Diving the VR3 dive computer

The VR3 dive computer was the de rigor technical dive computer that all technical dive computers are measured against. The VR3 is a full decompression dive computer supporting 10 gasses including air, nitrox & trimix that can be used on open circuit scuba & closed circuit rebreather.

For me, this is a bit overkill but should I really get back into mixed gas diving - I will have plenty of options.The VR3 computer was the first dive computer to offer full colour graphics with a green format for non-decompression stages of the dive, the format will change to yellow once a decompression obligation is required and red screen appears should a hazardous situation be encountered such as missing the deep stops, exceeding a PO2 or an incorrect gas switch.

The VR3 dive computer uses a derivative of the Buhlmann ZHL-16 algorithm; according to VR Technology, modified to assimilate micro-bubble avoidance for enhanced decompression safety - the deep stops represent bubble avoidance techniques. When undertaking decompression dives, the VR3 Buhlmann algorithm prompts for deep-water controlling stops of 2 minutes in duration.

The deep-water stops are recognised by their duration (normally two minutes duration) and a + displayed next to the time. It is important that these stops are conducted correctly for a safe decompression as they help to reduce the problems associated with potential micro-bubble growth during an ascent.

In my experience, this would involve a 2 minute stop at 16 metres and 2 minutes at 11 metres for most mild decompression profiles. These stops differ according to profile with some stops at 21 metres and 16 metres respectively, then the shallow stops apply.

The VR3 has user changeable batteries that may be a 1.5 volt alkaline or 3.6 volt lithium cell, access is available through the battery cap with a dedicated tool. I have found alkaline batteries to have insufficient capacity, the Eveready Ultimate 1.5 volt lithium battery is now my choice as both economical and suitably long lasting.

Two magnetic switches are toggled by either a short or long push to navigate the screens with changes to settings able to be made underwater. The advantage of the magnetic switches is that they do not provide a possible leak path, the I/O port is capped and if the seals leak then the compartment may be flushed with fresh water and dried appropriately.

The battery cover is the only possible leak path and the o-rings should be lubricated and changed when required. The final stop depth may be changed underwater; changing stop depths to either a 3 metre, 4.5 metre or 6 metre for the final stop depth depending on surface conditions.

Unfortunately, my quickly fading eyesight now makes such an operation hazardous, I should be wearing a prescription mask and can follow the prompts better, I haven't been gas switching lately but will be again once I upgrade my mask.

The VR3 dive computer is not a particularly easy dive computer to learn to use; much effort is required to read and understand the manual, that can’t be emphasised enough. The time spent practicing with the computer on the surface with the manual is time well spent, a number of shallow lead up dives within the no-decompression limits are mandatory.

 It is, of course, thoroughly recommended, no make that mandatory, that in any decompression dives, back up depth & bottom timer is used, a known dive computer is highly recommended to compare. I had been using an OSTC 2N dive computer until the screen failed, now back to my old Aladin Pro for air dives or Suunto Vyper in gauge mode and haven't switched gas after my 2N failed.

The VR3 dive computer is a powerful platform that could be purchased in the C1 configuration and can be expanded to trimix and closed circuit diving in the future. Once I learned the computer, and it did take a while, I find it an excellent dive computer and I now personally use the VR3 dive computer as my computer of choice.

The VR3 has now been replaced with the cut down version NHeO3 and the upgraded VRx, the later building on the technology platforms and lessons of its predecessor. The VR3 remains an excellent dive computer for both open and closed circuit nitrox & trimix diving, I won’t be upgrading my VR3 to the VRx just yet as I am happy with the performance of my VR3, all new users should seriously consider the VRx though.