How to Choose a Dive Computer


Most computers do the same thing.  There are some little features that may make one different than the other, for example, back lighting capability, some will have additional hardware you can purchase to upload data to your computer, etc.  The common features of all computers are; they calculate your depth, bottom time and dive table/no decompression time.  They also have ascent rate indicators, log your dives and they almost all have the ability to input Nitrox blends.

Essentially there are two differences between computer models and manufactures.  They are the computers configuration and what dive table algorithm the computer uses.  A third feature to look for is the customer service provided by the supplier.

Configuration has to do with its display (is it easy to read), its size (watch style vs. “puck” style) and how easy is it to access the various functions (dive plan mode, dive log mode, set nitrox mixtures, etc.).

The algorithm is related to which dive table it has integrated.  Of course most divers are familiar with the PADI dive tables as this is what they learn when they first start diving.  The PADI dive tables were created by DSAT (Diving Science and Technology) which is a sister company of PADI.  To this day, they are the only dive table tested for recreational diving.  Other common algorithms you will see are known as Buhlmann Z16 and RGBM (Reduced Gradient Bubble Model).  Both of these algorithms were primarily tested and used for decompression diving.  When comparing the DSAT algorithm with the other two algorithms, you will notice that the DSAT actually gives you more time underwater, especially at deeper depths (around 100 ft/30 m.).  Believe it or not, I think this is actually a good thing.  The problem I see with the decompression based algorithms is that they are overly conservative (due to the fact that they are based on decompression not no-decompression diving).  There are many draw backs to the conservative algorithms.  First they do not give you as much dive time (the idea of a computer is to give you more dive time – within safe limits), they often put you into false decompression meaning they may require you to do long decompression stops when they are actually not necessary.  If you do not or can not (based on your air supply) meet their decompression obligations, they are prone to lock out and will not allow you to dive again for 24 hours.  They also typically becoming increasingly more conservative for repetitive dives as they have a slower gas wash out tissue.  I can give you specific examples of this at the shop.

The brand of computers we recommend for most divers would be from Oceanic or its sister company Aeris as they have a range of computers that differ in their price, features and configuration.  They also give you the best options for algorithm, in fact, they are the only manufacturer that uses the DSAT algorithm.  Oceanic computers also give you the choice to use the more conservative Buhlmann algorithm as well.  Personally, I think the DSAT algorithm is the one to use for recreational diving as it is well tested and gives you more dive time.    The local Oceanic distributor also has excellent service (as do we!) should you ever have a warranty issue.

Another style of computers to consider are from a company called Liquivision.  Liquivision computers (Xen, Kaon, Lynx and XEO) use OLED display which make them incredibly easy to see underwater.  They are also feature rich and untilize tap technology which makes them very intuitive to use.  Liquivision computers also allow frimware updates which means you can update your computer anytime Liquivision puts out a new software upgrade.  Without question, Liquivision computers are one of the most innovative on the market and get a big thumbs up from me.

A note about air integrated computers:  If you choose an air integrated computer, we strongly recommend that you also have a back up analog pressure gauge.  The reason for this is if your computer ever fails underwater, you will lose all of your information including your air pressure.  This leaves you with only one safe option, go to the surface.  If you have an analog pressure gauge and your computer fails, you will still surface, however, you can rely on your buddy’s information to determine information such as depth and time, you can do a long safety stop as necessary, you may even be able to complete repetitive dives.

A note about purchasing used computers or buying on-line:  Used computers as well as computers purchased on-line do not come with a manufactures warranty.  Although computers are very reliable, they can still fail due to a warranty malfunction.  We are able to efficiently support any warranty problems with computers purchased through the Ocean Quest.  If a used or on-line purchased computer fails, you will have no service or support.

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Greg McCracken

Greg McCracken is the owner of Ocean Quest Dive Centre alongside his wife Deirdre McCracken. Greg earned his PADI Instructor rating in 1992 and his PADI Course Director rating in 1997. Before settling down in Vancouver, Greg has managed dive centres on Vancouver Island, Central America and Mexico. He has been actively involved in the scuba diving industry for over 25 years and continuing to teach and dive for fun.