NON-LATERAL SYSTEM
The non-lateral system consists of safe
water marks, ranges, isolated danger marks,
mooring buoys, and special marks.
Safe Water Marks
These aids are used to mark fairways,
mid-channels, and offshore approach
points, and have unobstructed water on all
sides (Table 5-4 and Figure 5-9).
They can also be used by the vessel
operator transiting offshore waters to identify
the proximity of intended landfall.
Lighted/unlighted buoy may show a
red topmark (ball).
Ranges
A range consists of a PAIR of beacons, usually
consisting of dayboards and/or lights.
When the beacons appear to be in line with
each other (Figure 5-10, see next page), they
assist the vessel operator in maintaining a
safe course within the navigable channel.
The appropriate nautical chart must
be consulted when using a range to determine
if the range marks the centerline of
the navigable channel and also what section
of the range may be safely traversed.
Ranges are generally, but not always,
lighted, and display rectangular dayboards
of various colors. Ranges that are lighted
24 hours a day may not have dayboards.
The rear beacon is taller than the
front beacon.
Any horizontal visual misalignment of
the two beacons alerts a boater to steer back
into the channel (Figure 5-11, see next page).
The segment of the range that lies
within the channel is usually indicated on
the chart by a solid line; whereas, other
parts of the range (non-navigable) are
dashed lines.
Always refer to a chart to determine
what portion of a range you may travel
safely.
Table 5-3. Preferred-Channel Marks When Returning From Sea
Color Red and Green horizon- Green and Red hori-
tal bands, top band red zontal bands, top
band green
Shapes:
Unlighted Conical (nun) Cylindrical (can)
Lighted Skeleton tower Skeleton tower
Topmark Red cone, point up Green cylinder
(if fitted)
Daymark Red triangle, Green square, lower
lower 1⁄2 green 1⁄2 red
Light
(if fitted)
Color Red Green
Rhythm Flashing 2 + 1 Flashiing 2 + 1
(2 short/1 short) (2 short/1 short)
Identification Letters Letters
Table 5-4. Safe Water Marks
Color Red & White Vertically striped
Unlighted shape Spherical
Lighted shape Skeleton tower
Topmark (if fitted) Red Sphere
Daymark Octagonal red & white
Divided vertically
Light Color White Morse “A”
(if fitted) Interval (short flash-long flash)
Identification Letters
Figure 5-9.
Preferred Channel
to the left
Preferred Channel
to the right
45
46
47
48
49
50
51
52
53
54
55
Section 5: Navigation Aids 67