Which bcd

If the BCD is inflated so that the diver weighs the same as the water they are displacing, they become neutrally buoyant, which is what divers want to be most of the time. BCDs become even more important when divers use neoprene wetsuits, which are buoyant at the surface. As divers go deeper, the little nitrogen-filled cells in the neoprene foam are pressed smaller and smaller by the water pressure, and the suit becomes less buoyant. So a suit that may have required the diver to add 10 kg 20 lb of lead weight at the surface in order to submerge will probably not have enough 'float' to keep the diver from sinking once he or she is 10 or 20 metres underwater.

Add a touch of air from the scuba tank there is a special hose and a button on the BCD that lets you do this and the ability to hover is regained. When the diver goes up, he or she releases air to offset the extra buoyancy as the wetsuit cells expand again. Many BCDs have more than one means of doing this.

A good BCD does more than just keep you off the bottom. It also allows you to maintain depth without kicking, and lets you swim in a horizontal, rather than angled, position. Less kicking means less energy required, and less air consumed. And swimming horizontally helps you stay as streamlined as possible — which again consumes less energy and less air. So a good BCD, used well, can literally mean the difference between a 20 minute dive and a one hour dive.

There's another benefit. When the diver gets back to the surface, the BCD can be inflated to keep the diver relaxed and afloat while working back to the boat or the shore. And the BCD can assist at the surface in carrying stuff you might find or catch while diving. With this in mind, you will often hear discussions of how much 'lift' a particular BCD has. This is a reference to how much weight it can support when fully inflated.

While the old adage, 'you get what you pay for' is true in most things in life, it's worth noting that price is not necessarily an indicator of the level of diving for which a BCD is intended. Deep, technical shipwreck divers often opt for a BC design that is one of the simplest — and therefore can cost less than some designs used for general recreational diving.

As with most dive gear, different types of BCDs are preferred for different types of diving. A weight- and space-conscious traveling diver may be willing to go without some features in order to have a BC that folds and packs compactly and adds little to the weight of a gear bag. A diver using tools such as line reels and work slates during a dive may want a BCD that puts most of the flotation in back, between the diver and the tank, and leaves the front of the BC open for attaching those tools.

A diving instructor who spends much of her day floating at the surface and talking with her class may prefer a BCD that moves some of that flotation to the front, so she can effortlessly float upright on the surface between dives.

And divers wearing drysuits to which air is also added during a dive will look for BCD styles that work harmoniously with the drysuit's design, and the buoyancy provided by the suit. All BCDs must do two things. When fully inflated, they must be capable of comfortably floating the diver, with all of his or her gear for the dive at hand, at the surface, with no other assistance. And they must fit well, with all releases and controls easy to reach. Beyond that, it's simply a matter of matching the BCD to the diving you want to do.

The first BCDs designed for recreational divers were based fairly closely on the inflatable personal flotation devices used by pilots and military aircrews. The good news was that this tended to float the diver face-up — a desirable attribute if an exhausted or injured diver had to be taken to the surface. The bad news was that this sort of BCD also tended to roll the diver face-up under water. Learning how to ride the bubble of buoyancy on one's chest was a skill easily acquired, but it was not effortless.

So gear designers began looking for a different approach. In the s, they came up with the Jacket Style BCD , also known in some regions as a stabilising jacket or stab jacket: a BCD in which the cells providing the buoyancy completely surrounded the diver's torso.

This made it possible for the diver to still float upright at the surface, but it made swimming underwater a much more intuitive process. In this design, the BCD's air bladder is worn on a harness and sandwiched between the diver and his or her tanks.

Because such a BCD allows you to 'trim out' horizontally so easily, it tends to be very popular with divers who operate in confined spaces, such as shipwrecks or caverns and caves. Also, because this type of BC does not squeeze in on the diver as it is inflated, it tends to work really well with drysuits, which must have room for air movement in order to work optimally. Since this type of BCD doesn't necessarily float an unconscious diver face-up at the surface, it tends to be used more by experienced divers who are experienced in distributing the weight of their equipment.

Both are often available in weight integrated forms, which sometimes do away with the need to wear a weight belt to offset the natural buoyancy of most wetsuits and drysuits. With a weight-integrated BCD, the weight is carried in specially designed pockets that allow the diver to 'ditch' or drop the weights in an instant if necessary. And as a reflection of the growing number of women diving, Women's BCDs are now available from many manufacturers.

These are anatomically cut and styled to fit women more comfortably. A number of other features and options are available on today's BCDs.

On some, the low pressure inflator used to add air from the cylinder can also be used as a back-up regulator. Many newer BCDs incorporate features to help streamline the diver and reduce or eliminate dangling items of gear. And because image is important, even when you're underwater, some BCDs are available in colours and even prints designed to complement the rest of your gear.

Because the two pieces of gear work so closely together, most people buy their first BCD at the same time that they buy their first regulator set. If you're pretty certain what sort of diving you're going to be doing, you might even purchase your BCD before you've started your Open Water Course, so you can practice with your own gear and get accustomed to it in the class.

Or if you're still uncertain what sort of diving you most enjoy, you might want to discuss the options with us and then buy your BC. Because fit is so important with a BCD, see if you can try the BC on with the wetsuit or drysuit that you will be wearing for your diving.

If you're planning on using more than one suit, try the BCD on with the bulkiest suit you intend to dive in, and ask us to help you assess the fit. You want a BCD on which you can reach all the controls and releases easily, without stretching or straining. If you have a scuba cylinder tank on when you try the BCD, it will probably hang a little low in back and pull the BCD back on your shoulders.

Don't be concerned about this, because the cylinder and BC will ride in a much more natural position when you're in the water. In the store, how the BCD hangs without a tank is a much better indication of how it will ride when you're using it in the water.

To help you select the correct size BCD we have drawn up an approximate size chart — some BCDs have their own size chart as supplied by the manufacturers which supersedes this chart.

This is only an approximate guide and you should always try your BCD as soon as you receive it and before actually using it to ensure the correct fit in case you find you need a different size. The measurements shown are chest measurements over your exposure protection, so if for example you have 42 inch chest and wear a dry suit which is approximately 2 inches of bulk, you should consider a size compatible with a 44 inch chest.

Weight integration built into a BCD can mean you may not need to wear a weight belt. This takes the bulky lead off your waist and puts it into quick release pouches either side of the BCD.

You still have the option to wear extra lead on a belt if you need it but integrated weights can't slip down your waist and are less likely to be forgotten than a belt. They're much easier to put on in the water too. The only downside to integrated weights is that it makes your scuba unit heavy when carrying it around on the surface and getting it out of the water. You can always take the pouches out to make it lighter but most divers leave them in. Generally, in warmer waters with no wetsuit or just a 3 mm wetsuit, you'll get all of the weight you need into the integrated weight pockets.

However, in temperate and cold water with a 7 mm wetsuit or drysuit, you'll probably need a weight belt or harness as well. Modern ladies BCDs offer female divers increased comfort and a much better fit compared to the unisex alternatives.

Key features are that the back length is reduced, which means the cylinder does not rest on the base of your spine and the shape of the BCD is made to fit the female figure. Integrated weights save ladies hips from the bruising sometimes suffered by using a conventional weight belt.

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