How To Choose Your Scuba Diving Computer
Equipment to buy
To start with, remember any dive equipment you buy should be as per your, (in the order mentioned)
need
fitting
comfort
functions
budget
brand
style
Scuba Equipment needed
Every open water diver or a new diver who has just started journey into scuba diving, is often recommended to buy a dive computer by his/her instructor or the dive centre.
With the use of Recreational Dive Tables becoming more and more absolute (read divers becoming lazy), and of course by the advancement of modern technology, the use to dive computer has become essential and access to it quite easy.
Dive Computer:
All the dive computers are based on the Decompression Algorithms coded into software. Most available in the market currently follow either of the following 3 broad algorithms,
- Buhlmann
- VPM
- - Based on the size of the bubbles that may be in divers’ body at given point of time
- RGBM
- - Based on combining concepts of both tissues and bubbles.
- - Very first dive Algorithm developed, Based on Theoretical concept of Tissue compartments
Above description of algorithms in very superficial and to understand them would require deep study of each. Each algorithms have their separate newer versions developed by each brand.
So, now where should the new divers start when they look to own a Dive Computer.
Along with the category considerations about equipment mentioned at the beginning, broadly, I would classify following categories that one can consider while buying a Dive computer.
- Need
- Modes
- - Gases
- Battery
- Dive Related Features
- Logging Memory Size
- Air Integration / Connectivity
- Service Options
- Style Features and Brands
Let’s look at each one of them in detail.
- Need:
What type of diving are you predominantly going to do. Recreational Diving, Technical Diving or Free Diving (discussed in Modes).
Depending upon the dives you do, you would want your computer to be more accurate with its algorithm, optimising safety and time allowed under water.
For recreational divers any of the dive computers should work without going much into details and abiding to dive conservatively.
RGBM algorithm dive computers are considered more conservative and suitable for recreational diving. Having said that, obvious (side)effect of conservationism leads to unpleasant compromise on underwater time. Divers may get lesser NDLs or NSTs in subsequent dives.
So, almost all technical divers prefer computers with variations of Buhlmann algorithm rather than RGBM or VPM, giving them flexibility to adjust algorithm variables for each dive (viz. GF, etc.)
Your diving type will also define the depths you are going to attempt. So, Depth limit of the Dive computer should be always considered while buying the dive computer.
- Modes:
A dive computer has particular “Modes” designed for the specific usage and should be switched as and when required.
The most common Modes are:
- Dive Mode
- Gauge Mode
- Free Diving Mode
- Watch Mode
Dive Mode
All basic Dive computers have Dive mode and Gauge mode in it, and normally when switched on, by default run on Dive Mode.
Dive Mode is the mode in which dive computer works with its very important function of measuring pressure, depth, and calculating NDLs, providing necessary information in real time, underwater, for the entire duration of the dive.
Many dive computers are by default in the dive mode and automatically start working and recording, the moment it submerges approximately 0.5 to 1 meter underwater.
Gases
Further into Dive Mode, a Category which comes into play is “Gases”
Which gases does the dive computer support?
Historically, all dive computers have been designed for AIR as default gas configuration, for all scuba dives. With the introduction of Enriched Air diving (NITROX), dive computers started having options of modifying gas percentage for dive calculations.
So, previously, there were only AIR computers available in market, and one might have had to consider, if he/she is going to use Enriched Air for their dives or not. If yes, while buying the dive computer one had to consider this mode/feature as well.
Nowadays, almost all the dive computers by default come with option of settings to modify Gas percentage for usage of Enriched Air (NITROX).
So basically, every computer may support minimum 2 dive gases.
More Than 2 Gases:
With scuba diving advancing for more deeper and longer dives, technical diving required usage of more gases to compensate for the higher intake of nitrogen. To that effect, more calculations are needed towards additional gas used.
Modern day dive computers have made this extremely easy to adapt to these advancements. And so, for anyone going for deeper Technical Dives, support of multiple or more than 2 gases is necessary in a computer. This is another important category which comes into play while purchasing your dive computer based on need. Currently, technical diving specific computers have support for TRIMIX – 3 gases, or latest versions may have option for experimental more gases.
(I am not aware of any, if anyone knows, please share so that I also learn.).
