200' on air for 5 min bottom time?

[boulderjohn]

If someone is asking the question for academic purposes, I suggest that they just start doing research rather than asking a question on a discussion board. I found an answer in the Navy Dive Manual in five minutes or so, and with more time I could research other sources, if needed. I've spent much more time reading this thread which have a myriad of conflicting answers and opinions, not to mention advice on how one should dive. It is that way in nearly every thread anywhere, for facts I'll do my own research, and for opinions I'll post. There is a need for both but one should not confuse the two.

A lot of divers, maybe the majority, have no idea how to find such an answer. I lot of divers, maybe the majority, have no idea how to access the Navy Dive manual. A lot of divers, maybe the majority, know so little about deep diving and decompression theory that they think the answer to such a question is ironclad and simple.

A lot of people have a reflexive need to go to social media for answer they could have gotten better somewhere else. If you were to go to the Instructor to Instructor forum, you will frequently see people ask questions like what is the PADI standard for ABC, or what is your understanding of PADI standard DEF. They then get a variety of answers. In the same amount of time that it took the OP to write the question, and the same amount of time it took for others to write their best guess responses, any one of them could have opened their instructor manuals or written an email to PADI for a definitive answer.

 

[drrich2]

If the OP is still reading, and wasn't trolling to 'get peoples' goat,' so to speak, and still checks the thread, I'll add:

1.) A number of our knowledgeable members do not want to see you die. They may not all be 'warm and fuzzy' about it, but at the end of the day, they want to quickly disavow you of any notion this dive is a good idea, because they don't want you or a buddy (or both) hurt trying it.

2.) Threads on ScubaBoard are open to the public, for the most part, and many people seeing them don't have the background to judge well whether a bounce dive to a given depth is a seriously bad idea. Yes, the recommended depth limit for rec. diving is 130', but the speed limit on a lot of highways was 55 mpg when it seemed most everyone on the road was doing 65+. So, people don't always know what limits are within reason to push a bit. Regardless of whether the OP ever tries such a dive, we don't want newer folks browsing the thread to get the idea this is a good idea to try.

Richard.

 

[Tortuga68]

If the OP is still reading, and wasn't trolling to 'get peoples' goat,' so to speak.

Maybe he wants to see a goat explode

 

[DCBC]

Getting back to the OP and his issue....if the Op and his friends could do their 200 foot air dive on surface supplied air with a full fask mask or helmet on, I don't think I would have to much concern over the dive...the typical FAILURE to monitor air supply would be moot.....For most of the problems you hear about, that recreational divers end up with from running "personal best" deep drops, the surface supplied air and helmet would eliminate the high potential for catastrophe....but then again, without the training for this, who knows what CF they could create for themselves

Dan, I don't see that surface supply has anything to do with this discussion. Your statement that "the typical FAILURE to monitor air supply" confuses me. There is no typical failure to monitor gas supply for any Diver that has been properly trained. If the person is properly trained/experienced/equipped to dive deep-air and chooses to do so, what problem do you have with this (other than you wouldn't choose to do this yourself)?

 

[danvolker]

Dan, I don't see that surface supply has anything to do with this discussion. Your statement that "the typical FAILURE to monitor air supply" confuses me. There is no typical failure to monitor gas supply for any Diver that has been properly trained. If the person is properly trained/experienced/equipped to dive deep-air and chooses to do so, what problem do you have with this (other than you wouldn't choose to do this yourself)?

DC,
Two issues jump out with this.....1 ) Properly Trained. This is a Red Herring. Even with AOW "training", there are a majority of divers certified with this that don't possess the fundamental skills of an advanced diver. Of trained and certified OW divers, a very large number could not survive by themself in a swimming pool for several hours without help..this is the state of Training in Scuba Diving today, given the large number of high volume operations that employ instructors that are poor divers themselves. For the purposes of this discussion, how would a new diver know if they had succeeded in finding one of the Good Instructors, or one of the Bad instructors? In other words, how could they expect they could become properly trained.
2 ) We are discussing this as it applies to recreational divers, and in this universe, the "typical" problem an underskilled, poorly trained diver will run into on a deep dive, is poor gas management, and low on air, or OOA. This is the reality just with baby dives to 120 feet. Run these divers to 160 and the OOA potential goes off the chart...200 feet would be like having a Euthanasia day.


As to myself, I thought you were well aware I dove deep air throughout the late 80's and into mid-90's...all the 225 to 285 foot deep sites we have from North Palm Beach to North Miami. Plenty of deep drifts on reefs, plenty of deep wrecks with penetrations. Just because I did it, does not mean I think it is fine to do, given the far superior mental clarity 100% of divers would feel at 280 on Trimix-- over doing 280 on air.

DC, you were kind enough to offer the Surface Supply solution, which in fact, addresses the most severe problem of the poorly trained diver--the guarantee that they won't run out of air that Surface Supply offers ( relative to whatever guarantee this same diver would have with their "planning" of a 200 foot dive with air and 80 cu foot tank...even with doubles for that matter).

