What really gets my blood pressure running on repetitive dives is the D6 is way too conservative for repetitive diving. Now firstly, you ask, why are you using a VR3 for standard recreational diving, why not I say, not every dive needs to be a mixed gas decompression stop dive with multiple gas switches. You have the computer for such dives but you complete plenty of standard dives too. If you are diving deep wrecks then that is what is required, if you are diving reefs on your holiday, why switch to another computer?
However, with the D6 as a back-up computer, you seem to have a hell of a lot of hang time while your specifically designed decompression computer is deco free. On one recent repetitive dive, it was the fourth dive of the day, the VR3 indicated 27 mins of no-decompression time remaining, your D6 is just going into deco but you keep going, you check your SPG and have ample gas remaining, hell, you are not even at your turn pressure yet.
The dive is well under 30 minutes duration, yet you are forced to ascend to a shallower depth, you are not seeing what you want on this expensive overseas dive trip and you are less than impressed. The D6 is hammering you, already you have 12 minutes of hang time and three quarters of a cylinder of gas remaining. Not that 12 minutes is an issue because you are really deco free and could ascend directly to the surface - not that you would. No one else on the dive has a pseudo decompression ceiling despite diving the exact same profiles, they are not diving Suunto.
You did two dives in the morning with an hour surface interval, back for lunch and a three hour surface interval with a one hour surface interval between dives three and four. That's a fair bit of bottom time in a day with multi-level dives, relatively conservative profiles and extended shallow water stops for added safety. It is not over doing it to any great degree. The gas is air, unfortunately in 2014, not every facility offers nitrox although with a Suunto dive computer, nitrox or not, you are still penalised.
So you had to ascend to 8 metres to complete your dive whilst everyone else stays at depth, you are above the 2:1 pressure gradient threshold and off-gassing whilst monitoring the VR3 on your left wrist. I don't mount the two computers side by side anymore as the bulky aluminium bodied VR3 was scratching the bezel of the nice shiny D6, so that computer is mounted on the right wrist instead.
At 50 minutes, you glance to your right wrist to check how much you have reduced the deco time, it won't be too much as a 3 metre stop is required and you are too deep to off-load too much time, maybe a minute or two. You can imagine my surprise when I realised that not only have I not reduced any deco, the time has now blown out to over twenty minutes.
Ascending to 3.5 metres, you know you have to maintain the shallowest depth for the greatest pressure gradient and to maintain that depth, that means no looking around and enjoying the shallow sections of the reef, there is to be no depth changes. Any one who has deco to do on a Suunto knows 20 minutes is not really 20 minutes; time remaining is drawn out and even though you are monitoring time with your other computer, in the Suunto world, time stands still.
Exiting the water at the 80 minute mark, I had performed a 30 minute stop at 3 metres, about 25 minutes at 8 metres and the rest at 20 metres depth. The next day, my D6 remained my back-up, it was however tucked away in my bag on the boat but no where near the water, it was now no longer an in-water redundency.
I was also careful not to wear it in the shower that evening just in case I ended back in deco from the water pressure of the shower head and having to stand in a trickling shower for another 30 minutes to reduce the water pressure while my computer cleared.
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