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complete adaptation for a night watch, spend 5 minutes
on deck before relieving the watch. These 5 minutes
allow the eyes to adjust to the amount of illumination
in which they will work.
NIGHT LOOKOUT TECHNIQUES
Dark adaptation alone is not sufficient to ensure
the highest visual keenness in the dark. Learning to use
the eyes at night is like learning to use a precision
instrument; you must practice to acquire the needed
ability. In night lookout work, don't sweep the sky or
horizon with the eyes. The eyes do not see well when
they are moving. Scan the horizon in a series of
movements which will allow your eyes to come to
periodic rests as they scan the sector. When you are
using night eyes, always look a little to one side and
out of the corners of your eyes. Pay attention to the
things on the outer edges of your field of vision. A faint
object may not be recognizable until your gaze has been
directed toward it a number of times. Likewise, direct
your eyes slightly above or below the horizon, as there
are times when you cannot see the actual horizon unless
your line of vision is purposely elevated or depressed.
One of the greatest aids to night vision is contrast
between object and background. Therefore, a good
technique is to concentrate on the point where the sky
appears to meet the water. Here objects may loom
above the darker water and be seen against the lighter
sky.
To summarize dark adaptation and night lookout
techniques, remember these things:
1. Protect your eyes from light before going on
night duty and while you are out.
2. Don't look directly at any light or illuminated
object.
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