Chapter 5- Introduction to Deeper Diving
Introduction to Deeper Diving
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using dive computers, end your dive when the more conservative
computer reaches its limit.
It is important that you proceed at a slow, easy pace
during deeper dives. Breathe continually. Avoid “skip
breathing,” and avoid heavy exertion. As you monitor
your air, keep in mind that one-half of your air supply is
for your bottom time, which includes your descent, and
one-half is for your ascent, decompression stop (safety
or emergency) and for contingency purposes. For dives
to even deeper depth, the rule is modified to one-third
for descent and bottom time, one-third for ascent and
a precautionary decompression stop, and one-third for
contingency.
A slow, controlled descent and a slow, easy pace on
the bottom can also reduce the likelihood of experiencing
nitrogen narcosis. There are numerous and various
symptoms of narcosis. If you experience any strange or
unusual feelings, you should immediately signal your
buddy and ascend until the feelings are alleviated. Even
if you just feel uncomfortable, you should signal your
buddy and ascend until you are again at a comfortable
depth. An established rule of diving, and one which is
especially important for deeper diving, is that anyone can
call an end to a dive at any time and for any reason. If
your buddy signals you to ascend, respond at once rather
than trying to communicate that you are still fine, have
time, air, etc. When in doubt, ascend and end the deep
dive.
One of the more popular types of deep diving is
“wall” or “drop-off” diving (figure 5-9). At many locations
in the Caribbean, the continental shelf drops off
steeply into extremely deep water quite close to shore.
The vertical walls of the drop-off offer spectacular diving,
but those who dive these areas need to follow recommended
procedures and practices. It is common to
anchor the boat near the edge of the drop-off. Buoyancy
must be trimmed precisely before venturing out over the
deep water. With proper buoyancy control, there is a feeling
of exhilaration as you hang suspended in space on a
wall dive. This type of dive is often led by a divemaster or
guide. You should not go deeper than the guide. If you
do, you can cause the dive to be shortened for everyone in
the group, and you won’t be very popular after the dive.
FIGURE 5-9. Deeper water diving is commonly conducted on dropoffs
or “walls.” It is important to follow instructions
and the dive plan to avoid problems.
A good practice is to move away from the boat along the
wall at a pre-determined depth and to return to the boat
at a shallower depth. There are other procedures that will
be explained to you. Pay attention during the briefing
and follow the instructions, which are for your benefit
and safety.
It is important that you adhere closely to your dive
plan on deep dives. One of the conventions for deeper
dives is that a dive plan should not be changed during
the dive with the exceptions, of course, to dive shallower,
ascend sooner, or respond to emergency situations.
Remember, “Plan your dive, then dive your plan.” This is
more important than ever for deeper dives.
Your ascent should be made on the down line, which
provides a reference, control, and a place to carry out
precautionary decompression stops. Your rate should not
exceed 9 meters (30 feet) per minute or the rate specified
by your dive computer. This rate is much slower than