used for navigation purposes. A label will
describe the landmark. It may be a tower,
spire, church, chimney, or flagpole. (See
Figure 18-5.)
Marine Hazards
Marine hazards are represented by a variety
of symbols and abbreviations. For instance,
there are different types of rocks and wrecks.
Visible wrecks have a different symbol
than those of sunken wrecks (Figure 18-6).
Asterisks (*) indicate rocks that cover and
uncover with each change of tide; crosses
(+) indicate rocks covered at low water.
Vertical Clearances
You will frequently want to know the clearance
under shore objects such as bridges
and utility lines. The clearance under a
bridge may determine if it is necessary
to ask for an opening. Sail-boaters must
always be careful to keep masts away from
overhead power lines.
In areas where water rises and falls with
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Figure 18-5. Chart symbols