14-4 Change A
U.S. Navy Diving Manual—Volume 3
1.
Place the diver on air on the surface.
2.
Make the appropriate predive checks.
3.
Have the diver descend to 20 fsw.
4.
At 20 fsw, shift the diver to the bottom mix and ventilate the diver for 20
seconds.
5.
Confirm the diver is on bottom mix, then perform a final leak check. The diver
is allowed 5 minutes to descend to 20 fsw, shift to the bottom mixture and per-
form equipment checks.
6.
Have the diver begin descent.
7.
Start bottom time.
!
If the diver spends 5 minutes or less performing above procedures, bottom
time starts when the diver leaves 20 fsw.
!
If the diver spends more than 5 minutes performing above procedures, bottom
time starts at the 5 minute mark.
8.
If it is necessary to bring the diver back to the surface from 20 fsw to correct a
problem:
!
Shift the diver from the bottom mixture back to air.
!
Ventilate the diver.
!
Confirm the diver is on air.
!
Have the diver begin ascent.
!
When the diver reenters the water, the 5 minute grace period begins again. No
adjustment of bottom time is required for the previous exposure at 20 fsw.
14-3.6
Aborting Dive During Descent. Inability to equalize the ears or sinuses may force
the dive to be aborted during descent.
1.
If it is necessary to bring the diver back to the surface from depths of 100 fsw
and shallower:
!
Ensure the diver is in a no-decompression status.
!
If the bottom mixture is 16% oxygen or greater, ascend directly to the surface
at 30 fsw/min.
!
If the bottom mixture is less than 16% oxygen, ascend to 20 fsw at 30 fsw/min.
