Diving BCDs (Buoyancy Control Devices)

BCDs – or buoyancy control devices – form the mainstay of a diver’s kit. These units hold the cylinder on to your back, provide lift on the surface and buoyancy underwater.

They come in all shapes and sizes, but basically, they can be split into two main groups – traditional ‘jacket’ style, and ‘back-inflate’ or ‘wing’ style. Jacket-style BCDs, as the name suggests, fit around the body, and the bladder comes around the sides of the torso and over the shoulders.

Wing-style BCDs have backpack-like harnesses holding the cylinder in place, and then the bladder sits on the back on either side of the tank. There are pros and cons to both kinds – for example, wings can push you forwards at the surface if you are not used to them, and jackets can be quite bulky – but each fulfils the primary purpose of buoyancy control.

Integrated weights
In the last few years, one of the biggest changes has been the growth of integrated weight systems. More and more manufacturers now offer BCDs with dumpable pockets that can hold several kilogrammes of weight. The advantage of these over a traditional weightbelt is that it is more comfortable having your weights in the BCD than sitting on your hips. Some jackets and wings also have non-dumpable trim-weight pockets on the back on either side of the cylinder.

Power inflators
All styles come with a power inflator which is connected to the regulator first stage by a low-pressure hose and used for putting in, and emptying, air from the bladders. In the majority of cases this power inflator unit is mounted on a simple tube running down from the left shoulder, but there are a few manufacturers that have tried alternatives, including a pneumatic power inflator mounted on the bottom left-hand side of the front of the BCD.

Pull dump valves
As well as emptying air from the bladders via the power inflator, many BCDs have pull-dump valves, where pulling a toggle releases the air. These are usually mounted on the right shoulder and the rear right-hand side.

D-rings
If the item you want to take with you is too big for a pocket, then most BCDs have D-rings – stainless steel or plastic loops – which enable you to clip stuff on to your jacket or wing.

Pockets
For storing gear, many BCDs have zippered or Velcro-closing pockets, and some even have expandable pockets which zip away when not in use. 

What to look for
The majority of BCDs on the market these days do exactly what they are designed to do – provide buoyancy in the water – so when it comes to choosing the right one for you, you need to consider a few important details.
If you are going to be diving abroad, then you will want to look for a lightweight BCD or wing to help in avoiding any nasty excess baggage charges.
If you are going to head off down the technical diving route in the future, it is worth considering one of the modular systems available which allow you to upgrade and change the capabilities as your diving skills develop, as opposed to having to buy a complete new BCD.

Servicing
It is advisable to have your BCD power inflator tested at least once a year, depending on the number of dives you do in 12 months. Also, ensure you thoroughly rinse your BCD in freshwater both inside and out at the end of a diving trip to extend its operational life.
 

buy the latest issue of Sport Diver magazine