The BCD: our key tool for perfect buoyancy!


What is a BCD and why is it so important?

All divers need to use a BCD to get wet! BCD stands for Buoyancy Control Device and it can also be called «jacket» and as its name suggests, it allows us to control our buoyancy while diving.  But a BCD has many other purposes like keeping our equipment clipped together, thus helping us to stay streamline underwater, it also has pockets to store any tool we need or to collect debris from the water. Some BCDs have integrated weight pockets that replace heavy weight belts that are sometimes uncomfortable. As you see, the BCD is an important part of diving equipment.



How do we use a BCD?

The shape of BCD reminds a jacket. It is attached to our tank with some straps with velcro cummerbunds and solid buckles. Usually we have one tank strap and one valve strap but some BCDs have 2 tank straps for a better bearing.  First we attach our BCD to the tank, then we have to connect it to the LPI (Low Pressure Inflator) of our regulator so that we can add air into it by pressing our inflator button. The deflator button serves to remove the air from our BCD, in order to make it work efficiently you should always place it vertically above your head. If you are in a horizontal position, you can also use one of the emergency dump valves located in various places in the jacket. Most of the BCDs have a valve by the right kidney and one by the right shoulder but this can also be different according the model. The inflator and deflator buttons are to be used delicately as you shouldn’t inflate/deflate the BCD too quickly when diving. Always press these buttons just slightly to adjust your buoyancy underwater. The principle of its use is simple: if you feel you are sinking, press the inflator button to reach neutral buoyancy; if you are ascending, then press the deflator button. You should also use your breath to adjust your depth. In case of a malfunction of the inflator, you can also orally inflate the jacket to adjust buoyancy or to float at the surface. If you have some doubts about usage if the BCD the professionals can always assist you and show you how the jacket works so don’t be afraid to ask for help and advice when diving with a dive centre. The instructor explains the importance and way of usage of the BCD to the new divers during the PADI Open Water course and you will have plenty of time to train. If you haven’t dived for a while, you can also follow a Scuba Review course in which you will be reminded of the use of all the equipment, including BCD.

What kinds of BCDs exist and which one is the best for you?

Each diver has different needs depending on which kind and place of diving he/she is going to do. For people who travel a lot and like to dive in many places in the world, we suggest to use a travel BCD because it is lighter and easier to pack.

There are two main kinds of BCDs: the jacket and the wing. The latter one comes from technical diving as it was used with a twinset of two tanks or with rebreathers but now it has spread to recreational diving with one tank use. It consists of a back metal plate (aluminium or steel), harnesses and an inflatable bladder that reminds wings with its shape. Almost the whole BCD of this kind stays on the back of the diver that gives more freedom of movement whereas a jacket BCD inflates all around the waist. Also all parts are replaceable on a wing BCD as everything goes separately: harness, bladder, pockets, straps… So if some part of your wing is worn or torn, you don’t have to buy a whole new BCD. Also, many divers say that the wing system makes them improve their trim underwater as the air is only located in their back. However, this kind of BCD is not as common as the jacket because most dive centres rent jacket-shaped BCDs so a lot of divers are most exposed to this kind of BCD and get used to dive with it. Another point is that with a wing it’s more challenging to stay on the surface as the inflated back part of it pushes you from behind so you it’s not easy to keep a vertical position. That’s why the beginners normally use the jacket kind of it, especially during the courses. A jacket BCD has another advantage as it has pockets that allow you to take some items with you. These are not present on the wing (though can be attached afterwards).


Many models and colours are on the market, some have specific shape for children or women and the prices vary a lot according the characteristics and the brand. If you want to buy your own Buoyancy Control Device, do it in a dive centre to be assisted in choosing the best one for you.


Read also:

Multilanguage Dictionary For Divers

Underwater Signs: How To Speak Underwater