Basically, dive computer is a device that shows you depth, Elapsed Dive Time, temperature, No-Decompression Dive Time Remaining and many other things, depending on the model you use, dive mode, and whether you are underwater or on surface.
But the main task of the dive computer- is to calculate the nitrogen loading and oxygen toxicity levels and compute the most optimal and the safest surfacing procedure, manage decompression, and the surface interval between the dives. In shorter words – it helps us staying out from getting into the Decompression Sickness as long as we obey safety rules, warnings and alarms.
It simplifies our diving by replacing Recreational Dive Planners (RDP) and Wheels (but it is still a good idea to keep RDP or Wheel as a backup)!
All models are manufactured in the following mounting options:
computer consoles (Aeris Atmos ai, Mares Puck Air, Suunto Cobra);
wrist dive computers (Oceanic OC1, Cressi Archimede 2, Tusa IQ-950 Zen Air);
wrist units (Mares Icon HD, Uwatec Galileo Sol, Tusa IQ-850 Sapience);
scuba masks (Aeris CompuMask, Oceanic DataMask
Depending on the computer, you may have following dive modes:
Some of the scuba dive computers may be programmed for up to 3 gas mixes and with possibility of switching between them during a single dive, and computer HelO2 by Suunto, may be programmed for up to 8 gas mixes, and can be used for diving with Air, Nitrox, and Trimix.
Next feature is the air-integration. You will meet three options here:
hose air-integrated dive computer;
hoseless air-integrated dive computer;
dive computer without air integration
With hoseless (wireless) air integration you need to have a transmitter installed on the regulator. Many of hoseless air-integrated models have Buddy Pressure Check feature, which means that you may check air pressure of your ‘buddy’ using your own computer if your buddy’s transmitter is correctly paired with your computer.
Another important feature is compensation for Altitude diving. Many units these days automatically compensate for altitude diving and give you adjusted no-decompression times and depths, according to your current altitude. In some models you may set up manually altitude in certain ranges, like in Suunto and Mares brands.
It is worth to mention here Personal Conservative Factor adjustment. Just as an example – if Aeris computers allow us to set this factor just to ON/OFF state, Mares and Suunto models give us possibility to increase or decrease level of conservatism by choosing between highest and lowest levels. And this gives us possibility to set our computer for either liberal or conservative diving.
These days majority of computers are made with the diver replaceable battery option, and some of them have ‘hot swap’ feature, which means that you need to replace battery within 8 seconds in order to keep nitrogen and oxygen calculations for next dives and other data stored in computer’s memory, like some settings, for example.
When you will be doing research to get the dive computer that is the best for you – go for one, which has ‘diver replaceable battery’ option. It will save you time and money, and also you will be able to continue your diving adventure without any interruptions.
Some of the models, like Oceanic OC1, Tusa IQ-900, Tusa IQ-950, UWATEC Galileo Luna, UWATEC Galileo SOL and few others have Data Retention function, which means that we may replace the battery at any time between the dives, without losing any nitrogen or oxygen calculations, because all data is stored indefinitely.
During diving, computer constantly monitors many crucial parameters, like depth, No-Decompression Time, Air Time Remaining and tank pressure (if your instrument is air-integrated), Elapsed Dive Time, temperature, nitrogen loading and oxygen toxicity level… When you go deeper – your safe dive time, or let’s say, No-Decompression Time is decreasing and if you exceed No-Decompression Limits (NDL) – computer activates Decompression mode. At that moment you will see the nearest decompression stop depth and decompression time are displayed.
It constantly monitors our nitrogen loading and oxygen toxicity level and it may give us a warning or alarm if levels come close to certain maximum allowed.
And, as well, if our ascent rate is faster than it should be – scuba dive computer will activate Ascent Rate alarm in order for us to slow the ascent.
When we are on surface, in order to make another dive, we have to calculate the nitrogen group by using Recreational Dive Planner, but if we have a computer – we just need to follow its recommendations. It will help us to perform this task by counting Desaturation Time and No-Fly Time as well.
Many modern scuba dive computers have possibility of downloading your diving history into the computer, using USB or infrared interface and special software. And you may even upload from your PC into the dive computer coloured or grey-scale bitmap pictures (Mares Icon HD, Uwatec Galileo Sol and Galileo Luna)!
So, as a conclusion, all of those features, significant or not very, as we may think of them, have only one the most important benefit for us – keep us on the safe side and avoid Decompression Sickness (DCS).