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Types of Diving computer

The dive computer is very popular with divers. A dive computer can make diving safer, more fun and easier. The computer displays a lot of information during the dive, such as decompression data, immersion time, depth and alerts you with alarms. It is also possible to download information before or after diving like previous dives. Almost every dive computer has a logbook and profile that can be read on a tablet or computer. It is a useful device that can handle many difficult calculations.

However, the best advice is to not rely solely on a dive computer. If you are going to dive with a computer you have to know how it works and what information it provides. In addition, it is necessary to do a good planning before the dive. You should also be able to perform the proper calculations through the dive tables or the computer. This is learned during diving training.

The calculations made by a dive computer, rather than the formulas, are still estimates. Diving with a dive computer has the risk, especially if you do in a day or week several dives, you are looking for limits. Do not do this and always stay on the safe side and do not look for limits! In addition, a computer may fail during diving so it is advisable to have amanometer or analog submersible watch as a backup.

Different Types and Models of Diving Computers

There are different models of diving computers. There are devices that can be carried on the wrist, wrist diving computers. These have a big display and a standard clock format that you can carry in your spare time. There are also computers that are integrated into the dive console, including whether or not a gauge and a compass.

A dive computer can also be integrated with air or gas. This means that the computer is connected to a hose or wirelessly through a transmitter to the first stage of the dive bottle and therefore the pressure is displayed on the screen. In fact an integrated dive computer calculates continuously how much air remains available and warns you if you have to ascend.

The Galileo Luna is an example of a wirelessly integrated air dive computer. The Mares Mission Puck 2 is an example of a gas diving computer integrated into the console

The Functions of a Diving Computer

A dive computer measures at least the environmental pressure (the depth) and the elapsed time (dive). Based on this and determined data, the computer calculates the time of the safe dive, the depth of the dive and the necessary decompression stops (depth and time) based on your dive profile. The computer continuously calculates the saturation of nitrogen in the different tissues of our body throughout the immersion. There are too many functions and mathematical models to treat them all here.

A dive computer is easy to operate and read. Some basic features that must be present in each dive computer are:

 The depth

 The maximum depth

 The remaining time for free climb (without decompression stops)

 The time of immersion (time under water)

 The battery indicator

Diving computers that only provide the above information are called a bottomtimer . Modern computers can indicate much more, depending on the model, on the following data (or offer the possibility to see the data):

The rate of ascent (and the rate of descent)

The temperature of the water

A logbook (data from previous dives)

If the decompression stop (depth and time)

No fly time (the time before being able to fly again)

A compass

The immersion profiles

Personal settings

Safety stops and depth stops

The desaturation time

Planning Tools

The pressure (air / gas integrated) in the bottle of diving

Estimated remaining immersion time (integrated air / gas)

Air, gas / nitrox or gauge dive mode

Date and Time

Always use a dive computer rightly!

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Diving Computer Algorithms

What are the computer algorithms for diving?

The computer is used to calculate the maximum immersion time that allows for a longer and safer immersion. The dive computer like took control of the dive table as the dive tool to calculate all the necessary parameters to enjoy diving.

Diving computers use algorithms to calculate these safe driving limits. They will make adjustments for both groups fast tissue and slow tissue. Use this information to estimate the nitrogen in your body. Based on the amount of time you have been submerged and its depth, the computer calculates how long it can safely remain under water.

Different types of algorithms Algorithms vary according to the model of each manufacturer and only a few algorithms are actually used. An algorithm used may also be a modification of an existing algorithm. When you want to consider buying your next dive computer, the main feature that you look at is the algorithm that uses the Air Decompression Limit Monitor.

Algorithms with different manufacturers use some factors that vary in their algorithms as mentioned with fast and slow tissue groups. The solubility, permeability, and contact of blood for a given tissue, for example, a kidney, is called a "tissue compartment or tissue group". Diving computers use these "tissue compartments" to simulate the effect of a gas on your body in depth. The more "woven" compartments measured from a computer, the more accurately (theoretically) the computer can measure the effect of a dive into your body. 9 to 12 compartments is quite standard, but a few consumer models have 16 or more.

Here are four of the major algorithms used for dive computers:

Group 1: Haldane / Spencer Algorithm The Haldane / Spencer model uses the results of the PADI science and technology dive test and was developed by Rogers and Powell. Within their algorithm they use 12 separate tissue compartments. Oceanic and Sherwood use this algorithm model for their dive computers.

Group 2: Modifying the Haldanian Algorithm This algorithm model was used by the Mares and is based on nine tissue compartments. Now the latest Mares dive computers use the reduced gradient bubble model.

Group 3: Suunto Reduced Gradient Bubble Algorithm This model is based in part on the work by Wienke and Hamilton and uses nine tissue compartments. Suunto was the first to use the RGDM and now other manufacturers are starting to use it as well. The great difference of this algorithm is to consider micro bubbles that are found in the bloodstream as a result of nitrogen. The theory was that they consider these microbubbles as a precondition for larger bubbles that can lead to DCS.

