SSI and turning off air?

[tep]

When I certed with NASDS in 1977 - turned off air and CESA'd from 30', open ocean with the instrutor beside you all the way. Practiced in the pool, first.

Two years ago, SSI cert - turned off air in pool, not in open water.

Did the cert in the same location, 30 years apart

 

[samcam]

I did mine two years ago and practiced it in the pool in the shallow end. He wanted us to experince the feeling. When we practiced it in the deep end we simulted we were out of air then shared air with our buddy on the way up.

 

[yarik83]

When I got certified I had to drag myself and my instructor on the way to the top. I did not have enough air coming from 30 feet. Apparently his idea was to shut it off and immediately turn it back on to trick us into thinking we really have no air. So i took off faster than a dolphin on steroids with my instructor hanging off my valve. About 10ft from surface i ran out of air in my lungs and i did not like the feeling. I do think its a very good exercise but also a valuable lesson. Ditch weights+swim normally and have energy for 30ft ascend... panic and take off with weights and you will be sinking to the bottom faster than titanic.

 

[jtbland1]

When I got certified I had to drag myself and my instructor on the way to the top. I did not have enough air coming from 30 feet. Apparently his idea was to shut it off and immediately turn it back on to trick us into thinking we really have no air. So i took off faster than a dolphin on steroids with my instructor hanging off my valve. About 10ft from surface i ran out of air in my lungs and i did not like the feeling. I do think its a very good exercise but also a valuable lesson. Ditch weights+swim normally and have energy for 30ft ascend... panic and take off with weights and you will be sinking to the bottom faster than titanic.

Ditching your weight would be the last resort as this will lead you into an emergency buoyant ascent, greatly increasing your chances of DCS or over expansion injuries. It becomes a last minute decision. A diver running out of air will will feel the regulator get harder to breath therefore let it be a warning take a deep breath relax and ascend as slowly as possible while exhaling, you'll be surprised how far you can go on that one breath of air from depth. The air in your lungs will expand keeping your lungs with a full breath of air. Just always make sure to exhale slowly. By know means unless absolutely necessary drop your weights. Keep in mind most of the time you will have neoprene on and the shallower you get the faster you ascend.

 

[dpaustex]

Yep, in the pool, the air is briefly turned off. This is all discussed beforehand. The whole idea is for the student to actually experience exactly what the sensation is to be underwater and suck on a dead regulator. As for the guy inhaling while doing an ascent, that's NOT what is taught. You are to exhale the entire way up. Remember, the air volume in your lungs is doubling on ascent for every 33 feet of depth. You're risking an expansive lung injury if you're breathing in, or holding your breath. You are the breath OUT during an emergency ascent.

 

[dpaustex]

Yep, in the pool, the air is briefly turned off. This is all discussed beforehand. The whole idea is for the student to actually experience exactly what the sensation is to be underwater and suck on a dead regulator. As for the guy inhaling while doing an ascent, that's NOT what is taguht. You are to exhale the entire way up. Remember, the air volume in your lungs is doubling on ascent for every 33 feet of depth. You're risking an expansive lung injury if you're breathing in, or holding your breath. You are the breath OUT during an emergency ascent, with your regulator in your mouth.

 

[Diveralan]

Remember, the air volume in your lungs is doubling on ascent for every 33 feet of depth. You're risking an expansive lung injury if you're breathing in, or holding your breath.

Dpaustex, this is not quite correct. You are correct in stating that in an accent from 33 ft to the surface the volume of air in your lungs will double. This is not correct as you go deeper.

When you descend from the surface (1 ATM) to 33 ft (2 ATM) the pressure doubles and the volume of gas will decrease by 50%. The reverse is true when you accent.
However when you descend from 33 ft (2 ATM) the pressure does not double again until 132 ft (4 ATM).

If you are at 132 FT you can accent to 33 ft before the pressure is reduced by half and the volume doubles.

This is why so much emphasis is put on the first 33 ft of decent ans the last 33 ft of assent. This is where the most pressure change occurs.

You are 100% correct in stating that holding your breath at any time during an accent puts you at risk of a over expansion injury.

Happy and Safe Diving
Alan

 

[RonMurray]

Ditto Tep,

NASDS certified in 1976 - the instructor briefed the class in the pool, then swam around and randomly turned off air valves. We were then instructed to signal our buddy OOA and buddy breathe at which time he turned the air back on.

In open water (Key Largo, nice place to certify) we did an ascent from 30' , air was turned on but we held the reg out of our mouth and of course blew bubbles all the way up.

(I have to say, I was certified with my dad, but the instructor would have us switch up buddies for different drills and my assigned buddy for the OOA pool drill was too preoccupied with his waist strap when it came my turn to respond to my OOA signal. - I ended up buddy breathing with the instructor after a few tense moments. My dad was pissed.)

Funny what you remember...

 

[Howard1022]

When I was 14 and certified by YMCA we did this only in the pool. In 1970 at 22 when I took a semester C-class in NAUI we did all of that and more (stripping to bare tanks) in the pool. In the ocean checkout some of us did it at the end of the class certification/diving. I have practiced several times from 100ft. My instructor actually had a regulator blow out at 90ft in Truk and safely and calmly did his assent with no ill effects. It is not for everyone to just go try without carefull planing. A responsible driving instrutor does not turn off the vehicle engine and say "Experience what happens when the engine stops running at 60 mph." My daughter and wife are not trained enough from their open water class to do what I did in 1970. After that extensive class I never approached diving without planning what I might have to do to rescue another diver or without subconsciously scanning other divers and their equipment preparation.

 

[TBURKE]

Wow how things have changed.
When I was training to be a DM and helping out at classes in the pool, I would be the one to turn off the air. The students knew it would happen but they didn't know when.
First the instructor would have them spit out their reg, blow bubbles and together they would do an ascent. (air on, reg in hand)
Then they were told to swim as a buddy team and I would turn off someones air. They were to do a buddy breathing ascent with the instructor and me beside them.
After that they got pony bottles and when their air was turned off they switched to their ponies and did a controled ascent to the surface.

We never did this in open water.
That was in the late 80's.