11
• PART II
• 8. DIVING WITH GENIUS
8.1. A FEW WORDS ABOUT
NITROX
Nitrox is the term used to describe breathing
gases made of oxygen-nitrogen mixes with
an oxygen percentage higher than 21% (air).
Because Nitrox contains less nitrogen than
air, there is less nitrogen loading on the
diver’s body at the same depth as compared to
breathing air.
However, the increase in oxygen concentration
in Nitrox implies an increase in oxygen partial
pressure in the breathing mix at the same
depth. At higher than atmospheric partial
pressures, oxygen can have toxic effects on the
human body. These can be lumped into two
categories:
- Sudden effects due to oxygen partial
pressure over 1.4bar. These are not related
to the length of the exposure to high partial
pressure oxygen, and can vary in terms of the
exact level of partial pressure they happen
at. It is commonly accepted that partial
pressures up to 1.4bar are tolerable, and
several training agencies advocate maximum
oxygen partial pressures up to 1.6bar.
- Long exposure effects to oxygen partial
pressures over 0.5bar due to repeated and/
or long dives. These can affect the central
nervous system, cause damage to lungs or
to other vital organs.
Genius keeps you safe with respect to these
two effects in the following ways (as long as it
is set to either AIR or NITROX):
• Against sudden effects: Genius has an MOD
alarm set for a user-defined ppO
2
max. As
you enter the oxygen concentration for the
dive, Genius shows you the corresponding
MOD for the defined ppO
2
max. The default
value of ppO
2
max from the factory is 1.4bar.
This can be adjusted to your preference
between 1.2 and 1.6bar. Please refer to
section 2.1 for more information on how to
change this setting. If Genius is set to AIR,
the ppO
2
max is set to 1.4bar by default.
• Against long exposure effects: Genius
“tracks” the exposure by means of the
CNS% (Central Nervous System). At levels
of 100% and higher there is risk of long
exposure effects, and consequently Genius
will activate an alarm when this level of
CNS% is reached. Genius also warns you
when the CNS level reaches 75%. Note that
the CNS% is independent of the value of
ppO
2
max set by the user.
8.2. ALTITUDE
Atmospheric pressure is a function of altitude
and of weather conditions. This is an important
aspect to consider for diving, because the
atmospheric pressure surrounding you has an
influence on uptake and subsequent release
of nitrogen. Above a certain altitude, the
decompression algorithm has to change in
order to account for the effect of the change in
atmospheric pressure. Genius automatically
adapts the algorithm by sensing the ambient
pressure every 20 seconds even when it is
turned off.
NOTE
We do not recommend diving at altitudes
above 3700m / 12100ft. If you do, set
Genius to BOTTOM TIMER and find
appropriate altitude dive tables.
8.3. LOGBOOK
From the home screen, press the LOG button
to access the logbook.
Genius can record the profiles of over 1000
hours of diving, at a sampling rate of 5
seconds. The information can be transferred
to a Smartphone (MySSI app, via bluetooth),
PC (Dive Organizer software, Bluetooth or USB
cable) or Mac (DiversDiary software, Bluetooth
or USB cable). In addition, Genius can show
most of the information directly on the display.
On the main page of the logbook you will see a
listing of all dives, including date, time the dive
started, depth and dive time.
By pressing SELECT you will access the details
of the dive, and from here you can view the
depth profile with either the temperature or
tank pressure data by pressing PROFILE.
8.4. DIVE PLANNER
From the home screen, press and hold the
PLAN button to access the dive planner.
This function allows you to plan your next dive.
In case you dived recently, you can enter an
additional surface interval between now and
when you intend to dive: the residual nitrogen
load will be adapted accordingly. Genius will
consider all active gases and set gradient
factors, listed for reference at the top of the
screen. Hit the SELECT button then use the
and buttons to define the additional surface
interval in 15-minute increments. Next hit
BACK and use the and buttons to scroll
through the no decompression limits for all
depths, in 3m / 10ft increments, up to the
MOD for the gas in use. If you wish to see what
would happen if for a given depth you extended
your dive time beyond the no decompression
limit, press the right button, labelled DECO.
Use the to increase your dive time and
see what your corresponding decompression
obligation would be. Press BACK to return to
the no decompression limits.
8.5. ALARMS
Genius can alert you of potentially dangerous
situations. There are six different alarms:
- Ascent rate alarm;
- Exceeding a safe ppO
2
/MOD;
- CNS =75%;
- Missed decompression stop;
- Low tank pressure/RGT < 3 min;
- Low battery during the dive.
WARNING
When in bottom timer mode, all warnings
and all alarms are OFF aside for the low
battery alarm.
NOTE
- Alarms are both visual and audible, as
described in detail below.
- If you are in any graphic display mode
(compass, dive profile, map viewing or
tissue graph) when an alarm is triggered,
you will be kicked out of that mode and
back to the standard numeric display.
- Ascent rate alarm has priority over
other alarms if they are triggered
simultaneously.
8.5.1. ASCENT RATE
As soon as depth decreases Genius activates
the ascent rate control algorithm and displays
the calculated value both numerically and
graphically.
WARNING
A rapid ascent increases the risk of
decompression sickness.
If Genius determines an ascent rate higher
than set limits, the fast ascent alarm is
triggered: an audible alarm goes off, the
arrows on the left side bar turn red and the
message SLOW DOWN is displayed in the
middle of the screen of the screen (Fig. 8).
This persists until the ascent rate is reduced
to below the pertinent limit. The limits are
dependent on the current depth as follow:
Depth
in m
Speed in
m/min
Depth in
feet
Speed in
ft/min
> 50 m
20 > 165 ft 60
30 – 50 m 15
100 – 165 ft
45
10 – 30 m 10
30 – 100 ft
30
< 10m 5 < 30ft 15
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