Help needed analyzing a dive

[Dody]

Well don't buy a Shearwater Perdix if you are not interested in a thorough read of the manuals and learn the setups you can DIY and know what each thing means. I'm basically a recreational diver but that is no excuse for not knowing my own DC and its functions.

It is not about me. I love reading and I love science so I read, read and over read. However, I will not put myself in deco or fast ascend to learn how my DC works . I just want to help my friend who thinks that because I am a geek, I can answer anything

 

[scubadada]

Hi @Dody

You sure make some interesting posts to SB. I am not terribly familiar with the Aqua Lung i300C or its logging application. I am very familiar with another Pelagic Pressure Systems computer, the Oceanic VT3, and it older logging application. I assume that the switch from blue to red in the dive profile represents going from NDL into deco. The yellow vertical line likely represents fast ascent. It appears that your friend cleared the deco obligation prior to surfacing and, thus, avoided violation gauge mode.

Here is a log from my VT3. In this case, I went into deco, and cleared it several minutes before ascending. My logging app allows me to look at dive details. In this case I only had a maximum decompression obligation of 4 minutes, some of it cleared before making the stop.

My advice to your friend would be to understand his dive computer and be aware of what it is telling him. If he is able to access dive details, it is likely he can come to understand what happened on this particular dive. The fast ascent speaks for itself, good thing he controlled it prior to surfacing.

To be perfectly honest, this example frightens me with regard to the knowledge and behavior of some divers. More than occasionally, I am asked why I think someone's computer does not seem to be working normally. My most frequent answer is that your computer is in violation gauge mode because you missed a mandatory deco stop.

 

[Dody]

I hope this is not true. If you meet these divers, and they are not newbies, avoid them.
I am telling you. Most of the rec divers are not science oriented (orientated?) and switched off when it becomes a pain. My usual buddy who is my beloved wife, is like that. She is very smart, but not into science at all.


I did not understand any of these examples... what is a SAT counter? And what is the PLAN menu?

SAT is saturation or most precisely desaturation. On your DC, it is often in the same menu as the no fly counter.
The Plan menu on your DC is what you use to plan a dive. It gives you NDL by depth. The values are fixed for single dives. But if you do multiple dives, the values are supposed to be automatically updated taking into account the Nitrogen that you have already accumulated.

 

[Gareth J]

Most computers will allow you to put them in simulate mode.

You can then adjust the depth, the 'time' then runs fast, e.g. 1 minute every 10 seconds.
So you can then see the no-stop reduce, eventually, the computer will switch from no-stop to decompression stop required.
This will allow you to get familiar with the how the computer presents information.
You can change, the depth, doing it 'fast' will cause the fast ascent alarm to be activated.

This is a good way to get used to the computer and how it behaves.

 

[ginti]

SAT is saturation or most precisely desaturation. On your DC, it is often in the same menu as the no fly counter.
The Plan menu on your DC is what you use to plan a dive. It gives you NDL by depth. The values are fixed for single dives. But if you do multiple dives, the values are supposed to be automatically updated taking into account the Nitrogen that you have already accumulated.

In case it isn't clear, I don't use so much DC But this thing about the SAT counter sounds a bit weird, while can't say anything about the PLAN thing...

 

[Gareth J]

Some computers use extra information to modify the decompression information.

So aggressive factors, such as low temperature, sawtooth, short surface intervals, fast ascents, etc will modify the decompression penalty (shorten the no-stop time).

PLAN mode changes on different computers (in fact some of the new the computers no longer have plan modes built in - which is piss poor in my opinion).
Suunto had the basic plan, which would cycle through the no-stop times stepping through in 3m depth increments. This was based on the current tissue code. Plus on some a Plan mode, that allowed you to add additional surface information and manual adjust the planned dive profile (this allowed planing of decompression dives).

 

[Blackcrusader]

It is not about me. I love reading and I love science so I read, read and over read. However, I will not put myself in deco or fast ascend to learn how my DC works . I just want to help my friend who thinks that because I am a geek, I can answer anything

Well Dody I am only responsible for my own diving with whatever dive buddy I have on a dive. I don't much care what the other 99% do. Maybe your friend should join the forums and discover lots of "geeks" with far better knowledge than you or I to explain his dive log. As I am not familiar with his DC and unlike when I downloaded the manual for yours and read it I am not going to do the same in this thread lol.

Get your friend to read the threads at least.

 

[Dody]

Hi @Dody

You sure make some interesting posts to SB. I am not terribly familiar with the Aqua Lung i300C or its logging application. I am very familiar with another Pelagic Pressure Systems computer, the Oceanic VT3, and it older logging application. I assume that the switch from blue to red in the dive profile represents going from NDL into deco. The yellow vertical line likely represents fast ascent. It appears that your friend cleared the deco obligation prior to surfacing and, thus, avoided violation gauge mode.

Here is a log from my VT3. In this case, I went into deco, and cleared it several minutes before ascending. My logging app allows me to look at dive details. In this case I only had a maximum decompression obligation of 4 minutes, some of it cleared before making the stop.

View attachment 661108 View attachment 661109

View attachment 661110

My advice to your friend would be to understand his dive computer and be aware of what it is telling him. If he is able to access dive details, it is likely he can come to understand what happened on this particular dive. The fast ascent speaks for itself, good thing he controlled it prior to surfacing.

To be perfectly honest, this example frightens me with regard to the knowledge and behavior of some divers. More than occasionally, I am asked why I think someone's computer does not seem to be working normally. My most frequent answer is that your computer is in violation gauge mode because you missed a mandatory deco stop.

Geez, your ascent was steep, wasn't it? Maybe not. 44 ft in two minues (once again, it would good to have the seconds). But you were aware that you were in deco, right?

 

[ginti]

So aggressive factors, such as low temperature, sawtooth, short surface intervals, fast ascents, etc will modify the decompression penalty (shorten the no-stop time).

Low temperature, really?

Is there any science backing the mathematical models of these computers? Which computers are you talking about?

 

[Blackcrusader]

Hi @Dody

You sure make some interesting posts to SB.

Are we not entertained by Dody and his friends? I enjoy the threads he creates