planning a deco dive

[Amphibic]

ı dont know your certificate degrees but if you dont have any experiance about deep diving, and if it will be first diving (for deep) u shouldnt do ı think.. firstly u should get a lesson about trimix or nitrox diving. Healt is the more important than your divings..

 

[andydiver06]

I know few people who have done dives to 60m on president coolidge wreck on single tank. According to them its quite common out there for divers to go past swimming pool, engine room, galley area. It is the largest divable wreck in the world near vanatu in south pacific.

 

[Bubble Junky]

60 meters - Within limits on air. (Extended range certifies you to 55m on air.)

How's that work ?? Certified to 55m and going to 60m. Would not recommend doing this unless properly trained and prepared. Going beyond trained/certified limits may have insurance ramifications too.

 

[Vie]

The wahwah article you referred to were for dives well below 100 meters, and PPO2 of 2.5 and above. Now that is silly deep on air. 60 meters - Within limits on air. (Extended range certifies you to 55m on air.)

I realise that. Otoh, I have dived in the 40m+ range using air (looking for hammerheads around Layang Layang, a place that does not offer nitrox or trimix) and lately on trimix; the difference in comfort level and enjoyment (for me) was huge. I personally don't think that "deep air," even "just" in the 50m+ range is ever a good idea when helium and training in its uses is readily available - I don't want to get into an argument regarding the pros and cons of "deep air" as this has been argued back and forth ad nauseum. Personally, I prefer to avoid using "air" altogether and dive EANx 32 exclusively (or TriOx/Trimix for deeper dives).

 

[espenskogen]

How's that work ?? Certified to 55m and going to 60m. Would not recommend doing this unless properly trained and prepared. Going beyond trained/certified limits may have insurance ramifications too.

Sure, fair point.
In light of this, I would also suggest that you stay within your certification limits.

E

 

[espenskogen]

I realise that. Otoh, I have dived in the 40m+ range using air and lately on trimix; the difference in comfort level and enjoyment (for me) was huge. I personally don't think that "deep air," even "just" in the 50m+ range is a good idea when helium is available - I don't want to get into an argument regarding the pros and cons of "deep air" as it is not my place to tell people how to dive. Personally, I prefer to avoid using "air" altogether and dive EANx 32 exclusively (or TriOx/Trimix for deeper dives).

I agree that for deep diving, trimix is the only viable alternative. On the other hand, unless you're certified for hypoxic trimix, air might actually be appropriate for the 60-70 meter depth range, simply because the narcosis (according to theories) can limit the chance of an oxtox incident. A better choice would of course be to stay within your certification limits for deep air, and if you want to go to 70 meters, then get the advanced trimix ticket.

As we all know though, people will do the dives they want to, and the fact that the cert agencies haven't given you the ticket doesn't automatically mean you're not going to do the dive. So as a general rule, stay within your training limits. However, if you chose to ignore those limits, then at least do the dive somewhat safely.

I think pretty much all experienced divers are guilty of pushing the limits a 'little bit' - As in the advanced open water diver who dives to 35 meters, the Deco diver diving to 50, and extended range diver diving to 60. This can be done in relative safety, because the environment does not actually change that much from 30 to 35 meters. The bits that cause accidents would be when the advanced openwater diver dives to 50 meters etc.

Interestingly enough, it is often the instructors and instructor trainers (as in the article about the TDI lot) who are the worst offenders when it comes to diving way outside the limit of their training. Whilst they should know better, I guess it's easy to get carried away. I know several Padi instructors who have done 120 meters on air. Is it stupid? Yes. Would I recommend that anybody go that far beyond their training? Absolutely not. Can it be done? Yes, just about.

 

[cerich]

If the dive is planned well, and you work up to the depth, it's perfectly doable. Sure, you'll be well narked. But it's doable. What is not advisable though, is to go from a 40 m no-deco dive to a 60 meter deco dive. Work your way up - Do 35 meter deco, then increment in 5 meter steps.

You need to consider gas planning (how much gas are you planning to bring), accellerated deco (possibly), thermal protection (an hour of stops are gonna make you cold - Where are you planning to do this?)

I have done 55 meters in the UK, and it really isn't that bad - I mean we have bad viz and cold water, but if you're prepared for it, then that's cool.

You will need an advanced nitrox cert, and I recommend you'd be comfortable diving twins (With everything that goes with that - Shutdowns etc)

As I say, if you plan it well, and know what you're doing, 60 meters on air is fine. Don't worry about the tox thing someone mentioned earlier - It's not going to be an issue with the exposure you're looking at. (Not to mention that the narcosis actually reduces the chance of O2 tox.)

