Decompression limits and long safety stops

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i was wondering about the Ascent rate was above 12m/minute recommended values 30ft/mn
Current recommendations are a maximum of 9-10 m/min (30 ft/min == 9.1 m/min). The most danger lies in the final ascent, and it's not uncommon to target a rate of 3 m/min in the last 5-6 m on decompression dives. I'll do the same on NDL dives, because why not?
 
Does the red flag next to the dive number in your log indicate a deco dive? If that is the case, it appears that dives 33 and 42 also had deco obligations.
Yes, the red icon means deco dive. Distressing that it is happening with no knowledge about it.
Even more distressing are the red dots on the profile; these mean the max ascent rate (12m/min) was violated. Bad practice.
 
Yes, the red icon means deco dive. Distressing that it is happening with no knowledge about it.
Even more distressing are the red dots on the profile; these mean the max ascent rate (12m/min) was violated. Bad practice.
For dive 38, the final ascent from about 75 ft to the stop appears to have been over about 6 min. an average of 10-11 ft/min.
 
Even more distressing are the red dots on the profile; these mean the max ascent rate (12m/min) was violated. Bad practice.
The computer may be sensitive to arm motions. The first (dive 37) is especially telling. The highest rate in that dive seems to be at about 0:22, for which I would estimate a rate of about 7 or 8 m/min. 0:28 is flagged, but is actually a descent. 0:29 is flagged but is a constant depth.
 
helo,
I have bought the IR connector to my PC and I hav downloaded the dive data, both dives were on deco, I would like to hear feed back from a professional people about what could be improved on those dives and mistakes have encountered.
I think you heard much of what you should do. You definitely were in deco, on both dives, though it cleared early on the first one. For the second dive, it almost doesn't appear that it cleared at all, but I'm not sure if we are seeing the whole graph on that second one, as it also appears that you never surfaced, which I know can't be right.

I'm not real familiar with your computer, but it should have some type of planning function. Learn how to use this. It will at least let you know if something doesn't seem right about the dive plan. The plan function for the 2nd dive could have been reviewed during the surface interval, and it should have alerted you that you do not have 57 minutes of NDL time available. That should have at least prompted some questions before that 2nd dive.
 
I see all of the red dots (!) but when I take his ascent starting depth and the time from the graph it does not appear he busted his max ascent rate?

James
 
Just following up on this...

You did two fairly serious deco dives without deco training or equipment. I want to take a minute to explain the importance of this.

A very general and simplistic way of explaining the difference between a deco dive and an NDL dive is that in an NDL dive, if you encounter an emergency, you should be able to go to the surface immediately, but in a deco dive you can't. That is because of the likelihood of decompression sickness. Decompression divers carry gear (including redundant breathing gases) and have training that allow them to solve problems without going to the surface. In your case, if you had had some sort of an emergency (like a free flow) that forced you to the surface, you would have likely suffered DCS. It could even have been fatal.
Hi MrBlenny, yeah I totally agree with you. Luckily no emergencies happened
 
I see all of the red dots (!) but when I take his ascent starting depth and the time from the graph it does not appear he busted his max ascent rate?

Cressis are twitchy. I have my profiles peppered with "momentary ascent rate warnings" (they come up as yellow triangles in subsurface) where I know there was no audible alarm. Those red dots mean nothing.

@Ahmedben download subsurface, import your logs, and see what it says about your deco at different GF-Hi settings. I expect you'll see the similar ceiling on the first dive at GF 75-ish, not so sure about the second.
 
@Ahmedben thank you for sharing your experience here, and it's good to see that you are making the effort to understand what happened, and improve as a diver. You've already gotten plenty of analysis and advice about the dives as reported from smarter people than me, so I won't try to give any more at this time.

But looking at the dive log photo, I did notice something strange. The screenshot is a little grainy and hard to read, but it appears that your dive has 3 logs from that date, not just 2:
- dive 36 at 11:35m to 28.7m for 6 minutes
- dive 37 at 11:45 to 36.4m for 30 minutes
- dive 48 a4 14:12 to 33.2m for 56 minutes

Screen Shot 2022-08-08 at 4.45.57 PM.png


From the logs, it appears that for dive 36, you descended down to 28m, briefly looked around, maybe encountered a problem, and then returned to the surface. You solved whatever the problem was at the surface, and then descended once again (dive #37 to 36m), where you eventually bumped into the deco obligation, as discussed upthread.

Maybe I have read that wrong. But if I'm reading this right, two things come to mind:

1) If the computer thinks that this is two separate dives, then you would have had a very brief (maybe 3-4 minute) surface interval between them. It sounds like the Cressi algorithm penalizes for a number of things, I wonder if a tiny dive, followed by a tiny SI, followed by a regular dive is one of these circumstances? @scubadada may have some insight here, since he seems to understand the ins and outs of the RGBM algorithm well. By the way, if there is such a penalty here, that may partly explain the gap between what your computer said (mandatory deco stop) and what others on the dive said (safety stop only).

2) From the Cressi dive software, is it possible to merge dives #36 and #37 into one dive? If so, this may give you a clearer picture of the entire dive. Also, you may want to configure the end-of-dive delay on your dive computer, if Cressi supports this -- I personally have mine set to 10 minutes.
 
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