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33a
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• Daybeacons are shaped boards affixed to
structures such as posts, pilings, or towers
and are usually found in shallow waters or
on shore. Red in color, triangular shaped
daybeacon boards present the same aid as
a red, nun buoy. Green in color, square
shaped daybeacon boards present the
same aid as a green, can buoy.
• Unlighted beacons appear on charts as
small triangles (as for a red, nun buoy) or
squares (as for a green, can buoy).
• Lighted beacons, called lights, appear on
charts with magenta exclamation points
(!). The dot identifies the location of the
lighted beacon.
LATERAL SYSTEM
Navigation aids in the lateral system generally
indicate the port and starboard sides of
the channel, and indicate on which side of
a mark a vessel should pass when channels
are entered from seaward. The lateral system
consists of side-of-channel marks and
preferred channel marks.
Side-of-Channel Marks
Side-of-channel marks may be buoys or
beacons or combination thereof. The
color, shape, lights, sound signals, and
numbers on the marks allow the boater to
easily identify the navigable waters. (See
Table 5-2 on page 66.)
In the U.S. and Canada (IALA System
B*), the rule is:
Red—Right—Returning (RRR) from sea
or going upstream. Going to sea or downstream,
green right going (GRG).
This is the 3R rule of the U.S. Aids to
Navigation System.
The 3R is the essential rule of thumb
for using the lateral system. It means that
when entering one body of water from a
larger body of water (e.g., when returning
to a harbor from a bay or sound), keep the
red aids to starboard (right) side. This also
means that you will keep green side-ofchannel
marks to your left-hand or port
side (Figure 5-4).
Returning is defined as:
• Entering a harbor or bay from the open
ocean (Figure 5-5).
• Traveling up a river from the sea; for
example, up the Mississippi River from
the Gulf of Mexico.
• Traveling in a clockwise direction around
a land mass; for example, southerly along
the Atlantic Coast or northerly along the
Pacific Coast to Alaska.
• On the Great Lakes, colors and numbering
of marks start at the outlet end of each
lake and proceed westerly and northerly
toward their upper ends, except for Lake
Michigan, where the direction of these
marks is southerly.
Red Marks
Unlighted red buoys are called nuns
(Figure 5-6, left).
Chart symbol is a red diamond with
a black circle marking the location,
labeled on chart with a R for red, a
N for nun, and an even number in
quotes. Example: R N “2”
Red daymarks are triangular shaped
(Figure 5-6, right).
Chart symbol is a red triangle whose
center marks the location, labeled
on chart with R for red and an even
number. Example: R “4”
Lighted red marks do not have a defined
shape.
Green Marks
Unlighted green buoys are called cans.
(Figure 5-7, top left, page 66)
Chart symbol is a green diamond with
a black circle; labeled on chart as G for
green and C for can. Example G C “3”.
64 Chapter Two
Tip: When going
through a lock, if you
are “locked up” you
are heading upstream
(RRR). If you are
“locked down” you
are heading downstream
(GRG).
Tip: The International Association of Marine Aids to Navigation
and Lighthouse Authorities (IALA) maintains standards. They define
two systems, A and B. B is used in the U.S. and Canada, A elsewhere.
The difference is primarily that side-of-channel marks are reversed
between the two systems.