What Are Scuba Diving Computers

A fundamental difference between the different models of dive computers is the underlying calculation model for the saturation of the tissue with nitrogen – because not all manufacturers use the same principle here.  As a beginner you don’t have to worry too much about this, because all calculation variants of the “remaining zero time” (time you are allowed to spend at a depth) are according to general knowledge about the same safety – furthermore most of today’s dive computers are set very conservatively.

1. “Normal” dive computer without air integration

Probably the most common and simplest model among dive computers is just a simple “decompression calculator” – depending on the model with further functions – which does not have a hose or wireless connection to the air tank (diving bottle).  So the air consumption is not included in the calculation of the “remaining zero time” and you have to read the value of the remaining air in your tank from your finimeter.

This variant is for beginners in diving, which is the most suitable model for diving computers.  These models are quite affordable, without air integration, with a starting price between approx. $150 to $200 dollars.  If you want to buy a better dive computer with more functions later, you can use this simple dive computer as a “BackUp” or sell it used.

2. Air-integrated dive computers with hose connection

Something out of fashion are dive computers that can be integrated into a console (holder for several instruments – such as finimeter, compass, depth gauge, etc.) and thus also serve as a kind of digital finimeter.

An advantage of this dive computer version is certainly the fixed, and therefore, very safe connection through the hose between dive computer and air tank – so your current air consumption and the residual air in your tank can be included in the calculations of the dive computer.

A small disadvantage of such a dive computer is that there are more instruments that sit in a console, making it more “chunky” – which is at the expense of a more desireable streamlined shape during the dive.  It can be difficult, especially for a beginner in stressful situations, to find the console with dive computer under water on the jacket (BC) right away.

3. Air-integrated dive computers with wireless transmitter

Even with air-integrated dive computers with wireless transmitter, the finimeter – i.e. the “residual air display” for your dive tank – is already integrated in the dive computer and the values can be included in the calculations.  Since the wireless connection to the transmitter of the dive computer can also be disturbed or interrupted, you should always have an additional finimeter attached to your dive tank with these models.  Otherwise you may have to stop your dive early in case of a malfunction.

From my experience not all manufacturers offer really reliable systems with radio transmissions of the tank pressure to the dive computer.  Some have big problems with the “pairing” of the transmitters when several divers with wireless transmitters are in the water during a dive or are disturbed by the electric charge e.g. by flash systems of an underwater camera.

First of all, the good dive computers with air integration are not really cheap and secondly, breaking the connection between the dive computer and pressure transmitter as a beginner can quickly make you nervous or even panic – which in any case leads to increased air consumption.

Advantage of a dive computer as wristband model

Whether air integrated or a simple dive computer, the most common version to wear both dive computer models today is the wristwatch model, similar to a wristwatch.  The alternative would be a  console model which is already an air-integrated dive computer with hose connections.

The big advantage of wearing the dive computer on your wrist is, in my opinion, that you have it directly in front of your eyes during the dive, depending on your arm position, so that you can easily follow the displayed values.

Which functions of the dive computer are important

After understanding the different types of dive computers, we look at the functions of a dive computer for beginners.  You should focus on the functionality of the dive computer.  The following is a list of scuba diving computer functionalities.

1. Residual Zero Time Display

The dive computer calculates the remaining time that you are allowed to spend at your current depth before you slip into the “decompression obligation” based on your previous dive depths and the duration of the dive.

2. Display of decompression stops

Beginning divers should always stay away from the no decompression time limit.  A dive computer will generally show the “Decostops” if necessary.  The display should show e.g. 5 minutes at 15 feet – in this case you would have to stop for 5 minutes at a depth of 15 feet before you emerge.

3. Current dive depth

The integrated depth gauge in the dive computer shows you your current diving depth.

4. Dive time counter with water contact

The integrated clock in the dive computer shows the current duration of your dive.  The dive computer automatically starts calculating your “bottom time” when you enter the water and will stop the time when you exit the water.

