Deep Diving on Air

[Tigerman]

Well, atleast my book says 18m/60ft recommended novice maximum, 30m/100ft recommended max and 40m/130ft absolute maximum. (Page 204 in the PADI OWD manual v2.5 norwegian).

 

[MauiScubaSteve]

So, have you taken a deco procedures course; or do you just intend to rely on your computer to get you back to the surface safely?
secondly, would you have felt safer doing your 137' dive on air or on 32% and why?

I have 5 major joints (entire right side) with significant "impact calcification" and during my one on one conversations with the "Father of recreational Nitrox" he advised that "deco diving" is perhaps riskier for me than for a "less impacted" diver. I have followed that advise; not progressing past Intro to Cave, because at that time the next levels of cave training all seemed to require deco.

As far as I understand my computer, dropping down to 50 m for a quick pic does not necessarily put me into deco. If you look at Trace Malin's posts in the Bahamas Diving thread, work (swimming) perhaps elevates risk, and I would be scootering if there is any "mandatory time" showing on the computer.

After my PADI EANx training, in the classroom adjacent to Dick Rutkowski's office, I was "programed" to be wary of PPO2's greater than 1.4. A month later, after spending more time "next door" I had a better historical knowledge of Nitrox.

The day we dived 28% to 137', we were also making the afternoon trip, so less nitrogen on the morning dives perhaps meant longer bottom time on the afternoon dives, or longer bottom time at the Bibb and "same" bottom time on afternoon dives. Those same TDI divers perhaps had even longer afternoon bottom times on those same afternoon dives.

I was showing the discipline of a prudent instructor and diving within my agencies Standards, as far as I understood them (137'?). Not sure that my feelings with regards to safety would have changed; I would have followed my training to stay safe no matter the mix.

 

[dumpsterDiver]

So I'm interested in "our" ambiguous discussions regarding diving below the "rec dive limit" partly because when I spent 6 weeks diving Key Largo the spring of '01 there were divers exceeding the published "rec dive limit" weekly; from PADI "5-Star" Boats.

I made the Bibb dive pictured below just a couple weeks after becoming a PADI EANx Specialty Instructor (and Wreck Specialty Instructor). We followed our training with regards to PPO2; my tank was an LP 95 with 28%, my buddy Adam (pictured; one of the MSDT's involved in my Instructor training) started the dive with 107 cf of 28% and he was also a EANx and Wreck Specialty Instructor. After I took the Goliath pic I turned around to find a TDI Nitrox "class" waiting their turn; something like 7 divers, including their Instructor, all on 32%. My computer registered 137' when I was taking that pic.

A couple weeks later, after accepting Hyper Dick's invitation to "cross-over" to IANTD, I could have followed my "new" training and made that dive on 32%. At that time it seemed to me that the last number in "all" the recommended "rec dive limit" mantras was still considered a recommendation; not the hard "rec dive limit" it seems to be today.

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Since then I have been to 146' and 138' on air, for a total of less than 2 minutes below 132' on air. I now have a dive site across the street where possible interesting outcrops between 130' and 150' are visible to me when cruising at ~110' deep. I am contemplating taking a quick closer look at one or two of these hard bottom spots, and since it is really only a few feet deeper than I have already dived my trepidation is minor, but having like minded and more experienced divers to converse with about this kind of activity would seem to be prudent.

Who does wreck dives with the pony bottle sticking out like that?

 

[MauiScubaSteve]

Who does wreck dives with the pony bottle sticking out like that?

And here I was expecting your posting to contribute something a little more relevant to the topic of this thread than my postings.

:shocked2:

 

[DivemasterDennis]

Years ago I had a flying instructor tell me " There are old pilots, and there are bold pilots, but there are no old bold pilots." I think the same is true of divers. I am not referring to trained techies who have the proper equipment and gas and training to dive to the center of the earth. That's their deal. But recreational divers going 200 plus feet on air is just stupid. I have two friends that have done this, one a dive professional, and they are stupid for doing it. Absent proper training, proper gas, proper equipment and as noted above, proper planning, diving to that depth is nothing to even talk about. Therefore, with this politically incorrect but very clear opinion, I label divers who do it "dumbass," and hopefully end the thread.

 

[blackvans1234]

I dive with my wife all the time.
#1. We wouldn't be doing a 300 foot dive on air without redundancy.
#2. If I don't have the air to go down there and get her and get back to the surface alive, what's the point in going after her if she is at 400ft?
#3. I wouldn't let my buddy get that far away from me.
#4. It is an easy statement to ribbit back. That is how we are trained. Follow your training. Just like in the military. Go against it and you are on your own.
#5. In this instance if the one person didn't go down to 400ft to get the other diver, he would be ok the other diver would be ok and we have only lost one diver. Instead we have a dead diver, a paralyzed diver, and one we think is going to recover. Cost to benefit? Never become the 2nd casualty. I can live with that.

Maybe said loved one / friend looks closer than they really are because of the tricks water can play on the eye. Add narcosis, and the fact that the person is probably still descending, maybe 100 feet under you only started out as 40 feet under you. (you look, notice they're far down, contemplate going, check gauge, check your depth, look down at them, maybe try to signal first, then decide to descend and get them)

If someone is not doing most of the things I listed then they're asking to be a second victim. But by doing those things they're allowing the person to descend further.

