Is Deep Air / Light Deco (bounce?) Discussible on ScubaBoard?

[MauiScubaSteve]

I think that 'light deco' is deco. Deco is technical diving. It doesn't belong in the recreational diving area.

Edit: How are this course (below) not directly applicable and suitable to the 'ground-breaking' dive activities that are being debated in this thread:

Tec 40
...to accommodate divers interested in very limited tec diving, the Tec 40 equipment requirements are only a bit beyond those of the standard recreational kit.


A Tec 40 diver is qualified to;

• Use decompression software and dive computers to plan and make decompression dives with not more than 10 minutes of total decompression and not deeper than 40 metres/130 feet.

• Use a single cylinder of decompression gas with up to 50 percent oxygen (EANx50) to add conservatism to the required decompression.

While I personally don't like using "sport" and "diving" in the same sentence unless the participants use "speedos"

the following are excerpts from the Standards section of my IANTD Sport Diving Instructor Manual

(with each page showing a 2001 copyright at the bottom);

Sport Diving
- the most common form of recreational diving.

Sport diving is performed using either air or Nitrox mixtures up to 50% oxygen on dives no deeper than 130 feet (39 meters). Sport divers may not engage in dives requiring a total of more than 10 minutes of decompression time, or dives with stops deeper than 20 feet (6 meters).

Advanced EANx Diver

Program Limits

• No dives may be conducted to depths greater than 130 feet (39 meters).
• All dives must be conducted using EANx (maximum 40% oxygen). A higher EANx (maximum 50% oxygen) may be used at the decompression or safety stops.
• Decompression stops are limited to a maximum of 10 minutes and 20 feet (6 meters)

So it seems there could be more than a few divers out there, even in North America, who do not consider themselves Tech divers, but have equivalent training to divers who consider themselves Tech divers.

It seems there could be divers for whom letting their Suunto computer show an ASC time of 17 minutes @ 130' is not a violation of their non Tech training.

The ascent time (ASC TIME) is the minimum amount of time needed to reach the surface in a decompression dive. It includes:
• the time needed to ascend to the ceiling at an ascent rate of 10 m/min [33 ft/min]
plus
• the time needed at the ceiling. The ceiling is the shallowest depth to which you should ascend
plus
• the time needed at the Mandatory Safety Stop (if any)
plus
• the recommended 3 minute Safety Stop
plus
• the time needed to reach the surface after the ceiling and safety stops have been removed.

After being certified to the level of IANTD Advanced EANx Divers, is a single air cylinders buddy team not diving within their non Tech training @ 130' with less than 18 minutes ASC time showing on both divers Suunto Viper computers?

 

[Thalassamania]

Lets say that you are at 40.5m and you have accumulated 7 mins of backgas deco and are getting ready to call the dive. Lets also say that you are diving with a buddy which some (but not all) of us tend to do. Your buddy, at that moment, goes out of gas and comes to you for help. How much time will it take to help your buddy? (Gas donation, handing over your pony, etc.) Optimistically, it will take 1 minute. Most likely, a lot more. How much deco obligation did that extra minute add?

From the time I see an OOA signal to the time my buddy is breathing off my supply will consume less that 10 seconds and will add no additional deco obligation. If it takes you longer, you need more training and practice before making such dives.

So, for you and your buddy, is a direct ascent to the surface now an option? Lets say it took you 3 minutes to sort out the emergency, what is your deco obligation now? Are your risks significantly increased if you decide to do a direct ascent now? If so, do you and your buddy have enough gas to complete whatever deco you are obligated to do?

Whenever I make a dive that is within 5 minutes of having a deco obligation I always have a plan for one step longer and one step deeper, and I am prepared for that longer/deeper dive. So even if it took 3 minutes to sort out, I have planned for at least and extra 5 minutes and and extra 10 feet, so I switch to my backup plan and proceed, no biggie.

I'm gonna guess that most of the masses who only have "recreational" training don't have the knowledge on how to deal with this situation and as such, are likely not only ill equipped but also unaware of their best options for minimizing the severity of the outcome.

That, my friend, is one of the problems with dive computers, people have lost the idea of planning for one deep and one longer because their plan now is to go down so deep and then come up as their gas supply or computer dictates.

Personally, I consider any dive that can go outside of the boundaries of what is taught in "recreational" dive training to be, not recreational. And in the U.S., PADI, NAUI and SSI seem to be pretty close when it comes to defining what the boundaries of their recreational training programs are.

