Question Practicing Out Of Air ascent: good idea, or bad idea ?

Please register or login

Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

Benefits of registering include

  • Ability to post and comment on topics and discussions.
  • A Free photo gallery to share your dive photos with the world.
  • You can make this box go away

Joining is quick and easy. Log in or Register now!

So the US Navy recommends to take 60 seconds to ascend to the surface from 10 meters ? That's 6 seconds per meter. It would require a lot of self-discipline for sure.
So from 30 meters, 3 minutes ? That sounds like an eternity.
Good to know that such a thing is doable, though ( in theory, at least ...).
Agree with @Marie13 , IMHO you are better off bringing some redundancy when you are 30m or deeper.

So it’s more than unlikely you have a double failure before you can ascend …
 
Is it considered a bad idea, or a good one, to practice Out Of Air ascents (with a functioning regulator in mouth, of course), and if so, what is the SLOWEST realistic and SAFE rate of ascent for a diver that is not panicking (and who does not want to panic) ?
To instill in me and my fellow open water students just how incredibly slow 60 fpm (1 fps) really is, the open water course I took (in 1986) had us swim/crawl the 25 yd length of the swimming pool, underwater, while releasing a steady stream of bubbles--a total of ten times!

Two students at opposite sides of the pool breathe, submerged, from two cylinders. A third student, after just having released his/her reg and cylinder to one of the two earlier students, swims/crawls U/W the 25 yds to the other student, and receives the reg and cylinder from him, releasing him to go the other way.

Each trip takes at least 01:15 min:sec (at least 75 seconds). So, the skill keeps all three students underwater for at least 30 times this length of time--a very long time, indeed!

The students do not wear masks.

A Teaching Assistant swims (with a snorkel) on the surface directly above the crawling student.

Believe me, at the end of this skill, each of us understood exactly how incredibly slow 60 fpm really is, and how incredibly calm we had to be to maintain this pace.

Back to the OP: Would I want one of my children (say) to practice an out-of-air ascent vertically? No. The risk is too high. Would I practice an out-of-air ascent vertically, myself? No. the risk is too high. (I need to remain reasonably healthy for a while, for my children.)

rx7diver
 
@Roger Hobden: Touch Weight Belt buckle to remind you to drop weight in an emergency. Orally inflate at the surface because you are pretending to be OOA and your wing inflator won't work...
The weight belt should not be dropped in a controlled emergency swimming ascent. If your BCD is working and expanding as you ascent, there is no need for it, and there is no need for the resulting out of control speed. From the depths you are talking about, a CESA can be done easily.

Weight belts are dropped at really serious depths or if you are in some doubt about your ability to swim to the surface, perhaps because of injury or illness (like feeling you've had a heart attack).

When I passed my instructor exam, we were specifically told by the examiner that even though the language of the CESA calling for a "normal ascent rate" suggests no more than 60 FPM, in a real situation, an OOA diver is likely to go faster than that, and that is OK. We were told not to be too anal about that ascent rate. (If I were practicing this on my own, I would not do it too fast.)

The biggest danger is holding your breath. You MUST exhale all the way to the surface. People who are concerned about their ability to exhale all the way, especially if they have just exhaled, should understand that for submarine escapes, the Navy teaches to exhale fully before beginning the ascent, and then continue to exhale the expanding air as you go. This has been done from 300 feet.

I never practice this because it is so easy. Just remember to exhale while you ascend.
 
To instill in me and my fellow open water students just how incredibly slow 60 fpm (1 fps) really is, the open water course I took (in 1986) had us swim/crawl the 25 yd length of the swimming pool, underwater, while releasing a steady stream of bubbles--a total of ten times!

Two students at opposite sides of the pool breathe, submerged, from two cylinders. A third student, after just having released his/her reg and cylinder to one of the two earlier students, swims/crawls U/W the 25 yds to the other student, and receives the reg and cylinder from him, releasing him to go the other way.

Each trip takes at least 01:15 min:sec (at least 75 seconds). So, the skill keeps all three students underwater for at least 30 times this length of time--a very long time, indeed!

The students do not wear masks.

A Teaching Assistant swims (with a snorkel) on the surface directly above the crawling student.

Believe me, at the end of this skill, each of us understood exactly how incredibly slow 60 fpm really is, and how incredibly calm we had to be to maintain this pace.

Back to the OP: Would I want one of my children (say) to practice an out-of-air ascent vertically? No. The risk is too high. Would I practice an out-of-air ascent vertically, myself? No. the risk is too high. (I need to remain reasonably healthy for a while, for my children.)

rx7diver
This sort of exercise is something I have campaigned against almost the entire time I have been an instructor. Doing a CESA horizontally is VASTLY different from a vertical ascent in a real emergency, where the air in the lungs expands rapidly. I have long argued that the horizontal CESA teaches the completely false notion that you won't be able to make it that far when in fact you can make it easily. I believe that false understanding may be the reason that the number one cause of accidental deaths, according to a DAN study, is divers getting air embolisms after a panicked ascent to the surface. The panicked divers assume they can't make it, and so they hold their breath.
 
