Tuesday, 26 March 2013



Suuntos previous watch style dive computer was the Suunto D9tx this included a full technical diving algorithm to utilise trimix for open circuit divers.
Suunto have now replaced the D9tx with the Suunto DX (D10) and once again they are leading the way.  The Suunto DX is the world’s first watch style dive computer that can be used with closed circuit rebreathers. Will rebreathers like nitrox in the past revolutionise diving as we know it? Well for technical diving they already have. I’m often the only open circuit diver on board for technical dives.
Here is a link to my previous reviews about the Suunto HelO2 and the Suunto D9tx technical dive computers. This will give you background http://mikeclarkdiveblog.blogspot.co.uk/2011/09/suunto-d9tx-dive-computer-review_29.html.
The Suunto DX has 2 major new features over its predecessor as well as slight design and menu upgrades. As with its predecessors anybody who has used a Suunto dive computer will find the controls very familiar.
The Suunto DX is the world’s first watch sized dive computer that has the capability of working with closed circuit rebreathers.  It is simple and easy to do as long as you have the new technology on your wrist.
The user can set 3 closed circuit (CC) gases and 8 open circuit gases (OC).  This is completed through the Closed Circuit Rebreather mode in the Menu and choosing the appropriate sub menu. High and low set points can also be adjusted here. The Suunto DX is not physically attached to the rebreather so it requires to be synchronised prior to diving. These are the PO2 pressures while at the surface and while at depth.  The Low Set Point is likely to be set at 0.7PO2 and the high Set point will be set around 1.3PO2. Once this is completed the switch points from low to high require to be set at around 20 metres. On the actual descent the DX will switch automatically to the high set point at 20 metres. Likewise on the ascent the low switch will be set around 4.5 metres. On the ascent the DX will automatically revert to the low set point to enable the correct decompression mix for shallow water. This is very easy to complete on the dive computer itself. Once diving this makes things far simpler as there is no need to manually switch mixes throughout a dive as you would on open circuit.  This is an impressive first for Suunto as no other manufacturer can offer this product type.
Most rebreather units do come with their own integrated control units. Whilst the DX can easily be used as a primary CCR computer it is likely that in reality it will be used as a backup for the rebreathers own dedicated units.

The Suunto Fused reduced gradient bubble model (RGBM) is the new decompression algorithm created by Dr. Bruce Wienke for the Suunto DX. Dr. Wienke has been working with Suunto for over a decade perfecting a RGBM to maximise bottom times and minimise ascent times.  Dr. Wienke had been working at the Los Alamos Nuclear Laboratory on the ‘full’ RGBM. This development was targeting the needs of deep divers and military personnel carrying out difficult dives. The new Suunto Fused™ RGBM combines the benefits of Suunto’s Technical RGBM (as used in the Suunto HelO2 and the D9tx) and the ‘full’ RGBM, bringing the benefits of both to recreational divers and technical divers. In shallow water the Suunto DX uses the Technical RGBM. Once the diver descends below 30 metres a linear transition will take place and the computer will switch from the Technical RGBM to the Full RGBM. The depth of the switch is not immediate but gradual and the switch is determined by what gas mixes are being used and whether there is helium in the mix. The transition will happen between 30 and 45 metres. This optimises the algorithm to best suit the dive type.
The DX also offers gauge mode and I am happy to say that it also retains a dedicated air diving menu. This enables you to dive on air without having to reset all of your programmed open circuit Nitrox or trimix gases.
All the menus are fast and easy to navigate and it’s very similar to the D9tx but there have been a number of small upgrades. Alarm times can be set for week day’s only so no rude awakening at the weekend unless you are diving.
Another minor change from the D9tx which may have a big impact is the colour of the watch. Gone is the Gun Metal of the D9tx. The sleek new DX is all black and secret opps.  Yes you will feel like James bond with the Suunto DX on your wrist.

A great link for all the technical product details can be found here http://ns.suunto.com/pdf/Suunto_Dive_Fused_RGBM_brochure_EN.pdf

East coast weather has really hindered my test of this new dive computer. This is really unfortunate as i do prefer to test kit in water. deadlines for magazines have required me to publish as is but hopefully a follow up will be possible should i have time before the unit is returned.

Mike Clark

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