Group 4: Algorithm of Uwatec Buehlmann ZH-L8 ADT and ZH-L8 ADT MB. This algorithm model uses eight tissue compartments and has recently been updated with two additional letters, the Buhlmann adaptive model has been expanded to be called the ZH-L8 ADT MB micro bubble acronym. This algorithm is used together with Scubapro Uwatec.

Short fall algorithms Algorithms can not account for age, previous lesions, room temperature, body type, alcohol / dehydration consumption and permeable oval foramen (hole in the heart).

Which algorithm is the best? Elimination of factors such as cost, looks, other characteristics etc. Then the more "woven compartments" measures a computer, the more accurately (theoretically) the computer can measure the effect of a dive into your body. 9 to 12 compartments are pretty standard at present, but some dive computers are now using 16 compartments.

Although two algorithms have the same results, manufactures will add there own security factor so it can set there to dive aggressive or conservative computers. An aggressive team gives you more background time than a conservative dive computer, and it is convenient to understand the properties of the dive computer itself to ensure it fits the skill and expected level of comfort.

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Dive Computer

Today with the advancement of technology and cost reductions in the prices of dive computers, it is not considered a responsible diver who dips without the use of their dive computer. This is for personal use, which can not be shared for reasons of diving safety.

First Automatic decompressor, Scubapro SOS model. It had a membrane that during the diving absorbed gas simulating the human body.

What is a Diving Computer?

A dive computer is basically an instrument that measures the depth to which the diver is submerged and the time of diving. It has an internal program or software that simulates the absorption of inert gas in the human body (the inert gas in the case of breathing air is Nitrogen). As our organism does not metabolize the inert gas, it will dissolve and accumulate in our tissues based on Henry's physical law

(at greater pressure or depth, more gas will dissolve in the tissues),

and this gas is absorbed by The tissues that must be controlled, to avoid what is called Decompression Disease.

Due to this physiological limitation caused by breathing air under pressure,

There is a maximum time limit that can tolerate the human body and depends on the maximum depth of the dive.

There are tables and computers that indicate these maximum times for each depth, not to enter what is called Decompression Diving.

Therefore, these maximum times must be respected and not exceeded during diving.

If there are factors that may increase the chances of suffering from Decompression Sickness (being out of state, very cold water, strenuous diving, wounds or operations, adipose tissue, old age, etc.),

the safety level of diving should be increased.

Not to enter what is called Decompression Diving.

Therefore, these maximum times must be respected and not exceeded during diving.

If there are factors that may increase the chances of suffering from Decompression Sickness (being out of state, very cold water, strenuous diving, wounds or operations, adipose tissue, old age, etc.),

the safety level of diving should be increased.

Not to enter what is called Decompression Diving.

Therefore, these maximum times must be respected and not exceeded during diving.

If there are factors that may increase the chances of suffering from Decompression Sickness (being out of state, very cold water, strenuous diving, wounds or operations, adipose tissue, old age, etc.),

the safety level of diving should be increased.

Why the Diving Computer?

A dive computer allows you to optimize dive times and have a control of them. This does not eliminate the prior planning of the dive, which  

should always be done

having a clear idea of:

If he or dive can be performed, (we consider non-decompression dives in sports or recreational diving).

If the dive interval must be increased, to be able to perform the scheduled dive.

If there are conditions that favor the absorption of nitrogen to take into account, that the computer does not.

If we should make safety stops.

If the percentage of oxygen should be programmed, in Dive with Enriched Air or Nitrox.

If the dive is of altitude, and if the computer has automatic correction of the height.

The use of the computer allows us to increase the time of diving, thanks to the real time processing, which allows to calculate multilevel dives with very small intervals. It is important to note that this does not make diving unsafe.

Dive computer:

Of course in addition to the depth, the time of diving and whether or not we enter decompression, today the computer offers much more information and options, some of them

(we take as an example the

OCEANIC OCi

with transmitter module Wireless)

:

Different modes of use: clock mode, dive mode, apnea mode and gauge mode (or depth gauge), digital compass.

Information on tank pressure, gas consumption, maximum time according to this consumption, has a wireless transmitter that transmits the pressure information from the tank to the computer by means of a sound pressure wave.

Possibility of diving with air or enriched air Nitrox or EANx, up to 4 different gases, (the computers of trimix are special for Technical diving, and much more expensive)

Possibility of activating manually or when entering the water.

Program the oxygen fraction and the maximum oxygen partial pressure for EANx dives.

Indicate the dive plan or the maximum time limit for each depth (taking into account the residual nitrogen of the organism).

Automatic correction for altitude dives.

