NAVIGATION TRAINING
Section 6
Navigational Aids
Table of Contents
• Section 1
• Section 2
• Section 3
• Section 4
• Section 5
• Section 6
• Section 7
• Section 8
• Section 9
• Section 10
• Section 11
Types of Navigation
Terrestial Coordinates
Charts
Compass
Nautical Publications
Navigational Aids
Buoyage
Position Lines and Fixes
Tides
Currents
Weather
Navigational Aids
Significance of
Navigational Aids
•Navigational Aid: Any device
external to a vessel or aircraft
intended to assist in
determining position and safe
course, or to warn of dangers
or obstructions.
Navigational Aids
Navigational Aids
Navigational aids will include:
Lighthouses
Transit Marks
Leading Lines
Buoyage
Beacons & Day Marks
Identifiable charted object
Navigational Aids
Positive Identification of Navigation Aids
DAYTIME
•Location
•Shape
•Colour Scheme
•Auxiliary features
•Special Markings
NIGHT
•Phase characteristic
•Period & Colour
Navigational Aids
Positive Identification of Navigation Aids (at night)
Phase Characteristics
Chart Symbol Meaning
Fixed
F
Steady, unblinking
Flashing
Fl
Flashes at regular intervals
Quick Flash
Qk. Fl.
Flash at least 60x/min
Group Flash
Gp. Fl.
Group of two or more flashes
Navigational Aids
Positive Identification of Navigation Aids (at night)
Phase Characteristics
Chart Symbol Meaning
Morse Code
Mo. (A)
Morse alpha (short/long)
Occulting
Occ.
On longer than its off
Period = Length in seconds of repetition
Colour= (red, green, yellow, or white)
Navigational Aids
CHARACTERISTICS OF LIGHTS
Flashing pattern and period (|-----|)
Type
Description
Abbreviation
Fixed
A light showing continuously and steadily
F
Fixed and flashing
A light in which a fixed light is combined with
a flashing light of higher luminous intensity
F Fl
Flashing
A flashing light in which a flash is regularly
repeated (frequency not exceeding 30 flashes
per minute)
Fl
Group flashing
A flashing light in which a group of flashes,
specified in number, is regularly repeated.
Fl (2)
Composite group flashing
A light similar to a group flashing light except
that successive groups in the period have different numbers of flashes
Fl (2+1)
Isophase
A light in which all durations of light and
darkness are equal
Iso
Single occulting
An occulting light in which an eclipse, or
shorter duration than the light, is regularly
repeated.
Oc
Group occulting
An occulting light in which a group of
eclipses, specified in number, is regularly
repeated.
Oc (2)
Composite group occulting
A light, similar to a group occulting light,
except that successive groups in a period
have different numbers of eclipses
Oc (2+1)
Quick
A quick light in which a flash is regularly
repeated at a rate of 60 flashes per minute
Q
Interrupted quick
A quick light in which the sequence of flashes
is interrupted by regularly repeated eclipses of
constant and long duration
lQ
Group quick
A group of 2 or more quick flashes, specified
in number, which are regularly repeated. (Not
used in the waters of the United States.)
Q(3)
Morse code
A light in which lights of two clearly different
durations (dots and dashes) are grouped to
represent a character or characters in the
Morse code.
Alternating
A light showing different colours alternately
Al RW
Long flashing
A flashing light in which the flash is
2 seconds or longer
LFl
Mo (A)
Navigational Aids
Special Purpose Lights
Sector Lights
• Red light used in dangerous sectors
• Sector limits are expressed in degrees
true as observed from a vessel, not from
the light!
Navigational Aids
Other Navigational Aids
Other navigational aids, providing they are charted, will
include:
Navigational Aids
Navigation Marks and Buoyage
Navigational Aids
Determining the Computed
Visibility of a NavAid
Horizon distance = the line of
sight from a position above the
earth’s surface to the visual
horizon.
Geographic range = the
maximum distance that a light
may be seen in perfect visibility
by an observer’s eye who is at
sea level
Bella Bella
Navigational Aids
Determining the Computed
Visibility of a NavAid
Computed range = the distance at
which a light could be seen in
perfect visibility (taking into
account elevation, observer’s
height of eye, and the curvature
of the earth). Computed Range =
Horizon Distance + Geographic
Distance
Bella Bella
Navigational Aids
Determining the Computed
Visibility of a NavAid
Computed range = the distance at which a
light could be seen in perfect visibility (taking
into account elevation, observer’s height of
eye, and the curvature of the earth).
Computed Range = Horizon Distance +
Geographic Distance
Navigational Aids
Determining the Computed
Visibility of a NavAid
Computed visibility = The maximum distance at which a light
can be seen in the current meteorological conditions.
Luminous range = the maximum distance at which a light may
be seen under under the current meteorological conditions.
Nominal range = a special case of the luminous range. It is the
distance a light could be seen in “clear” weather. Also called
the charted range.
Navigational Aids