out of air emergencies

[lmarks]

Hi,

Despite diving for 37 years and being somewhat of a "techie" I am new to ScubaBoard and I am thrilled that thsi forum exists. I presume that this is a well-worn topic of discussion, but I would like to raise it for discussion.

I just returned from a fairly "tame" diving trip to Bonaire. Maximum depyhs all below 100 feet and virtually no current. I am an avid underwater photographer and, as such, often get distrated by an interesting subject and lag behind the group. Furthermore, I have notices that the buddy system is really non-existent on these group dives. There were no emergencies, but I got to wondering how we have come to rely on our equipment to such a degree that we are not really prepared for out-of-air emergencies. Thus, I have the following questions:

What is the maximum depth from which one can make a safe free ascent and what are the guidelines for doing so ?

Does the expansion of air that occurs with a free ascent depress the feeling of a need to breath, which would obviously be disastrous, and if so, for how long ?

For recreational non-deco dives, do people think it is excessive to carry a redundant air supply ?

If not, what are your experiences with such air supplies - camparing pony bottles, the "spareAir device," the "dive buddy" and the H2Odyssey (or others) ?

I look forward to your responses and hope to be an active scubaBoard participant.

Lloyd

 

[El Orans]

Hi LLoyd,

welcome (Scub)aBoard!

Rule #1 get a good buddy, one that will stay with you.

Rule #2 you don't want a SpareAir.

Rule #3 recreational dives can be very diverse. Even so, I do not carry a redundant air supply.

 

[Diver0001]

I'm going to enjoy this. Welcome to the board, Lloyd.

R..

 

[Michael Schlink]

First welcome to the board, you'll find a wealth of info and opinions here, of which I'm sure you're about to find out.
Unfortuantley the so called buddy system has been failing for sometime now and not because of any great improvements with equipment, but more than likely a decline in the emphasis of the importance of staying close to your buddy.
In my experience, and that is rather extensive, I often see divers " out of range" of their buddy and noy really aware of the fact of the danger they are in or have put their buddy in. That said to answer some of your ???

Free ascent-that is a PRACTICED skill, one that few ever practice and so from what depth a person can make an "emergency ascen" from will vary greatly. Most divers should be able to make a CESA from 40'-60', much deeper and your going to start to see divers exceeding a safe ascent rate and breath holding

Expanding air in the lungs won't depress the desire to breathe, but blowing out the expanding air will help, a build up of CO2 is going to trigger the urge to breathe so getting rid of excess CO2 may help. Regardless, a constant exhalation, is an absolute must do.

How different people feel about a "totally redundant air supply" I can't say, as you are probably about to get a bunch of them (opinions). But I almost always dive with something, A stage or pony type. However, and I feel the flames at my feet, I'm a big proponent of a Spare Air or similar device, the caveat, "when properly used".

LET THE GAMES BEGIN

 

[TSandM]

The dive to breathe is generated from carbon dioxide. Because it controls your acid-base status in your blood, carbon dioxide is VERY tightly regulated. What determines the carbon dioxide level in your blood is the number of liters of air per minute that are passing through your lungs. During a CESA, you are not exchanging air, and therefore CO2 is building up in your blood. Therefore, I would not expect someone to be free of the drive to breathe during a long CESA. I would expect you would have to use a fairly rapid ascent rate to make a CESA successfully from depths below 100'.

I did chat with an elderly gentleman one day after a dive, who told me he had been a submariner and they had had to practice CESAs from 100'.

I take a redundant air supply with me on my recreational non-deco dives. His name is Peter

 

[spectrum]

Carrying a substantial pony bottle is not excessive and you can read here on the board of many who travel and dive with one. I have some well travelled local buddies that use them and even keep the as SOP for local shore dives. Some sort of redundant air supply is often required for significant (non techical) boat dives around here.

Deeper than 60 feet you are pushing the limits of a CESA. This is loosely regarded as part of the logic for 60 foot rule for new (OW) divers. After 60 feet life is a little less forgiving.

Remember that as you ascend the ambient pressure will be dropping and your regulator may be able to deliver another breath or two along the way. This is one reason to keep the regulator in your mouth no matter what. As you "go and blow" you can always try to inhale if the discomfort is too much.

Pete

 

[OE2X]

Personally I like my backup to be my buddy. If I am to solo dive on a single tank - which is what I dive anyway - then I'd take a 40 cft deco bottle slung. It's overkill in size, but I wouldn't take anything less than a 30 cft anyway.

Don't bother with spare air.

Years ago we were trained to do CESA's from 60'. I suspect that still wouldn't be an issue now.

I take a fair number of pictures underwater. I also dive with other people that do the same. The one thing in common that we keep in mind, is buddy awareness. I know it's hard to comprehend two divers totally involved in taking different pictures and yet still be near and aware of each other at the same time. It does take practice and it won't happen with a buddy of circumstance (BOC) unless you do the following.

In that case - when I buddy up with someone new, in the pre dive plan, I explain what I'm trying to accomplish with the dive. If my BOC has no problem with that, then great. If he or she does, then I evaluate whether or not I want to find a new buddy or not take pictures. Generally I opt for the latter choice and enjoy the dive with good buddy skills.

 

[Gary D.]

A Free or Buoyant assent (ECSA) can be made from any depth within safe SCUBA limits as well as much much deeper. Granted you might be looking at getting bent depending on time at depth and a host of other things but that’s not the question here.

There is no urge to want to breathe and it is quite a trip to exhale for two minutes or longer.

Gary D.

 

[Mr Carcharodon]

The LA County UICC program did emergency assents from 100' as a standard part of the class around 20 years ago. I remember talking to a student who did this and she said while this exercise was approached with trepidation everyone did it and no one was harmed. Everyone was required to demonstrate swimming 60' horizontally underwater in a pool prior to that exercise. So I imagine that preconditioning helped. That course has since switched over to a NAUI curriculum and dropped the 100' assent. Was this risk free? Probably not, but it was a required part of the curriculum for a period of time. So what we are capable of may be greater than most suppose.

 

[Gary D.]

The LA County UICC program did emergency assents from 100' as a standard part of the class around 20 years ago. I remember talking to a student who did this and she said while this exercise was approached with trepidation everyone did it and no one was harmed. Everyone was required to demonstrate swimming 60' horizontally underwater in a pool prior to that exercise. So I imagine that preconditioning helped. That course has since switched over to a NAUI curriculum and dropped the 100' assent. Was this risk free? Probably not, but it was a required part of the curriculum for a period of time. So what we are capable of may be greater than most suppose.

As time goes on more and more gets taken out of the training and a specialty course made up to replace it. The minute the least bit of danger arises the courses get changed to eliminate the danger.

One of these days someone will realize that the possibility of drowning exists while diving so water will be eliminated all together.

Free and Buoyant assents are a good skill to know and should have never been eliminated.

Gary D.