could enter the dive tables at a depth that is equivalent to
only 68/79ths of the absolute pressure at the actual dive
depth. (Note that the fraction is applied to the absolute
pressure at depth, not just the depth.)
The NOAA Nitrox I tables looked exactly like the U.S.
Navy tables from which they were derived. Only the numbers
changed because of the time credits for the reduced
nitrogen partial pressures. EAN32 turned out to be a very
convenient oxygen fraction because in the depth range
from the surface to 33 meters (110 feet), the NOAA Nitrox
I tables exactly corresponded to the U.S. Navy air tables
for the next shallower depth increment. In other words,
an EAN32 diver diving to a depth of 21 meters (70 feet)
had 60 minutes of bottom time, which was the USN nodecompression
limit for an air diver diving to only 18
meters (60 feet). An air diver descending to 21 meters (70
feet) would have only 50 minutes of bottom time. NOAA
Nitrox I divers could, in effect, use standard U.S. Navy air
tables to plan and execute dives, if they knew how to
adjust for their equivalent air depth. In the fourth edition
of the NOAA Diving Manual (2001), two sets of EAN32
tables were presented. An “Abbreviated” version copies
the NAUI EAN32 Dive Tables with a few changes; an
Chapter 5 - Dive Tables and Dive Computers
“Expanded” version presents a fuller set of tables (with
stage decompression information) modeled on the U.S.
Navy tables format.
When NOAA Nitrox II information was published by
NOAA in the fourth edition of the NOAA Diving
Manual, an Abbreviated version and an Expanded version
of tables were presented for EAN36, similar to the
EAN32 tables. Although the correspondence is not as
striking as it is with NOAA Nitrox I, still for actual depths
from 21 meters (70 feet) to 33 meters (110 feet), the
NOAA Nitrox II tables corresponded to dives that were
two increments 6 meters (20 feet) shallower on the U.S.
Navy air tables. For example, an air diver diving to 21
meters (70 feet) using the U.S. Navy air tables would
have a no-decompression limit of 50 minutes and an
ending repetitive letter group of “J.” An EAN36 diver
could descend to 27 meters (90 feet) for that same 50-
minute bottom time and ending letter group. An air
diver descending to 27 meters (90 feet) would have only
30 minutes of no-decompression dive time. If an air
diver were to dive 50 minutes at 27 meters (90 feet), he
would face a required decompression stop of 18 minutes
at 3 meters (10 feet) and would emerge as an “L” diver.
Dive Tables and Dive Computers
55
No-Required-Stop Dive Times for Single Dives
Depth
fsw
Depth
msw
U.S. Navy
Air Table
NAUI Air
Table
NAUI RGBM
Air Table
NAUI/NOAA
EAN32
Table
NAUI RGBM
EAN32
Table
NOAA
EAN36
Table
NAUI
EAN36
Table
NAUI RGBM
EAN36
Table
30 9 310 130 150 310 150 unlimited 250 150
40 12 200 130 110 310 150 405 250 150
50 15 100 80 80 200 115 310 200 150
60 18 60 55 55 100 85 100 100 115
70 21 50 45 40 60 60 100 60 85
80 24 40 35 30 50 47 60 60 60
90 27 30 25 25 40 38 50 60 46
100 30 25 22 20 30 30 40 40 35
110 33 20 15 16 25 25 30 30 31
120 36 15 12 13 25 20 PO2 > 1.6 PO2>1.6 PO2>1.6
130 40 10 8 10 20 N/A PO2 > 1.6 PO2>1.6 PO2>1.6
FIGURE 5-1: THIS TABLE COMPARES THE MAXIMUM DIVE TIMES FOR A SINGLE DIVE USING U.S. NAVY TABLES, NAUI DIVE TABLES, NAUI RGBM
TABLES, AND NOAA DIVE TABLES. ALL DIVE TIMES ARE IN MINUTES. SHADED AREAS EXCEED 1.4 ATA PO2