5. Display of the safety stop

At the end of each dive you should make a safety stop for 3 minutes at 16 feet. The current generation of dive computers detects this and automatically switches on a “countdown timer” of 3 minutes as soon as you reach the 16 feet dive depth.

6. Acoustic ascent warning

If you ascend faster than the recommended 60 feet per minute (which is also much too fast for an ascent), the dive computer will give an audible warning signal to slow down your ascent.

7. Displaying the “No Fly Time

After diving you should not get directly into an airplane because of the fluctuating air pressure.  How long you have to wait after your last dive is indicated by your dive computer.  Even if your dive computer shows you a shorter time, it is usually safest not to dive within 24 hours before your flight.

8. Residual saturation during repeat dives

If you make several dives in a row, your dive computer remembers the remaining saturation of your “body” with nitrogen and calculates for you the decomposition of the nitrogen in the tissue during the surface interval.  On this basis, your dive computer can also calculate the no decompression limits for repeat dives.

9. Maximum Dive Depth (Nitrox Mode)

Due to the increased oxygen content in the breathing air, you must not exceed a certain diving depth for a longer period of time when diving with Nitrox instead of normal compressed air – as this can lead to “oxygen poisoning”.  This maximum diving depth is indicated by your dive computer and warns you by an acoustic warning signal if you exceed this depth.

How to choose a dive computer

Now that you know the benefits of owning your personal dive computer, it’s time to start shopping for your own!  This may seem complicated at first, as there are several brands and models available.  There are some questions to ask yourself before investing.

First of all…

To choose the right dive computer you must first ask yourself the following question: “What kind of diver are you and what kind of diver do you want to become?”  It does not make sense to buy an integrated airless computer that is not compatible with nitrox if your goal is to become a technical diver.

It is important that you know where you want to dive?  What kind of dives do you want to do?  What is your budget?

It is important to educate yourself a bit before you make your purchase.  On the other hand if you are not convinced, consult your local dive shop experts who are always ready to answer your questions.

Wrist or console?

Diving computers are separated into two categories.  There are the computers that are on the wrist and computers built into your console. C omputers on the wrist, of course, are worn on the wrist like a watch.  In addition, they are easy to carry around.  The console computers are generally larger and easier to read for people with certain vision problems, and are directly attached to the first stage of your regulator.

Air enriched nitrox

Do you dive daily with Nitrox enriched air?  Does using a Nitrox enriched air mix interest you?  Most computers have the ability to calculate Nitrox enriched air dives to ensure everything goes well underwater during your dive.  Having the ability to use your computer in Nitrox computer mode will make your dives safer and increase your time spent underwater.

Sound signals

Being underwater is both serene and extraordinary.  Sometimes we find ourselves in a Zen state of mind, relaxed under water.  It is not always easy to watch your computer continuously while diving.  It is therefore more reasonable to buy a computer with light and sound notifications.  These features are not standard for all computers, but for safer dives, it is important to include in your computer.

Color

Many dive computers are like modern phones, with futuristic and more colorful graphics.  They are easier to read underwater thanks to their increasingly illuminated screens.  Choosing a good quality screen is an option to consider since a quick glance is all that is required to get your information.

Integrated air and transmitter

With the help of some transmitters, divers can, at a glance, get all the information about their gas.  This technology is indispensable and with experience helps you stay within the limits of recreational and technical dives.

Backlight

Night dives are magical dives and extremely different, because you can see many beautiful things that you cannot see during the day.  If you already have or if you think in the near future you will dive at night, you will need a computer with backlight.  Most dive computers already have this option right, but it’s important to confirm it.

Bluetooth

Bluetooth technology is essential for many electronic gadgets nowadays.  It is easier to download your dive computer data directly to your mobile phone or personal computer.  Whether you are a  recreational or technical diver you will not want to go without trying this type of computer.