Exceptional exposure dives are those dives in which the risk of decompression
sickness, oxygen toxicity, and/or exposure to the elements is substantially greater
than on normal working dives. Decompression schedules for exceptional exposure
dives are contained in the Standard Air Decompression Table. These exceptional
exposure schedules are intended to be used only in emergencies, such as diver
entrapment. Exceptional exposure dives should not be planned in advance except
under the most unusual operational circumstances. The Commanding Officer must
carefully assess the need for planned exceptional exposure diving and prior CNO
approval for such diving is required. Selected exceptional exposure dives have
been proven safe in controlled conditions and are authorized at the Naval Diving
and Salvage Training Center during certain phases of diver training.
The long
decompressions times associated with exceptional exposure dives impose unusual
demands on a diver’s endurance. There is also limited assurance that the dive will
be completed without decompression sickness. These two risks can be reduced by
using surface decompression techniques rather than completing decompression
entirely in the water.
1. Complete the entire 30 fsw in water stop on oxygen, interrupting oxygen
breathing after each 30 minutes with a 5 minute air break. The air breaks
count as part of the stop time.
2. Ascend to the surface at 30 fpm. Minor variations in the rate of travel between
20 and 40 fpm are acceptable.
3. Once on the surface, the tenders have three and a half (:03::30) minutes to
remove the breathing apparatus and diving dress and assist the divers into the
recompression chamber.
4. Pressurize the recompression chamber with air to 30 fsw at a travel rate of 60
fpm.
5. Upon arrival at 30 fsw in the recompression chamber, the divers are placed on
the Built-in Breathing System (BIBS) mask breathing 100 % oxygen.
6. The 30 foot stop time commences once the divers are breathing oxygen.
Repeat the 30 fsw in-water stop time.
7. The divers breathe oxygen throughout the 30-foot stop, interrupting oxygen
breathing after each 30 minutes with a 5 minute air break. The air breaks
count as part of the stop time.
8. Ascend to 20 fsw at 30 fpm. Complete the 20 fsw in-water stop time. The
divers breathe oxygen throughout the 20-foot stop, interrupting oxygen breathing
after each 30 minutes with a 5 minute air break. The air breaks count as
part of the stop time.
9. Ascend to 10 fsw at 30 fpm. Complete the 10 fsw in-water stop time. The
divers breathe oxygen throughout the 10-foot stop, interrupting oxygen breathing
after each 30 minutes with a 5 minute air break. The air breaks count as
part of the stop time.
10. Ascent to the surface at 30 fpm.
1. Complete the entire 20 fsw in the water.
2. Ascend to the surface at 30 fpm. Minor variations in the rate of travel between
20 and 40 fpm are acceptable.
3. Once on the surface, the tenders have three and a half (:03::30) minutes to
remove the breathing apparatus and diving dress and assist the divers into the
recompression chamber.
4. Pressurize the recompression chamber with air to 20 fsw at a travel rate of 60
fpm.
5. Upon arrival at 20 fsw in the recompression chamber, the divers are placed on
the Built-in Breathing System (BIBS) mask breathing 100 % oxygen.
6. The 20 foot stop time commences once the divers are breathing oxygen.
Repeat the 20 fsw in-water stop time.
7. The divers breathe oxygen throughout the 20-foot stop, interrupting oxygen
breathing after each 30 minutes with a 5 minute air break. The air breaks
count as part of the stop time.
8. Ascend to 10 fsw at 30 fpm. Complete the 10 fsw in-water stop time. The
divers breathe oxygen throughout the 10-foot stop, interrupting oxygen breathing
after each 30 minutes with a 5 minute air break. The air breaks count as
part of the stop time.
9. Ascent to the surface at 30 fpm.
If the oxygen systems fails during a
chamber stop, complete the remaining decompression time on air.
