SOME YEARS AGO while I was on a boat off Cocos Island, the news came through that 3000 US Marines at a location in Iraq were being replaced by 600 soldiers of the Black Watch.
American passengers on the boat were busy laughing at perceived British military inadequacy when an elderly South African gentleman quietly opined that 600 of such men would “be enough”.
This brings me neatly to another black watch, the new Suunto DX (pronounced D Ten), a watch that is intended to be enough for any diver.
Some members of the public are quite content to spend many thousands of pounds on something that does no more than tell the time. Witness those vast numbers wearing the Rolex Gold Crown, with starting prices way above five grand.
Don’t get me started on those exclusive brands such as Panerai and Blancpain.
Suunto has addressed this market with a watch that’s just as smart, but does a lot more than simply tell the time.
You can take it diving, when it becomes an air computer, or you can take it snorkelling, when it will record your freedives. Get further into diving, and it will compute your nitrox dives.
Become a bit more technical, and it will compute your nitrox dives for up to three mixes, so that you can switch tanks during a dive and spend as little time decompressing as possible.
Want to go deeper This computer-watch will manage trimix dives too, with up to eight primary mixes and seven secondary gases, any of which can have a helium content.
By now you may be asking, what makes the DX different from the D9tx Well, as many of you are aware, get into diving, get into deep diving and the path often leads you to the purchase of a closed-circuit rebreather.
The Suunto DX is the first computer-watch to have a closed-circuit mode, and as such will certainly outrank any Panerai wearer in the pub – or would it be the Emirates First Class lounge

A crucial difference between Suunto nitrox-only computers such as the D4i, D6i, Vyper Air and Cobra, and those designed for use also with helium mixes, such as the D9tx and the HelO2, is the algorithm.
The first group use a type of RGBM (Reduced Gradient Bubble Model) algorithm designed specifically for Suunto by Bruce Wienke, with the option of iterative deep stops.
The second use his technical-diving RGBM algorithm, which includes mandatory deep stops once the diver has gone deeper than 20m. These both attempt to take into account silent micro-bubbles, which might become significant during a second dive or series of dives, but they do it in slightly different ways.
Some people with the benefit of a little knowledge have criticised these algorithms for not being a full RGBM model.
The all-purpose DX employs a fusion of two algorithms. Use it at shallower diving depths and it performs like a leisure-diving computer, but with the technical-diving RGBM.
Go deeper and it switches over to the algorithm that the marvellous Mr Wienke has specifically designed for the job, now with the full RGBM.
It’s not a sudden switch, however. It gradually slides from one to the other, so that the switch is hardly noticeable. They call it the “Suunto Fused Algorithm”.
In use, you might notice a displayed deep stop disappear for a short time when the DX is changing from the first algorithm to the mandatory deep-stops of the second, but that’s all.
You can set two levels above normal for added conservatism or, should you so wish, you can set two levels below normal to make the computer more aggressive in its deco calculations. I left it at zero.
For open-circuit mixed-gas use, you can set up to eight primary gases and seven secondary gas mixes. Of course, you can opt for 0% helium and use it simply with nitrox.

Closed-Circuit Mode
Nearly all modern eCCR units now come with their own on-board decompression computers, so the DX is worn simply as redundant back-up.
It can also be used as a primary computer for those with the older classic versions of rebreathers. However, in the former and probably more common case, it is important that it is set for the same diving parameters as the CCR’s main unit, and there are all the pre-settings that allow you to do that.
You can preset the low and high set-points and the depths at which they automatically switch on the way down and on the way back up. You can preset a choice of three diluent mixes. You can preset up to eight open-circuit bail-out gases and seven secondary gas mixes.
When changing gases under water, you just work your way through the menu until you find what you want, and confirm it with a long push on the bottom-right button. It’s all very familiar to anyone with previous Suunto experience.
APD Vision users will also find that it ties in nicely with deco and ascent times calculated by your onboard computer, except that it might ask for an extra minute’s stop somewhere halfway between your deepest depth and the surface.
For those of us busy doing other things while we’re diving, the timer alarm proves quite useful.
You can set it to remind you to get the hell out of there when you might otherwise have become engrossed in some task.
There’s also a depth alarm, and I know of one test diver in 2012 who made many dives with a prototype and always had this set at 50m, just to remind him that he should have switched to trimix by this point during a descent.
Of course, I can’t tell you who that was, because he was sworn to secrecy at the time.

Gas Integration
Not really intended for use with rebreathers, with which gas consumption might be less significant, the DX still has the facility to integrate wirelessly with a transmitter fitted to the first stage of a regulator.
That is only for one gas, so it is intended to be used for less complex dive plans.
The latest Suunto transmitter has a glowing LED that tells you that it’s working.
This is helpful when your transmitter battery might be dead but your computer is indicating that it’s picking up a signal – presumably from someone else using the same channel for their computer while sitting nearby on the aft deck of a dive-boat.
It will be interesting to see whether Suunto can adapt this technology to wirelessly integrate ongoing PO2 levels in future, rather than resorting to a Fischer connection, as all other integrated CCR computers do.

Suunto is the Finnish word for “direction”, and direction-finding solutions was how the company originated.
The Suunto electronic compass in the DX is now calibrated by rotating the wrist, rather than by the user rotating his or her whole person in a circle.
You can use it to time out after one minute or up to 20 minutes, something that will prove useful for those of us who have been lost at sea in a small boat, and the cox’n unexpectedly asks whether anyone has a compass.
This has happened to me, and a compass that times out after a short duration in such situations only adds to the tension.

The DX is Suunto’s first foray into the world of closed-circuit rebreathers.
Critics might say that the display of a computer-watch is too small for use at the deep dark depths encountered by technical divers, and for some that might be correct.
We will have to wait to see if Suunto can come up with a processor suitable for use with this software that will work in something bigger, similar to the HelO2. We may have to wait a long time.
This said, I would like to remind those critics that there are divers who use rebreathers for relatively shallow dives, in order to get close to skittish wildlife such as scalloped hammerheads, and who are prepared to spend vast sums of money travelling to the places that enable them to do that. These are the people for whom the DX has appeal.
Of course, instead of those people like Harry Enfield’s character Loadsamoney who always asked “Haven’t you got something
more expensive”, this is also for those watch-buyers who might ask: “Haven’t you got anything more capable”
This is the watch that does everything – and you can even turn the diving functions off, so that it doesn’t confuse your time-checking while swimming off the beach outside your Caribbean retreat.


PRICE £995 with elastomer strap, £1195 with titanium bracelet; £250 optional gas-pressure transmitter
MODES Air/Freediving/Open-Circuit Nitrox & Trimix/Closed-Circuit Rebreather
COMPASS Tilt-free electronic
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%