CHAPTER 9 Air Decompression
Change A 9-3
Equivalent Single Dive Bottom Time. The equivalent single dive bottom time is
the time used to select a schedule for a single repetitive dive. This time is
expressed in minutes.
Unlimited/No-Decompression (No D) Limit. The maximum time that can be
spent at a given depth that safe ascent can be made directly to the surface at a
prescribed travel rate with no decompression stops is the unlimited/no-decompres-
sion or No D limit (Table 9-6).
Repetitive Dive. A repetitive dive is any dive conducted within 12 hours of a
Repetitive Group Designation. The repetitive group designation is a letter used to
indicate the amount of residual nitrogen remaining in a divers body following a
Residual Nitrogen. Residual nitrogen is the nitrogen gas still dissolved in a
divers tissues after surfacing.
Residual Nitrogen Time. Residual nitrogen time is the time that must be added to
the bottom time of a repetitive dive to compensate for the nitrogen still in solution
in a divers tissues from a previous dive. Residual nitrogen time is expressed in
Single Dive. A single dive refers to any dive conducted more than 12 hours after a
Single Repetitive Dive. A single repetitive dive is a dive for which the bottom
time used to select the decompression schedule is the sum of the residual nitrogen
time and the actual bottom time of the dive.
Surface Interval. The surface interval is the time a diver has spent on the surface
following a dive. It begins as soon as the diver surfaces and ends as soon as he
starts his next descent.
Chapter 5 provides information for maintaining a Command Diving Log and
personal diving log and reporting individual dives to the Naval Safety Center. In
addition to these records, every Navy air dive may be recorded on a diving chart
similar to Figure 9-1. The diving chart is a convenient means of collecting the dive
data, which in turn will be transcribed in the dive log. Diving Record abbrevia-
tions that may be used in the Command Diving Log are:
LS - Left Surface
RB - Reached Bottom
LB - Left Bottom