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 computer provides real time decompression information during the dive based on gas mixtures that the diver sets before the dive. They can however be also changed underwater if this becomes necessary. Dive Rite says that the computer is simple to use and the menus are intuitive which means that a complex user manual is not needed. As with all such promises, the reality is that it does pay to familiarise yourself with this unit fully before diving – it is pretty straight forward though.
If I was able to have two computers I would choose one wrist mounted model suited to the diving I was doing currently and also one console mounted version that was integrated with my air supply. The reason for this would be that for most of my diving at home I would use the console and when travelling I would take the more portable wrist computer along with basic mask and fins – as I would be hiring my dive gear at my destination.