■Buoyancy Adjustment Using the BCD

Air should be added to the BCD when resting on the surface, or when buoyancy decreases with depth and you begin to sink despite normal breathing.

If your weighting is correct and your breathing is controlled, you may be able to maintain neutral buoyancy at shallow depths (around 5–8 meters) primarily with lung control.

However, because wetsuit and BCD buoyancy change with depth, neutral buoyancy must be readjusted whenever depth changes.

If you add air when your lung volume is low (after exhaling), you may become too buoyant when you inhale next and start to rise.

Therefore, add air to the BCD after inhaling, when your lung buoyancy is at its maximum.

Inhale before adding air.

Buoyancy does not increase immediately after adding air. There is a slight delay between inflation and the change in buoyancy.

To avoid an uncontrolled ascent, add air in small bursts several times rather than in one large amount. This technique is often called “pumping.”

During ascent, continuously vent air from the BCD to prevent rapid expansion and uncontrolled ascent.

Always raise the inflator hose above your shoulder when venting, since air rises to the highest point inside the BCD.

If the inflator hose is lower than your shoulder, air may not vent properly.

Some BCDs also allow quick venting by pulling a dump valve or inflator mechanism.

Familiarize yourself with your equipment and use all available venting features properly.