max depth with standard air

[MikeFerrara]

It really depends on the person. I have a half a martini buzz at 150ft (hardly noticeable) and a full martini buzz at 185ft (my limit on air ... but not at a party). I know other instructors on this board that start to feel narced at 100ft. At whatever point you feel that you are not in control, you better ascend or risk the long deep sleep. However, the risk is mine to take ... I don't want someone else telling me that I can't go deeper than 100ft on air simply because that is their limit. We are all grown ups and can chose for ourselves to accept the risk or to refrain from going deep. There is still alot to see <100ft.

The scary thing is that how "in control" you feel has little to do with how you'll perform if you have to reason through a problem that can't be handled by aytomatic responses. How you "feel" may do more to fool you than anything else.

I don't think any one is telling you what to do. You can go as deep on air as you want. Some of us would just rather not be with you.

 

[IndigoBlue]

...Dives below 100ft on air are quite possible and enjoyable and so accomplish exactly what the diver sets out to do - enjoy it.

Most people i know can enjoy a good ship wreck at 120ft and remember it afterwards.

Change the 100ft to 200ft and i maybe more inclinded to agree with you.

OK I will be glad to split the difference: dives below 150 ft on air or nitrox do not accomplish very much, if anything, because the PN2 is excessive.

For additional safety, to reduce the exposure to N2 DCS, I would suggest that dives between 50 and 150 ft be done with EANx using conservative tables like RGBM. And a bail out bottle of 20 to 30 cu ft.

 

[nyresq]

There has been alot of research into different gas mixes for deep diving, moving from helium toward other inert gases. Argon for one is a gas that can be mixed with O2 for breathing mixes.
As helium becomes alot more costly in the years to come you'll see new trimixes with alternate gasses pop up from the US navy and other research projects with deep ocean exploration.
untill then, if you can't pay the entrance fee then get out of the game...

diving is about the most expensive hobby you can get into, aside from collecting cars or something like that. So if you want to save money, then play tennis. All you need then is a racket and a few tennis balls, but if you want to dive, then its going to cost you.
I think most people figured that out when you had spent about $500 just to get your OW btw the class, fins, a mask, booties, gloves and a knife.... and still using rental gear for the checkout dives. But I guess there are still some people who are using stuff that was given t them 25 years ago and wonder why new regs are so expensive...

 

[DA Aquamaster]

There has been alot of research into different gas mixes for deep diving, moving from helium toward other inert gases. Argon for one is a gas that can be mixed with O2 for breathing mixes.
As helium becomes alot more costly in the years to come you'll see new trimixes with alternate gasses pop up from the US navy and other research projects with deep ocean exploration.
untill then, if you can't pay the entrance fee then get out of the game...

diving is about the most expensive hobby you can get into, aside from collecting cars or something like that. So if you want to save money, then play tennis. All you need then is a racket and a few tennis balls, but if you want to dive, then its going to cost you.

There is more to diving than having money and being able to afford trimix. Having a little common sense and an open mind will take you a long way.

Argon is a breathable gas but is narcatic as he** being over twice as narcotic as nitrogen. Good choice there nyresq but to your credit krypton and xenon are even worse.

One of the two viable options is hydrogen which is a little less than half as narcotic as nitrogen, but the saftey issues of handling and breathing hydrogen and oxygen are obvious. Hydrogen, unlike helium is most definitely not inert and while it has been used experimentally as a breathing gas, I don't ever envision its use becoming common.

That leaves neon which is still not as good as helium and as pointed out above would be prohibitively expensive. It would require a CCR to be economically feasible for all but the really rich.

Diving is not nearly as expensive as skydiving or flying. But yes some people have a great deal of cash to devote to it and will do odd and needless things like using trimix at 100 to 150 feet when the dive could be more efficiently. Just proof that money and all the training in the world will still not cure stupidity and also perhaps that those with excessive amounts of cash often see little need to conserve a precious resource.

Rather than telling divers to "get out of the game if they can't pay the entrance fee", my preference is to encourage more people to get into the hobby. I also don't neccesarilly think old equipment is bad. I rebuilt a pair of Scubapro Mk 10's last weekend that were in exceptional shape. I offerred to buy them on the spot as they are frankly better regs than I can get today despite their being 20 years old. Much better than the newer MK 20/Mk 25.

