Cressi NEPTO, Instruction Manual

Page: 14 / 36

ENGLISH
14
NEPTO Algorithm and reducing the risk of Taravana
Similarly to dives with tanks, during freedives - and especially following continuous
exercise - nitrogen accumulates in the tissues of the body, which can lead to the
occurrence of decompression sickness.
This phenomenon has been known since the '40s, when Polynesian pearl divers
presented with this kind of problem. Since then, this pathology has been named
Taravana, which in Tuamotu Polynesian means "to fall crazily".
The risk increases particularly with intense fishing/freediving activity (sessions last-
ing longer than two hours) and with short recovery intervals between dives. Other
contributing causes include dives at high elevations, dehydration, etc.
To prevent this from happening, freedrivers should leave a surface interval be-
tween dives of at least twice the time spent freediving to allow the body time to
free itself from excess nitrogen.
The algorithm used in the CRESSI NEPTO watch/computer takes these factors
into account, and after each dive will indicate the recommended recovery time
before undertaking the next dive.
After each dive, the NEPTO watch computer will calculate the recovery time, taking
into account the time elapsed during the dive, the depth reached, the dive profile,
and the temperature of the water.
The bottom line on the display will show a countdown, along with the flashing
word RECOVERY, which tells the freedriver how much recovery time remains on
the surface to avoid the risk of Taravana.
If the freediver should begin diving again before the count is over, thus violating the
recovery time indicated, the TRV (Time Ratio Violation) icon will appear, indicating
that the recovery time was not followed.
In this case the time remaining will be added to the recovery time for the next dive.
This indication will also be visible in the watch logbook.
The algorithm can be set to eight levels, and the level of conservatism increases
with each level.
The ratio between dive time and recovery time is shown in the following table:
level - dive time ratio: recovery time
L1 - 1:
≥
2.0
L2 - 1:
≥
2.4
L3 - 1:
≥
2.8
L4 - 1:
≥
3.2
L5 - 1:
≥
3.6
L6 - 1:
≥
4.0
L7 - 1:
≥
4.5
L8 - 1:
≥
5.0
WARNING :
It must still be specified that the CRESSI NEPTO watch computer
is not intended for professional use, but exclusively for recreation. Freediving
entails a number of risks that cannot be completely eliminated, and therefore
the CRESSI NEPTO watch computer CANNOT GUARANTEE that the neurolog-
ical condition of EDEMA/TARAVANA will not occur in the freediver. In no way
can the CRESSI NEPTO watch computer take into account the health or phys-
iological condition of the diver. It can only provide information to aid in the dive.