Nitrox vs Air

[in_cavediver]

Before everybody overdramatises this situation.

The wreck has a permanent large buoy and cable.



It is most unlikely that you would be able to lose your DM even if you wanted to. As you start down the line you see the whole wreck before you. Group size is maximum 5 or 6 with 2 DMs.

The operator normally requires you to do 3 dives with them in the 40m range before taking you on this dive so your SAC and other abilities are established beforehand.

Still, this dive in not a recreational level dive. We are talking mandatory deco and that makes it a tec dive. If you want to do those dives, then get the training so you can do those dives properly. Reliance on a DM is a 'trust me' dive. Its not safe or sane. As much as I hate to do this, I have to quote PADI on this: Diving below 130' with recreational dive equipment is not technical diving, its stupid. (paraphrased - Found in the deep section of the AOW book)

Your opinions may vary.

 

[emelotto]

Still, this dive in not a recreational level dive. We are talking mandatory deco and that makes it a tec dive. If you want to do those dives, then get the training so you can do those dives properly. Reliance on a DM is a 'trust me' dive. Its not safe or sane. As much as I hate to do this, I have to quote PADI on this: Diving below 130' with recreational dive equipment is not technical diving, its stupid. (paraphrased - Found in the deep section of the AOW book)

Your opinions may vary.

I couldn't post before, but it 's nice to see how people with a poor base info start to imagine profiles and criticizing what they didn't see. I expected to hear more statements like DA Aquamaster has done and not coments like, take a course before doing that.

So, in order to give you what the real situation was let me report the dive in more detal;

The Dive shop responsible for that dive was Aguas Claras (http://www.aguasclaras-fn.com.br/) and as Mike said, they don't take you to Corveta if you don't dive at least 4 dives evaluation with them before diving Corveta.

To dive Corveta they require 50 logged dives, advanced and Nitrox certification. The gear you take includes a 15l air cylinder. The instructor takes a double and O2 stage cylinder with 2 regalators, so 2 divers can breath at the same time from it.

Our dives before corveta :
Sapata Cavern at night => 22m and 37 min
Sapata Cavern at day => 26m and 46 min
Laje 2 Brothers => 21 m and 50 min
Devil hole => 16m and 50 min
Cordilheiras => 22m and 56 min finished at 10 am of 25/5/2005

At 11:30 am of 26/5/2005 we started our Corveta V17 dive. We were 4 dives plus the instructor (more than 2400 dives) and a hired film maker (more than 1000 dives). A second instructor who tied the line to the Corveta waited for us with a doubles and a second O2 stage at 6m.

The plan was descent in 3' maximun to 50m, dive around Corveta for 12' and start ascent to 24m, stop 1 or 2' (I can't remember exactly) and ascent to 6m where we changed to O2 (I am not sure, but guess for 10´).

Due the current to descent, the line was not so vertical and we took more time to get 50m, but there wasn't any current, 50m visibility and 28°C.

The profile was like that :

1' - 15m
2' - 25m
3' - 33m
4' - 39m
5' - 45m
6' - 49m
7' to 16' - 49 to 51,2m
17' - 46m
18' - 43m
19' - 31m
20' - 24m
21' - 23m
22' - 19m
23' - 17m
24' - 14m
25' - 11m
26' - 10m
27' - 8,5m
28' - 6m
29' to 30 - 7m
31' to 35' - 5m
35' to 45' - 5m with O2 100%
45' to 52' - 4m with air and END of dive. My required Deco with air showed by mosquito got 0' at 50' and the graph shows that I 've ended the dive with 96% saturation on the medium compartment, 13% at the fastest and 25% at the slowest;

I've dived with 2 kg, 15l steel cylinder, starting with 215 bars and finishing with 80 bars, my SAC was 11,9 SLM (my average SAC is about 10 SLM) and the dive was wonderfull.

I am SSI Advanced whith specialties : navigation, night diving, search and recovery, deep diving, Nitrox and PADI with EFR and Rescue.

So now you guys have enough material to discuss about.
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Tell me how many of you with more than 50 dives never went to 130m with recreational gear. I guess only a few....

 

[miketsp]

..snip..

The Dive shop responsible for that dive was Aguas Claras (http://www.aguasclaras-fn.com.br/) and as Mike said, they don't take you to Corveta if you don't dive at least 4 dives evaluation with them before diving Corveta.
..snip..
Our dives before corveta :
Sapata Cavern at night => 22m and 37 min
Sapata Cavern at day => 26m and 46 min
Laje 2 Brothers => 21 m and 50 min
Devil hole => 16m and 50 min
Cordilheiras => 22m and 56 min finished at 10 am of 25/5/2005
..snip..

?
Have Aguas Claras dropped the pre-requirement of the deep dives?
In 2002/3 it was obligatory to dive Pontal do Norte (40m+) before doing the Corveta.
Or was there a reason why they didn't require this?

 

[emelotto]

?
Have Aguas Claras dropped the pre-requirement of the deep dives?
In 2002/3 it was obligatory to dive Pontal do Norte (40m+) before doing the Corveta.
Or was there a reason why they didn't require this?

Well, I guess it was because in our group was Daniel (instructor and friend of the Aguas Claras instructor Beto). So going to Corveta was 2 instructors and 3 of us already known by Daniel.

Cordilheiras, the dive we did before, was not so deep, but with a strong current, so I guess we have proved we could do Corveta. Another guy, who we also knew, was prohibited to go to Corveta because he made a lot of mistakes at the previous day.

Anyway, sometimes we don't need a very deep dive to show our skills, it depends on our behavior into the water.

