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PRACTICAL NAVIGATION
As divers, our primary navigational goals are finding some
special point of interest during the dive and finding the
boat or exit point at the end of the dive. Points of interest
are easy because you can navigate directly to them if
you know where they are and you have good instrument
navigation skills. Finding the exit point, however, can be
quite difficult, even for experienced divers. Since most of us
usually exit the water at the same point we entered, it is a
good habit to identify a prominent bottom feature near you
as soon as you descend. Then look for some of the natural
navigational clues that are present on nearly every dive site.
Sites near beaches, for example, will typically have ripples
in the sand that are parallel to the shoreline. On sites where
there is a predominant direction of current flow, there are
usually depressions in the sand upcurrent of solid objects
and mounds of sand downcurrent. Cues such as these can
keep you swimming in the right general direction and help
bring you back to where you started. For example, to swim
out and back perpendicular to the beach you only need to
swim perpendicular to those ripples in the sand.
Reef lines, debris fields from wrecks and other physical
structures can also be used to navigate but should be used
with caution. These features do not always proceed in uniform
directions, and if there are multiple structures it is easy to get
off course. However, if you note your initial direction of travel
with your compass and note the time, you will be able to use
your compass in addition to these physical cues to help get
you back to your starting point. If you start swimming north,
and after five minutes you turn 90° to the left at the huge brain
coral and then swim another seven minutes, you can return to
the boat by reversing your direction, swimming about six or
seven minutes and looking for the brain coral where you will
turn 90° to the right and swim five minutes back to the boat.
Just as diving experience teaches us to enjoy being
underwater without fixating on our gauges, navigation
experience teaches us to find our way around without
keeping our eyes permanently glued to our compasses. By
spot checking the compass when you make your usual gas,
depth and time checks, you will look like an expert by arriving
back at the boat every time without the hazards of surfacing
repeatedly to see where you are.
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