It reminds me of a statistic I heard regarding professional security drivers vs normal drivers.
A normal driver will take TEN seconds to respond to an attack, the trained professional will take about 3 seconds.

 

[MauiScubaSteve]

...But recreational divers going 200 plus feet on air is just stupid. I have two friends that have done this, one a dive professional, and they are stupid for doing it. Absent proper training, proper gas, proper equipment and as noted above, proper planning, diving to that depth is nothing to even talk about. Therefore, with this politically incorrect but very clear opinion, I label divers who do it "dumbass," and hopefully end the thread.

Without you quoting a post, it is hard to follow your "proper planning" quip, but I did not read anything from the OP in this thread that makes me conclude that proper gas, equipment and planning did not happen for the dives the OP posted about, nor am I able to conclude that his dives were deeper than 200 feet.

I am quite fine with limiting discussions of Deep Air Diving to 1.6 PPO2.

I am still saying that since "Pandora is definitely out of her box" a forum where Deep Air Diving is intelligently discussed, with a Mission Statement something like "putting at least a 40 on the vast majority" would be a logical advancement to the safety of diving.

 

[dumpsterDiver]

And here I was expecting your posting to contribute something a little more relevant to the topic of this thread than my postings.

:shocked2:

OK, I'll try, really....do your silly little drop to see a ledge 25 feet deeper than your normal dive for 2 minutes. It isn't going to be a big deal. You aren't going to freak if that dacor scooter cracks, floods, gets heavy and takes off when the internal water shorts it out right?

I thought Rick's post was excellent and pretty much covered the issue. Most of the remaining posts are poo flinging back and forth, often between people who are commenting about something they've never experienced.

I dive to 185 feet on air, solo with a single tank, a pony bottle in a high current environment without any ascent or descent line. I try to spear fish and keep my deco to less than 12-15 minutes and hope my buddy finds me floating a mile or so away from the wreck when my deco is done.... a few times every month.

My biggest worry is sharks, second is entanglement, third is decompression sickness and fourth is narcosis. My training has never been past recreational depths.

Maybe that is relevant to the OP's original question, but I'm sure people will think I'm calling the kettle black when I bitch about the pony bottle placement.

 

[TechDeep]

I can dive to xxx ft. on air, no problem = I can drive just fine after drinking xx beers in an hour, no problem. And the worst part is, they both are convinced they are right.

Couple of points...

OxTox -
Air reaches a PO₂ of 1.6 ATA at about 220', so if you plan to spend more than 45 minutes on the bottom (!) at 220 then OxTox might be a problem... but I reckon the 6+ hours of deco might be a bit more of a concern, eh? In the only real high PO₂ experiment I know of, all the test subjects endured a PO₂ of 3.1 ATA (about 450 FSW on air) for at least five minutes before any signs of OxTox (test subjects were put on 100% oxygen at 70FSW in a chamber every day for 30 days running; each day until OxTox symptoms were observed). And as alluded to earlier, it appears that high PN₂ takes the edge off OxTox as well, so of the big three (OxTox, Narcosis and decompression obligation), it appears that for most "Deep Air" dives OxTox is rarely a significant factor.
Narcosis -
Often underestimated. Why? Because you are your own worst judge of narcosis. I hear people say "I don't get narced at all at xxx feet." It just ain't so... There was a fellow over in England not long ago that ran a little narcosis class at 100FSW. Nearly *all* his students were *absolutely sure* they didn't have any narcosis at 100 FSW. But he was able to demonstrate that every single one of them was in fact narced at 100' simply by getting them to do something stupid that they'd agreed not to do under any circumstances before the dive! I can nearly hear the "not me"s out there as you read this, but his results are conclusive. I know, for example, that when I pass 100' going down, that when I look at my gauges I have to think about what they're telling me and consciously register the information, otherwise I'll look at 'em and stow 'em and then realize that though I read them I didn't register the info. Perhaps my favorite narcosis story comes from my brother-in-law John. He relates how after tracking a grouper for a few minutes at 130', "pretty soon I was a fish... right up 'til I ran out of air." Scuba history is replete with divers who "just kept going" on deep air until it was too late to make a safe ascent... who either perished at depth or ended up hurt really bad or dead from DCS. (Two very recent cases attest to this)
Narcosis is the one of the big three that usually gets divers to violate the limits of the other two. If a diver insists on diving deep on air, he must make all critical dive decisions - depth, time, minimum ascent gas, abort criteria - before getting in the water, and stick to the plan period. I don't care how confident you are of your decision-making at depth, it is impaired. Make the decisions topside.
Decompression obligation -
In my deep air days I must admit I often carried far too little gas for contingencies. It was only by being totally anal about the dive plan that I didn't slip into that "just another minute" at depth that runs the deco obligation beyond the gas supply. Many divers today still dive deep air with too little gas onboard. It literally takes "just one more minute" or "just a few more feet" to get that big fish and to put the diver at extreme risk for DCS due to not enough gas.

Bottom line... there are ways to do (moderately) deep air with a margin of safety that's acceptable to me, but my envelope has shrunk considerably with age, and especially with the wider availability of helium.
Rick

 

[MauiScubaSteve]

You aren't going to freak if that dacor scooter cracks, floods, gets heavy and takes off when the internal water shorts it out right?

Well, the Apollo AV-1 brochure lists the recommended max depth as 165 feet.

Andy likely does not now mount pony's like he did on his first mounting, over 10 years ago; my pony mounting looks like this...

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:shocked2: