Green daymarks have a square shape,
labeled on chart as G with a number.
Example: G “213” (Figure 5-7, right).
Lighted green marks do not have a defined
shape.
Preferred-Channel Mark
Preferred-channel marks are found at
junctions of navigable waters which mark
channels for transits to different destinations
(Figure 5-8).
A vessel may normally pass this aid on
either side, but the top color band indicates
the preferred channel.
Example: If the top band of the aid is
red, it is treated as a red mark and kept to
starboard as the vessel passes it while returning
from sea.
Caution: It may not always be possible
to pass on either side of preferred channel
aids to navigation. The appropriate nautical
chart should always be consulted.
This aid has alternating colors with the preferred
color on top.
A preferred channel buoy chart symbol
is a split-color diamond; preferred
color on top (away from circle) with a black
circle, labeled on chart as:
• RG (red over green) and N for nun
(unlighted). Example: RG N “B”
• GR (green over red) and C for can
(unlighted). Example: GR C “D”
A preferred channel daymark has colors
and shapes like a preferred buoy; red over
green within a triangle; green over red
within a square (Table 5-3).
Lighted marks do not have a unique
shape.
Figure 5-7. Can buoy and green
daymark
Table 5-2. Side-of-Channel Marks When Returning From Sea
Port Starboard
Color Green Red
Shapes: (add red bar)
Unlighted Cylindrical (can) Conical (nun)
Lighted Skeleton tower Skeleton tower
Daymark Green square Red triangle
Light (if fitted) (add green bar) (add red bar)
Color Green Red
Rhythm Varied flashing Varied flashing
Identification Odd numbers Even numbers
Figure 5-8. Preferred-channel mark
33b
34
35
36
37
38
39
40
41
42
43
44
66 Chapter Two