SCUBAPRO’S LONG-AWAITED COMPUTER-WATCH, the Meridian, finally arrived at my door – but it was a pre-production model without an instruction manual.
Andy from Scubapro said he was sure that I’d figure it out, and I thought I had until I first got into the water with it and found that I really couldn’t understand what it was trying to tell me. Then I realised that I’d strapped it the wrong way up on my wrist. Doh!
As a watch, it’s quite brutal-looking, like something they’d issue to a tank commander.
Its four buttons are big and stand up loud and proud, with a good throw and strong return springs. It’s constructed from 316 stainless-steel.
As is common with most computer-watches, it requires an extension strap to fit around the wrist of a drysuit.

Setting Up
As promised, setting up the Meridian proved to be a doddle, although I had to get my head round the fact that “ScubA2G” on the display stood for two-gas scuba settings.
It uses the same algorithm as the Galileo or the Aladin Tec 2G, so if you understand either of those, you’re almost there.
The Meridian uses a modified Buhlmann ZH-8L predictive multi-gas algorithm. You can set one of five micro-bubble levels (MbL) that come into play during repeat dives, or you can choose to switch off that function altogether, so that it performs just like a good old-fashioned Aladin Pro.
Without an instruction manual to confirm things, I found that I could only set a nitrox percentage for Gas One from 21 to 31% O2, with a PO2 maximum from 1.45 to 1.6 bar (or even turn that latter function off).
I could also set a separate deco gas in the same way with a choice of mixes of 31 to 100% and a PO2 range of 1.0 to 1.6.
These settings may not be as wide-ranging as I had expected, but they covered most eventualities.
Text messages back to Andy at Scubapro in the UK confirmed that it was a very early pre-production model that had been sent to me, and that I should have been able to set the nitrox mix from 21 to 100% on both mixes, together with a max PO2 setting from 1.2 to 1.6bar. It’s a pity I didn’t get the final computer-watch that you’ll find in the shops.
Nevertheless, it was perfect for someone like me who often dives to leisure depths with the added safety of a richer nitrox for the journey back up. I just needed to switch the computer gases set when I switched tanks.
I could also set predetermined maximum depth and dive-time alarms.
The Meridian can be used with a heart-rate monitor such as the one that comes with the Galileo, but the battery in my monitor died and I never replaced it – or missed it, either.
You can set the 5m safety-stop from 0 to 5 minutes, turn off the activation by contact with water (why would you) and, of course, choose between metric and imperial measurements.
The Meridian can also be used in gauge mode or set for breath-hold diving, when the sampling rate is much more frequent.

In The Water
Once strapped the right way up on my wrist, the display was easy to understand. It gives all the information you need: depth, maximum depth, dive time, remaining no-stop time, deco-stops depths and total ascent time.
When it asked for a level stop to reduce micro-bubble level risks and I chose to miss it, it simply reverted to a less cautious micro-bubble level setting.
It also gives the user the chance to use PDIS. This is Scubapro’s own version of deep stops – “profile dependent intermediate stops”.
The computer calculates a unique PDIS for every dive, or you can turn it off.
When it came to gas-switching on ascent, it was just a question of pushing the mode button for a second or so and confirming the switch with a second push.
However, at any given moment the Meridian doesn’t appear to tell you whether you are on your main gas or deco gas, and because I was playing, rather than using it seriously, I had both set to the mix of the single tank I was using.
This meant that I had to switch back and forth several times to confirm that I’d switched.
The ascent rate is monitored and displayed as a percentage of the suggested maximum at that particular depth. It tells you when to make a safety stop, and the time is counted down in both minutes and seconds. This is comforting, because whole numbers can seem so long when you’re waiting close to the surface.

Now that Suunto offers with all its computer- watches the option of wireless gas integration with the main gas supply, this Scubapro watch fills a hole in that it’s a simpler type of device.
It does what most divers want. Just be sure that it does what you want before you buy it.

Comparable computer-watches:
Mares Matrix, £415
Suunto D4i, £395 (without transmitter)
Suunto D6i, £625 (without transmitter)

PRICE from £399
NITROX Two mixes per dive, 21-100%
ALGORITHM Buhlmann ZH-L8 with MB-levels and PDIS
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