Personally I'd appreciate it if you'd take the snob act somewhere else and leave this discussion to people who really want to discuss and debate the issues from an informed point of view.

 

[String]

OK I will be glad to split the difference: dives below 150 ft on air or nitrox do not accomplish very much, if anything, because the PN2 is excessive.

For additional safety, to reduce the exposure to N2 DCS, I would suggest that dives between 50 and 150 ft be done with EANx using conservative tables like RGBM. And a bail out bottle of 20 to 30 cu ft.

Below 150ft on "Nitrox" fair enough, O2 toxicity.

As for doing them on air, PN2 im guessing you mean narcosis as opposed to deco obligations. Its a personal decision as to risk and so on. I know many people that have had sub 150ft meaningful dives.

 

[MikeFerrara]

There is more to diving than having money and being able to afford trimix. Having a little common sense and an open mind will take you a long way.


Diving is not nearly as expensive as skydiving or flying. But yes some people have a great deal of cash to devote to it and will do odd and needless things like using trimix at 100 to 150 feet when the dive could be more efficiently. Just proof that money and all the training in the world will still not cure stupidity and also perhaps that those with excessive amounts of cash often see little need to conserve a precious resource.

$100 for a seat on a tech boat for a single dive with 30 minutes max on a wreck. That's 200/hour without considering gas (no matter what it is) or travel. In both time and money that's way more expensive that what it costs to fly most planes that private pilots fly. Training costs also are right up there and surpass that of private flight training especially when considering travel. My father's a pilot and tecnical diving is every bit as expensive.

At this point I would ask you to present some kind of evidence that using trimix at 150 ft is useless. You then go on to suggest that it's stupid? I've dived those depths on air and I've done it on helium. Helium is definately better especially when in cold, dark or otherwise challanging conditions. In this case we can, if you want, define better as far more enjoyable. Nitrogen has absolutely no advantage at depth (until you get deep enough to have to worry about HPNS). All the evidence suggests that while you can learn to compensate while performing rote tasks while narced, you just can't learn to think up new solutions to new problems or avoid the perceptual narrowing. Avoiding these pitfalls is not stupid or useless.

In addition there is the increased density of the gas and the potential for it to contribute to increased levels of CO2. Increased CO2 levels of course magnify the effects of narcosis and predispose us to oxtox. There just isn't anything at all good about air on a deep dive.

Rather than telling divers to "get out of the game if they can't pay the entrance fee", my preference is to encourage more people to get into the hobby. I also don't neccesarilly think old equipment is bad. I rebuilt a pair of Scubapro Mk 10's last weekend that were in exceptional shape. I offerred to buy them on the spot as they are frankly better regs than I can get today despite their being 20 years old. Much better than the newer MK 20/Mk 25.

Personally I'd appreciate it if you'd take the snob act somewhere else and leave this discussion to people who really want to discuss and debate the issues from an informed point of view.

Indeed part of responsible technical diving is having the discipline to dive within the limits of your abilities and equipment. If you can't pay the entrance fee you might be better off doing something else. It's expensive, a lot of work and all around demanding in a lot of ways compared to recreational diving. Stretching the depth limits of a gas to save money is, IMO, the perfect example of how not to do it. Oh, and I don't encourage any one to get into technical diving.

Martini any one?

 

[DA Aquamaster]

I spent $9000 on an instrument rating (and that was in 1990) and did it in a normal amount of time. That figure does not include the total flight time and pilot in command time requirements to even be eligible for an instrument checkride under part 91. So 125 hours at a minimum of $40 per hour equals another $5000 (not including the cost of dual instruction for the private ticket) so we are in the neighborhood of $16,000 and that would buy a lot of tech diving equipment and training. Makes a CCR and the required training look positively cheap.

Then of course you have to maintain currency to be able to fly IFR legally with a minimum number of hours and approaches every 90 days. Rental for a instrument equipped aircraft is at least $75.00 per hour, a complex single is at least $120 per hour and a light twin will top $200 per hour. So the money drain to stay current is rather constant.

A hop an pop skydive with about 10 seconds of freefall and maybe 3 minutes under the canopy will run you $35.00. Since you are not counting the boat ride, I won't count the plane ride and we'll call it $675 per hour. Diving, even tech diving, is a relative bargain.