Select the decompression algorithm according to the type of dive to be performed.

Storing the parameters of the dives made (digital logbook), can also be done by software and cable store with higher performance on the PC.

History of accumulated dive.

Define alarms: sound, maximum depth, maximum background time, maximum nitrogen bar, time before entering decompression.

Enable deep stops, safety stops and all necessary stop information when entering decompression.

Surface range between dives.

Desaturation time (time to remove residual nitrogen from the body)

Surface time before you can fly.

Green-yellow-red traffic lights, as visual information of the most important variables: nitrogen absorption, oxygen toxicity, ascent rate.

Unit of measure between metric or English and other parameters of functionality of the screen or the sampling of the data to be stored.

Safe diving using a dive computer

Here are some rules for safe diving using the computer:

Always plan the dive, at least check with the computer's plan mode the updated limits based on residual nitrogen and the maximum depth of the dive.

Always limit the dive to the level of your training and experience.

Always perform the deepest diving first.

Always perform first the deepest part of the dive, (multilevel dive).

Always make a safety stop at each dive.

Allow adequate surface interval between dives.

Allow a suitable surface interval between dive days, (until the computer is set to zero).

Technical Diving: Diving algorithm for diving with decompression decompression math models are used to calculate decompression needs. There are variations of these models, but in general they can be divided into 2 basic types: Neo Haldanianos and Bubble Models.

Neo Haldanian Models These models are based on studies done by John Scott Haldane (1860-1936) at the beginning of the 20th century. In this model the concept of dissolved gas is used and it is considered that if the decompression profile is correct, the inert gas remains dissolved in the tissues and there is no decompression sickness (DCS). Advances in diving have updated and improved the concept of Haldane, which led to Neo Haldanian models, widely used in non-decompression diving as in decompression diving. During decompression the gases diffuse from the tissues into the bloodstream and from the lungs to the lungs without bubbles. Nowadays it is known that this is incorrect because small bubbles called microbubbles are produced being important that these microbubbles are minimal and asymptomatic, that is to say that they do not produce DCS. What is wanted in these models is to control the size and quantity of these bubbles rather than avoid them.

As in these models it is considered that there are no bubbles, the strategy is to take the diver as fast near surface without forming bubbles (symptomatic). In this way, the greatest differences (pressure gradients) between the dissolved gas in the body tissues and the pressure of the medium (water pressure at that depth) are produced. The greater this gradient, the greater the elimination of gas through respiration. As the gas in the body decreases it is passed to the next stop, and thus are respected the different stops for a safe dive. From the Neo Haldanian models the model of Dr. Albert Buhlmann (1923-1994) Zurich, called ZH L-16, is the most used for repeated decompression and deep dives, with software versions for PC and dive computers. It is a conservative model (more than the DSAT known as Roger and Powell, which is the one that uses the PADI table), and can be modified according to the application, using the pressure groups and adding the deep stops, to vary the Conservative degree of diving. (Subject of an upcoming note). Any algorithm or mathematical model must be verified practically, being the databases of each model the statistics that are possessed of real or laboratory dives and that allow to check the validity of this one.

Oceanic Computers with Double Algorithm Oceanic computers use a double algorithm allowing to adapt to different conditions of diving. The Pelagic DSAT algorithm , based on DSAT (Diving Science and Technology), known as Roger and Powell with the SPENCER M values , which is used by the PADI RDP Table , is consistent with non-decompression dives, Multilevel, repetitive at sea level. This model is used for: Recreational Diving. The DSAT algorithm maximizes the time of diving for repeated dives, recreational multilevel. This algorithm is based on Doppler studies in humans used to develop the RDP or PADI Recreational Scuba Planner, And has been the algorithm most used by Oceanic computers and other manufacturers for a long time.The Pelagic Z + algorithm , based on BUHLMANN ZHL-16C; Their data are consistent first with repetitive decompression dives and altitude. This model is used for: Deep Repetitive and Decompressive Dives. The Pelagic Z + algorithm uses the Buhlmann ZHL-16C database, designed for the rigorous demands of decompressive repetitive diving in cold waters and decompression in altitude. Pelagic Z + maximizes deep diving times without penalty. Their data are consistent first with repetitive decompression dives and altitude. This model is used for: Deep Repetitive and Decompressive Dives. The Pelagic Z + algorithm uses the Buhlmann ZHL-16C database, designed for the rigorous demands of decompressive repetitive diving in cold waters and decompression in altitude. Pelagic Z + maximizes deep diving times without penalty. Their data are consistent first with repetitive decompression dives and altitude. This model is used for: Deep Repetitive and Decompressive Dives. The Pelagic Z + algorithm uses the Buhlmann ZHL-16C database, designed for the rigorous demands of decompressive repetitive diving in cold waters and decompression in altitude. Pelagic Z + maximizes deep diving times without penalty.