John 

IM NOT AN ICTHYOLOGIST BUT, as I understand it, there are no clownfish in the Red Sea. There are, however, plenty of anemonefish.
I just want to say this because, since the movie was made, everyone calls the anemonefish of the Red Sea Nemo fish - even though Nemo was a clownfish. Well, I'm glad I got that off my chest!
It's clear that Mares would like to produce a wirelessly connected air-integrated computer, but Scubapro-Uwatec has the patent sewn up, and so far only Suunto has agreed to pay to use the idea. This means that the Italian company is limited to supplying one at the end of a hose.
I know that divers in the big US market like consoles, so it might not be too much of a disadvantage for them.
The Nemo Air is connected to the regulator first stage via a high-pressure hose with a quick-connect bayonet, so you dont have to leave it permanently on your tank if, for example, you are on a liveaboard.
It has a massive screen, as big as that of the Nemo Wide wrist-mounted computer (as big as its name implies), although it has extra information to display. Its meant to be future-proof, too, because it can be updated with new software as it is developed, over the Internet. There is also the option to fit a rather nice, yet conventional, magnetic compass to the top of the computer.
When raised, this compass brings a sight-glass into convenient position for taking a bearing. The only problem is that, when compared with some other full-function computers, this one really is a bit of a lump.

Algorithm
Some computer algorithms have in the past left me feeling a little insecure, because they vary so much from those of mainstream European computers.
Not so this one. The Nemo Air gave me no qualms, and I set it for the middle personal factor setting, which brought it nicely into line with my Suunto D6 (set in the same way). I use this as back-up when trying new computers.
I should not have been surprised, because the Nemo Air uses the Mares RGBM algorithm supplied by Bruce Wienke, who supplied the Suunto RGBM too.
You can also set it for one of four different altitude ranges. I had complete confidence in it.

Settings
The computer is set up using three buttons,
so you simply go through each of 10 operating modes. Naturally, you can choose metric or imperial measurements.
I was bemused to note the option to set the size of your tank (eg, in litres). Thats unusual but it gives the computer the ability to display your gas consumption in litres/min.
Ive never needed this before but it was interesting to see that a relaxed deep dive without a camera had me using air at only 10 litres/min, whereas a 3m dive fighting 30 Italian snorkellers to get a decent picture of a dugong cost me more than 30 litres/min. The displayed breathing-rate is updated every 20sec.
You can set nitrox from 21 to 50% (with max ppO2 of 1.2 to 1.6 bar). You can also choose to set various tank reserves, but 50 bar was the least cautious, and that doesnt suit an underwater photographer like me who likes to live on the edge. Audible alarms can be turned off.

Legibility
You can vary the contrast of the large LCD to make it more or less readable. The use of a modern dot-matrix allows complicated messages in words to be displayed. I was surprised to see the word Danger appearing every time I reached 50 bars. It seemed a bit over-dramatic for someone who habitually gets back in the boat only after the last good picture is taken.
When I first saw it come up, I wondered what Id done wrong!

In The Water
Ignoring the inconvenience of having to lift the unit up to look at it, which was easily sorted by attaching a karabiner that allowed me to clip it to a highly visible D-ring on my BC, I was amazed that I could read the major information without needing my corrective mask.
This could be of major importance to any divers whose arms are no longer long enough to allow us to read books without glasses.
Normally displayed are remaining tank pressure, remaining gas-time based on your performance previously during the dive and your current depth, breathing-rate, current depth, remaining no-stop time, dive time, ascent-rate (if ascending) and water temperature. Pressing the plus or minus button reveals an alternative display (see Specs).
Once into deco mode, the Nemo Air shows the first stop depth and minimum ascent time. Deep stops, when set, are variable and calculated on the fly, often consisting of more than one at different depths.
The computer allows an ascent rate of 10m/min but does not raise the alarm until you reach 120% of this value. Visual alarms are very clear, and the deco ceiling is unmistakable.
The computer automatically displays a safety stop once you reach 6m, and counts down three minutes. I liked the fact that should you drift down slightly deeper for a moment it pauses the countdown, rather than reverting to three minutes, as some computers do.
I noticed that the Nemo Air continues to calculate no-stop time right up to 6m, though some other computers will go to a maximum no-stop time once 9m is reached, provided no deco-stop is needed.
This caught me out once when I went into deco-stop mode when expecting to get a safety stop. I was at 7m at the time, so hung around at less than six until the 1min/3m deco requirement had cleared. I then found that the safety stop was omitted from the display.
Getting tank information, including a prognosis of remaining gas-time, means that if you keep the total ascent time displayed always at a lesser figure, you cant get into trouble.
The built-in tank reserve takes care of that sudden increased breathing rate when you come face to face with an oceanic whitetip shark in the shallows.
When used correctly, its one of the greatest safety factors to have been added to open-circuit leisure diving.

COMPARABLE COMPUTERS TO CONSIDER:
Suunto Cobra, £456


Divernet Divernet
SPECS
PRICE
£380 (compass £55 extra)
FAST ASCENT WARNING Yes
OTHER WARNINGS Reserve tank pressure reached. Deco ceiling
NORMAL IN-WATER DISPLAY Remaining tank pressure, remaining gas-time based on your performance previously during the dive and your current depth, breathing-rate, current depth, remaining no-stop time, dive time, ascent rate (if ascending) and water temperature
ALTERNATIVE DISPLAY Maximum depth achieved, the time of day and any deep stop that might be suggested, plus all the gas information as above
DECO INFO Full
DEEP STOPS User Option
DIVE-PLANNING Yes
PC INTERFACE USB optional
MODES Air/Nitrox/Gauge
BATTERY User-replaceable lithium CR2450
DEPTH RATING 200m
CONTACT www.mares.com
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