Nitrox is a great gas, but [...]]]> Now that enriched air diving is pretty standard and nitrox can be bought from most dive shops and dive stations around the world, dive computers have all developed so that they can plan and execute any dive – sometimes including when more than one mix of nitox is being used.

Nitrox is a great gas, but has its limited when deeper diving is being carried out. The deeper you go the less oxygen you can add to your mix as a result of the poisonous effects of oxygen on the bodies nervous system at increasing depth. The less oxygen you breath at depth, the more nitrogen tou must have in the mixture. Unfortunately nitrogen causes more than decompression sickness (which can be avoided by suitable dive profiles and decompression stops etc) – it causes nitrogen narcosis. Apart from being very dangerous, even mild narcosis means that a divers awareness is reduced with an unexpected consequence – there is often very limited recall of the experiences of the dive!

So more and more divers are beginning to see the advantage of diving with helium added to their breathing gas mix – not only to allow reduced oxygen partial pressures as the diving gets deeper, but also on relaatively shallow dives of 30 metres or so to increase the perception and this enjoyment during and importantly – after the dive.

The Suunto HelO2 dive computer is the first simple to use, intuitive and straight forward mixed gas diving computer allowing several gas switches during a dive (3 gases can be programmed into the start of each dive).

The Suunto HelO2 menu is similar to its stablemates the D6 and D9 watch versions. With four buttons it is easy to use and there is not the having to start over again if you make a mistake as often happens when only one or two buttons utilised.

Oxygen content from 8 to 100 can be accommodated in air, nitrox and trimix programmed as one of 8 gas mixes into the HelO2. It can dive to 120 metres which is deep enough for any recreational deep diver who is likley only to qualify up to a maximum of 80 or so meters depth. It uses the Suunto Reduced Gradient Bubble Model algorithm.

The Suunto HelO2 Diving Computer can be used in conjunction with wireless gas integration.

The Suunto trimix computer is priced at around £700 but you can pick one up for under £600 from the large scuba gear outlets – for example Divers Warehouse will send one post free for £591 within the UK.

Yes it was a very well engineered bomb proof and clever dive computer. You could [...]]]> I had always wanted a VR3 diving computer from makers VR Technology. When I finally bought one this year I was disappointed. Why? Because the pinnacle of diving computers turned out to be a heavy and impractical lump of confusing electronics!

Yes it was a very well engineered bomb proof and clever dive computer. You could easily change the batteries yourself and it was capable of adjusting to some very advanced scuba diving. At a cost you could upgrade to all sorts of things, so if your thing is diving to 1000 feet, with up to 8 different gas mixes, it was the bees knees of dive computers for the job.

The trouble is that I was moving into the slightly more technical arena – would be using air and various different nitrox mixes with stronger NO2 for decompression. I would also be instructing during easy sports dives, traveling to the Red Sea and other places to see new sights and perhaps try my hand at photography. The VR3 was more than I needed, ate through the batteries and was confusing to use.

Would the C be a better choice and should I trade in for one?

The makers claim that the NHeO is much more intuitive to use – however this turns out to be because they have simply removed many of the functions of the VR3. It is a cut down version of the VR3. One of the attractions to me of the VR3 was the great British engineering of the indestructible case – yet in use this computer was too clumsy. Fine on a dry suit but it would not seat well on a wet suit (forget a bare arm!) unless you tightened the strap enough to restrict your blood supply. The new NHeO is housed in a plastic case which promises to be a more comfortable item to wear.

The back lit display is smaller than many, but easy to read underwater so long as you opt for the colour option (at an extra £160). The VR Technology NHeO lags behind the Suunto HelO2 in terms of ease of use but is the choice (as was the VR3) if you are planning to upgrade to closed circuit diving.

I would rate it as a computer for the serious mixed gas diver who only needs up to 4 different gases on any one dive who also has an old Suunto Gekko for his or her holiday diving and instructing – and aspires to a Buddy Inspiration!

Marks: 6 out of 10 – Performance & 6 out of 10 for value