How to Breathe from a BCD

Some time ago, Undercurrent presented tips for emergency breathing from your BCD. This seems like a good time to repeat them:

To gain confidence in your ability to act in an emergency, practice this and all other BCD breathing skills with your gear in shallow, calm water. Be sure to disinfect your BCD first.

Clear your mouthpiece. Tom Phillipp, Aqua Lung's product manager for BCDs, points out that many oral inflators have holes behind the deflator button to prevent water from being blown back into the bag while purging, so the best method is to first blow a little air in so the water runs out the holes. Then hold the deflator valve down as you continue blowing. Your exhaled breath will now go into the BCD, and the holes will be sealed so no water can re-enter.

Bret Gilliam prefers to raise the inflator overhead, and then put the mouthpiece in while rolling to the left to let as much water as possible slide down the hose before inhaling. Air will rise in the hose at the same time. He notes that even after the diver purges the mouthpiece, it's still likely that he'll get 10 to 20 milliliters of water with his first breath. This problem would be less severe if the diver used short tugs on his shoulder or back-mounted dump valve to vent; water would still enter the BCD but not the hose, and would settle to the lowest part of the flotation bladder.

Once you've begun getting air from your BCD, don't release your tight hold or water will leak in through the holes. With older models, bend the mouthpiece up, seal your mouth, look down and, as before, blow air in as you push the valve. The water will flow from the mouthpiece and become trapped in the hose, but air will be able to get past it.

Take your first breath cautiously. Inhale slowly and carefully, as you would with a wet snorkel, trying to catch the moisture on your tongue. Then try to swallow the water. If you do cough or gag on a few droplets, don't remove the mouthpiece, just cough into the BCD.

Control your ascent. Exhale normally and watch your ascent rate. You still face the danger of an embolism if you retain air breathed at ambient pressure. Don't let go of the valve or remove the mouthpiece from your mouth as you ascend. If you are rising faster than your bubbles, exhale through your nose. Flaring out horizontally will also help slow your ascent.

Use air from your tank. As long as your power inflator is working, you can add more fresh air to your BCD as you rise, and you can continue to breathe it at ambient pressure. Keep the mouthpiece valve closed tightly while putting air into your BCD so none escapes. Press your power inflator intermittently, take a breath and exhale it through your nose to insure a continuous supply of fresh air. You can also breathe from your BCD while a buddy is breathing from your tank. Since your power inflator bypasses your regulator's second stage, you can inhale from the BCD at any time without over-breathing. If your buddy is in danger of over-breathing the second stage you've shared with him, wait to feed air into the BCD until you see his bubbles. Keep feeding air intermittently between your buddy's inhalations.

When no air is available from your tank. Air in your BCD will become more available as you rise just as air in your tank does, allowing additional breaths as ambient pressure decreases. Start up immediately, keep trying to inhale and exhale, and air will become available. If you have a BCD-mounted safe second such as the Air 2, you can access the air in your BCD by pressing the deflate button when inhaling. In one study, basic scuba students were able to rebreathe this way for a full minute with no problems. Stay relaxed because rising CO2 levels will cause you to breathe faster and faster, which could lead to a sudden blackout.

Sound complicated? The industry obviously thinks so. Still, although no one's making you learn these new skills, one day you might be glad you or your buddy did.