DD Exam Preparation:
Essential Topics and
Strategies
1. What are aids to navigation? devices specially
constructed to
as- sist
navigators in the
safe navigation
of their vessels
or to warn them
of dan- gers or
obstructions to
navigation.
2. What do they include? These include
light- houses,
navigation lights,
buoys, and
beacons.
3. What are light lists? Publications
in books
4. What are the three principal phase characteristics fixed, flashing,
of navigational lights? Briefly describe each and occulting.
Fixed lights burn
steadily.
Flashing lights
show single
flashes of light at
regular in-
tervals-never
more than thirty
flashes per
minute Occulting
Lights are totally
off at regular
intervals
5. What is meant by the visibility of a navigation light? the distance in
nau-
tical miles that a
1/
6
, DD Exam Preparation:
Essential Topics and
Strategies mariner can see
the light at night.
6. Upon what factors does it depend? depends on its
in- tensity and
height above
sea-level, the
2/
6
Essential Topics and
Strategies
1. What are aids to navigation? devices specially
constructed to
as- sist
navigators in the
safe navigation
of their vessels
or to warn them
of dan- gers or
obstructions to
navigation.
2. What do they include? These include
light- houses,
navigation lights,
buoys, and
beacons.
3. What are light lists? Publications
in books
4. What are the three principal phase characteristics fixed, flashing,
of navigational lights? Briefly describe each and occulting.
Fixed lights burn
steadily.
Flashing lights
show single
flashes of light at
regular in-
tervals-never
more than thirty
flashes per
minute Occulting
Lights are totally
off at regular
intervals
5. What is meant by the visibility of a navigation light? the distance in
nau-
tical miles that a
1/
6
, DD Exam Preparation:
Essential Topics and
Strategies mariner can see
the light at night.
6. Upon what factors does it depend? depends on its
in- tensity and
height above
sea-level, the
2/
6
