Overshooting NDL and mandatory deco stops

[Mike1967]

I am no subsurface expert,

Me either. It's subsurface mobile and looks like it does not much at all. I can edit certain things like gas but it's only changing the text nothing else. It doesn't even show NDL as far as I can tell

 

[atdotde]

Did that and like DiveLog nothing else changes.

View attachment 562411

This is the mobile version of subsurface. That does not do any deco calculations. You need to look at this dive in the desktop version and turn on the display of ceilings.

 

[Mike1967]

@atdotde thanks mate, I figured as much.

 

[KenGordon]

Subsurface Version 4 User Manual | Subsurface Section 6.5.3 looks like there are tools to play with that will show the NDL as calculated by subsurface.

Maybe I should look into it again if the mobile part does more than acquire the data now. I use DiveLog on my iPad as my main logger as I have my iPad with me out diving not a laptop.

 

[atdotde]

I created a dive with a profile roughly like yours in the planner. It seems to me, diving on air, there was a bit of a ceiling left when you surfaced but that would go away in another few minutes (after 46min of runtime), assuming GF 35/75 or said differently: you surfaced with a gradient factor of 85 which is probably ok most of the time.

 

[J-Vo]

Yes but we don't buddy check DCs are set right, does anyone?

Yes. "My PDC is set to..." and announce the gas content. Typically reading from the display. Very important when diving hypoxic mix.

 

[Mike1967]

I created a dive with a profile roughly like yours

Thanks for that mate

 

[Gareth J]

Its part of my buddy checks, gas quantity and set on DC. I say aloud, check mine and buddy acknowledges and check theirs.

I dont see a lot of thorough buddy checks out in the wild though.

Others will have said it.

As a buddy pair, you should know each others limits for the dive. Crucial to this is an understanding of how deep you are each happy to be, for how long, and how much decompression you will run (or the 'No Stop' dive limit).
Inherent in this is you need to know what each of you is breathing. As the Nitrox diver, you need to know that the dive time and decompression is dictated by the air diver (or diver on the weakest mix). As the air diver (or weakest mix Nitrox diver), you need to acknowledge that the maximum depth of the dive is dictated by the Nitrox diver. This a fundamental part of all Nitrox courses.

It is the nature of my diving that I now often dive mixed teams with mixed breathing mixes. This is because I am on CCR, and most of my buddies are on OC.
Time and depth is normally dictated by my buddy. As such, one of my computers is normally set to the mix my buddy is breathing. Especially if they are an unknown, or a 'newer' diver.

The issue that limits my depth, is what's in my DIL, and what Bailout I am carrying. As a general rule. If I''m using Air in the Dil, MOD is around 40m. My 'recreational' Bailout is normally 27%. Which is a MOD of 42m (at 1.4 PO2).

As a dive pair you made a mistake. Nothing bad happened. Learn from it, and avoid the same error in the future. You should have been suspicious when his computer cleared when yours did, he should have ensured that he had the correct mix set.

 

[Storker]

I dont see a lot of thorough buddy checks out in the wild though.

I guess I'm weird. When diving with a new buddy, I try to make sure that both of us know the other person's gear and limitations, and I really prefer to do a proper, formal buddy check. All the works. If I'm diving with someone I've dived with several times before, a lot of stuff goes without saying as we know each other, each other's gear and each other's limitations.

But if I ever mess up because I didn't do a proper - if informal - buddy check, feel free to chastise me in any way you want.

 

[Mike1967]

I'm diving with someone I've dived with several times before, a lot of stuff goes without saying as we know each other, each other's gear and each other's limitations.

This ^
It won't happen again.