Question Suunto Computer Weirdness

[Knabe189]

Hello,
I'm trying to figure out if my Suunto Vyper has bit the dust. It seems to work okay on dives but when I upload them into my computer occasionally the second dive of the day reads much deeper than I actually went. Looking at the dive computer logs on the computer itself they depths are correct. That said, I've recently gotten into tech diving and on one of my first deco dives my Suunto tallied up 25 minutes of deco stop time while a shearwater I was also wearing gave me 6 minutes. Not only that but the suunto didn't seem to be counting down the deco time correctly either. When I cleared the shearwater I still had 24 minutes left on the Suunto. I know about the lawsuit around them and have already gotten my free PADI course out of them but figured I'd use the computer until it crapped. Am I at that point?

 

[Alaskan Scuba Dude]

Change it to gauge mode, if possible, and use it as a back up timer. Carry wetnotes or slate.

 

[Belzelbub]

Hello,
I'm trying to figure out if my Suunto Vyper has bit the dust. It seems to work okay on dives but when I upload them into my computer occasionally the second dive of the day reads much deeper than I actually went. Looking at the dive computer logs on the computer itself they depths are correct.

That's strange. If it's reading correctly on the dive, and the onboard log looks correct, then it sounds like something is getting messed up during the upload.

That said, I've recently gotten into tech diving and on one of my first deco dives my Suunto tallied up 25 minutes of deco stop time while a shearwater I was also wearing gave me 6 minutes. Not only that but the suunto didn't seem to be counting down the deco time correctly either. When I cleared the shearwater I still had 24 minutes left on the Suunto. I know about the lawsuit around them and have already gotten my free PADI course out of them but figured I'd use the computer until it crapped. Am I at that point?

I think you are at that point. Perhaps the Suunto is working as intended, but as you've found out doesn't match up well with the Buhlmann algorithm. A backup is still a good idea, but with differences like you've seen, the Suunto doesn't make a good backup to the Shearwater. I know it's easy for me to say, because it's not my money, but I'd pick up a Buhlmann based backup. Lots of computers are starting to offer Buhlmann now, so the list is growing.

 

[Zef]

Hello,
I'm trying to figure out if my Suunto Vyper has bit the dust. It seems to work okay on dives but when I upload them into my computer occasionally the second dive of the day reads much deeper than I actually went. Looking at the dive computer logs on the computer itself they depths are correct. That said, I've recently gotten into tech diving and on one of my first deco dives my Suunto tallied up 25 minutes of deco stop time while a shearwater I was also wearing gave me 6 minutes. Not only that but the suunto didn't seem to be counting down the deco time correctly either. When I cleared the shearwater I still had 24 minutes left on the Suunto. I know about the lawsuit around them and have already gotten my free PADI course out of them but figured I'd use the computer until it crapped. Am I at that point?

Suunto's algorithm is notoriously conservative, particularly compared to Shearwater...it would be helpful to see the dive profiles from each of your computers....for instance, at what depth(s) were your deco stops performed?

I believe the general consensus is that, since Suunto and Shearwater use two different algorithms that they are not considered a good match match to use one as backup for the other.

-Z

 

[boulderjohn]

Belzebub is correct. A Suunto makes a bad backup to Buhlmann. It makes a bad backup to any other algorithm in a tech dive, in fact. I got that lesson early in my tech diving.

More than a decade ago, I did a deep deco dive (260 feet) with a buddy who had been my trimix instructor. Back then, we were using VPM with a V-Planner based written ascent schedule. VPM is pretty close to the Suunto algorithm. My buddy had just bought a dive shop, and Suunto, trying to convince him to sell their computers, gave him their tech computer, the HelO2, as a demo. We planned our ascent with VPM, wrote the plans on our slate, and he brought the HelO2 along as a backup to our VPM plan. Well, by the time we were on maybe our 3rd deco stop, we were in trouble. Our VPM schedule told us to ascend to the next stop, but the Suunto wanted us to stay longer. We ended up following the Suunto, and our deco was far, far longer than planned. We were in the water something like 15 minutes longer than any of the other divers who had done the dive with us. (And they were pissed at how we had screwed up the schedule.)

A couple days later, we repeated the experience. My buddy had changed the Suunto settings as best he could to match VPM. Same problem. This time we went with the VPM schedule, and within what seemed a few minutes, the Suunto went into Error mode, which meant it was essentially in gauge mode and useless in guiding our deco.

VPM is pretty much out of favor these days, and current popular GFs for Buhlmann will have you ascend more quickly than VPM ever did. Suunto has not changed, so the discrepancy will be even greater. If you use the Suunto as a backup for Buhlmann, you MUST follow the Suunto instead, or it will go into gauge mode and no longer function as a dive computer.

 

[Belzelbub]

A couple days later, we repeated the experience. My buddy had changed the Suunto settings as best he could to match VPM. Same problem. This time we went with the VPM schedule, and within what seemed a few minutes, the Suunto went into Error mode, which meant it was essentially in gauge mode and useless in guiding our deco.

In water? That's just nuts. I can sort of understand the reasoning for gauge mode lockout after a dive, even if I don't like it. I can't, however, understand why a company would think that locking out in-water is a good idea.

 

[boulderjohn]

In water? That's just nuts. I can sort of understand the reasoning for gauge mode lockout after a dive, even if I don't like it. I can't, however, understand why a company would think that locking out in-water is a good idea.

About a decade ago I asked a Suunto rep about that and about 4-5 other Suunto characteristics I did not like. That rep had an answer for every one of them explaining why the Suunto feature was superior to the way other computers do it. It is better, for example, to have to input your altitude setting than to have it done automatically.. Once you put it in air mode, it is better to have to wait 24 hours before you can program it for nitrox rather than be able to change to nitrox on the next dive. If you aren't going to follow the computer's advice (for whatever reason) during a decompression ascent, it is better to have it shut down than to try to fit the ascent into an inferior algorithm. For some reason, none of those explanations come back to me now.

 

[NitroxSam]

The Vyper, IMO, is for rec diving only, conducted totally within the accepted rec diving times (not anywhere near deco), and depth limitations. Other than that, use it as a backup in gauge mode.

 

[dmaziuk]

I have it on good authority that you can plan a decompression dive in Suunto DM5 and the plan will work with the Vyper. You'd just have to stick with the Suunto algorithm, as John explained above.