Oh, and go take some technical training if you haven't got it already. A 60 meter air tech dive done the right way is reasonably safe. But a 60 meter dive without the training isn't tech, it's just stupid.

You are not going to like what I am about to say.

You present this as easy and BTW get some training. I am amazed that in your first week as an instructor you are OK with giving advice to somebody on the other side of the world that quite honestly is contrary to sound advice 99% of instructors would give and beyond any "deep air" limits taught by those few agencies (except one)that still teach deep air. The tech community by and large with all its BS and factions still are united againts just what you propose is "perfectably doable"

Please point me to where narcosis reduces the chance of O2 tox because that is also BS.

You are talking about a dive that is less than 6.5 meters from a partial pressure of 1.6 O2 while narced out of their mind , 20 meters deeper than they have ever been and you expect them to control bouyancy so O2 isn't a factor as you so nicely advise?

Work load and anxiety will increase the chance of an O2 hit, all of which is very likely for these divers doing something new without training while narced out of their minds!

Then after all your "it's not bad" crap you realize what you wrote so put the disclaimer paragraph at the end? You should have just not hit submit.

Why am I coming on so strong? Because I don't want people reading your post and actually thinking you have a clue about what you are saying in regards to this.

Best,

Chris

NAUI Course Director, Tech Instructor and NAUI Rep Cayman
PADI MSDT
ACUC Advanced Instructor
expired TDI (instr # CI-0017) and CMAS Instructor

 

[cerich]

I agree that for deep diving, trimix is the only viable alternative. On the other hand, unless you're certified for hypoxic trimix, air might actually be appropriate for the 60-70 meter depth range, simply because the narcosis (according to theories) can limit the chance of an oxtox incident. A better choice would of course be to stay within your certification limits for deep air, and if you want to go to 70 meters, then get the advanced trimix ticket.

As we all know though, people will do the dives they want to, and the fact that the cert agencies haven't given you the ticket doesn't automatically mean you're not going to do the dive. So as a general rule, stay within your training limits. However, if you chose to ignore those limits, then at least do the dive somewhat safely.

I think pretty much all experienced divers are guilty of pushing the limits a 'little bit' - As in the advanced open water diver who dives to 35 meters, the Deco diver diving to 50, and extended range diver diving to 60. This can be done in relative safety, because the environment does not actually change that much from 30 to 35 meters. The bits that cause accidents would be when the advanced openwater diver dives to 50 meters etc.

Interestingly enough, it is often the instructors and instructor trainers (as in the article about the TDI lot) who are the worst offenders when it comes to diving way outside the limit of their training. Whilst they should know better, I guess it's easy to get carried away. I know several Padi instructors who have done 120 meters on air. Is it stupid? Yes. Would I recommend that anybody go that far beyond their training? Absolutely not. Can it be done? Yes, just about.

You are wrong on so many levels and I have had friends who thought the way you do. Of those friend many now think differently and at least 7 of them are DEAD from the exact same mindset you display.

Honestly, if I had been your course director and you had displayed these attitudes you would not be an Instructor.

Please take some time to really learn about this stuff.

Best,

Chris

ps- reintroducing nitrogen(narcosis) deep (really deep like below 400fsw when using helium based mixes) has proven to reduce HPNS, NOT O2 tox. That may be one small area where you are confused among others.

 

[MikeFerrara]

I agree that for deep diving, trimix is the only viable alternative. On the other hand, unless you're certified for hypoxic trimix, air might actually be appropriate for the 60-70 meter depth range, simply because the narcosis (according to theories) can limit the chance of an oxtox incident. A better choice would of course be to stay within your certification limits for deep air, and if you want to go to 70 meters, then get the advanced trimix ticket.

No technical diver that I know uses nitrogen to control the effects of O2 exposure. The way we do that is by limiting O2 exposure. Do you teach technical diving?

 

[espenskogen]

You are not going to like what I am about to say.

You present this as easy and BTW get some training. I am amazed that in your first week as an instructor you are OK with giving advice to somebody on the other side of the world that quite honestly is contrary to sound advice 99% of instructors would give and beyond any "deep air" limits taught by those few agencies (except one)that still teach deep air. The tech community by and large with all its BS and factions still are united againts just what you propose is "perfectably doable"

That's not how I meant it to come across. Deep air is not advisable, it's not easy, it's a technical dive, and require technical training and technical experience. HOWEVER, that's not to say it's not doable. I would have no way of knowing if the original poster are capable of this kind of dive, nor do you. That's something for a local tech instructor to figure out.