With all the people you must have trained through the years, certainly you must have come across those that had no tolerance for narcosis.... I have personally witnessed dozens of divers in the last 30 years with no tolerance even to 140 foot dive depths...I have witnessed massive differences in personal tolerances between divers--and I try to avoid divers that still need training

 

[boulderjohn]

DC, you were kind enough to offer the Surface Supply solution, which in fact, addresses the most severe problem of the poorly trained diver--the guarantee that they won't run out of air that Surface Supply offers ( relative to whatever guarantee this same diver would have with their "planning" of a 200 foot dive with air and 80 cu foot tank...even with doubles for that matter).

I have never dived surface supplied in a helmet, but I would guess it would be a lot better that way in case of an O2 toxicity seizure. Even narcosis is less likely to cause a problem. Remember that in the ScubaMau incident, it was supposedly narcosis that sent her plummeting at least 100 feet past her planned depth.

 

[danvolker]

I have never dived surface supplied in a helmet, but I would guess it would be a lot better that way in case of an O2 toxicity seizure. Even narcosis is less likely to cause a problem. Remember that in the ScubaMau incident, it was supposedly narcosis that sent her plummeting at least 100 feet past her planned depth.

Not to mention that with the umbilical and a tender, going down 100 or more feet beyond the plan--just would not be allowed
These commercial guys are a lot smarter about the way they do deep air, than our typical AOW diver wanting to feel the narc at 180 or 200!

 

[ScubaInChicago]

1.) A number of our knowledgeable members do not want to see you die.

Jumping to conclusions, aren't ya?

 

[DCBC]

DC,
Two issues jump out with this.....1 ) Properly Trained. This is a Red Herring. Even with AOW "training", there are a majority of divers certified with this that don't possess the fundamental skills of an advanced diver. Of trained and certified OW divers, a very large number could not survive by themself in a swimming pool for several hours without help..this is the state of Training in Scuba Diving today, given the large number of high volume operations that employ instructors that are poor divers themselves. For the purposes of this discussion, how would a new diver know if they had succeeded in finding one of the Good Instructors, or one of the Bad instructors? In other words, how could they expect they could become properly trained.

I agree that much of today's diver training is poor. Standards for Diver's and Instructors are at an all time low. I also agree with you that "of today's trained and certified OW divers, a very large number could not survive by themselves in a swimming pool for several hours without help." What's also unfortunate, is that many of today's current Instructors have yet to recognize that this poses a safety problem at all and some even quote statistics that the Diver fatality rate isn't increasing, so everything is fine.

What you may be missing is any Diver who seeks 'technical training,' is not dealing with the typical Instructor or "high volume operations that employ Instructors that are poor divers themselves." I certainly can't speak on behalf of all Technical Instructors, but I'm a hardliner when it comes to any type of Diver training (OW through Technical Instructor). I'll work with the student for years if I have to, but Standards have to be met before they get the card. The card is well earned before I'm through.

Jim and I discussed this recently. We both agree that we don't certify anyone to dive unless we feel comfortable in them diving with a member of our family. This use to be the standard that was applied by most Instructors, but today it's a relic of a by-gone era (like me). That doesn't mean that we don't have it right; it's just not a profitable attitude to have in today's Society (where many people seek instant gratification)...

2 ) We are discussing this as it applies to recreational divers, and in this universe, the "typical" problem an underskilled, poorly trained diver will run into on a deep dive, is poor gas management, and low on air, or OOA. This is the reality just with baby dives to 120 feet. Run these divers to 160 and the OOA potential goes off the chart...200 feet would be like having a Euthanasia day.

Agreed, but almost everyone can be trained properly and proper training should be available through a Technical Instructor.

As to myself, I thought you were well aware I dove deep air throughout the late 80's and into mid-90's...all the 225 to 285 foot deep sites we have from North Palm Beach to North Miami. Plenty of deep drifts on reefs, plenty of deep wrecks with penetrations. Just because I did it, does not mean I think it is fine to do, given the far superior mental clarity 100% of divers would feel at 280 on Trimix-- over doing 280 on air.

Personally, I only dive air under 250 FSW. If Helium is available, I prefer to use it. Unfortunately, it hasn't been available in every place I've wanted to do a deeper technical dive. At such times, I use air. In my early days, Helium was seldom available at all job sites, so I didn't have a lot of choice. After I became more experienced with air at depth, it didn't present the same concern as it once had.

DC, you were kind enough to offer the Surface Supply solution, which in fact, addresses the most severe problem of the poorly trained diver--the guarantee that they won't run out of air that Surface Supply offers ( relative to whatever guarantee this same diver would have with their "planning" of a 200 foot dive with air and 80 cu foot tank...even with doubles for that matter).

I don't believe that surface supply "addresses the most severe problem of the poorly trained diver" at all. The training it takes to use SS, is much greater than if the diver was trained to use SCUBA properly. Poorly trained divers shouldn't be diving at all (in my opinion).

