1. Reverse Dive Profiles Are OK
New Rule It is permissible to dive
deeper on your second dive than on your first, and to dive deeper on the
later part of a dive than on the early part.
Old Rule Until this year, all divers have been
taught to go to their greatest planned depth early in the dive and then
gradually work upward in a regular "stair-step" pattern. Similarly,
they've been told to make the deepest dive of the day the first one. The
rationale was that the shallower depths later provided decompression
for the preceding greater depths.
Reason for the Change
Dive computers. Because
computers can track your depth and time constantly and are pretty good
at math, it's possible to know your nitrogen exposure accurately
regardless of your profile. Tables, by contrast, can account for only
your greatest depth, and this crude approximation of nitrogen exposure
still mandates a conservative approach.
Exceptions to the Rule
Obviously, divers using
only tables must still follow the old rules. And even when using a
computer it's still smart to dive deeper first. Ascending profiles give
you more bottom time and a greater margin of safety against DCS.
2. Lower Minimum Age
New Rule
The Recreational Scuba
Training Council, which sets many industry standards, dropped its
minimum age requirement for junior certification near the end of 1999.
As a result, PADI, SDI, SSI and NASDS (which has merged with SSI) have
dropped their minimum age requirements for junior certification to 10.
SSI has a pool-only "Scuba Ranger" program for 8- to 12-year-olds. NAUI
and YMCA are retaining the age-12 minimum, at least for now.
Old Rule
Minimum age for junior certification was 12. (Junior certification requires supervision by a fully certified adult.)
Reason for the Change
To promote the sport.
Lots of baby-boomer divers have kids, and the growing popularity of
resort diving meant a market for family dive vacations. "The future of
diving will be determined by kids," says Bret Gilliam, president of SDI,
the first agency to lower the age. "It's a great step forward to
recognize the family unit as key to our sport's growth."
Exceptions to the Rule
It's still up to the
instructor to decide whether a child is mature enough to dive. Being 10
does not create a right to be certified.
The new junior certifications typically have various restrictions.
In PADI, kids are limited to 20 feet in confined water first, then 40
feet in open water. Juniors must be accompanied by an agency-affiliated
instructor, a certified parent or another certified adult. Check
specific agencies for their rules.
3. Universal Referrals
New Rule Getting certified? Beginning
in 1998, you could take classroom and pool sessions in your hometown
from an instructor with Agency "A," then fly to warm water for
open-water sessions under an instructor with Agency "B"—as long as the
agencies had agreements to recognize each other's standards and
instructors. This means you can choose from many more warm-water resorts
for your open-water sessions.
Old Rule Classroom, pool work and open-water
dives all had to be with the same training agency. If you wanted to do
the open-water dives in the tropics, you had to pick a resort with an
instructor affiliated with the same agency.
Reason for the Change Customer convenience.
Smaller agencies with few instructors in place at resorts found it
necessary to band together to offer greater options—especially when
certification standards are virtually identical.
Exceptions to the Rule PADI. According to
PADI, it issues 70 percent of all certifications. The agency still
requires that all phases of your training be with PADI instructors.
4. Slower Ascent Rate
New Rule
Ascend no faster than 30 feet per minute—one foot every two seconds.
Old Rule
The usual rate was 60 feet per
minute until the U.S. Navy adopted the 30-foot-per-minute rate in 1996
and training agencies followed suit.
Reason for the Change
Research. Navy studies
found that a 30-foot-per-minute rate resulted in fewer cases of DCS than
the older 60-foot-per-minute rate. A slow ascent is really a rolling
decompression stop, allowing your body to flush out and exhale dissolved
nitrogen before it forms bubbles.
Exceptions to the Rule The 30-foot-per-minute
rate may not always be practical for the whole ascent, especially when
you are deep and low on air or approaching hypothermia. In that case a
faster rate, up to 60 feet per minute, is acceptable, but for the final
60 feet of your ascent, you should slow to 30 feet per minute.
5. The Safety Stop
 |
| New rule - Make a safety stop at 15 feet for
at least three to five minutes before ascending to the surface?longer
for deeper and more strenuous dives. Safety stops allow your body extra
time to eliminate nitrogen. |
New Rule
Make a safety stop at the end
of dives. That means you should pause at about 15 feet for a minimum of
three to five minutes before your final ascent to the surface. Some
experts recommend safety stops as long as 10 to 15 minutes under certain
conditions.
