First dive at 40 meters - Newbies recreational

[Storker]

You are underestimating either the gas consumption or the time it took them to ascend.
With a 10 m/min ascent rate, it would mean their consumption during ascent was around 45 l/min.

Huh? If you're at 40m and ascend at 10 m/min, that's 4 minutes. Average depth is 20m, that's 3 barA. I calculated 180 L consumed during those 4 minutes at average 3 barA, which translates to 45 actual liters per minute on average.

But IME very few ordinary rec divers, particularly very few n00bs, are able to ascend at 10 m/min in a controlled fashion. If I were betting, I'd put my money on "cork"

 

[Blackcrusader]

I love the math. SSI states 5 minutes @40m.
But I am interested in what you think I did wrong for continuous improvement and I am not sure that I understand. Can you please explain further?

OK first thing you did wrong, you were too slow to get to the deepest part of your dive and you did not allow enough NDL time and still descended. Also the fault of your DM guide who should never have let you go to 1 min to NDL. One minute you cannot calculate as your DC does not show NDL in seconds. Your other major malfunction was assuming a sac rate of 11l/min for your calculation. Even if I plan a dive I do not calculate my SAC at my average I plus 50% or more. If I want to plan for a difficult dive assisting a buddy then twice my average.

Yes it can be fun to go to 40m. But at 40m you don't go around doing celebrations and forget to allow enough time for a safe ascent. Your ascent speed is fast as others pointed out. 10m a minute is the max rate to surface so yes TTS 4 mins plus deco and safety stops. I have never ascended that fast on any dive. Again see the ascent video I posted. Going deep and trying to do a fast ascent to avoid an already gone into DECO is a bad thing. He should not have stayed above you are you wrote but at same depth as you. Failure to understand to use a BCD which would have saved a lot of air consumption at depth doing a forced swim to ascend. The failures on this dive belong to you, your wife as your buddy and your guide. You wife failed you as well as herself.

However on the bright side you are both still alive and you are posting here. You also need the bad experiences so you can learn from them. We have all screwed up on dives.

 

[Dody]

if you have a deco stop the it is a deco dive. You wrote your computer beeped to get you to do deco stops yes? You had to do a 2 min stop at 20m so that sir makes this a deco dive even if you say you only planned a dive not to exceed NDL limits. You say you had 1 min to NLD at 40m and struggled to ascend, while struggling you are finning and could have been in deco already but been back in NDL clock later as you ascended.

No. It was not deco stop. The computer is set to order a 1st safety stop at half the max depth when it is below 30meters. It clearly indicated safety stop. Deco time was at 0 during the entire dive.

 

[Dody]

Huh? If you're at 40m and ascend at 10 m/min, that's 4 minutes. Average depth is 20m, that's 3 bars. I calculated 180 L consumed during those 4 minutes at average 3 barA, which translates to 45 actual liters per minute on average.

But IME very few ordinary rec divers, particularly very few n00bs, are able to ascend at 10 m/min in a controlled fashion. If I were betting, I'd put my money on "cork"

Exactly. My software indicated a SAC of 14l/ min.

 

[Dody]

Thanks all for your comments. I learnt a lot.

 

[Blackcrusader]

No. It was not deco stop. The computer is set to order a 1st safety stop at half the max depth when it is below 30meters. It clearly indicated safety stop. Deco time was at 0 during the entire dive.

You can exceed NDL and clear deco obligations as you ascend even if you were not aware of having done so.

 

[David Novo]

Huh? If you're at 40m and ascend at 10 m/min, that's 4 minutes. Average depth is 20m, that's 3 barA. I calculated 180 L consumed during those 4 minutes at average 3 barA, which translates to 45 actual liters per minute on average.

But IME very few ordinary rec divers, particularly very few n00bs, are able to ascend at 10 m/min in a controlled fashion. If I were betting, I'd put my money on "cork"

Your calculations are correct with your assumptions. They just seem aggressive as the OP spent 1320 liters to ascend.

 

[Dody]

You can exceed NDL and clear deco obligations as you ascend even if you were not aware of having done so.

So you say we were in deco? @#$%^!!!

 

[David Novo]

No. It was not deco stop. The computer is set to order a 1st safety stop at half the max depth when it is below 30meters. It clearly indicated safety stop. Deco time was at 0 during the entire dive.

Why did the computer tell you to stop at 12m also?

 

[Dody]

Why did the computer tell you to stop at 12m also?

After the fact, I thought that I had pretty much well managed the dive. Now, not so much. If I was in deco, I clearly messed up. I was neither trained nor prepared for that and I hate not being in control :-( . I won't tell my wife until I get the whole thing sorted. Thanks.