Diving past 130' on air with a single 80?

[Whale Whisperer]

Can anyone give me their opinions on diving greater than 130' on air with a single 80 tank? Since the begining of my training I was taught that going past 100 with air on a single 80 is unsafe. I'm new to the Diving world and certified up to PADI Wreck diver. The Tec world sounds like something I'd like to dive into the near future (I've Been doing alot reasearch).

I'm asking this because I recently visited Guam and inquired about Wreck, Tec, and Cave diving because I may end up moving there in the near future. In one of my conversations at a Guam LDS, I was told about a cave dive that started in a wall down at 180', so I said "WOW! That's advanced Trimix levels with Doubles!?!? Right?" The answer I got was laughter in the entire room LOL (I'm laughing with them). I felt pretty stupid and ignorant, and I tried to understand why they thought this was humerous. Some explained that Trimix was unnessecary and it would be impossible to fit the enterance with doubles, and Narcosis wouldn't be that bad. I have personnaly experienced narcosis, and I can say that my reaction/processing times are noticeably reduced.

Then there's the machismo saying that I've heard "You haven't dived yet till you've been down to 200'!". I have talked to some that have been to 200', and they do it just for braggin rights and have done it more than once, to share the experience with others. The explanations I've heard are trust your eyes and focus on something to keep your wits, and as long as you follow the Deco instructions on your computer, you'll be fine.

So far I haven't found any threads about this subject. So... Am I missinformed and overly cautious about this? or reasonable? :06:

Thanks in advance!!!

 

[Walter]

Everyone is severely impaired on air at that depth. Depending on your air consumption your gas volume might be OK.

 

[RikRaeder]

Is it possible that the LDS in Guam was pulling your leg?

 

[H2Andy]

people have done air dives much deeper than that. most survived. some didn't.

with Trimix being available, there really is no reason to risk the dive on air.

also, that deep, i wouldn't dive on a single tank unless it had an H-valve (i.e.
two independent first stages), minimum. doubles would be preferred, or in
this case, independent singles due to constriction.

speaking of which... you are now talking major restriction... do you know
how to handle restrictions? overhead environments? may seem easy, but
it can really bite you.

not to mention that, assuming you have any air left on an AL80,
you are going to hit deco in less than 10 minutes. are you
prepared to deal with deco? what about emergency reserves?
what's your safe minimum turn pressure to get your buddy and
yourself back to the surface safely? i don't think you're
going to have much of a dive... maybe a couple of minutes,
if that much, at depth, if you build in a proper reserve
(it may even be impossible).

i think your response is the safe, sane response.

can it be done? sure, and it has been done before.

is it a good idea? probably not.

finally, it's all about confort level. dive the level of comfort YOU are
comfortable with. if it doesn't sound good to you, don't do it.

when the brown stuff hits the fan, it's going to be your butt
on the line, not theirs. you need to be confident you can get out
safely.

but, seriously, this dive on an AL80 is a bit ridiculous. are you
sure they weren't messing with you?

 

[AaronR103]

Assuming you have the proper training, experience, and expertise (big assumption I know), there is no reason you shouldn't be able to dive to 180 on air. Ox-tox shouldn't be a problem at that depth, but at 1.36 atmospheres pO2 you are pushing the low end of the 1.4-2.0 pO2 that you need to start being wary of. Back before trimix tech divers used to make runs like that all the time. Your biggest problem is going to be burning air once you get down that deep. I have yet to hit that depth but I can't imagine a standard 80 would last very long, particularly not to start a cave dive. You are right to be wary and very right not to fall into the machismo trap. Stay within your comfort zone till YOU are ready to push a new limit.

A

 

[Rick Inman]

I would consider 180' on air an overhead. I don't know anyone with proper overhead training that would do it on an al80.

 

[ianr33]

I suspect I could do a brief dive to 180 on a single 80. But,in the event of a freeflow,burst O ring etc etc I suspect I would be dead in rather short order.

 

[DennisS]

I was in Cozumel and some guy that had been through various rehabs was thrilled that he got 200 on his computer. He was using a single 80. He said that now he was justified to wear the shirt "At 200' no one can hear you scream".

Yes it can be done.

 

[scubak]

I would not go to 180' on a single 80, that is too slim for me and I hate "bounce" dives...heck, I would do it on my HP 80 twins, but the NN on air is very great...I go by the plan that Oxygen toxicity starts at anywhere between 180 and 235 depending on your own pysiology (that varies day by day), for me it is "too deep" a dive just on air.
Just my 2PSI
K

 

[Vayu]

One of the interesting things about diving is the variety of opinions around the world about what constitutes safe diving practice. As a wreck diver certification holder you have probably developed some opinions about safe practice that are in conflict with the proposed dive. Here are a few of my concerns:

1. Respect narcosis. At 180' it is very likely you will be hit by the rapture of the deep. Most deep air dives are done in controlled environments with as little extra work on the divers part as possible. I have spoken to a notorious deep air diver on the subject and he was very explicit about the need for relaxation and the need for progressive levels of deep air training. I will not deep air dive but those who do it take it pretty seriously and I doubt they would be cought in a cave in guam with people who think its funny.

2. Respect the amount of gas in your tank. As the pressure increases at depth the density of your consumable air will also increase. As you continue to breathe in the same volume of this gas you will find that it does not last as long as it would at the surface. On a single AL80 it is unlikely that at 180' you will have enough in the cylinder to enter overhead not to mention help anybody else in the case of an emergency. At that depth you are messing with an absolute pressure near 7!

3. Respect tissue saturation. Goes without saying at that depth on air you will ongas pretty quickly. Combined with point 2 if you should have a gas failure it is unlikely you will be able to surface without getting into trouble unless it is a bounce dive... which this does not seem to be.

4. Respect the environment. If you have aspirations to continue with technical and cave training, do not do it with these people. Cave training should not begin with entering deep restrictions. If you can't enter it on doubles due to the size of the entrance chances are you should not be there for your early training. I am not a caver but this seems to be a common sense issue.

5. At 180' on air it is not likely you will be able to make sense of what your computer is telling you. Gauges can get really wierd when you are narced and I have experienced this first hand. If you are relying on the computer to keep you safe during a particular dive than chances are you are taking a chance being there.

That is just how I would approach it. Alot of people have gone deep and into overhead without training but it doesn't mean they will always get lucky and it doesn't mean newbies like you and I should be doing it. Just take it slow and tackle Guam progressively until you are confident you can make this sort of dive. Find some buddies or mentors that won't laugh at you when you bring up valid safety concerns. You are right to question the logic of these types of dives and it will likely save your life. The ability to recognize problems before you hit the water is worth its weight in gold.

-V