15-34 Change A
U.S. Navy Diving Manual—Volume 3
“Rest Stops.” At what hours these rest stops occur are determined by the daily
routine and operations schedule. The 2-hour post-excursion hold may be consid-
ered as one of the rest stops.
15-23.5
Saturation Decompression Rates. Table 15-9 shows saturation decompression
rates. Saturation decompression is executed by decompressing the DDC in 1-foot
increments not to exceed 1 fsw per minute. For example, using a travel rate of 6
feet per hour will decompress the chamber 1 foot every 10 minutes. The last
decompression stop before surfacing may be taken at 4 fsw to ensure early
surfacing does not occur and that gas flow to atmosphere monitoring instruments
remains adequate. This last stop would be 80 minutes, followed by direct ascent to
the surface at 1 fsw/min.
Traveling is conducted for 16 hours in each 24-hour period. A 16-hour daily
travel/rest outline example consistent with a normal day/night cycle is:
This schedule minimizes travel when the divers are normally sleeping. Such a
daily routine is not, however, mandatory. Other 16-hour periods of travel per 24-
hour routines are acceptable, although they shall include at least two stop periods
dispersed throughout the 24-hour period and travel may continue while the divers
sleep. An example of an alternate schedule is:
The timing of the stop is dependent upon operational requirements.
15-23.6
Atmosphere Control at Shallow Depths. As previously stated, the partial pres-
sure of oxygen in the chamber shall be maintained between 0.44 and 0.48 ata, with
two exceptions. The first is just before making the initial Upward Excursion and
the second during the terminal portion of saturation decompression. Approxi-
mately 1 hour before beginning an Upward Excursion, the chamber ppO2 may be
increased up to a maximum of 0.6 ata to ensure that the ppO2 after excursion does
not fall excessively. The ppO2 should be raised just enough so the post-excursion
ppO2 does not exceed 0.48 ata. However, when excursions begin from depths of
Daily Routine Schedule
2400–0600
Rest Stop
0600–1400
Travel
1400–1600
Rest Stop
1600–2400
Travel
Alternate Sample Schedule
2300–0500
Travel
0500–0700
Rest Stop
0700–0900
Travel
0900–1500
Rest Stop
1500–2300
Travel
