Cressi Cartesio Computer

The appearance of the dive computer was one of the greatest advances in this sport.
This device allows us to dive with total freedom, with the security of being permanently informed about the depth we can reach or the time we have available, without fear of mistakes. Next we will go deeper into the knowledge of the dive computer.
THE OPERATION OF THE COMPUTER
The dive computer is based on a totally different concept than the tables; so if with the tables the most important thing is to know the time you have been diving, for the computer the most important thing is to know the remaining time.
All computers work on the basis of algorithms, comparing their decompression model with the data obtained during the dive. Currently the most commonly used algorithms are those of Bühlmann and Spencer, followed by those of Haldane, Rogers and Powell.
Thus the computer bases its operation on the collection of a large amount of data, such as the duration of the dive, the depth of the dive at any given moment and even the water temperature, which it uses to calculate the level of saturation reached by the diver's tissues at any given moment. From this calculation, the device will calculate how long the diver can remain at that depth without decompression or, if decompression is necessary, what stops he will have to make.
Obviously, the more data we give the computer, the more accurate the calculations it will make.
It is also important to know the most important functions that a dive computer must perform. These are the following:

• Indication of the current depth.
• Maximum depth reached during the dive.
• Depths at which decompression stops must be made.
• Indication of elapsed dive time.
• Time remaining before decompression is required.
• Time required for each decompression stop.
• Total ascent time.
• Water temperature.
• Air management.
• Audible alarms.
• Visual alarms.
• Altitude adjustment.
• Surface desaturation time.
• Time interval to leave before flying.
• Dive simulator.
• Battery charge indicator.
• Dive logbook.

In addition and in case Nitrox is used, there are other functions that we will have to demand to our computer:

• Oxygen content in the mixture.
• Oxygen partial pressure.
• Oxygen toxicity.

Finally to comment that at the present time the great majority of the computers count on connection to PC, an important function that will serve us to unload in the personal computer all the information of the immersion; some data on which we will be able to work.
A COMPUTER FOR EVERY DIVER
Before acquiring a computer, stop and think what are my real necessities? The market can blind us with equipment that offer a thousand and one functions, so the most important thing is to be clear about what our needs are and buy a computer that meets them, without going for very sophisticated models that will only complicate our lives, without ever getting the most out of them.
So if you are starting out in the world of diving, we recommend that you buy a simple computer, looking above all that it is easy to interpret (underwater you will certainly have many other things to worry about). Para if you are a beginner, it is not bad if your device has alarms to warn you if you exceed the maximum allowed depths.
Para If you are an experienced diver, the level of sophistication of the computer will also depend on your level of diving and the time you can devote to this activity.
There are two main types of computers:

• Wrist computers: they only have the data of the dive and the parameters that we manually include.
• Air management: in addition to the above data, they have information on air consumption at each moment of the dive.
  There are two types:
  • Console: connected to the first stage of the regulator by means of a hose.
  • Wireless transmission: connected by waves, through a transmitter/receiver system.

This type of air management computers are the most suitable for successive dives or for diving in extreme conditions (cold water, currents, work).
On the other hand, there are manually activated and automatically activated computers. The latter are activated mechanically when the diver is immersed in the water, which is very convenient, although it has the disadvantage that it will interpret a simple sweetening of the device after use as a dive. Manual activation does not have this disadvantage, but it does have the possibility of forgetting to activate the device (although we always think that this will not happen to us).
TIPS FOR THE USE OF THE COMPUTER

• Each diver should bring his own computer: in case the data given by the computers are different, we should always be guided by the most conservative one.
• Check the condition of the computer before each dive.
• The computer should be viewed from the vertical, otherwise some computers with digital numbers may give different readings if not read in this way.
• Take a look at it from time to time during the dive: it is a good habit to check it from time to time.
• In case of a trip, it is important that the computer is not stored in a hermetically sealed container, as this could cause an error in its atmospheric pressure sensor that continuously recalculates atmospheric conditions.
• It never hurts to carry decompression tables, a watch and a depth gauge in case the computer fails; anything can happen and it is better to be safe.
• It is of vital importance to carry out the periodic revisions recommended by the manufacturer of the equipment.