It all started with the camel and the donkey. Man found that he needed to strike both if they were to obey his will.
We’ve been striking things ever since.
I remember my Uncle Albert battling with an indoor aerial when he first got a black and white television set. After struggling for some time with a snow-covered picture or one that completely broke up, he resorted to hitting the TV screen.
Half a century later, many of us have been guilty of tossing the remote control across the room in frustration.
If it’s in our nature to bash things to get them to work, Liquivision has borne this human trait in mind when designing its computers. The Kaon is the latest of these to come my way.
I was less daunted by it than I might have been, because I had only recently been using its big brother, the Xeo, and found it easy – once I had overcome my prejudice against the tap-switch idea.

The Interface
In fact the tap-switch is completely intuitive. It seems I’m a natural when it comes to giving anything a slapping. It has no buttons, for goodness sake!
Three sharp taps (you can adjust this to five if you’re that way inclined) startle the unit into life. You simply tap the menu list up or down and across, then up and down. It’s so simple, anyone can do it.
I love the instructions, however. Designed for Americans, the method of tapping is described along the same lines as “this coffee may be hot”.
You will need to familiarise yourself with the method. The manufacturer calls it “the one-beer learning curve”. You will also need a sofa for this!
You can even adjust the computer’s sensitivity to taps. Cave- and wreck-divers might prefer a system of hard knocks, so that they aren’t adversely affected if the instrument gets a tap from an obstruction in the dark.
There are loads of options, including choosing the colours that you prefer for various parts of the OLED display.
This is a leisure-diving nitrox computer, but it can be used with up to three mixes during one dive if you wish, so it’s good for that once-in-a-lifetime trip to Bikini Atoll or Truk Lagoon.
It can also be used in Gauge mode for those trimix dives.
Once you’ve tapped in your PIN number to get the Kaon up and running for the first time, you need to tell it which of a selection of batteries you have fitted it with. Then it’s date and time and so on.
In Recreational mode (one nitrox mix) it can be set between 21 and 40% O2, while in Tec mode this range is extended to 100% O2 for deco gas three.

The Kaon uses the popular Buhlmann ZH-L16C algorithm with two levels of conservatism possible in Tec mode and the highest level set by default when it’s in Rec mode.
That’s equivalent to added gradient factors of 100/100, 30/85 and 30/75. If you don’t understand gradient factors, leave it at Conservatism 0.
The instructions warn that you should base your dive on the gas you have remaining and not the no-stop time you have left. Remember, this is written as if for the sort of people who think roadside “Deer Crossing” signs should be moved to where it’s safer for deer to cross.
There are several visual alarms that can be set, including maximum depth, dive time, ascent rate and descent rate. The display will start by blinking and eventually invert black on a coloured background.
You can opt to silence the audible alarm completely, or once you’ve heard it.
In Planning mode, you have the opportunity to enter quite complex dives that are either square-profile or multi-level.

In The Water
The Kaon detects the pressure change to turn itself on, but it’s a good idea to turn it on yourself before a dive, just to check the state of the battery indicator and let the computer sample the air pressure.
The colourful display is loud and proud, with the most important data in large figures.
You can choose the colour of all parts of the display in the setting-up preferences. There’s a choice of words, or some alternatives in the form of icons, if you prefer.
You can adjust the brightness and set it to auto-dim for when you go deep, enter a dark place or use it at night. The display refreshes often and you might notice it flash off for a moment. You can set this refresh mode to faster, but it will shorten the life of the battery.
The Kaon tells you all you need to know: depth, dive time, no-deco time, time to surface, first stop depth, stop time, temperature, the nitrox mix it is set for and so on.
In Tec mode, not only can you switch between the gases you breathe but if for some reason you lose a gas you can mark it as such.
This will stop the Kaon assuming that you might have that gas available later, and including its use in total ascent times.
If you no-stop dive in one-gas mode, it will prompt you to make a safety stop for three minutes at 5m. The Kaon runs at the equivalent of a gradient 30/75 factor, which is its most cautious setting. A PO2 alarm is triggered if you go beyond the maximum operating depth (MOD) of the nitrox for which it is set.
In Multiple Nitrox Gas mode (with up to threes mixes set) all the options are open. It does not automatically switch gas mix but it will flash a suggestion if it detects that you may have a more appropriate mix set to breathe at a particular depth on the way up.
I lent the Kaon to TA Colonel David Moggs to use alongside his own computer on a Red Sea trip aboard Blue Pearl. He had forgotten that army maxim of the five Ps, and had no spare battery for his own computer, which left a question mark hanging over its ability to manage all the dives he would do that week.
He seemed to enjoy using the Kaon, though I did finally manage to get it back off him before we returned to Blighty.
An OLED display really comes into its own on a night dive. It’s obviously a delight to read its highly colourful illuminated display.

After Surfacing
Immediately after surfacing, the Kaon displays information about your last dive, including surface time, last depth and duration.
You can download your dives either onto a PC or a Mac using an interface sold separately. I like the Mac method, because you don’t need to download drivers. You download firmware updates from the Internet in the same way.
Changing the battery merely calls for cleanliness and a bit of care with the sealing
O-ring. Finally, if you dislike the long strap provided, you can exchange it for a couple
of bungee cords.
If I have a criticism, it’s that Liquivision really needs to employ the services of a product-case designer. All that magic technology is housed inside a unit that looks as if it was designed not on the back of a fag-packet but by copying the fag-packet itself.
This really is an unimaginative and featureless rectangular lump of plastic. Its strength lies in what it does, rather than in any shop-counter appeal.

Scubapro Galileo Sol (without transmitter), £599
Mares Icon HD (with transmitter), £670
Oceanic OCS, £445

PRICE £620
DISPLAY Full-colour OLED
NITROX MIXES 21-40% (Rec) and 21-100% in Tec mode (up to three mixes per dive)
BATTERY User-replaceable lithium 3.6V (rechargeable and non-rechargeable options)
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%