The "boundary," however, is nonsensical in that it maps a binary choice onto a continuum. Now, if a case could be made for the idea that anyone could make a free ascent from 130, or that at 130 there is almost always too much narcosis or the ppO2 is too high ... fine, but the reality is that the recreational world is trying to map a nonsafety based military decision onto recreational rules ... which is absurd. At 131 fsw do you shrivel up and die? Is it a problem if your fin tip dips below or is only a problem if you get your depth gauge that deep?

 

[MauiScubaSteve]

Thal is on the prowl!

His "previous" post, from the Advanced Diving forum, also belongs here, IMHO!

I don't really understand the current idea of, "going tech." Tech is not a thing, it is not a set of rules, it is not a uniform, it is not a gear configuration, it is not a philosophy, nor is it a curriculum. It is simply and solely diving in any situation that does not permit a normal direct ascent to the surface, thus most cave diving, and most wreck penetration, and all decompression diving, is technical diving. I have been diving, routinely, below 130 feet since at least 1972 (maybe earlier). Back then, there was neither a concept of a 130 foot recreational limit nor of technical diving. Going deeper than 130 was possible, within the no-D limits, it just meant short dives and we dove down to 190 fsw, carefully avoiding decompression. When we had to stay longer it meant significant planning, preparation and practice, but had nothing to do with black drysuits and blue drygloves, it had everything to do with the aforementioned planning, preparation and practice. It had nothing do with some separate and/or unique codex that is passed from apostle to acolyte that alters the diver's state of consciousness and suddenly solves the deadly problems encountered by the uninitiated at 131 fsw.

emphasis added

 

[waterpirate]

For the life of me I can not fathom the reasoning for your ongoing posts other than pure entertainment value???
The certs that you mention above are rarely done stand alone and at best they are gateway drugs used to identify that if you are at the top of the bottom, there is a whole nother set of standards above the bottom pile for which you can measure your skill set.
If you choose to remain at the top of the bottom, it is hard to justify your position to anyone else that has moved on to the bottom of the next set of standards.
Be happy dive the way you wish, and dive on.
Eric

 

[Adobo]

From the time I see an OOA signal to the time my buddy is breathing off my supply will consume less that 10 seconds and will add no additional deco obligation. If it takes you longer, you need more training and practice before making such dives.

10 seconds to donate to your buddy. Then what? Direct ascent to the surface? You have a deco obligation, remember?

Doesn't it strike you as odd that a buddy team is diving to 130ft and one diver goes to the other being out of gas? Clearly, there is more to situation like this.

I imagine this would only happen if a) one is diving a single tank or b) both have redundant gas supplies, one diver goes OOG on his primary gas supply and gets confused and can't get to his redundant gas (i.e. pony bottle).

In scenario a, wouldn't the more important question be, why are divers incurring deco obligations without redundant gas sources and abundant reserves? In scenario b, wouldn't it be prudent to take a minute to figure out if the buddy's redundant gas supply is accessible and was not utilized due to confusion/panic?

So in scenario b, I would anticipate 1 minute to get the situation sorted out. But in practice, I have seen such things take as much as 3 minutes. And not from your average vacation diver but from divers who regularly dive at home.

Oh, and lets not forget, there is a bag shoot that may be needed as heading up the anchor line may no longer be option in this situation. Now, I now some of the 20 year, thousand dive veterans of Hawaii diving can probably fart in an SMB and have it up to the surface in 3 seconds but for the rest of us, should we budget another minute?

Whenever I make a dive that is within 5 minutes of having a deco obligation I always have a plan for one step longer and one step deeper, and I am prepared for that longer/deeper dive. So even if it took 3 minutes to sort out, I have planned for at least and extra 5 minutes and and extra 10 feet, so I switch to my backup plan and proceed, no biggie.

That, my friend, is one of the problems with dive computers, people have lost the idea of planning for one deep and one longer because their plan now is to go down so deep and then come up as their gas supply or computer dictates.

Where should the average "never gonna go tech" diver go to learn about that "plan one deeper" and "plan one longer" business? Remember now, the context of this thread is "light deco deeper than 40 m air diving" for "the never going to tech dive but probably will dive air deeper than 40 m divers in the world." The divers might already be in "light deco" when they have to go into one deeper and/or one longer mode.

It's a "no biggie" for you. But as it turns out, this is not about you. Or me. Its about a diver who has no technical dive training. Is this "no biggie" for him/her?