This sort of exercise is something I have campaigned against almost the entire time I have been an instructor...
Two main purposes of this exercise, as I understood it, are (1) to instill in the students just how incredibly slow a 60 fpm pace really is, and (2) to give the students the confidence that they can maintain this incredibly slow pace for over 75 (!!) seconds, while continuing to release a steady stream of bubbles (if the students remain very relaxed).

Some people, myself included, find/found these lessons invaluable.

Many of the exercises in that 1986 course stressed just how long a diver can function if his/her scuba ceased delivering air, just how much time a recreational diver actually has, in reality, for resolving an U/W issue.

rx7diver
 
Sure, it's always a good idea to periodically practice basic skills like simulated out-of-gas emergencies and gas sharing ascents. The trouble is that many divers never learned these skills properly in the first place (or have forgotten) and if they try to practice on their own, they end up creating bad habits or even putting themselves in danger. If you are unsure of your skills, then taking a GUE Fundamentals course is a great option; the instructor will take you through it step by step and then help you practice in a safe environment.

The exact ascent rate in terms of feet or meters per minute is not super important in a real recreational diving (within NDL) emergency. The important thing is to keep the team together and make a crisp, controlled ascent to the surface. Not too fast to cause a lung overexpansion injury and not too slow to run the donor out of gas. No bouncing up and down.

As others have pointed out, it's obviously better to avoid running out of gas in the first place. So, on the priority scale it's more important to focus on proper gas planning and management. But even if you do everything right, it's still possible to end up out of gas (or without access to the gas you do have) due to equipment failure. Or another diver who just happens to be nearby might come to you for help. Be prepared for that instead of thinking that it will never happen.
 
Sure, it's always a good idea to periodically practice basic skills like simulated out-of-gas emergencies and gas sharing ascents. The trouble is that many divers never learned these skills properly in the first place (or have forgotten) and if they try to practice on their own, they end up creating bad habits or even putting themselves in danger. If you are unsure of your skills, then taking a GUE Fundamentals course is a great option; the instructor will take you through it step by step and then help you practice in a safe environment.

The exact ascent rate in terms of feet or meters per minute is not super important in a real recreational diving (within NDL) emergency. The important thing is to keep the team together and make a crisp, controlled ascent to the surface. Not too fast to cause a lung overexpansion injury and not too slow to run the donor out of gas. No bouncing up and down.

As others have pointed out, it's obviously better to avoid running out of gas in the first place. So, on the priority scale it's more important to focus on proper gas planning and management. But even if you do everything right, it's still possible to end up out of gas (or without access to the gas you do have) due to equipment failure. Or another diver who just happens to be nearby might come to you for help. Be prepared for that instead of thinking that it will never happen.
I agree on these points. Assuming you learned a CESA properly to begin
with (not rocket science, must be a very poor instructor if you didn't learn it properly...), you must practice it for it to be of any use. Just like anything else you learn anywhere (unless with some things if you have an eidetic memory). Like my old pet peeve of people taking CPR once every 2 years, doing nothing in between and figuring they know it.
 
I agree on these points. Assuming you learned a CESA properly to begin
with (not rocket science, must be a very poor instructor if you didn't learn it properly...), you must practice it for it to be of any use. Just like anything else you learn anywhere (unless with some things if you have an eidetic memory). Like my old pet peeve of people taking CPR once every 2 years, doing nothing in between and figuring they know it.
I think you might be mixing up two separate procedures. A controlled emergency swimming ascent (CESA) as taught in the PADI OW course is for a single diver to go straight to the surface without sharing gas. That is only intended as a last resort if you're out of gas and separated from your buddy.

Personally, I am skeptical about practicing CESA outside of a training course as there is some risk of a lung overexpansion injury. Whereas practicing gas sharing ascents is very safe as long as the divers follow the correct procedure.

For a gas sharing ascent in open water, you shouldn't be actively swimming (at least not much). Both divers are supposed to manage their own buoyancy using their BCs (and possibly drysuits) and be neutral to slightly positive throughout the process. They should maintain horizontal trim and shouldn't swim up. If they try to swim up, then it's really tough to stay together. In real emergencies if both divers try to swim up together then usually one diver ends up ascending faster than the other and the donated regulator gets yanked out of the receiver's mouth. Even if you hold onto the other diver's arm or harness it's easy to lose your grip and get separated.
 

Back
Top Bottom