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What are Dive Computer Algorithms?
The dive computer is used to calculate your maximum dive time which allows for a longer and safer dive. The dive computer as took over from the dive table as the diving tool to calculate all your necessary parameters to enjoy scuba diving.

Dive computers use algorithms to calculate these safe diving limits. haldanes They will make adjustments for both fast tissue groups and slow tissue groups. It uses this information to estimate the nitrogen in your body. Based on the amount of time you’ve been submerged and your depth, from this the computer then calculates how much longer you can safely remain underwater.

Different Type of Algorithms
Algorithms vary by model from each manufacturer and only a few algorithms are actually used. Some algorithm used may also be a modification of an existing algorithm. When you want to consider buying your next dive computer, the main feature to look at is the algorithm that the air decompression limit monitor uses.

Algorithms with different manufactures use some varying factors in their algorithms such as mentioned with fast and slow tissue groups. The solubility, permeability, and blood contact for a given tissue, say for example a kidney, is called a “tissue compartment or tissue group.” Dive computers use these “tissue compartments” to simulate the effect of a gas on your body at depth. The more “tissue compartments” a computer measures, the more accurate (theoretically) the computer can gauge the effect of a dive on your body. 9 to 12 compartments is fairly standard, but a few consumer models have 16 or more.

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

Group 1: Haldane/Spencer Algorithm
The Haldane/Spencer model uses test results from PADI’s Diving Science and Technology 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: Modified Haldanian Algorithm
This algorithm model was used by 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 work by Wienke and Hamilton and uses nine tissue compartments. Suunto were the first to use the RGDM and now other manufactures are starting to use it too. The big difference of this algorithm is they consider micro bubbles that are in the blood stream as a result of nitrogen build up. The theory was they consider that these micro bubbles are a precondition of larger bubbles which can lead to DCS.

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

Short fall of Algorithms
Algorithms may not be able to account for age, previous injury, ambient temperature, body type, alcohol consumption/dehydration, and patent foramen ovale(hole in the heart).

Which Algorithm is the best?
Removing of factors like cost, looks, other features etc then the more “tissue compartments” a computer measures, the more accurate (theoretically) the computer can gauge the effect of a dive on your body. 9 to 12 compartments are fairly standard nowadays, but a few dive computers are now using 16 compartments.

Even if two algorithms have the same results, manufactures will add there own factor of safety so they can set there dive computers to aggressive or conservative. An aggressive computer gives more bottom time than a conservative dive computer, and it’s wise to understand the properties of one’s own dive computer to ensure it fits the skill and comfort level expected.

Simon James has been diving for 15 years and is an authority in the field so take a look at this website called diving so


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