Shearwater Petrel EXT, Operation Manual, Page: 24 / 65

Shearwater Research Inc. Revision 1.1.0 24
Shearwater Petrel
Simple Example Dive
Here is an example of a simple OC air dive� It will help to introduce
the screen displays as the diver progresses, the dive starts, the depth
increases� The display is showing the computer programmed for open
circuit (OC) air�
As we pass through 30 feet, the time-to-surface (TTS) shows one
minute� This shows that the computer is expecting the diver to ascend
at approximately 30 feet per minute or 10 meters per minute� The dive
predictions are based on this ascent rate�
The no-decompression limit (NDL) starts off showing 99, but then
starts to show a smaller number as the depth increases� The 3rd
screen shows that we will go into deco in 12 minutes�
We have now entered decompression. Our first stop, or ceiling, is
at 20 feet and we will need to remain there for up to one minute�
Although stops are shown in minutes, the computer will calculate and
change the ceiling in real time and the stop may be less than a minute�
As we ascend, the ascent rate indicator shows about 20 fpm or 6
mpm�
When we go shallower than our first stop, the stop depth starts to flash
red �
When we clear the last stop, the stop depth and time goes blank, and
now we see a NDL of 99 minutes again� Once we surface, the depth
is 0 and a minute later when the computer comes out of dive mode,
the NDL goes to 0 as well�
DEPTH TIME STOP TIME
3O 1
GasPPO2
OC 21/OO 99 1
O2/HE NDL TTS
DEPTH TIME STOP TIME
GasPPO2
11O 3
OC 21/OO 12 3
O2/HE NDL TTS
DEPTH TIME STOP TIME
GasPPO2
12O 8 2O 1
OC 21/OO O 7
O2/HE NDL TTS
DEPTH TIME SURFACE
GasPPO2
O 4hr39mn
OC 21/OO O O
.21
O2/HE NDL TTS
DEPTH TIME STOP TIME
12O 8 2O 1
OC 21/OO O 4
O2/HE NDL TTS
DEPTH TIME STOP TIME
GasPPO2
21 11 2O 1
OC 21/OO O 2
O2/HE NDL TTS
DEPTH TIME STOP TIME
12O 8 2O 1
OC 21/OO O 4
O2/HE NDL TTS
DEPTH TIME STOP TIME
GasPPO2
19 12 2O 1
OC 21/OO O 2
.33
O2/HE NDL TTS
DEPTH TIME STOP TIME
GasPPO2
9 15
OC 21/OO 99 O
.27
O2/HE NDL TTS
.4
.9
.97
.34