Using Your BCD

Maintaining Neutral Buoyancy

You are neutrally buoyant when you neither sink to the bottom nor float to the surface. You'll want to maintain neutral buoyancy throughout your dive so you don't stir sand off the bottom, damage marine life, or exhaust yourself while swimming.

You can adjust and test your buoyancy using a skill called a fin pivot. To perform a fin pivot:

  1. Lie face-down at the bottom.
  2. Take a breath of air and add a burst of air to your BCD. Then exhale the breath.
  3. Repeat this process until you rise up as you inhale, and sink as you exhale.

Your buoyancy will change as your depth changes. Add more air to your BCD as you descend, and release air as you ascend. This will help you to maintain neutral buoyancy.

Using the BCD Oral Inflator

If your power inflator fails during a dive, you can continue the dive using the oral inflator to adjust your buoyancy. You may also want to use the oral inflator to save air as you inflate the BCD at the surface. To orally inflate the BCD:

  1. Take a breath from your regulator, and remove it from your mouth. Remember to exhale a small stream of bubbles any time the 2nd stage is out of your mouth.
  2. Place the power inflator's mouthpiece in your mouth.
  3. Press the deflate/oral inflator button, and exhale into the power inflator.
  4. Replace and clear the 2nd stage, and continue the process until you are neutrally buoyant.

Removing Your BCD

You can remove your BCD at the surface or underwater to correct a minor equipment problem. To remove your BCD:

  1. Inflate the BCD if you are at the surface, or deflate the BCD if you are underwater.
  2. Unfasten all clips that are secured across your waist and chest.
  3. Slip your left arm out of the shoulder strap.
  4. Bring the BCD around your right side until it's in front of you. Remove your right arm from the shoulder strap.
  5. Hold the BCD in front of you so it doesn't float or drift away from you. If you are at the surface, use the inflated BCD as a flotation device.

Remember to remove your left arm first, then your right arm. This prevents the 2nd stage hose from pulling away from your mouth as you bring the BCD forward.

Replacing Your BCD

There are several methods for donning your BCD while at the surface or underwater. Your instructor will demonstrate these methods during your confined water sessions. The method described below works both at the surface and underwater.

  1. Place the 2nd stage in your mouth.
  2. Hold the BCD in a tank-down position with the valve pointing towards you.
  3. Position your arms down through the shoulder straps and place your hands on each side of the cylinder. Make sure the 2nd stage hose is between your arms. This prevents it from being caught underneath a shoulder strap.
  4. Lift the BCD over your head and onto your back.
  5. Fasten all straps and clips.