The "boundary," however, is nonsensical in that it maps a binary choice onto a continuum. Now, if a case could be made for the idea that anyone could make a free ascent from 130, or that at 130 there is almost always too much narcosis or the ppO2 is too high ... fine, but the reality is that the recreational world is trying to map a nonsafety based military decision onto recreational rules ... which is absurd. At 131 fsw do you shrivel up and die? Is it a problem if your fin tip dips below or is only a problem if you get your depth gauge that deep?

I agree 100%. The boundary is nonsensical. It's a boundary that might work fine under ideal circumstances such as great vis, low current, warm waters and an incident free dive. How well does that boundary work if there is murky vis? How does it work in cold water? In a lot of current? How good is that boundary if all of a sudden you have to make intelligent decisions to save your and your buddy's bacon?

Even at 130ft, an average diver is consuming ~3.75cu ft of gas/minute. That's 150 psi/minute in an aluminum 80. Now, lets say that the the divers are sharing gas. That's 300psi/minute - if they do not have have elevated SAC rates due to the emergency.

We haven't even touched on gas density of air/nitrox or narcosis from not only nitrogen but also CO2 which btw, has a higher narcotic potential.

So no, you do not shrivel up and die at 131ft. But that really isn't the point.

I guess I am really just baffled by you professional recreational diving instructors that seem to have a problem with folks like me who think that any diver thinking of venturing even further than the standards (which I find in many situations to be not only arbitrary but also sketchy), to get additional information on how to plan and execute those dives as the training these divers have taken in the past are likely to be woefully inadequate to prepare them for what they might be getting into.

 

[Adobo]

I don't really understand the current idea of, "going tech." Tech is not a thing, it is not a set of rules, it is not a uniform, it is not a gear configuration, it is not a philosophy, nor is it a curriculum. It is simply and solely diving in any situation that does not permit a normal direct ascent to the surface, thus most cave diving, and most wreck penetration, and all decompression diving, is technical diving. I have been diving, routinely, below 130 feet since at least 1972 (maybe earlier). Back then, there was neither a concept of a 130 foot recreational limit nor of technical diving. Going deeper than 130 was possible, within the no-D limits, it just meant short dives and we dove down to 190 fsw, carefully avoiding decompression. When we had to stay longer it meant significant planning, preparation and practice, but had nothing to do with black drysuits and blue drygloves, it had everything to do with the aforementioned planning, preparation and practice. It had nothing do with some separate and/or unique codex that is passed from apostle to acolyte that alters the diver's state of consciousness and suddenly solves the deadly problems encountered by the uninitiated at 131 fsw.

Thal is on the prowl!

His "previous" post, from the Advanced Diving forum, also belongs here, IMHO!

So... what's your point?

 

[dumpsterDiver]

10 seconds to donate to your buddy. Then what? Direct ascent to the surface? You have a deco obligation, remember?

Doesn't it strike you as odd that a buddy team is diving to 130ft and one diver goes to the other being out of gas? Clearly, there is more to situation like this.

I imagine this would only happen if a) one is diving a single tank or b) both have redundant gas supplies, one diver goes OOG on his primary gas supply and gets confused and can't get to his redundant gas (i.e. pony bottle).

In scenario a, wouldn't the more important question be, why are divers incurring deco obligations without redundant gas sources and abundant reserves? In scenario b, wouldn't it be prudent to take a minute to figure out if the buddy's redundant gas supply is accessible and was not utilized due to confusion/panic?

So in scenario b, I would anticipate 1 minute to get the situation sorted out. But in practice, I have seen such things take as much as 3 minutes. And not from your average vacation diver but from divers who regularly dive at home.

Oh, and lets not forget, there is a bag shoot that may be needed as heading up the anchor line may no longer be option in this situation. Now, I now some of the 20 year, thousand dive veterans of Hawaii diving can probably fart in an SMB and have it up to the surface in 3 seconds but for the rest of us, should we budget another minute?

So now Thal and I both said the exact same thing. Somebody hits either of us up for air at 140 feet with a little deco ceiling, we are going to donate air and be initiating an ascent IMMEDIATELY!

There is no reason to be dicking around on the bottom, the best thing to do is to be moving toward the surface at a controlled rate. The "low on air guy" is going to feel a hell of a lot better to be under the control and supervision of a someone who takes immediate and decisive action and gets the ascent started.

As for deploying an SMB....? That would NOT be one of my priorities... In 3 minutes we are going to be at a depth of 40-60 feet, air consumption is drastically lower, and if we stop at this depth, even an accelerated ascent rate can most likely be compensated for.

