Chapter 5- Introduction to Deeper Diving
Introduction to Deeper Diving
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you complete the “Dive Plan” section of your NAUI “Dive
Planning and Recording Worksheet” on the back of your
NAUI Dive Tables (figure 5-7). This contingency information
provides instantaneous time limit information in
the event that you should exceed your planned depth. For
deep dives, it is recommended that an expanded contingency
plan be written on your slate and taken along on
the dive. This provides previously determined information
for various times plus various depths. This approach
is preferred to attempting to reference the dive tables
underwater where errors are more likely to occur.
These are the minimum preparations for deeper
dives, but don’t be misled into believing that this is all
there is to going to increased depths in diving. There are
more procedures, more things to be learned, and additional
training requirements to be met before you should
make excursions approaching the maximum recommended
40-meter (130-foot) depth limit for traditional
recreational diving. It is important now for you to learn
and apply the basics of preparation and planning during
this Advanced Scuba Diver course so you can dive with
confidence to deeper depths. In your own diving, stay
within your “comfort envelope” by advancing gradually
towards greater depths. You should understand why
advanced specialty training is necessary if you desire to
dive even deeper. Diving beyond 40 meters
(130 feet) is to enter the realm of “technical diving,”
where additional special procedures and gas mixes are
employed, and mandatory decompression is a virtual
certainty.
PROCEDURES AND PRECAUTIONS
Upon arrival at the dive site and determining that
conditions are suitable for the dive, you should check
emergency communications systems and determine that
they are functional. Telephones or radios are of no value
if they do not work.
When applicable, set up a “down line” and an air
cylinder with a regulator attached. Place the cylinder and
regulator at the precautionary decompression stop depth
of 5 meters (15 feet). This extra cylinder is often called a
“hang-tank.” It should be turned on to ensure that it is
full and that the regulator is functioning properly, but it
should then be turned off to prevent loss of air if the regulator
should free-flow while the unit is hanging on the
line. All of the divers in the group should be informed that
they will need to open the valve on the hang-tank if it is
needed. The down line should be vertical and taut. This
is accomplished by placing weights on the bottom of the
line and suspending it above the bottom. If the line is suspended
from a surface float rather than a boat, an anchor
and line can be rigged from the weights at the end of the
line to the bottom.
MDT =
MDT =
RNT = 0
ADT =
TNT =
AMDT =
AMDT =
RNT =
ADT =
TNT =
AMDT =
AMDT =
RNT =
ADT =
TNT =
FIGURE 5-7. The dive planning worksheet is useful to plan ahead and for recording data after the dive.