Here is an easy starting point to learn about BCDs and Scuba Diving.
This page discusses:
This page discusses:
• What Does "BCD" Stand For?
• What Are the Three Main Purposes of BCDs in Scuba Diving?
• Should I Buy My Own BCD?
• What Kinds of BCDs Are Available for Purchase, and How Should I Choose One?
What Does "BCD" Mean, and What Does a BCD Do?:
BCD is an abbreviation for Buoyancy Control Device or Buoyancy Compensating Device. This is a fancy name for the inflating jacket that a diver wears. The BCD is used to keep the diver neutrally buoyant (so that he does not sink or float up) as he is diving.
Are There Any Other Names for a BCD?:
Yes. BCDs are also known as BCs. BC is an abbreviation for Buoyancy Compensator. There are also specific styles of BCDs known as air cells, wings, or bladders.
What Are the 3 Main Functions of a BCD in Scuba Diving?:
1. A BCD's primary function is to help a diver control his buoyancy both underwater and on the surface.
On the surface, wetsuits and other dive gear tend to float. Why does a diver need a BCD to make him float underwater when he already floats on the surface? Because dive gear and divers tend to float, a diver must wear weights to be able to descend and begin a dive. A diver needs additional weight to offset the positive buoyancy (tendency to float) of his tank as it empties. A properly-weighted diver will sink slowly at the beginning dive without any air in his BCD.
As a diver descends, the air trapped in his gear and his wetsuit/drysuit will begin to compress according to Boyle's Law. Because of this compression, the diver becomes less and less buoyant the further he descends. Without a BCD, a diver would be negatively buoyant once he reached his desired depth and would struggle to maintain his level in the water.
Underwater, a diver's goal is to maintain neutral buoyancy (so that he neither floats upwards nor sinks downwards). To maintain neutral buoyancy, a diver adds air to his BCD as he descends to avoid sinking too quickly, and releases air from his BCD as he ascends to avoid floating up in an uncontrolled manner. (Confused? Review these simple buoyancy basics for scuba divers).
On the surface, a diver inflates his BCD completely in order to float comfortably with his head out of the water.
2. The BCD Attaches the Tank to the Diver:
Jacket-style BCDs have an integrated tank band (or cam band) which holds the tank in place on the diver's back. This is the most common method of attaching the tank to the BCD in recreational diving. Modular air cells, such as wings and bladders, attach to the tank(s) via a backplate (for double tanks) or a tank adaptor (for singe tanks). Depending upon the model, a BCD may have one or two tank bands.
3. The BCD Provides Attachment Points for Accessories:
Most BCDs have pockets and d-rings to hold scuba diving accessories such as knives, back-up masks, lights, and dive slates. Divers should make use of these attachment points to ensure that all their gauges, alternate air source regulators, and accessories are clipped off or tucked away so that they do not drag along the bottom and damage aquatic life and the environment.
Learn more about BCDs• How to Buy a BCD - Illustrated Guide
• 3 BCDs Designed for Travelers
• Vest-Style vs Back Inflation BCDs
• 4 Easy Methods for Deflating a BCD
Should I Buy My Own BCD?:
Owning a BCD is great! A diver's personal BCD is more likely to fit perfectly and be more comfortable in the water than a rented BCD. A diver who uses his own BCD regularly will learn its functions and idiosyncrasies well, and will use it more effectively.
However, BCDs are pricey. Most dive shops offer a variety of rental BCDs that will fit most divers adequately and which will work well. If a client is not buying all of his dive gear at once, I advise him to first purchase equipment that must fit perfectly - such as fins, masks, and wetsuits - and to purchase regulators and BCDs later. Furthermore, a diver may find it useful to rent and "test-dive" different styles of BCDs (such as back-inflation and a backplate/wings combo) before deciding which style fits his needs.
However, BCDs are pricey. Most dive shops offer a variety of rental BCDs that will fit most divers adequately and which will work well. If a client is not buying all of his dive gear at once, I advise him to first purchase equipment that must fit perfectly - such as fins, masks, and wetsuits - and to purchase regulators and BCDs later. Furthermore, a diver may find it useful to rent and "test-dive" different styles of BCDs (such as back-inflation and a backplate/wings combo) before deciding which style fits his needs.
What Kinds of BCD Are Available for Purchase, and Which Should I Buy?:
There is a huge variety of BCD styles available to fit almost any diver's needs. Start by deciding which style of BCD you prefer: vest, back inflation, or back-plate and wings. Next, consider what kind of tanks (and how many) you are likely use. This will affect the amount of lift you will need in the BCD. Consider features like integrated weight pockets, d-ring placement, and accessory pockets. Check out an Illustrated Guide To Purchasing a BCD.
The truth is that there is no one "best" BCD, but there are BCDs that are better suited to certain diver's needs than others.
The truth is that there is no one "best" BCD, but there are BCDs that are better suited to certain diver's needs than others.