With all the people you must have trained through the years, certainly you must have come across those that had no tolerance for narcosis.... I have personally witnessed dozens of divers in the last 30 years with no tolerance even to 140 foot dive depths...I have witnessed massive differences in personal tolerances between divers--and I try to avoid divers that still need training

I was the Diving Operations Officer (Navy) at DCIEM (in the 70's and 80's) and was involved in testing numerous subjects regarding narcosis. I coincidentally did my Masters thesis (Hyperbaric Physiology) in-part on N2O narcosis (affect on ventilation during resistive breathing). Most people will show measurable changes in problem solving skills in as little as 50 FSW. There are some degrees of variance in how narcosis affects people (perhaps similar to some medications) and how it will affect the same person in different ways at different times.

The important thing to remember, is not how narcosis will affect you (it will), rather than the amount you allow it to before it becomes an unnecessary hazard. If you are being notably affected, you scrub the dive. Some days I wont dive below 150 FSW on air and at other times I'm fine at 225 FSW; 200' usually doesn't present a problem for me. Sometimes I have a problem with my ears and I scrub the dive at 20 FSW. Again, it's all about knowing what to do and what not to do. Proper training makes the difference.

I suppose I take exception to anyone saying: It's crazy to dive deep-air when there's another gas; It's crazy to dive in a Cave or a Wreck when you don't have to; It's crazy to use a CCR because they are dangerous; It's crazy to dive at all because the Sharks will get you... Deep-Air, Cave, Wreck, or even Diving at all, can be safe or unsafe. They each have a degree of risk. The only thing that's important is to do it responsibly and choose the level of risk that's acceptable to you. To best evaluate this, get educated about the facts and then you're in a position to make your decision...

 

[danvolker]

I agree that much of today's diver training is poor. Standards for Diver's and Instructors are at an all time low. I also agree with you that "of today's trained and certified OW divers, a very large number could not survive by themselves in a swimming pool for several hours without help." What's also unfortunate, is that many of today's current Instructors have yet to recognize that this poses a safety problem at all and some even quote statistics that the Diver fatality rate isn't increasing, so everything is fine.

What you may be missing is any Diver who seeks 'technical training,' is not dealing with the typical Instructor or "high volume operations that employ Instructors that are poor divers themselves." I certainly can't speak on behalf of all Technical Instructors, but I'm a hardliner when it comes to any type of Diver training (OW through Technical Instructor). I'll work with the student for years if I have to, but Standards have to be met before they get the card. The card is well earned before I'm through.

Jim and I discussed this recently. We both agree that we don't certify anyone to dive unless we feel comfortable in them diving with a member of our family. This use to be the standard that was applied by most Instructors, but today it's a relic of a by-gone era (like me). That doesn't mean that we don't have it right; it's just not a profitable attitude to have in today's Society (where many people seek instant gratification)...



Agreed, but almost everyone can be trained properly and proper training should be available through a Technical Instructor.



Personally, I only dive air under 250 FSW. If Helium is available, I prefer to use it. Unfortunately, it hasn't been available in every place I've wanted to do a deeper technical dive. At such times, I use air. In my early days, Helium was seldom available at all job sites, so I didn't have a lot of choice. After I became more experienced with air at depth, it didn't present the same concern as it once had.



I don't believe that surface supply "addresses the most severe problem of the poorly trained diver" at all. The training it takes to use SS, is much greater than if the diver was trained to use SCUBA properly. Poorly trained divers shouldn't be diving at all (in my opinion).



I was the Diving Operations Officer (Navy) at DCIEM (in the 70's and 80's) and was involved in testing numerous subjects regarding narcosis. I coincidentally did my Masters thesis (Hyperbaric Physiology) in-part on N2O narcosis (affect on ventilation during resistive breathing). Most people will show measurable changes in problem solving skills in as little as 50 FSW. There are some degrees of variance in how narcosis affects people (perhaps similar to some medications) and how it will affect the same person in different ways at different times.

The important thing to remember, is not how narcosis will affect you (it will), rather than the amount you allow it to before it becomes an unnecessary hazard. If you are being notably affected, you scrub the dive. Some days I wont dive below 150 FSW on air and at other times I'm fine at 225 FSW; 200' usually doesn't present a problem for me. Sometimes I have a problem with my ears and I scrub the dive at 20 FSW. Again, it's all about knowing what to do and what not to do. Proper training makes the difference.

I suppose I take exception to anyone saying: It's crazy to dive deep-air when there's another gas; It's crazy to dive in a Cave or a Wreck when you don't have to; It's crazy to use a CCR because they are dangerous; It's crazy to dive at all because the Sharks will get you... Deep-Air, Cave, Wreck, or even Diving at all, can be safe or unsafe. They each have a degree of risk. The only thing that's important is to do it responsibly and choose the level of risk that's acceptable to you. To best evaluate this, get educated about the facts and then you're in a position to make your decision...

DC, my commenting about the SSA addressing the severe problems of the poorly trained diver was supposed to be taken with some humour....Few divers on this board would suggest they know anything at all about the HOW of doing a Surface Supplied Air dive to 100 or 200 feet.... A handful have used a Brownies 3rd lung to 50 or 60 feet, and none would feel this qualifies them to do anything but joke about this topic.

Please don't think I am making light of Commercial diving ---- I think it is incredibly demanding, and it "scoops" from a different gene pool than recreational diving agencies do