Help needed analyzing a dive

[Dody]

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.

He is French like me and can't read English.

 

[Blackcrusader]

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?

Yes he wrote he went into deco.!!

 

[Gareth J]

{ @ginti Low temperature, really?

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

You should already account for low temperatures.
Low temperatures mean reduced circulation, reduced circulation means poor off gassing. This is a particular problem because you are generally colder (especially the extremities) at the end of a dive in comparison to the start.
So, you will have higher on gassing when you are warmer at the start of the dive, especially to the extremities.
You have to balance the extra decompression time with the increased risk of hyperthermia.

Its potentially more of a risk if you are using heated vests. Much better to use the vest towards the end of the dive, to ensure the battery isn't/doesn't go flat. Basically manage the battery.

 

[scubadada]

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.

The desaturation value has little to do with a single dive. It is the cumulative value of nitrogen loading based on a series of dives. It is not difficult to attain a desaturation value of greater than 24 hours after a long series of multiple dives per day. This is due to progressive loading of longer half life compartments. The very same thing can be seen in detail by examining the Shearwater tissue loading graph.

 

[Blackcrusader]

He is French like me and can't read English.

Is that why he cannot read his DC? It's also in English?

 

[Belzelbub]

@Dody @scubadada
What software are those profiles from? They both seem to display a deco obligation in the same way, but it’s not one that I’m familiar with. If I were to look at both of those profiles with no context, I would assume some sort of alarm, but wouldn’t immediately think of a deco warning.

I’m used to seeing the deco obligation displayed as a cored or grayed out portion of the top of the graph marking the ceiling.

 

[Dody]

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

Common. you guys are also here to educate us newbies, right? Is there a most rewarding occupation than teaching? Now, if my posts are out of line for a reason I ignore, please let me know because I am pretty sure that as my diving learning curve evolves, there will be more from peronal or third party experiences.

 

[Blackcrusader]

The desaturation value has little to do with a single dive. It is the cumulative value of nitrogen loading based on a series of dives. It is not difficult to attain a desaturation value of greater than 24 hours after a long series of multiple dives per day. This is due to progressive loading of longer half life compartments. The very same thing can be seen in detail by examining the Shearwater tissue loading graph.

As you know I often do 3 or 4 dives 10 - 12 days straight and my no fly is more than 24 hours on my Shearwater.

 

[Dody]

The desaturation value has little to do with a single dive. It is the cumulative value of nitrogen loading based on a series of dives. It is not difficult to attain a desaturation value of greater than 24 hours after a long series of multiple dives per day. This is due to progressive loading of longer half life compartments. The very same thing can be seen in detail by examining the Shearwater tissue loading graph.

Well, in many occasions, my DESAT counter on my DC is over 9 hours. But it never prevented me from diving because the N2 graph was at zero.

 

[ginti]

{ @ginti Low temperature, really?

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

You should already account for low temperatures.
Low temperatures mean reduced circulation, reduced circulation means poor off gassing. This is a particular problem because you are generally colder (especially the extremities) at the end of a dive in comparison to the start.
So, you will have higher on gassing when you are warmer at the start of the dive, especially to the extremities.
You have to balance the extra decompression time with the increased risk of hyperthermia.

Its potentially more of a risk if you are using heated vests. Much better to use the vest towards the end of the dive, to ensure the battery isn't/doesn't go flat. Basically manage the battery.

Thanks for the reply.

I am aware of these problems, and I take them into account when I do mandatory deco stops in cold water. But I am not aware of any mathematical model that can take into account, so I am curious about the algorithm inside the computer. Is it just a safety coefficient multiplied times the deco time? How do they pick the coefficient? Or maybe is it anything more complicated?