,000 lbs. N/A 16,200 lbs.
Cleat considerations: If the chock isn’t smooth and
well-rounded, the line quickly chafes through as
it moves back and forth in a storm. Also, when a
line is being compressed at the chock under storm
loads, it can lose half its strength. Lastly, all of
the stretching back and forth under tremendous
pressure generates enough heat at the chock to
melt the nylon fibers; eliminate the chock altogether
by locating the cleat directly on the rail as shown,
above.
*Source: Yale Cordage
5. Line quality. As noted, better-quality
line is pre-shrunk and has lubricant added
to the fibers. The way a line is woven is also
important. Look for three-strand twist with
a medium lay construction. This has more
twist (“mechanical twist”) and absorbs
energy more readily than rope made with
soft-lay construction. While easier and
cheaper to manufacture, soft-lay rope is
much more prone to failure. If it’s easy to
separate the strands, the line is probably
soft lay.
Electrical tape might do in calm weather but won’t
hold up as chafe protection in storms.
What’s Best In A Storm?
The question for boat owners is what
type of line will stand the best chance in a
storm? First, the obvious: using more and
larger lines. For example, a 3/4-inch line outlasts a 1/2-inch line and two 3/4-inch lines
outlast a single 3/4-inch line. The size of the
Ideal for anchor rodes and docklines where chafing
could cost you the boat, Secure Chafe Guards from
Davis Instruments measure 16” long and are made
of tough nylon with a Velcro hook fastener; it fits
lines from 3/8” to 1”.