There is a lot more that can be discussed about algorithms and gases, but that will not remain under the scope of this article. Please read and self-research while opting for specific dive computer.
Gauge Mode
Second mode which most dive computer will have is - Gauge Mode. In this mode, the computer only records depth and dive time underwater without calculating the NDLs or safety stops. This mode was predominantly used when manual dive tables and calculations were used. Nowadays divers use this mode as a secondary/backup depth gauge.
Free Diving Mode
By the recent, increasingly popular trend of Free Diving, many scuba divers are also learning to Free dive and would rather want related feature in the same computer. So, now most dive computers also now come with specific Free Diving mode.
Free Dive mode is very similar to Gauge mode, but additionally will also calculate your surface interval required by Free Divers.
Watch Mode or Land Mode
Not necessarily a mode, but many dive computers now come with stylish watch faces and can be used just as a watch while not diving. Switching to this mode, computers preserve batteries when out of water. Some of the computers with more advanced features of land GPS also call it Land Mode.
So again, remember to switch to dive mode when you go diving.
Battery:
The next most obvious consideration while buying a dive computer is, its battery life and battery type.
Dive computers nowadays come with different options of Batteries.
Battery type would depend on number of dives that it can last. Some computers define that it may last for a particular number of dives or a particular number of hours of diving.
In this event batteries may need,
- to be replaced – option of User self-Replaceable (or replaceable only by authorized service centers).
- To be recharged – rechargeable batteries like smartphones
- And some also come with option of Solar recharging.
- Dive Related Features:
Apart from basic functionality of Dive Calculations, most dive computers come with multiple other features which may be useful while diving.
- Altitude Diving
- Digital Compass
- Dive Alarms
- Dual Time Zones
- Logging:
Another important category to be considered for a dive computer is Dive Logging. Almost all dive computers will have a feature of logging – storing the dive details.
All the Dive logs will store details like,
- Dive Start Time
- End time
- Maximum Depth
- Average Depth
- Total Dive Time
- Surface Interval.
Other features that may get logged are water temperature, room temperature, dive violations, etc. Some may also show small graph of the dive profile instead of only storing text values.
Considering the details being logged, the logs will take up memory space in your computer. Hence, one should always consider how many dive logs does the computer store at a time.
And how does it delete/replace old dive logs when the limit is reached. Most dive computers follow First-In-First-Out principle to replace older logs.
Modern dive computers give an option of transferring the logs either to a PC or a mobile app avoiding to permanently losing the logs once the logging limit is reached.
- Air Integration / Connectivity:
Ability to transfer logs brings us to another aspect to consider is connectivity. What type of external connectivity does the dive computer has.
- Wired: Now an old feature, only able to connect to a mobile or desk computer via cable. Logs may be transferred /exported only in a particular format, and most cables would be model or brand specific
- Wireless / Bluetooth: A more advance option is wireless – Bluetooth connectivity. This allows the dive computer to connect to an app on a mobile or desk computer wirelessly.
- Service Options:
Dive Computers are complex and by its nature of use (human life dependency), rigid to be understood and repaired by every tom dick and harry.
So apart from the self-replaceable Battery options, one should consider
- Frequency of software updates
- servicing history of the brand
- availability of the Authorised Service Centres near your diving regions
- warranty / guarantee conditions
- Style Features and Brand:
Dive computers are kind of the primary safety device. Your life depends on the accuracy and reliability of the information provided. So, if all the above features discussed are considered, a diver may consider the other features provided on the dive computer.
Many dive computers now come with feature like,
- Colour Display
- Stylish Watch face
- Alarms
- Land GPS
- Mobile Call/App Notifications
- Smart Watch Notifications – Heart Rate, Step counts, etc.
All these features severely add onto the complexity of the software code, battery usage and sometimes size of the dive computer. In terms of software code, more the features, more the possibilities of software crash are introduced. You would not want the computer to stop working under water while on a fantastic, dive.
Like the rule would dictate, any malfunction of the equipment, you would have to end your dive.
With all the above factors considered, it is recommended to of course check the brand history for reputation and reliability.
And last but not the least now, you have the option of consideration of cost.
Your budget will of course decide what feature you want in your computer.
I would just say compare the feature and cost factor to your own life, as it depends on it under water.
Happy Diving, Stay Salty. 🙂