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What
WasThat? (22-1)
By Mark King
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 Feeling
and hearing the bottom of your boat connect with an
underwater obstruction can be a frightening moment.
There are dangers lurking below the surface of our favorite
waterways and the worst part is, in the case of floating
or semi-submerged objects, they can be almost anywhere.
Obstructions below can be identified in three categories.
They can be fixed objects such as old piers, rocks,
cables, dams and seasonally shallow water. Or they can
be currents and eddies, which change with water depth,
flow and wind direction. They can also be miscellaneous
objects that can range from pieces of an old dock and
trees to old logs and tires that have broken free and
are now drifting just under the surface waiting to meet
the bottom of your boat and tear your lower drive unit
to pieces.
We have all heard stories about boats hitting objects
“in the middle of the channel.”
For the most part, investigation would reveal the objects
were either well-marked and not in the channel, or they
were unmarked because they were not in the channel.
And this leads to the first key to avoiding underwater
obstructions.
Recreational boaters must have all the latest and largest
scale charts of the area they are cruising in. As well,
they must have any other publications that provide information
about the area such as Sailing Directions – which
are not just for sailors – and canal regulations
if you frequently cruise on a canal. Of course these
publications will not be able to assist you if you don’t
understand the symbols or don’t pay attention
to them.
Charts will show you where the fixed objects are located.
Old pilings, rocks and shoals, cables, dams, shallow
water, underwater structures will clearly be shown,
while Sailing Directions will tell you in words where
such obstructions are located.
It's also important to study the charts. In heavily
traveled waters, these dangers may even be marked by
buoys. It's your responsibility as the vessel operator
to be aware of all these dangers.
Additionally, in many places, currents are regular and
measurable. The prudent boater knows that such currents
can be affected by wind and water depth. In any shallow
area, or location where water depth can change substantially
over the course of a season, currents can build and
cause difficulties for boaters at certain times of the
year or in certain weather conditions.
The final category of obstruction are loose, floating,
submerged and semi-submerged objects, which are not
easy to pin-point. Boaters should generally be aware
of their location and realize that winter ice and deep
water can dislodge shore-bound objects and set them
free. Wind storms can cause trees and large branches
to fall in the water as well.
Many of these objects may be reported to the Coast Guard
and may be broadcasted on the Coast Guard continuous
VHF radio channel. But most go unreported.
It's up to you to be aware that they might exist and
proceed with appropriate caution.
Floating debris is often an indicator of something just
below the surface. Small branches sticking up out of
the water can indicate there is a tree below the waterline.
If you are operating in an unfamiliar area, ask the
local marina operator or boaters if there is anything
to be aware of beyond what the charts show. It's not
unusual for obstructions to appear on a waterway at
any time during the season.
For example, a large amount of boat traffic can stir
up the bottom of some rivers and suddenly float old
debris to the surface. If you are not certain of the
waters in which you are operating, stick to the marked
channels and recommended routes.
Finally, before you set that hook for the night, be
sure to consult the chart to make sure your anchor is
not about to become permanently affixed to an old wreck,
an underwater cable or anything else that can be potentially
dangerous. (Page
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