The need to maintain currency should also be true for tech diving but it isn't regulated. Unfortuately some divers choose to make fewer dives and maintain less currency in order to make their dives on trimix even at depths where it is not required (100 to 150 ft.) because they have been trained to believe that doing the dives on air is unsafe. I agree you have to know your limits to do it safely, but that is not the same as saying that dives to 150 ft cannot be made safely on air.

 

[nyresq]

At no point did I say that anyone shouldn't dive, and I think that you took my statement to say that diving is only for the rich. I am far from rich, a standard blue collar get my hands dirty every day kind of guy, and I do not see my attitude as being snobbish. My attitude is if you are not prepared to spend the money for redundant equipment, the required training, and the associated expensive little add ons (fills) that go with deep or technical diving then don't try to half a$$ your way through it by cutting corners.
I'm not trimix certified yet and I don't dive deep air, not because I can't afford it but because I don't see a need for it. I have plenty of wrecks in the NY area above the 150' limit I feel comfortable at.
At some point I'm sure I will seek out a good trimix instructor and get my cert, but I won't walk around complaining about how much mix fills cost, or trying to do something on air because I'm short on cash this week.
Like I said before If you wanna play it is going to cost money, and if a mix fill is beyond your financial means, then technical diving isn't a viable option for you. Cut some corners and you're likely to end up bent, or worse.
I encourage every one I know to try scuba diving, and have made a few die hard divers by doing so, but I also tell people that the deeper you go the more it will cost.

 

[DA Aquamaster]

I'm not trimix certified yet and I don't dive deep air, not because I can't afford it but because I don't see a need for it. I have plenty of wrecks in the NY area above the 150' limit I feel comfortable at.

I took your statement to mean you were one of those well meaning but over cautious people who denouce the use of air at depths from 100 to 150 ft. and who do not always objectively weigh all of the pros and cons of using air at those depths. For many the definition of deep air seems to be anything below 100 ft.

So you have my sincere apologies as your last post clearly indicates you have not yet gone over to the dark side.

 

[padiscubapro]

The scary thing is that how "in control" you feel has little to do with how you'll perform if you have to reason through a problem that can't be handled by aytomatic responses. How you "feel" may do more to fool you than anything else.

I don't think any one is telling you what to do. You can go as deep on air as you want. Some of us would just rather not be with you.

Mike,
The part of you brain that is responsible for your personal awareness is also the part thats most effected by inert gas narcosis..
Narcosis is a very variable situation from person to person and from day to day.. I know from past experiences repetetive deep exposures APPEAR to raise a persons resistance or ability to cope with narcosis at least for a limited time.
Personally, when I am diving locally I always have helium in the mix (I dive a CCR so there is no reason not to), but I know I can function reasonable well with high PN2s even in "emergency" situations. I have been on deep wrecks before I dove helium (200ft range) where the guidline was severed and still had my wits to do the right thing..
Last year in truk I was inside the Aioku Maru (sp) second level on my CCR with air dil, I was at about 220 (I don't remember the exact depth)with a setpoint of 1.3 (so my narcosis was even higher).. I had no problems navigating the wreck, taking pics and controlling my RB( I do alot of manual control).. Would I have rather done in on Helium YES!, but I never felt out of control and was definately aware that impairment was present.

BTW for all those that say Helium is not narcotic its not true.. Its true for low exposures as the PHe rises narcotic effects BEGIN to set in (COMEX studies show it starts about a PHe of 6, but much less narcotic than Nitrogen) . They also have evidence that at low and moderate pressures a little Helium goes a long way, alot of helium is not necessary(definately not in the range some people advocate).. The resulting narcosis is lower than what is "predicted" by END formulas (even those that only look at the Nitrogen component as being narcotic)

Another fact that always seems to get lost my many is that high narcotic levels tend to lower the risk of CNS type seizures. PO2 exposures that would risk a seizure at low narcotic levels, doesn;t seem to happen with very high narcotic levels. This is not to say other OTOX symptoms are not present, just the most dangerous one seems to be held at bay.
The one thing I forsee is that someone is going to have a CNS seizure at a moderate PO2 level that otherwise wouldn't have happened and some may call for lower PO2 exposures.