John 

MANY DIVING COMPUTERS currently popular with European divers are made either by Suunto in Finland, Uwatec in Switzerland or Seiko in Japan. Many other well-known brands get the Japanese manufacturer to supply them with a computer-watch for sale under their own brand name, so it comes as a surprise to see that the new Mares Nemo Excel is actually made by a Mares sub-contractor in Switzerland.
This super-modern-style stainless-steel computer-watch will please those who are not besotted with tradition. Its liquid crystal display is safe behind a mineral glass with a sapphire coating. It can display dual time modes, as well as being a calendar/day/date chronometer.
Mares didnt send me the vast instruction manual, but I could work out that this computer was easily adjusted for nitrox by manipulating the four buttons: Mode, Escape, Plus and Minus.
The Nemo Excel can be used as a nitrox (and air) computer or as a simple depth-gauge and timer. In free-diving mode, alarms can be set for maximum dive time, maximum depth, surface intervals and pre-set depth intervals.
This is a useful, if simple, computer that can be worn every day as a digital watch.

Algorithm
The Nemo Excel uses the same RGBM algorithm, developed in collaboration between Mares R&D Centre and Los Alamos decompression guru Dr Bruce Wienke, as is used in other Mares computers.
It features a reduction in permissible gradient factors (M values) in the case of repetitive or multi-day dives. It has a 10-model tissue algorithm and features four levels of adjustment that can be used as personal factors. There are similar adjustments for diving at altitude. I used the unit at its most incautious setting.
It also features an iterative deep-stop function that can be ignored without losing any other functionality.
Checking the no-stop time for 30m in Planning mode revealed no surprises, yet the Nemo Excel seemed a lot more conservative than the already cautious Suunto I used alongside it once I was into repetitive dives.
I sometimes had as many as five more minutes of no-stop time left on the Suunto when the Nemo Excel was about to go into decompression during an ascent.

Display Legibility
A four-second backlight enables the display to be seen in low light conditions. Because it shows the minimum of information at any one time, the display is quite legible. The man from Mares told me proudly that the steel buttons on this computer were superior to those of other computer-watch manufacturers because they were easier to operate with a gloved hand, but I found that, irritatingly, they tended to stick in.

Settings
In Nitrox mode, a ppO2 warning can be set between 1.2 and 1.6 bar ambient pressure in combination with O2 mixes between 21 and 50%. Audible alarms can be disengaged.
There is also the option to wipe the memory, useful for dive centres that hire out computers to different divers each day.

Display
Press the ESC button on the dive and the computer will display the estimated Deep Stop required. A safe-ascent rate indicator varies between 12m/min and 3 m/min. A safe stop of 3 minutes is displayed between 6 and 2.5m.
Oxygen toxicity is displayed as a percentage of the maximum allowed, and there is a ppO2 exceeded warning.
In Deco-Stop mode, the computer shows a Deco icon, the depth of the deepest mandated stop, current depth, duration of the required stop and duration of the dive so far. The battery is said to be good for more than 170 dives.

COMPARABLE COMPUTERS TO CONSIDER:
Suunto D4 £295
Cressi Edy II £294
Scubapro Xtender £299


Divernet
SPECS
MARES NEMO EXCEL
COST
£290
MAX ASCENT RATE 10m/min
WARNINGS Omitted deco stop, excessive ascent-rate, maximum depth for set ppO2, deep stop
NORMAL IN-WATER DISPLAY Current depth, no-stop time remaining, dive time
ALTERNATING DISPLAYS Deep Stop, %O2, %CNS or temperature, ascent time, primary time
DECO INFO Yes (including deep stop)
SAMPLING RATE 20sec (freediving 4sec)
DIVE PLANNING Scrolling no-deco limits
LOGBOOK Scuba (36 hours) and freediving (2000 dives) modes
PC INTERFACE Optical connection to PC
DIVING MODES Air/nitrox
BATTERY CR2430
CONTACT www.mares.com
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%