 

[in_cavediver]

I couldn't post before, but it 's nice to see how people with a poor base info start to imagine profiles and criticizing what they didn't see. I expected to hear more statements like DA Aquamaster has done and not coments like, take a course before doing that.

So, in order to give you what the real situation was let me report the dive in more detal;

The Dive shop responsible for that dive was Aguas Claras (http://www.aguasclaras-fn.com.br/) and as Mike said, they don't take you to Corveta if you don't dive at least 4 dives evaluation with them before diving Corveta.

To dive Corveta they require 50 logged dives, advanced and Nitrox certification. The gear you take includes a 15l air cylinder. The instructor takes a double and O2 stage cylinder with 2 regalators, so 2 divers can breath at the same time from it.

Our dives before corveta :
Sapata Cavern at night => 22m and 37 min
Sapata Cavern at day => 26m and 46 min
Laje 2 Brothers => 21 m and 50 min
Devil hole => 16m and 50 min
Cordilheiras => 22m and 56 min finished at 10 am of 25/5/2005

At 11:30 am of 26/5/2005 we started our Corveta V17 dive. We were 4 dives plus the instructor (more than 2400 dives) and a hired film maker (more than 1000 dives). A second instructor who tied the line to the Corveta waited for us with a doubles and a second O2 stage at 6m.

The plan was descent in 3' maximun to 50m, dive around Corveta for 12' and start ascent to 24m, stop 1 or 2' (I can't remember exactly) and ascent to 6m where we changed to O2 (I am not sure, but guess for 10´).

Due the current to descent, the line was not so vertical and we took more time to get 50m, but there wasn't any current, 50m visibility and 28°C.

The profile was like that :

1' - 15m
2' - 25m
3' - 33m
4' - 39m
5' - 45m
6' - 49m
7' to 16' - 49 to 51,2m
17' - 46m
18' - 43m
19' - 31m
20' - 24m
21' - 23m
22' - 19m
23' - 17m
24' - 14m
25' - 11m
26' - 10m
27' - 8,5m
28' - 6m
29' to 30 - 7m
31' to 35' - 5m
35' to 45' - 5m with O2 100%
45' to 52' - 4m with air and END of dive. My required Deco with air showed by mosquito got 0' at 50' and the graph shows that I 've ended the dive with 96% saturation on the medium compartment, 13% at the fastest and 25% at the slowest;

I've dived with 2 kg, 15l steel cylinder, starting with 215 bars and finishing with 80 bars, my SAC was 11,9 SLM (my average SAC is about 10 SLM) and the dive was wonderfull.

I am SSI Advanced whith specialties : navigation, night diving, search and recovery, deep diving, Nitrox and PADI with EFR and Rescue.

So now you guys have enough material to discuss about.
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Tell me how many of you with more than 50 dives never went to 130m with recreational gear. I guess only a few....

Now that I have seen the profile, I change exactly nothing. The dive above does have madatory deco. Your post above states that you personally are diving a single tank (no redundancy). Your dive training is all recreational - No advanced nitrox or tec nitrox or trimix. You are not carrying you own deco gas. I was a bit off on the depth (took the english conversion from a prior post) but it still was deeper than the 130 foot rec limit. There is a reason why technical dive training exists.

As for the last bit, prior to advanced nitrox, I did not exceed rec limits.

As I stated above, your opinions may vary.

 

[emelotto]

Now that I have seen the profile, I change exactly nothing. The dive above does have madatory deco. Your post above states that you personally are diving a single tank (no redundancy). Your dive training is all recreational - No advanced nitrox or tec nitrox or trimix. You are not carrying you own deco gas. I was a bit off on the depth (took the english conversion from a prior post) but it still was deeper than the 130 foot rec limit. There is a reason why technical dive training exists.

As for the last bit, prior to advanced nitrox, I did not exceed rec limits.

As I stated above, your opinions may vary.

This was my deepest dive and I just went there because there was something to see, and the conditions at Noronha are the best ones. I wouldn't go so deep with 10m visibility or real strong current nor a line to follow. I agree with you I haven't a stage with me, but we dove as a compact group and as Mike posted, the total group redundancy was enough to overcome a single failure.

But you are right....opinions may vary!

 

[DA Aquamaster]

Well... to be fair scuba diving is an adjustable risk sport and divers can choose what risks they want to take as well as when and where they want to take them.

There is nothing overly hard about deco diving as long as every thing goes well, it's when something happens and things go wrong that the proper training and equipment becomes a lifesaver. So personally, I think it is always wise to have the proper training and equipment to get yourself out of any potential problems that your choices in combination with chance and circumstance can create for you. And to me, it's a little too risky do do any overhead dive (soft or hard) where I don't have the gas and equipment to get myself to the surface safely independent of buddies, DM's etc as in my experience, eventually, something will go wrong. With the right training and equipment, you will live to talk about it and learn from it, without the right equipment and training you won't.

 

[emelotto]

With the right training and equipment, you will live to talk about it and learn from it, without the right equipment and training you won't.

DA, I agree with everything you said, but the last statement, well, I don't know if it's because I am not a native english speaker, but sounds to me like fatalist...

In my "portuguese" version of that, I would say " ...without the right equipment and training you maybe not survive to ...." if there is no difference, please ignore.

 

[espenskogen]

DA, I agree with everything you said, but the last statement, well, I don't know if it's because I am not a native english speaker, but sounds to me like fatalist...

In my "portuguese" version of that, I would say " ...without the right equipment and training you maybe not survive to ...." if there is no difference, please ignore.

Exceed limits enough times, and I think the 'will not' is probably more accurate than 'may not'