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Why Dive a Computer? – Gas Mixtures!
SKubaSteve - 12/10/2013 3:01 PM
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Why Dive a Computer? – Gas Mixtures!I’m a gear-o-phile. Okay now that we got that out of the way…

NOTE: I forgot to credit Mika’s fantastic lightstream photo! Thanks to Mika Hiltunen once again for sharing!

Dive computers are a great addition to your dive system. When a diver on a limited budget asks me what they should purchase first, a dive computer is always high on the list (usually right below regulators – but every situation warrants some thought). I don’t sell diving computers, I don’t get commission when one a diver buys one but I’m passionate about getting divers into computers.

And here’s why…
  • Increased dive time
  • Safety
  • Dive Planning
  • Gas Mixtures
  • Dive logging
  • Convenience
Even as recreational divers we have variety of gas mixtures to choose from. This is yet another great reason to dive a computer…

Computer Features

Generally speaking recreational divers with enriched air nitrox training are limited to oxygen (O2) concentrations of less than 40% O2. In practical terms higher concentrations produce such a shallow maximum operating depth that they become limiting to divers and; therefore, aren’t frequently a good choice as a primary breathing gas.

Modern dive computers generally have settings that allow the diver to enter the gas mixture that they will be breathing. A good dive computer that has gas mixture adjustability should provide:
  • Maximum Operating Depth (MOD) for your breathing gas
  • Bottom Time adjusted for the O2 percentage of your breathing gas
  • Integrated O2 percentage in the dive planning mode

Common Gas Mixtures

There are several popular recreational gas mixtures and reasons to continue your education and learn why & when each can be beneficial. Some of the popular training agencies’ Nitrox courses are found below:
  • SSI – Enriched Air Nitrox
  • PADI – Enriched Air Diver
  • NAUI – Enriched Air Nitrox
Three popular recreational gas mixes are:
  • Air – 21% O2
  • EAN32 – 32% O2
  • EAN36 – 36% O2
Some thoughts on safety…
  • Read the owner’s manual and understand how the display functions for modified gas mixtures before you dive.
  • Set the computer to the gas that you are using (link will take you to my brief overview of safety & dive computers), you can even make verifying gas mix settings part of your buddy check before entering the water.
  • Always verify the maximum operating depth (MOD) of your breathing gas. Any time you buy a new computer or dive a different gas – check the MOD vs. another reliable source (not your buddy’s dive computer). Now that I think about it – even better – when you get a new dive computer find an MOD ‘gold standard’ and set your dive computer to the various gases that you dive then verify the MOD is close to the standard. There’s more to this that I can’t cover here (already 124 words longer than I was shooting for…) but I’ve made a note to put a full post together about ‘validating’ (using the term loosely) your computer as an appendix to this six part series.
For me, the ability to adjust my computer for the breathing gas I’m using is a must have feature for my dive computers and; luckily for all of us, many do! This feature provides convenient dive planning tools as well as real-time information during the dive and is my number 4 reason for diving a computer.

What do you dive? Let us know!

Take Our Poll

Okay, I won’t skew the poll with my own answers but I dive:
  • SCUBAPro Luna
  • Suunto Mosquito
I also own but don’t use often:
  • VR-4 (not many dives on it – maybe 30, all upgrades installed – oh and it’s FOR SALE!!!!! contact me if your interested) This is a good dive computer but I am not tech diving at this point so it’s more computer than I need.
  • SCUBAPro – SmartCOM (Works great – my son is diving it now)
The surface interval’s over … get out there and dive!

SKuba Steve

© 2013 Stephen Krausse – All rights reserved.