That's not to say I'm clever, just that the Suunto HelO2 is exceptionally easy to understand.
Someone on an Internet forum said that this computer was intended for mainstream trimix diving. That's an oxymoron, as there are relatively few people actually using trimix, but I knew what he meant.
Just to give you an idea, the ex-boss of Suunto told me that, although Suunto is the market leader, total annual production of all its diving products equated to just five minutes production at Nokia. He now works for Nokia.
No degree in computer science is needed with the HelO2. Its designed to be simple, and this goes hand-in-hand with fewer user errors, which must be a good thing.
Internet forums can be useful, so long as you are aware that not all the information posted is accurate. A lot of it is twittering.
Another so-called informed poster said that a well-known but un-named diving writer had stated that Bruce Wienke and his Reduced Gradient Bubble Model (RGBM) had nothing to do with Suunto computers, and that Suunto had simply applied the name to its products.
Now I have met Mr Wienke, and he is no shrinking violet. He would have kicked up more than a fuss had this been true, but the guys at Suunto were so irritated by such allegations that they have included a video-clip of BW on the HelO2 website, talking about this very thing. So, yes, the HelO2 really does employ a Wienke RGBM algorithm.
Naturally, its arrival has been the subject of further twittering on the part of those who have invested in more expensive bespoke trimix computers.
No way would they receive with open arms an instrument that costs half of what theirs cost, but if youre moving on from nitrox diving and are used to having a Suunto computer manage your decompression, it would be a logical move to progress to one of these.
True its only for traditional open-circuit use, but if you move to a closed-circuit rebreather, dont all the CE-rated CCRs come with their own integrated computers anyway
Why would Suunto waste time trying to enter this market, when its already well catered for
I can foresee a lot of Suunto users progressing to a HelO2 from a Vytec or Vyper 2, and they will be able to integrate one of the gases they use (the bottom gas, say) with the same transmitter they probably already own.
Suunto kindly lent me a beta version before production models were available, and as usual in such cases there was no instruction manual.
To find out what the unit did, I took it on some simulated mixed-gas dives while diving off Sudan, using air/nitrox and actually managing my dive with a D6/D9.
It was a good way to learn what the buttons did. In the event, no manual was needed.

Algorithm
The Suunto RGBM combined continuous decompression algorithm is used; it all sounds very familiar, and it is.
The only difference is that when it comes to setting the mix, instead of putting in the nitrox mix via an oxygen percentage, you have the option to enter a helium percentage too - and deep-stops are not optional.
Settings
The four buttons will feel very familiar to any current Suunto computer-user. However, for mixed-gas use there is the option to enter up to eight different mixes for a single dive. You dont have to use that many, of course.
Oxygen content varies from 8 to 100%, while helium settings range up to 92%. Chosen mixes are locked in for the dive, but you can switch between them, provided your depth does not disallow this.
As usual, you can set one of three different altitudes, and the personal caution settings range through zero from minus 2 to plus 2. Sample rates can be set in four stages, from every 10 seconds to every minute.
Anyone who knows how to set a nitrox mix on a Suunto computer can set the mixes on the HelO2. Theres just an extra layer of sub-menu.
I cant think of a trimix computer thats easier.

Display Legibility
The use of a dot-matrix display makes this computer at least as legible as any other Suunto model. You can switch from gas-mix display to gas-pressure display (if you have the optional transmitter fitted to that particular first stage) at the press of a button.
The backlight was not particularly bright, but would have been good enough. Unfortunately I could never get it to switch on at depth on the beta HelO2 I had been loaned.

In the Water
It proved exceptionally easy to scroll between pre-planned mixes and confirm the one chosen to match the gas being breathed, as and when required. I was actually breathing from a single mix of nitrox, so was limited to 40m with my test dives, but I used a mix of 19/55 for a bottom gas, air as a travel gas and Nitrox 50
for decompressing once I got shallower than 18m (while actually monitoring my real decompression with another nitrox computer).
You dont have to be a whizz-kid to understand this trimix computer and, of course, you can still use it as a straight or multiple-mix nitrox computer should that seem to be more appropriate.

Planning
The HelO2 works in conjunction with Dive Manager software, which takes into account what you actually did on the previous dive, rather than what you expected to do.
It can then download your plan back to the dive computer.

COMPARABLE COMPUTERS TO CONSIDER:
VR Technologies VR3 £839
Dive Rite Nitek X £1490

SPECS
PRICE £695 (plus £260 for the transmitter)
FAST ASCENT WARNING Yes
NORMAL IN-WATER DISPLAY Depth, remaining air-time, remaining no-stop time, tank pressure, dive time, ascent-rate, oxygen exposure.
ALTERNATE DISPLAYS Nitrox mix, set ppO2, OLF, maximum depth, current time, water temperature.
DECO INFO Full
MAX DEPTH Deco computed to 120m
DIVE PLANNING Yes (including dive simulation)
LOGBOOK Recording interval adjustable with up to 42 hours of diving recorded
PC INTERFACE Suunto Dive Manager
MODES Nitrox/Trimix/Gauge
BATTERY User-replaceable CR2450 lithium
CONTACT www.suunto.com/diving
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%