THE TOWBOAT OPERATOR TOOK ONE LOOK and said, “I think we’d better wait.” No brainer. The tide was low. The megabucks fast cruiser was in only inches of water, and under those inches was a very hard sand shoal, obvious in the shallow water and very far away from the channel. And somewhere down there were very
expensive props and rudders. Floating the boat was out of the question without
a blimp the size of the Hindenburg. But the skipper was in a hurry. He had to get this boat
to a boat show. “Can’t you just tow me off?” The towboat had the capacity to do that, but it
would have probably left the bottom in the shoal.
Five hours of waiting and the boat could be pulled off with no additional damage. The
haulout revealed twisted running gear and a nightmarish wavy bottom. But the skipper had
new props and shafts shipped in, and soon was on his way. “The chartplotter didn’t refresh fast
enough, so that shoal wasn’t showing when I got there” was his explanation. Electrons and a
fancy screen don’t excuse the navigator from thinking. Here are a few tips for making the most
of this remarkable aid to navigation.
DATA, NOT INTELLIGENCE
Chartplotters have made everyday navigation a dream. But, like all technology, they have their
limits. The first is the user. As in the case above, if you’re going fast enough it’s possible that
the screen might not refresh quickly enough to keep up with your position. That could be
because of processor speed, but it could also be a function of the GPS chip, and the amount
of data you’re displaying. When you are navigating in areas with obstructions, you need to rely
THE LIMITS OF CHARTPLOTTERS
Avoid being led astray by your well-meaning electronics BY TOM NEALE
on something lower tech than your chartplotter – your throttle. All you have to do is pull
it back. While modern plotters have better
processing power and faster refresh times,
slowing down when you’re unsure can prevent a big headache later.
Refresh rate is just one of several things
you need to understand about your plotter.
Chartplotters can provide so much information that usually a few hours of training are
needed to use them well. But there’s a strong
temptation to “hook ‘em up and start pushing buttons.” It’s fun and you want to get
out on the water. But push those buttons for
awhile at the dock with the manual until you
become familiar with your new tool. You may
be surprised how much information it can
provide you, if you just use it correctly.
For example, you need to know if your
chartplotter is set to give you latitude and
longitude in degrees, minutes, and seconds,
or degrees and decimal degrees. Failure to
report and/or record position without knowing which “language” is being used has
resulted in serious errors, even death.
GETTING A FIX
Seeing your boat’s icon sailing along on
the screen, up in the trees, isn’t reassuring.
But it’s a common event with chartplotters.
PRACTICAL BOATER | SKILLS
It’s not enough
to know what
is telling you.
You’ve got to
it can’t tell you