Once we get to 50 feet, we should both be calmer, we can take an inventory of our resources, deco status etc. Once we do this and stop for a few seconds at 40-50 ft, THEN I would be beginning to think about deployment of an SMB.

 

[MXGratefulDiver]

Yes, I was right to perceive that you still fail to perceive that I was not talking about "working/deco" PPO₂'s.

I am allowed to switch to a "deco" tank with up to 50% O₂, but my computer does not accelerate my deco and the 1.8 has no bearing on the deco.

1.8 is the "contingency" or "exceptional exposure" PPO₂, with the "printed" caveat that ...

and my Exceptional Exposure Limits table shows ...

• 2.0 .............. 30 min
• 1.9 .............. 45
• 1.8 .............. 60
• 1.7 .............. 75

Then, during happy hour at Dick's Round Table one can hear dive legends like Thal get "anointed in IANTD holy water" and confidentially agree that calm "exceptional" 10 minute photo sessions are not illogical exceptions.



Warning; if you are not one of the so "anointed", you should follow all your applicable training and experience to be safe!

Interesting ... by your own admission you've been below 130 feet exactly three times in your life ... making knowone's prior appeal to your vast decades of experience completely meaningless in the context of this topic. But I'm curious what you're breathing down there? In order to hit a PPO2 of 2.0 ATA's, you'd have to be breathing EAN40 at that depth.

Do you really do that?

How often have you actually gone into deco?

From what depth?

What were you using for deco gas on the ascent?

At what depth did you make your switch?

Sitting around a table with Dick Rutkowski and other diving gods 20 years ago is all well and good ... but what did you really learn? I went to dinner once with John Chatterton, but frankly that didn't teach me anything about wreck diving. More to the point, if in 20 years you only put what was discussed into practice three times, how much do you really remember ... or understand ... about what was said?

Stick with getting advice from people that hand themselves
over to an agency and are no longer able to differentiate


Or you can continue to listen to Bailey and Lynne
who with a combined existence of 115 years have a
TOTAL OF FIFTEEN YEARS DIVE EXPERIENCE
HAVING STARTED AT FIFTY YEARS OF AGE

Now there's me and halemano with almost a combined 100
years of life, with probably NINETY YEARS IN THE OCEAN

Emile's prior appeal to authority on your behalf falls a bit short ... granted I have been diving fewer years than you have ... but when it comes to diving below 40M ... which was the topic you chose for this thread ... you have less than 1% of my experience.

... Bob (Grateful Diver)

 

[MauiScubaSteve]

For the life of me I can not fathom the reasoning for your ongoing posts other than pure entertainment value???
The certs that you mention above are rarely done stand alone and at best they are gateway drugs used to identify that if you are at the top of the bottom, there is a whole nother set of standards above the bottom pile for which you can measure your skill set.
If you choose to remain at the top of the bottom, it is hard to justify your position to anyone else that has moved on to the bottom of the next set of standards.
Be happy dive the way you wish, and dive on.
Eric

For the life of me, I can not fathom why you (and others) feel the need to repeatedly post in threads you don't think are worth posting in.



One of my most important mentors, who teaches many of the Big Dive Dogs important parts of their Hyperbaric Medicine, advised me that "deco diving" is perhaps more dangerous for me due to a lifetime of catastrophic orthopedic joint and limb trauma, so he advised me to not worry about Technical diving.

If a recreational diver, in 2001, was looking to attain the top of the pile, most advanced, recreational open circuit training, was there something better than IANTD Advanced EANx Instructor from the father of recreational EANx diving? If that diver continues to expand their knowledge by "shaking the pillars" on an internet forum, is it bad because it's also entertaining?

 

[Adobo]

So now Thal and I both said the exact same thing. Somebody hits either of us up for air at 140 feet with a little deco ceiling, we are going to donate air and be initiating an ascent IMMEDIATELY!

Is that what he said? I should go re-read what he typed.

I will concede that if you go down the road of single tank deep air dive, the choices are pretty limited. You really do not have the gas to evaluate options (or even to calm an OOG diver who might be near panic). And anyway, trying to make intelligent decisions while at 5+ ATA on air with a near panic buddy attached to you, you are probably just as likely to make things worse. You basically gotta get shallow and fast. In fact, it really doesn't matter what you mean by "little deco". On a single tank deep air dive with two divers sharing gas... getting bent sure beats getting drowned.

If only there were a way to get information on how to not be in this situation in the first place. You know, alternatives to deep air, single tank, back gas deco diving.