However, I remember another US technical-diving computer of many moons ago that used a tap-switch to excess and drove you crazy, because it needed so many specific taps for each function, and if you put it down carelessly, it counted that as another tap!
I’m pleased to say that the Canadian-made Liquivision Xeo uses finger-taps to each side of its casing that are relevant to the menus displayed.
Tapping the top moves you down and tapping the bottom moves you up, while tapping at the side enters the item.
The Xeo is also one of those technical diving computers that peels away menu after menu to set what seems like thousands of different parameters for either closed-circuit or traditional open-circuit scuba, and I felt a bit of a fraud merely using it for some single-tank nitrox diving.
I first took it on a trip to the Philippines’ Tubbataha Reefs, and couldn’t make head nor tail of how to use it successfully.
The manual comes on a CD, but I later got James at Sea & Sea, the importer, to print me out a copy.
The weighty tome soon arrived, and I’m glad I didn’t have to pay for the paper, but it made good bedtime reading. With its brightly coloured OLED display, the Xeo feels a bit like a computer game, and I spent many hours in bed playing with it.
In fact my wife was heard to say: “Will you put that bloody thing away and let me sleep!”
So, boned up on its thousands of functions, I took the Xeo diving again.
A word of clarification about the tap-switch.
Its default position is that you need to give it three quick taps to turn it on.
If you think that you are in too much danger of knocking it inadvertently, you can alter that to five quick taps in succession.
If you think you are likely to knock it against a hard surface while diving as many times as that, it’s not for you, but with that amount of finesse I worry that perhaps diving isn’t for you either!
You can also preset the tap sensitivity level. You soon get the hang of it, and there are no buttons to go ping and disappear off the side of the boat.

Arrgghh! There seem to be reams of alternative settings. One I discovered later than I would have liked is the display brightness.
You can also set the Xeo to automatically dim according to ambient light levels, which would have been very useful on a brightly lit Red Sea reef while descending into the gloom down a wall.
You can set this computer for up to 10 different gases in trimix mode, and in CCR mode (optional extra) you can preset fixed PO2 set-points.
The Xeo gives you the unique possibility to customise the display and, for example, you can choose to have times displayed in hours and minutes or simply minutes.
It uses a Buhlmann ZH-16C algorithm, and you can elect to set gradient factors in the deco settings section. Don’t do this unless you fully understand the consequences – I recommend that you look up the relevant explanations available on the Internet before doing this.
You can also set the maximum PO2 of the dive, maximum PO2 of your deco gas used, and maximum END (Equivalent Narcotic Depth).

The OLED Display
The organic light-emitting diode display can be read in total darkness and at a wide range of angles. Of course, it all comes in pretty colours, and I have to say that the photographs I took of the display on a dive don’t do justice to it.
It uses a unique ceramic pressure sensor, and because there is only the battery compartment cap that breaks the outer surface of the unit, which is rated for use to 200m, it promises to be extremely reliable.
Power is supplied by a user-changeable lithium ER1 6V battery.
The unit measures only 6.4 x 5.5 x 3.8cm, very compact for a technical-diving computer.
If I have a criticism, it is only that the keeper-loop on the strap went missing almost immediately.
There is however the option to replace the strap with bungee cord and the fixing points for that.

VRX OLED, £945
Shearwater Predator, £893

PRICE £778
OPTIONS CCR software, PC interface
ALGORITHM Buhlmann ZH-16C with optional gradient factors
BATTERY User-changeable
DIVER GUIDE width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100% width=100%