Decompression limits and long safety stops

[Esprise Me]

If you did all the stops your computer told you to do, chances are you won't suffer DCS this time. But I would encourage you to rest, drink water, pay attention to how you feel, and seek medical attention if anything feels off. It sounds like you might be a little unsure about what your computer was telling you, which might mean you didn't actually do all the stops.

 

[Jcp2]

Second dive was mostly at depth

What size were your cylinders, what were the pressure before and after this dive? That’s a long time for a single aluminum tank for a novice diver.

 

[Ahmedben]

It is a 12 litter steel cylinder. Started with 200 and after deco stop ended with 30. The one while dive was 57 includes the 11 minutes safety stop.. and I am not super novice. I am an AOW but **** happens. And didn’t dive for a while.

What size were your cylinders, what were the pressure before and after this dive? That’s a long time for a single aluminum tank for a novice diver.

What size were your cylinders, what were the pressure before and after this dive? That’s a long time for a single aluminum tank for a novice diver.

 

[Alaskan Scuba Dude]

No mention of Surface Interval. You probably activated your Safety Stop twice by moving out of depth.

 

[Esprise Me]

@Alaskan Scuba Dude, post #5 said the SI was 1 hour and 50 minutes.

@Ahmedben, when you say the second dive was "mostly at depth," do you mean it was mostly at a depth of close to 33 meters, or just that most of the dive wasn't spent on safety/deco stops? The first one is what is usually meant by the question, but unless I've screwed up the math, you'd have to have a pretty impressive SAC rate to spend anywhere near 46 minutes at anywhere near 33m and only use 170 bar.

Also, I'm not a tech diver, but for those in the thread who are: wouldn't that kind of profile on air incur a lot more than 11 minutes of deco? My Teric's deco planner says that after 45 minutes at 33m/100 feet on air, I'd need 4 stops totaling 49 minutes, and that's with no residual nitrogen. Obviously coming up even just a little helps a lot in that regard, but even if I drop it down to a max depth of 80 feet (24m) for 45 minutes, I get 3 stops totaling 24 minutes. I'm thinking most of the dive had to be spent at a much shallower depth.

 

[scubadada]

Your Cressi computer, running Cressi RGBM would be considered conservative. It is possible that your DM and other divers were diving computers with more liberal decompression algorithms and/or diving nitrox. Other than reviewing the operating procedure for your computer, you might pursue nitrox certification, to extend your bottom time.

 

[Aquaviolator]

Was your dive computer set to match the gas that was in the tank you were diving? Also knowing what the dive plan was and what you actually dove can be totally different if you do not pay attention. Curious to know if you were the only one in the group with this incident. Good decision to not blow off the extra minutes like even some "experienced" divers would do.

 

[Ahmedben]

Was your dive computer set to match the gas that was in the tank you were diving? Also knowing what the dive plan was and what you actually dove can be totally different if you do not pay attention. Curious to know if you were the only one in the group with this incident. Good decision to not blow off the extra minutes like even some "experienced" divers would do.

Yes, it does match the gas. Yeah, mine was the only one that have a long deco time and all of us were diving almost in the same depth

 

[Ahmedben]

Your Cressi computer, running Cressi RGBM would be considered conservative. It is possible that your DM and other divers were diving computers with more liberal decompression algorithms and/or diving nitrox. Other than reviewing the operating procedure for your computer, you might pursue nitrox certification, to extend your bottom time.

Thanks, a good point, never though that the difference in algorithm can lead to big difference between them.

 

[Blackcrusader]

Thanks, a good point, never though that the difference in algorithm can lead to big difference between them.

Not just the algorithm but also the settings as most computers have 3 basic settings from very conservative to more liberal.
I have done dives where my DC has more than 10 minutes to NDL when other divers would be in deco already.

As you note you are responsible to monitor your own DC not your dive buddies or the guide on a dive. Perhaps you could upload the two dive logs from your computer to this thread so that others can see the dive logs.