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.

The new Vyper Air has an integrated electronic diving compass that continues to work within a massive 45 degrees tilt range. The [...]]]> The Vyper by Suunto has been a well known dive computer model for several years. Now an upgraded version has been released that has provision for adding a wireless receiver to manage gas consumption.

The new Vyper Air has an integrated electronic diving compass that continues to work within a massive 45 degrees tilt range. The wireless transmitter allows the user to monitor tank contents (one gas mix only) and gas consumption rate.

This is an easy to use computer that will suit most divers taking their diving up to a semi-technical standard. The next step would be a Suunto Vytec which would give you three gases for a few pounds more or a Helo2 which would allow trimix within the different gases on a complex dive.

As a step up to your Gekko, the Vyper Air is a good value diving computer that is more advanced than it brother the Vytec, which has been around for a while now. The Helo2 does everything the Vytec does with the addition of multi gas and helium for £250 more. I would leave the Vytec out of the equation and choose between the Vyper Air and the Helo2 depending on what your short term plans are! Personally I have decided on the Vyper – and if I do have a go with Trimix in the next year or two I will use it in gauge mode while I am learning to cut my own decompression tables!

This is something people forget – when choosing a computer get one that is ideal for your diving now, not what it might be in a year’s time. If I bought a helium computer now I would be tempted to use it and not get acquainted with the new deco regimes. In a similar way I believe my air diving was so much safer for spending years on BSAC 88 tables before I even owned a computer!

Technical specifications:

• Reduced Gradient Bubble Model
• Option of 1 or 2 minute deep stops
• 4 button ease of use
• Air, nitrox, gauge modes
• Option of secondary deco gas
• Personal safety adjustable
• Back light – soooo important!