Computer Sherwood Wisdom Console
I am always amazed that, even with millions of people buying mobile phones, there are so few companies making them. I can think of only around half-a-dozen manufacturers.
     With such a small minority of the worlds population going diving, you might think that there is a relatively large number of makes of diving computer on the market, but in fact there are not many of these either. Only Suunto, Uwatec/Scubapro, HTM, Benemec and Beuchat in Europe, Seiko in Japan and Pelagic in the USA come to mind.
     The new Sherwood Wisdom looks very much like a product from Pelagic (which Im sure will tell me if I have got this wrong).
     US-made computers are aimed at the typical American leisure-diver, which sounds reasonable. That diver rarely dives deeper than 30m and often stays at no more than 18m. He or she doesnt like going into decompression by which they mean they dont like to incur mandatory decompression-stops, and they usually choose to dive where the water is warm and comfortable. And, given the choice, whats wrong with that
     The Sherwood Wisdom uses a decompression model based on dive schedules successfully tested by Rogers and Powell to depths not exceeding 27m and without mandatory decompression stops. The decompression-stop predictions are based on US Navy tables.
     It is air/nitrox-integrated by high-pressure hose. The unit I tested had a quick-release connector and came in a console with a compass. It is water-activated, so there is never any risk of entering the water having forgotten to switch it on, but it has two control buttons which make setting it up for your own preferences exceedingly easy.
     The first thing I had to do was set the date and time and set it for metric units of measurement. Easy!
     Then I had to set it up for the mix of nitrox I was using, although one still has the option of leaving it as an air-only computer or simply using it in gauge mode. Nitrox-users have the option of setting a PO2 alarm from 1.2 to 1.6 bar and the percentage of O2 in the mix. Easy!
     You also have the option of having various alarms set to sound or not. These include fast-ascent, maximum-depth, tank-pressure at halfway or wherever you would like it, tank at minimum pressure, an end-the-dive pressure setting, a tank reserve setting, an into-mandatory-deco alarm and a high PO2 alarm.
     You can use the options to fine-tune the audible warnings you would like or simply turn some or all of them off. Its easy!
     Besides planning, logbook and PC interface modes, the Wisdom also features a dive-simulator, which is very useful in that it allows you to get to know the instrument thoroughly long before you get anywhere near the water.
     The display has a powered backlight on demand and I am pleased to say that, although the fact that it has so many user settings is initially daunting, setting it up is childs play. The display is big and bold enough for elder-statesmen divers to be able to read it easily, too. I could!
     I often hear nonsense talked about gas-integrated computers. Yes, they do cost extra, but bearing in mind the number of divers lost to drowning, probably as a result of bad management of their air supplies, I would say that air-integration is one of the single most important advances in diving instrumentation after proper ascent-rate monitoring à another thing revolutionised by computers.
     You get a read-out of tank pressure throughout the dive and of remaining air-time based on your usage and your actual depth. Tank pressure, measured electronically, is a lot more accurate than that shown on a mechanical pressure gauge. The simplest way to use it is to be sure that your remaining air-time is always greater than your total ascent time.
     Bar graphics build up to indicate nitrogen- and oxygen-loading. The Wisdom shows stop depths and times as well as total ascent-times once into deco-stop diving mode, and displays maximum depth, elapsed dive time, current depth, air-time remaining, and tank pressure. If you press the side button, an alternate display shows current PO2, preset percentage of oxygen, current depth and current tank pressure.
     Using a decompression computer or even a simple set of tables is a matter of faith. You never really can tell how close you come to the edge. If you use a US-made computer and your buddy uses a European one, you will notice sometimes very different mandatory deco requirements. It is tempting to say that one party has got it wrong, but how can we tell
     Its a bit like following different religions. You each hope to get safely to the same place in the end.
     I suggest that where possible you always pair up with someone using a computer based on the same decompression philosophy - whichever one you feel confidence in. I have my own beliefs and Im sticking with them.
The Sherwood Wisdom with compass and quick-release hose-coupling costs £664.
  • Sea & Sea 01803 663012, www.sea-sea.com

  • Divernet
    + Lots of options
    + Easy to set them
    + Clear dissemination of information

    - Deco algorithm aimed more at leisure diving than serious deco-stop diving