Please point me to where narcosis reduces the chance of O2 tox because that is also BS.

I am looking for the source of this one - Will post it once I find it. The theory behind it though is the following:

I'm sure you are familiar with chamber procedures, where you are exposed to a rather high PP02. The chamber operators usually try and reduce the chance of a tox hit by administering a drug such as diazepam. What this does is inhibiting the neurotransmitters. Now, once a high PPO2 is causing your body to start forming free radicals, it's exactly these neurotransmitters that start triggering uncontrollably.

Now, apparently, research has shown that it's a surprisingly low number of tox incidents on deep air dives, and the theory goes that the nitrogen narcosis inhibits the neurotransmitters in a similar way to diazepam or alcohol (or any other 'downer' so to speak), and that this effectively makes you more likely to get an O2 hit diving trimix with a high PPO2 than with deep air.

You are talking about a dive that is less than 6.5 meters from a partial pressure of 1.6 O2 while narced out of their mind , 20 meters deeper than they have ever been and you expect them to control bouyancy so O2 isn't a factor as you so nicely advise?

I think any dive to that kind of depth for the first time should be attempted in a place where you have effectively a hard bottom, which avoids that issue. Trying to maintain buoyancy whilst loads of other things may be going wrong is not a great idea. Also, if you read my earlier post, I also said it would be silly to jump into it - That it was advisable to work your way towards depth, as it 35 meters with a bit of deco, and then move in 5 meter increments to the depth you want to do, over a duration of MANY dives. So in fact I'm suggesting that IF he decides to do the dive, he'd be doing a dive 6.5 meters from a HARD bottom, 5 meters deeper than he ever has been before, whilst being narked off his shoulders, AFTER completing the appropriate training for that kind of diving. (As in being completely comfortable diving with twins and two slings, staged accellerated deco etc)

I get your point about recommending deep air, and don't get me wrong, I am not suggesting deep air is a good idea, and that you wouldn't be better off diving trimix. HOWEVER, this thread is about deep air, and clearly the fella in question wanted some input on it. I wouldn't promote deep air diving to anybody, but if they're set on doing a deep air dive, the standard response of "Don't do it, you're gonna die", isn't helpful. Also, the fact that I can now wear the instructor hat teaching recreational diving, does not in any way inhibit me participating in tech discussions.

Personally, I feel the greatest danger on that kind of dive, assuming you already have the skills and experience to execute a deco dive safely, is the risk of narcosis. The risk of taking an O2 hit within the exposure limits of NOAA is far lower than the other risks you're facing. So all I'm saying is let's keep things in perspective here - There are risks associated with diving deep, and even more risks associated with deep air. But at 60 meters on air, O2 tox is one of the more manageable risks. You're realistically going to get a maximum exposure of between 5-10 minutes at close to a PPO2 of 1.6. According to the NOAA tables, an exposure of 45 minutes is acceptable at this PPO2. So you can see where I'm coming from regarding the oxtox issue.

More importantly, if you feel deep air diving is dangerous due to the level of narcosis, then that is fair play to you. We all agree that it is dangerous to dive way above your level of experience, and I think I made that perfectly clear. If you feel the PPO2 issue is a big one, then so be it, but bear in mind that even Padi teaches a maximum PPO2 of 1.6. (Although we plan with 1.4 in mind)
This dive plan would have a PPO2 of 1.47, and I feel that's a fairly safe PPO2 to dive with.

I'm proposing we discuss deep air on it's merits, not on the basis that it's all deep, dark and dangerous because it's deep air. Because like it or not, people are going to dive deep on air regardless of your view - In some places because that's all that is available. Others because they enjoy the experience.

I had a chat in the pub with one of TDI's instructor trainers yesterday. This fella is an advanced trimix instructor trainer (Amongst others), and held the depth record on Open Circuit for a while. He chooses to dive deep air (100M) when he's on holiday. Does he know the risks? Sure. Can he do that kind of dives? Absolutely. Would you or I be able to do the same thing? Probably not.

Let's just keep things in perspective, Chris. When I said something was doable it does not mean that joe blogs who finished his openwater 2 days ago should try it. I'm all for role model behaviour, but let's give people some credit shall we? I think our fellow divers on this board would be better off making an informed choice of what kind of diving they want to do, than listen to instructors and course directors preaching 'stay within the limits of the course you've taken'. It simply does not encourage furthering ones knowledge on the subject, and it ain't going to stop them from going deep anyway.