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.
Watch our 5 minute guide:
BCDs come in two basic shapes; jackets and wings. Most divers learn to dive using a jacket style BCD, these inflate all around your body and around your waist so you feel nice and secure in the water and you sit in a nice position on the surface. Wing BCDs only inflate behind you in a donut or horseshoe shape between you and your cylinder. Wings are preferred by more experienced divers because they hold you in a horizontal position in the water and do not obstruct your movements when fully inflated.
Wings are lighter and usually have greater adjustment in the straps with a simpler harness style strap system. Jackets have pockets built in either side of them for storage which makes them heavier for travel.
|Jacket Style BCD||Wing Style BCD|
Travel BCDs are designed to minimise 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. Thinner material makes them lighter but also more fragile, they can cope with plenty of dives but too much rough and tumble around sharp rocks or wrecks can puncture the bladder so they’re best for open water diving.
Often steel D-rings will be replaced by plastic or aluminium ones which are strong but much lighter to help reduce the weight of the BCD.
|Jacket Style Travel BCD||Wing Style Travel BCD|
Click here to see our full range of Travel BCD’s.
Weight integration built into a BCD can mean you won’t 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.
Learn about different weighting options:
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 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.
Click here to view the full range of Ladies BCD’s.
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 over your shoulders to flare outwards towards the bottom which makes attaching clips much easier than with flat D-rings which tend to lay flat against the BCD or straight out, usually found around your waist.
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 but you can always use thigh pockets for extra storage.
Dump valves are one-way over pressure valves to allow excess gas to escape when you’re fully inflated and allow you to dump gas in the water to adjust your buoyancy. Usually located behind your right shoulder and near the kidneys you’ll have a small cord that you can pull to open the valve. Most BCDs have at least two so you can alter your buoyancy in any position.
Modern BCD’s sometimes have pull dump built into the inflator on the left shoulder by a small cable inside the corrugated hose so when you pull the inflator down in an upright position you will dump gas. You should learn where these are by feel so you can quickly and intuitively dump gas without looking.
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. AquaLung have released the i3 system which allows for fine tuning for streamline buoyancy adjustment.
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 utilise 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.
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 donate 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 with your buddy.
Watch below to understand the benefits of using an A.I.R.:
|Extra Extra Large||48-50|
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. Always try your new BCD over the exposure suit you plan on wearing it with.
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. You have 28 days to return it if the one you choose doesn’t fit – please see our returns policy for full details.
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 and most recreational BCDs will hold a single 12 or 15 litre cylinder.
As with all diving you should ensure you are correctly weighted before the dive so you shouldn’t need to use your BCD too much.
You should always avoid being over weighted otherwise you waste a lot of gas adjusting your buoyancy when you change depth. With this in mind, all BCDs offer plenty of lift for single cylinders. 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 is plenty. 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+