Scuba BCDs - Buoyancy Compensator Devices
What Divers Use to Control Buoyancy Underwater and at the Surface
© Jim Bray
Oct 26, 2008
A BC is an inflatable jacket worn by divers. A scuba dive BC enables divers to float at the surface and fine tune their buoyancy by filling or emptying the BC of air.
The Purpose of a Scuba BCD and How It Works
A BC provides flotation at the surface. This helps a diver rest at the surface before descending or after ascending. When properly inflated, a BC will keep a diver's head well out of the water. An inflated BC also makes it easier for a diver to make a surface swim to their exit point after a dive.
While diving, divers can add small amounts of air to fine tune their buoyancy. By filling or emptying small amounts of air, divers can become stationary at a desired depth. This is neutral buoyancy, perfect balance underwater. Knowing how to properly use a BC to achieve perfect buoyancy control in scuba diving means a diver will use less effort and air while diving.
BCs can also reduce buoyancy. By emptying air from the BC, a diver can make a slow, safe ascent. A deflation button is located at the end of the corrugated hose. Divers can also empty air from the BC by pulling a cord attached to a dump valve.
There are two ways to inflate a scuba BCD. The BC is connected to the scuba tank via a low pressure hose on the scuba regulator. This hose connects to a corrugated hose on the left shoulder of the BC. At the end of the hose are the automatic buttons for inflating and deflating the BC.
Also at the end of the corrugated hose is a mouthpiece that allows the diver to inflate the scuba dive BC orally.
In addition to adjusting buoyancy, a BC is used to attach other scuba equipment. The scuba tank attaches to the BC with a strap and back plate. There are hooks and D-rings to clip an alternate air source, scuba gauges and other items of scuba gear. Many BCs have an integrated weight system.
Choosing a BC for Scuba
There are many styles of scuba BCDs. Basic models are like a padded vest and can only be adjusted at the waist. Advanced models will have adjustable straps for the shoulders, across the chest and a cumber bun style strap across the waist. Specialty jackets may have a wing design that provides a larger air capacity for extra lift.
A BC that fits properly should feel like a comfortable vest, snug but not too tight. The jacket should not roll round with a scuba tank attached. The jacket should be easy to take on and off. Every strap needs enough adjustment in case of changes in wet suit thickness or body shape.
It is best to try on several different styles to ensure the best fit. The jacket should suit the type of diving the diver is doing the most.
Maintaining a Scuba Dive BC
Proper care of a BC will keep it in good working condition for many years.
- Rinse the jacket with fresh water after every dive.
- Rinse the inside of the jacket by putting fresh water through the corrugated hose.
- Empty the jacket by turning it upside down and letting the water drain out through the corrugated hose.
- Inflate the jacket slightly to see if any water remains.
- Store the jacket in a cool dry place on a sturdy hanger. The jacket should be slightly inflated.
- If the jacket has not been used for more than 6 months, have it serviced at a recommended dive shop.
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