Dock Lines
I walked around
the marina a few days ago and looked at the dock lines that were being used to
secure the boats in their respective slips.
I was pretty amazed at what I saw.
Some boats were secured properly.
Other boats were not secured well at all. Some of the poorly secured boats showed
significant chafe and wear on the lines (a couple boats actually had lines that
had broken and the owner simply tied the two broken ends in a knot and retied
the line to the cleat on the boat). Some
of the boat owners were using line that was significantly undersize for the
boat - - one eighth inch line for a 26 foot long boat for instance. Many boats were tied to the dock with dacron
(doesn’t stretch much) line. Every time
one of these boats surges against the line, a considerable shock is imparted
through the cleat to the cleat’s fasteners and to the deck of the boat. How many times can you bend a credit card
before it breaks???? Remember that we
have experienced some very strong wind storms recently. A dock line with only what looks like a
little bit of chafe will be considerably weakened.
So, here is some
information compiled by West Marine in their catalog and on-line in the West
Advisor –
Dock Lines:
What they do – Dock lines secure your boat to a dock, or to
another boat when rafting, either temporarily or semi-permanently. These applications demand different types of
dock lines.
How they work – When your boat is away from its regular slip
or mooring, you need to have some designated nylon lines aboard, preferably with spliced eyes, ready for
use when you tie up somewhere. We call
these transient dock lines. The
eye in the end is easily passed around a cleat or piling by someone on the dock
and the bitter end is adjusted on board.
There are dozens of combinations of diameters and lengths.
Permanent dock lines are also made of nylon, but differ from transient
dock lines in several ways. First, they
must be protected from chafe, the enemy of all lines in constant use. This calls for leather, rubber or fabric
chafe gear where the line passes through the chocks, and possibly a chafe
sleeve on the eye where it goes around the cleat on deck. At the dock, lines should be protected from
chafe using eye splices and shackles if the dock has rings, or eye splices and
short lengths of chain if the dock has cleats.
Permanent dock lines should be cut to fit the particular boat in the
slip.
What to look for – Dock lines should be made from nylon, which has a superior
combination of strength and stretch.
Both three-strand and braided construction are common. Three-strand stretches more, is very abrasion
and snag resistant and less expensive.
Braided nylon is
stronger, comes in colors, and has a nice feel or “hand”.
Diameter – We recommend one eighth inch of line diameter for
every nine feet of boat length. Larger
lines will wear longer but stretch less.
Boat length and dock line diameter:
Up to 27 feet - - three eighth inch diameter
28 to 31 feet - - seven sixteenth inch diameter
32 to 36 feet – one half inch diameter
37 to 45 feet – five eighths inch diameter
46 to 54 feet – three fourths inch diameter
Length of line – Transient dock lines should be about two
thirds of the boat’s length when use on the bow and stern. Spring lines should be equal to your boat’s
length.
Here’s an of
example of good anti-chafe gear.
Here’s some
examples of dangerous dock lines in use.
Lines chafing...
This dock line has actually chafed through one of the three strands...
This line is way too small (diameter) for the boat
And more chafe...
Your boat is one
of your most expensive investments.
Having the wrong dock lines or worn out dock lines will jeopardize that investment. Next time you are out to your boat, take a
close look at the dock lines and make
corrections (if needed). - This does not mean find an old jib sheet to tie the dock to the boat with. - If one
of your lines breaks during a storm, your boat will start banging against the
dock, piling, or other boats. And, you
will find out just how good your boat insurance really is.
