Commonly referred to as BCD (Buoyancy Compensating Device) or BC (Buoyancy Compensator) or Stab (Stabilizing) Jacket the modern BCD allows the accurate addition and subtraction of air whilst in the water to adjust buoyancy.
Read down for more information or alternatively go to the Scuba Diving BCD department
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 supercedes 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 42inch chest and wear a dry suit which is approximately 2 inches of bulk, you should consider a size compatible with a 44 inch chest. You have 28 days to return it if the one you choose doesn't fit - please see our returns policy for full details.
Weight integration built into a BCD can mean you won't need to wear a weight belt.
However, most systems available today will not necessarily hold enough weight to totally remove the need for a weight belt when worn with a dry suit or thick wet suit.
For warm water divers (and especially ladies who are fed up of having bruised hips after diving), weight integration should seriously be considered.
The weights that usually fit on the belt are now stored in special removable pockets.
These pockets can be dumped in an emergency or easily released and passed to the boat crew when exiting from deep water.
Modern ladies BCDs offer female divers increased comfort and a much better fit. Key features are that the back length is reduced (ladies have shorter backs than men), which means the cylinder does not rest on the base of your spine.
Integrated weights save your hips from the bruising sometimes suffered by using a conventional weight belt. Also, often the chest straps are removed on a ladies BCD to avoid constriction across the bust.
New ladies BCD's like the Aqua Lung Pearl i3 even have an integrated sports bra.
The rule of thumb with selecting whether to go for a wing or normal jacket style BCD is your experience level. A normal jacket style BCD offers good all round buoyancy when inflated.
A wing style BCD only has inflation on the rear, meaning that at the surface it will have a tendency to turn the diver face down. A lot of divers go for wing style BCD's for the "techie" look and whilst this is fine for those techies who really know what they're doing, one must remember that safety is paramount and that performance is key rather than looks.
Reasons for choosing a wing are if you want to keep your front area free from clutter, if you are an experienced travelling diver or if you need to use multiple cylinders. Travel wings are becoming more popular due the size they pack down to but remember the points listed above when deciding whether or not you should buy one.
A lot is said regarding the lift capacity of a BCD, however lift of the BCD (i.e. the amount of negative weight the BCD can float) should not replace proper weighting.
As with all diving you should ensure you are correctly weighted (this was one of the first lessons you should have learned when you were taught to dive).
You should always avoid being over weighted. With this in mind, all BCDs offer plenty of lift. The exceptions come when you start to carry multiple cylinders or extra tools which will increase your need for extra lift.Tropical Diving (with little or no wet suit protection): 8 to 12 kg
Recreational Diving (with a full wet suit or dry suit): 10 to 20 kg
Technical Diving (or diving under other demanding conditions): 20 to 40 kg+
Alternate Inflator Regulators
An alternate inflator regulator can replace the normal inflator/deflator mechanism on your BCD and still allows you to inflate and deflate in the standard way but also gives you a built in spare second stage regulator.
These are usually only slightly bigger than the normal inflation units that are available. Using an alternate inflator regulator means that you do not have to have an octopus (secondary second stage) and in and out of air situation, you give away your primary second stage and breath off the alternate inflator regulator (you can still control your buoyancy even when it is in your mouth).
These systems are ideal for travelling divers who wish to reduce the weight and bulk of equipment. However like all new equipment we would recommend practising using yours in a controlled environment first.
Travel BCDs are designed to minimize weight and bulk to make travelling with them easier.
They tend to be made of lower denier materials with only basic features and are most suitable for tropical locations.
Often steel D-rings will be replaced by plastic ones which are virtually as strong but much lighter to help reduce the weight of the BCD.
Generally speaking, the more dump valves on a BCD the better. Usually located on the rear right shoulder area and rear left hip area, most BCDs have two.
Modern BCD's sometimes have a third built into the inflator/deflator mechanism on the left shoulder. You should learn where these are by feel.
Pockets & D-Rings
Make sure that your BCD has enough pockets and D-rings for the kind of diving that you are planning to do most. Often D-rings are pre-bent to flare outwards towards the bottom which makes attaching clips much easier than with flat D-rings which tend to lay flat agiainst the BCD.
In tropical waters, only one or two small pockets will suffice useful for carrying things like your Fish ID slate. For UK and cold water diving, you will probably want to carry more equipment such as a DSMB and reel or spare mask.
BCD inflation can either come from the traditional over the left shoulder inflator/deflator hose or from "air trim" style inflators that are located lower down in a more natural hand position. Balanced Power Inflators like those featured on all Scubapro BCDs still remain the best for performance but in recent years "air trim" styles have become more popular. More recently AquaLung have released the i3 which is explained below.
Mares pioneered Air trim systems: "Air trim revolutionizes and simplifies the search for optimal buoyancy underwater. It features a single, simple and ergonomic command for inflating and deflating the BC. Two oversized buttons, easy to operate and convenient, ensure simple and accurate buoyancy control. The absence of a corrugated tube makes the BC more hydrodynamic, enhancing its safety and comfort underwater."
The Scubapro BPI (Balanced Power Inflator) offers the following benefit. "High inflation speed, especially at depth. It is of primary importance for safety as well as for progressive flow. Allows the diver to precisely inject the correct volume of air in the BC resulting in the most accurate buoyancy control. To be used even in pitch black water, and when wearing thick gloves. Self flushing double action purge valve. Allows the diver in extreme cases to breathe air from the BC and exhale in the water"
Aqualung i3 is simple and intuitive. Move the lever up to go up; down to go down. Unlike a traditional inflator at the end of a floppy hose, the i3 never moves. It is stationary at the same location where your left hand normally rests. It is always in the right place at the right time. The i3 does not utilize pneumatics or hydraulics to activate the Flat E-Valves. Therefore, there is no possibility of failure due to leaks. Using push-rod technology, as found in aircraft, the design remains simple and robust.