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COMPUTER Mares M1 AirLab RGBM

I OFTEN GET TO SEE NEW PRODUCTS long before they reach the marketplace. Many never make it, usually because of problems that arise only once production is meant to be underway.
     Mares has recently brought its diving computer component manufacturing in-house. Before that it depended on an outside supplier, which was obviously unable to come up with a reliable version of an air-integrated-by-hose computer.
     A computer called the AirLab was announced long ago but never reached the shops. Now the first examples of the M1 AirLab RGBM, made by Mares in-house, are filtering through.
     The Mares M1/Dacor Darwin computer has established a share of the market at a time when Suunto has been taking the lions share. However, the Italian-made computers have proved just as capable of managing a single-gas divers deco safely, whether on a no-stop or a deco-stop dive.
     Im happy to follow the information displayed, though I prefer to treat the optional safety-stop shown in the zone from 5-3m as mandatory. Mares computers also benefit from being user-changeable and having very easily obtained AAA batteries.
     If you are familiar with the M1, you will quickly recognise the AirLabs display (right).
     The only difference is a second display which tells you your tank pressure and how much longer it reckons your air will last till you reach reserve pressure, based on breathing demands so far on the dive. Comparing this time with your total ascent time, and being sure that the first exceeds the second, should keep you out of trouble.
    
Considering the number of computers that pass through my hands, you might assume that setting one up would be intuitive for me. With the M1 AirLab, Im afraid nothing could be further from the truth. With only two buttons I found, manual in hand, that the operation was fraught with disappointment.
     I deduce that it is not which button you press when, but how long you press it for, that counts.
     I had sore fingers and little temper left by the time I had set the date and time, the nitrox mix, the size of tank I was using (why thats needed, heaven knows), maximum ppO2, salt or fresh, metric or imperial, et al.
     You may see this as more a criticism of me than of the equipment, but if that is the case, so be it. Im a dork.
     In the water, the algorithm seemed to give me the information I have come to expect. Like Suunto, Mares has bought into Bruce Wienkes research into bubbles that might form within your body during an ascent that are silent, or have no apparent symptoms. Simplified, the theory is that these can form the nucleus of dangerous bubbles later, with dire consequences.
     Wienkes Reduced Gradient Bubble Model (RGBM) is incorporated in the mathematical calculation that the computer makes.
     A simple explanation of its effect while diving is that the computer asks you, the diver, to make a stop much deeper than you might be used to. I found this to be in the order of 18m after a short visit to 45m and beyond, or if I got well into deco-stop mode.
     The idea is that instead of going directly to the first conventional shallow stop, where any silent bubbles that have formed are hopefully passed through your lungs and got rid of before they might cause trouble, you stop deeper and these bubbles are less likely to form in the first place.
     Proponents of RGBM say that other algorithms bend a diver and then attempt to unbend him in the shallows. Its an emotive subject, especially among those selling diving computers. One should not confuse the theory with computers that take micro-bubble formation into consideration during surface intervals.
    
The fact is that if you are doing a square profile dive on a wreck, for example, you will have to make a stop on the line much deeper than you might be inclined to do, and watch the shallow-water deco rack up as a consequence.
     Dont worry. I have discovered that when comparing two similar computers, one with the RGBM-modified algorithm and one without, the stops incurred in the shallows usually turned out to be less in the end with Wienkes version. If you are likely to be diving on a reef, or anywhere else where a gentle swim up a slope is possible, you may find that you have been doing these deep-water stops all along!
     I used the Mares M1 AirLab RGBM in the Red Sea and it allowed me to control my decompression almost identically to how the Suunto RGBM 100 computer used alongside it required me to control it. It has a similar fixed maximum ascent-rate of 10 m/min and an easily understood graphic display.
     Much other information is shown, including stop depths and time, total ascent time, current tank pressure and remaining air-time down to the pre-determined reserve pressure.
     A lung icon indicates how heavy a breather you are. I really had to heave to get a medium figure - how much effort would you have to make to indicate a heavy breather I was amused to find that in Maress book I was a very light breather. If only that matched my own assessment!
     The lung icon is also augmented by a digital display equivalent to the breathing rate in litres/min at the surface. When in nitrox mode, this is substituted for the CNS loading figure.
     All the divers around me knew my remaining air-status, too, because I had set it to flash yellow lights on reaching 80 bar and red when I got to 50. These lights are not discreet. They make the whole console light up at the sides. On night dives on the Thistlegorm, everyone said they could see me flashing away!
     I especially appreciated that I could swiftly disconnect the computer from its hose and take it safely below decks when logging the dives. This is a very useful diving computer for those who use a single tank with either air or nitrox.
The Mares M1 AirLab RGBM costs £365.

  • Blandford Sub-Aqua 01923 801572, www.divernet.com/blandfrd


  • Divernet Divernet
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    + Detachable from its hose
    + Reliable algorithm
    + You should never run out of air!



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    - Everyone knows if you are low on air
    - Needs three buttons!