The console affords a convenient mode of stowage and a reliable gas integration method allowing diving gas usage to be monitored accurately. The Mares Nemo Air is a gas-integrated computer that includes dive computer and gas pressure gauge in one. The Mares Nemo Air is a competent computer for recreational diving and the addition of gas-integration via a console route has made it an even better choice.

The Nemo will tell you current scuba cylinder pressure, how much remaining breathing time you have left at your present breathing rate and also what that breathing rate is.

Mares diving computers use the Mares-Wienke Reduced Gradient Bubble Model algorithm for diving decompression software which takes into account micro bubbles formed in the body and attempts to reduce their likelihood. The algorithm is very similar to the Suunto RGBM.

The diving information included on the display is very similar to most other dive computers – showing no-stop time remaining, current and maximum depth and stop information. This includes a countdown of both deep stops and safety stops.

As a recreational computer it will only allow a single gas mix of up to 50% nitrox – and when diving on air the computer should be set to 21% nitrox rather than the air setting as not doing so would incur a 49 hour lockout when switching from air to nitrox.

The dive computer unit easily detaches from its hose fitting for safe transport away from the bulk of your dive gear. It has a bayonet fitting that involves a simple quarter turn to fit or remove. Without an electronic compass included, however the console does have an attachment for a traditional analogue unit.

At £499.95 mrp this is not a cheap diving computer but for gas integration it is reasonable value – 7. Performance is good, ease of use brilliant – 7

I always found the standard 3 litre pony cylinder to be a clumsy addition to my single 12 litre tank, and my buddy with his 15 litre set was even more burdened. I was finding that it was hard to balance the lop sided effect of the additional tank, even by putting counterweights on the other side. So we decided top move to a twin set.

For anybody who has dived using a twin set I am sure they will agree that they are marvelously balanced and feel superbly comfortable in the water. I did and my buddy is equally happy with his, even though we both bought different makes. Me a Halcyon rig and him a Frog wing with Fabers. I on the other hand found that carting 40KG of gear on my back along a quay and into a boat to remove some of the enjoyment from my diving. Furthermore, I was using the twinset for two and often three dives, as I am pretty efficient with my breathing. I also saw that if I was going to do a typical dec dive, say to 40 metres for 20 minutes, I still did not need a full 24 litres of gas if I was taking some higher O2 nitrox down also to decompress with.

I think that it is very important to be comfortable with all aspects of your diving. We find that when we start out, using ill fitting club gear. The difference when we find a BC or a mask that actually fits properly is noticable. The same goes with the size of the cylinders you carry. I started with a 15 litre because that is what everybody had in my club. I found that I was always surfacing with 120 plus bar. So I moved to a 12 litre whjich is fine for most pleasure dives. In fact I use a 10 litre that I blagged from my daughter when she gave up diving – particularly for second dives of the day (I also use it for instructing as it is a doddle moving it around the pool).

So now I have taken to paper and calculator and worked out my likley gas consumption for the sort of dives that I will be doing in the forseeable future. Guess what…twin 7 litre tanks will fit the bill. No, I am unable to get two dives out of them so I will need some provision for the times when I go out on a day boat for two dives (e.g. to the Farne Islands of our North East Coast) but I will be comfortable (and happy) during 90% of my diving.

I considered 300bar cylinders, twin 10 litres, non-manifolded sevens etc etc. Why is there such a choice. In the end I was only able to choose by working out my air needs for the actual diving I was going to do – not what I might or might not be doing in five years time. Now all I need to work out is what computer I will upgrade to!

I spent hours playing with it at my desk…it is quite a complicated beast. I finally felt that I had mastered it enough to take it underwater. Yes it worked fine, screen needed to be back lit in all lighting conditions, above or below water, if you wanted to be able to see the details at all. Then a red screen…telling me to change to a different nitrox mix (I was on air). I ignored it which did not matter as I was only doing a shallow dive in a quarry.

Back on land and I investigated the problem. No different gases had been stored. I asked questions on the diving forum. The response was helpful as usual but did not resolve my question. What I was told was that often this computer would throw up funny readings from time to time!

So I toddled off to the Red Sea for 20 cracking dives on a liveaboard. I was the only one with a VR3 and everybody including the guide (who was using an Inspiration re-breather) wanted a look. Great, only it was like having a lump of steel on your wrist, it contiually moved on your arm like the gimbals in a ships galley! It had seated itself all right on my padded dry suit back in the UK but was useless on my 5mm wetsuit arm. I dread to think what it would be like on bare arms!

So only a cold water computer then – though I am sure with a bit of ingenuity I could have overcome the problem. It’s just that the offending item was beginning to annoy. And did I tell you that I was on the second new battery after only 30 dives? Admittedly they were only alkaline ones but the backlit screen was only used for the duration of the dive – it switched off on land.

So I resorted to eBay and now am looking to find a new candidate. Meanwhile I am using the Suunto Gekko that I bought for my daughter before she decided she didnt want to dive anymore. Apart from the fact that it has no back light and only one gas it is a cracking computer. I think that I will upgrade to one of its older brothers, the Vyper, Vytec or HelO2.

I believe that the VR3 is a little obsolete now anyway, with newer models replacing it.