The numbers on the D5 are actually quite large, so the information I had been struggling to read were the functions to which these figures related, such as whether I was still within my NDL.
The D5’s custom functions let you change the screen layout to suit your preferences as to which and where information is presented. The MIP colour screen is always illuminated by a powerful, adjustable-intensity LED, and I loved this!
Parts of NEMO, such as the connecting tunnel between the two deep pits, are quite dark, and the D5 shone brightly there.
On many dives it can be tricky to press a backlight button without having to rearrange your grip on a shotline, torch, reel or camera, and shining a torch on a computer screen with your other hand is a pain, because unless you get the angle just right, glare can render the numbers unreadable.
With all the deco, navigation and, using the POD, gas info beautifully back-lit, seeing all your dive status at a glance in the dark is a real bonus.
The first dive was about getting to know the D5’s basic NDL display. My read-outs had been pre-set and, I guess, will be the default ones on the production unit. Key information such as current depth and remaining no-decompression time are very clear, with less important info, such as maximum depth attained and temperature, shown more discreetly.
There is also a graphic display, but I find that reading numbers forces me to concentrate and actually retain the information. Graphics are for smart people, like divEr readers.
You can pre-set audible alarms to beep at a given depth and time. I wore a hood to test these, but failed to hear them through it. However, as I crossed the depth threshold, a depth alarm was displayed on a strapline across the face of the D5, and remained there until I had acknowledged that I’d seen it by pressing a button.
I tested the ascent-rate audible alarm by ascending quickly but, again, couldn’t hear the beep, although the graphic warning was very prominent.
The trouble with most dive instruments is that they’re passive – if you don’t look at them, there’s not much they can do to tell you how to stay safe.
I remember unintentionally straying into deco when I was at 12m shooting pictures, and plenty of divers have lost track of time, depth and air through inattention. So I was very interested in the Suunto D5’s unique selling point – a vibrating alarm.
Back on the surface, I spent some time going through the D5 menus, including how to set this alarm. The D5 uses three push-buttons to access the menus. The centre one is basically a select button. A simple short or long press enters or exits the menu. The upper and lower buttons scroll up and down to access functions. It’s a very straightforward, intuitive operation, and even I could read the displays easily.
Among the functions I selected were high altitude and maximum conservatism because, on the next dive, I wanted to see the full-on deco read-out without actually going into decompression myself.
Back at 33m, it wasn’t long before the unit asked for stops. The vibration alarm was sustained and unmissable, and I consider this a fantastic safety feature.
Here’s why. Years ago, a good friend and very competent diver made the same mistake I had. He was photographing a clownfish off the stern of the Carnatic some 30m down. He had checked his NDL and felt he had plenty of time remaining. When he next looked, he had an eight-minute decompression stop on the go.
From that depth, on a single, underfilled 12-litre, having enough air for decompressing can become an issue, the more so if the situation is compounded by being slow to begin your ascent, swimming against current or needing to share air. If you aren’t prepared for a decompression dive, it’s not good to be overtaken by mandatory stops.
The vibration alarm, a bit like a pilot’s stall warning stick shaker, should be unmissable. Begin your ascent immediately and, chances are, the stop will clear before you reach it.
However, I would have liked to test it with the D5 worn over a suit rather than a bare wrist.
Once into deco, the information needed to manage it is neatly displayed. If you’re linked to your gas supply using the POD, you can see an estimate of how long your gas will last. You can see your TAT (total ascent time) and gas duration and ensure that there’s enough breathing gas to cover it.
I’m casual about dives with up to 20 minutes of stops so, if I’m having a good dive, these features let me decide how far I want to push things. Along with TAT, the D5 indicates your ceiling, the optimum depth for decompressing, and works its way down, starting at 3m.
It also has a deep-stop option that, even on no-stop dives, will ask for a brief stop at around half the deepest depth attained.
On both NEMO dives, this was at around 16m. If you don’t care for deep-stop theory, you can turn it off. Decompression and safety-stop time is clearly counted down once you’re in the correct depth zone.
There are the usual visual and audible alarms if you rise above the ceiling.
The electronic compass has an easy-to-see degree scale set around the D5’s perimeter. You can also preset your heading, helping you to navigate back to your exit-point, for example.
The ability to customise displays might well help when using the compass, as a lot of information can be presented at once, which you might want to tame.
Suunto made a great deal of the D5’s strap range, as it’s likely to be worn as a dress watch.
For diving, a Zulu strap offers similar security to a NATO strap, passing through both pins to prevent the loss of the D5 and all that dive-management information should a pin break.
For those with huge wrists and thick dive-suits, extension straps are offered. The range of strap and casing colours should make it easy to keep track of your unit if your buddy also owns one.