Old Rule Make a what? Safety stops were not taught prior to the mid-1980s.
Reason for the Change More research. The new
rule recognizes that all dives are decompression dives, and that DCS can
and does occur even when you've stayed within so-called
"no-decompression limits." Studies clearly show that pausing at about 15
feet allows you to offgas nitrogen before ascending through the zone of
greatest pressure change, near the surface. Nitrogen that hasn't been
eliminated can bubble out of tissues rapidly during the last part of the
ascent, causing DCS.
There are other safety reasons for the stop. The air in your BC and
the bubbles in your wetsuit also expand rapidly during the last 15 feet
and may cause you to become significantly positive without realizing it.
Stopping gives you a chance to adjust your buoyancy so you don't lose
control of your ascent.
Safety stops also allow you to survey surface conditions and boat traffic before surfacing.
Exceptions to the Rule You needn't stay at
exactly 15 feet, especially if you're elbowing a crowd of other divers.
Anywhere between 10 and 20 feet is fine. And although three to five
minutes is a good minimum, longer, deeper dives call for longer safety
stops.
6. Neutrally Buoyant Ascents
 |
| New rule - Remain neutrally buoyant during
ascents. Neutral buoyancy eliminates the risk of run-away ascents and
the strain of finning against negative buoyancy. |
New Rule Become neutrally buoyant before beginning your ascent and maintain neutral buoyancy throughout.
Old Rule Dump all air so you are negative before beginning your ascent and fin upward against negative buoyancy.
Reason for the Change The old rule was
designed to prevent runaway ascents. But Navy studies revealed that the
strain of finning hard while ascending sometimes causes divers to hold
their breath. Also, it can lead to air trapping in the lungs. Both
present embolism risks. The change also reflects greater confidence in
modern BCs, particularly their dump valves.
Exceptions to the Rule In an ascent from very
shallow depths, say 30 feet or less, it's OK to fin up against slight
negative buoyancy. The risk of losing control because of rapid buoyancy
changes in your BC and exposure suit, and the low stress in finning such
a short distance, makes this the better bet.
7. No More Buddy Breathing
New Rule
In a no-air emergency, depend
on a redundant system or your buddy's octopus, or make an independent
emergency ascent. Do not attempt to "buddy breathe" from a single
regulator unless you and your buddy have practiced it.
Old Rule Before octos, ponies and devices
like the "Spare Air" were common, divers were taught to pass one
regulator back and forth while making a slow ascent.
Reason for the Change Safety. Experience
showed that unless both buddies had practiced buddy breathing and were
skilled at it, the attempt was likely to injure both divers, not just
one.
Typically, buddy breathing divers become so absorbed in passing the
regulator that they neglect to control their buoyancy, and a too-rapid
ascent with embolism could result. Or the diver who has passed the
regulator holds his breath instead of exhaling slowly, also an embolism
risk.
If you are out of air and neither you nor your buddy has a backup
system, your best move is to make an emergency swimming ascent: swimming
to the surface while keeping your throat open by slowly exhaling.
8. The Buddy System
Every training agency is emphatic on the need to always dive
with a buddy. Yet solo diving has long been common, particularly among
underwater photographers. Experience, and incomplete statistics, don't
indicate that solo diving is more dangerous than buddy diving, and some
divers argue that solo diving is actually safer.
9. The Snorkel
Most of us were taught that a snorkel is mandatory gear on
every dive, just like a pair of fins. But increasingly, divers are
leaving the snorkel in the gear bag much of the time.
Why? They've come to the conclusion that a snorkel, when attached to
your mask, is more often a hazard than a help. The long tube—dangling
from its midpoint so the hook-like gizmos at the ends can wander
around—is pretty effective at catching kelp, fishing line and camera
straps. And, given the importance of your mask, your mask strap is about
the worst place to mount it or anything else.
Many divers now save the snorkel for special occasions, like a long
surface swim from their entry point to the dive site, and carry it in a
pocket or strapped to their body.
10. The Dive Computer
The dive computer is probably the most important safety
advance in the sport. Much more important than a snorkel, and arguably
more important than an octopus, a dive computer may well be considered
mandatory equipment before long. SDI already incorporates dive computers
into student training from the outset. "Virtually all divers now use
dive computers to make diving safer and more enjoyable. Why not
establish that practice from the beginning?" says CEO Bret Gilliam.
"Dive tables have simply been supplanted by advances in technology."
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