Why dive Deep Air?

[ktomlinson]

Speaking about when helium runs out (or becomes cost prohibitive)...I have read that neon may become a more popular mix. Some commercial divers use hydrogen from what I've read, although because of risk that probably will not become mainstream. I am just advanced open water so I don't dive helium, or neon etc yet so if anyone has info to contradict whet I've read please share.

 

[Sas]

Speaking about when helium runs out (or becomes cost prohibitive)...I have read that neon may become a more popular mix.

Neon is more expensive than helium, a fair bit more I think. You might find this link interesting: Exotic diving gases

 

[Dantheengineer]

That Is interesting! Thanks.

 

[drbill]

I did a fair bit of deep diving on air to a maximum depth of 200 ft (my self-imposed basement). My primary reason was to film a few species that were not found in recreational depths. A secondary reason was to "experimentally" test my response to narcosis.

However, I achieved that depth after gradually increasing my max depth over a period of about two months. I found I was able to function quite well down there... locating, framing and following the subjects I was filming (at least the ones that actually moved!). I don't know how many dives I did in that range, but I dove deep for about a year.

However, I lost the primary tank (a 119) due to failure and haven't dived deeper than 150 ft since that happened. I've got enough video footage for the purpose so I don't need to do such dives any more. Today, with no recent experience diving at such depths, I've gotten far more obviously narced at depths of 110-150 ft than I did at 180-200 ft.

I should add that these were not bounce dives, as many lasted up to an hour (total duration of course). All involved deep stops plus a very extended stop in shallow water (15-20 ft). I would double or even triple the deco obligation to be safe.

 

[DCBC]

Deep Air and Trimix each have their uses. None should be used by the untrained. There is also more to diving deeply than the mixture we breathe. Every person has their own personal limits; we should know and respect them.

Like in all types of diving, whether it be Deep Air, Cave, Wreck, Trimix, or CCR diving, there are increased risks that result from each particular activity. Only the individual can say which risks they accept and the ones they don't. A person shouldn't be criticized for diving Deep Air any more than Cave Diving or using a CCR. I would just hope that they plan the dive carefully and dive within the parameters of their experience & training.

 

[TMHeimer]

drbill, in reading these posts I've been wondering how you guys are able to stay that deep for an hour. Doing deco explains the N part, but what about air supply? I know how fast my gas goes at 120 feet. Even with doubles, I can't figure how one could stretch it to an hour at 200 ft. Stage bottles for the deco helps with supply, no doubt, but still?

 

[Cave Diver]

drbill, in reading these posts I've been wondering how you guys are able to stay that deep for an hour. Doing deco explains the N part, but what about air supply? I know how fast my gas goes at 120 feet. Even with doubles, I can't figure how one could stretch it to an hour at 200 ft. Stage bottles for the deco helps with supply, no doubt, but still?

I haven't read through every post here so I'm not entirely sure the context they are using an hour in.

However, keep in mind there is a difference in bottom time and in run time.

Bottom time is the time spent at depth. Run time is the cumulative total of bottom time plus mandatory deco time.

A 200' dive may have a 20 minute bottom time, with an hour of deco, for a total run time approaching an hour and a half.

 

[TSandM]

I'm not sure that the OP really wanted to know about deep air, as opposed to wanting to know what would make people do deep bounce dives. I'm with him -- I don't know what makes people do those. It's always made sense to me, as Mike Ferrara said any number of times, that such dives should be planned and executed as proper staged decompression dives, with the right training and the right resources, no matter what gas you decide to breathe at depth.

Being at 200 feet on a single tank is an awfully long way from the big gas tank in the sky.

 

[DCBC]

A while ago a trusted old freind told me that in his 20s, he and a buddy did a bounce dive on a single air tank to 200 ft. off the coast of San Diego. Said later that night his eyes burned a lot. Also, that it was the stupidest thing he's ever done. Unbelievable narcosis--he said that if they hadn't agreed to keep ONE thing only in mind--to turn around when it reads 200, they may have kept on going to China. I believe I've come across some posts on SB saying stuff like "I wouldn't go below 150 ft. on air, etc."-and some of these posts from folks who seem to have a lot of experience and pretty much seem to know what they're doing. We all know 130 ft. is the rec. limit, one which I never (intentionally) intend to go below. But other than to say "hey, guess how deep I went", are there any other reasons to do this? Got to figure that the incredibly short NDLs down there plus all the ongassing on the way down (AND up to a point) makes it awfully risky. As well, what can you do down there with about 4 minutes bottom time? I'd like to hear from those who have done this for reasons OTHER than bragging, or just to see if they could do it.

Most of the time I've dove air below 150', it's been because I've had a job to do. This has resulted in me using OC and surface-supply. Recreationally I've done dives on air past 200' (some with a single cylinder with others staged). Because of my personal limitations, I max my depth at 250' on air for short periods, but prefer to use Helium below 200 if it's available. The gas selected will depend upon the length of the dive and the availability of Helium.

If I have a short dive to 150' that I want to do, I will not use Helium even if it's available, as it's just not required. It depends upon the complexity of the dive, but it's just usually not needed until much deeper. I've worked many many hours underwater safely at 150' + with air.

Reviewing the statistics, experienced divers are not dieing because of nitrogen narcosis. I'm not saying that I promote the use of deep air to inexperienced and untrained divers, but the fact remains that many of us have used deep air for years safely.

The "Why use Deep Air when you can use Helium?" debate is analogous to a young person saying "Why would anyone walk, if they could drive?" Years ago people did that. It wasn't insurmountable regardless of the statistics that they may show of the high number of pedestrian accidents.

The sport diving limit is 130'. Technical, Navy and Commercial divers go past this limit after they are trained to do so. If you personally require Helium to dive to 150' doesn't mean we all do. Like I said in a previous post, you have to know your personal safety envelope and dive within it.

People that dive deep just to see if they can are taking an unnecessary risk as far as I'm concerned, but it's there life. I've just wanted to complete the job and come home to my wife and kids.

If there is a drop-off or wreck I want to see on deep air, I make a judgment call in the same way as I would with a decompression dive, diving a cave, CCR, or an ice dive. I accept or reject the added risk. If I decide to make the dive, I prepare myself to dive by having the requisite training, proper equipment and planning. There's nothing reckless about it.

 

[diver 85]

To get a picture of a concrete cross @ 165' off Hole in the Wall outside the Inn of Last Resort, Roatan.....Also, to dive Devil's Throat @ CZM, 145 ? I think....