Maximum Dive Times (in minutes)
Chapter 1- Introduction
Introduction
7
Credit for developing and introducing nitrox diving
techniques for standard scuba goes to Dr. Morgan Wells.
As the first Director of the NOAA Diving Program, Wells
began experimenting with the use of nitrogen-oxygen
mixtures in about 1970. Using “equivalent air depth”,
the NOAA Diving Program began utilizing nitrox on diving
projects in about 1975. A 32% oxygen mixture for
NOAA divers was settled upon as a standard. The second
edition of the NOAA Diving Manual, which appeared
in December 1979, published the results, calling the
32% mix NOAA Nitrox I and including a set of NOAA
Nitrox I dive tables that allowed the scuba diver to plan
nitrox dives. Several methods for mixing nitrox were
also published. For common diving ranges, the diver, in
effect, was allowed to use a depth on the NOAA Nitrox I
dive tables that was one 10-foot increment shallower
than the actual standard air dive profile. At the same
time as NOAA Nitrox I was making its appearance, Wells
and the NOAA Diving Program were using equivalent
air depth calculations to develop additional protocols
for other nitrox blends. EAN36 soon became known
among nitrox users as NOAA Nitrox II, although it
was not until 2001 that the NOAA Diving Manual
(fourth edition) finally published it as an “official” mix
and included appropriate NAUI developed and designed
dive tables.
In 1985, Dick Rutkowski, who had served as Deputy
Diving Coordinator under Morgan Wells and helped to
develop the oxygen-enriched air techniques, retired from
NOAA. Upon his retirement, Rutkowski founded
Hyperbarics International and the International
Association of Nitrox Divers to make available courses
for recreational divers and teach them the NOAA nitrox
diving techniques. Awareness of Rutkowki’s nitrox
course grew slowly but steadily, and over the next few
years a growing, but largely disregarded group of recreational
nitrox divers appeared.
Rutkowski’s course was especially popular with cave
divers and wreck divers, who wanted to have longer dive
times without drastically increasing their decompression
obligation, and partially for this reason nitrox became
identified by many as a kind of “technical diving” in
itself. This view tended to preserve a mystique of exclusivity
and surround nitrox use with an esoteric aura. On
the other hand, there were those who presented nitrox as
“as easy as air.” During this time, two special purpose
“nitrox” training agencies were established, but the
more conventional community of recreational training
agencies and equipment manufacturers seemed caught
in the middle. Was nitrox “the devil’s gas” or “the gods’
ambrosia”? The time was one of misunderstanding and
dissension within the recreational diving industry. It was
also during this period that many of the myths about
nitrox appeared. The development of a more balanced
view took several years, and some of the myths persist to
this day.
In 1988, a symposium on oxygen-enriched air was
held at Harbor Branch Oceanographic Institution in
Florida. The Harbor Branch Workshop on Enriched Air
Depth
fsw
Depth
msw
Air EAN32 EAN36
NAUI Tables NAUI RGBM NAUI Tables NAUI RGBM NAUI Tables NAUI RGBM
60 18 55 55 100 85 100 115
70 21 45 40 60 60 60 85
80 24 35 30 50 47 60 60
90 27 25 25 40 38 50 46
100 30 22 20 30 30 40 35
110 33 15 16 25 25 30 31
FIGURE 1-3: A COMPARISON OF THE NO-STOP DIVE TIMES USING NAUI DIVE TABLES AND NAUI RGBM DIVE TABLES FOR AIR, 32% NITROX, AND
36% NITROX. SHADED AREAS INDICATE OXYGEN PARTIAL PRESSURES ABOVE 1.4 ATA.