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Known by several names, BCD (Buoyancy Compensating Device), BC (Buoyancy Compensator) or stab Jacket, modern BCD’s allow the simple addition or release of air during your dive to maintain neutral buoyancy.
BCD’s come in 2 basic forms, Jacket style or Wing style. The jacket style BCD is probably the most common well know system. The jacket wraps around the torso allowing the air pocket to inflate around your waist and back. The Jacket style BCD is generally the go to system for schools and clubs for training beginners as the wrap around nature of the system makes the wearer feel secure and holds them in an upright position on the surface.
The Wing style BCD has all the air in a cell on your back in either a donut or horseshoe shaped bladder. The advantage of this system is underwater it holds you in a nice horizontal position and they generally have simpler harness systems giving you much more freedom of movement as there are no bulky air pockets around your waist.
Most divers when starting out will start with the Jacket style BCD. They are comfortable and as this is generally the system you train in gives you a bit of continuity as your starting out. As divers experience levels increase, many divers will upgrade to a wing system as they give you a more streamlined presence underwater holding you in a nice horizontal position.
Jacket style BCD’s generally have 2 large pockets positioned on your hips giving you plenty of storage space for slates, finger reels and compact DSMB’s etc. and depending on the model will have various D-rings positioned on the chest, hips, above the pockets or on some models all three. Wing systems however tend to be more basic systems, they generally consist of a harness system with various D-rings positioned to allow you to clip off your accessories. Some models will have small fold out pockets large enough for a compact DSMB but in general Jacket style BCD’s offer more storage options than wing systems.
Due to their simplicity, wing systems tend to be lighter less bulky systems meaning they tend to be more travel friendly as they are easier to pack down and have less impact on your weight allowance.
The type of diving you do will influence your choice in BCD. If your strictly a warm water diver then one of the travel BCD’s would be a good choice. These tend to be constructed of lighter grade material which gives you an overall lighter system for travel but does compromise the overall durability of the system. These are great for the travelling diver but wouldn’t stand up as well as some of the heavier more robust systems if you’re diving regularly all year round. Many UK divers will have 2 BCD’s, one system for regular diving at home in the UK, then a lighter, simpler system they can pack up easily for diving holidays abroad. Travel BCD’s are available in both Jacket and wing styles, so you can still pick your preferred system but the wing systems tend to be by far the lightest option.
If you carry a lot of accessories while diving; Torches, slates, DSMB, reels etc. then the extra storage capacity a jacket style BCD offers would be a good choice as you can store everything neatly without the added expense of buying some sort of thigh pocket system.
For the wrecks enthusiasts out there a wing system would be the best choice. The simple less bulky harness systems give you a more streamline presence in the water and the rear air cell holds you in a nice horizontal position. This system makes wreck penetration/exploration a lot easier with less snagging hazards.
For the Ladies out there, there is a whole range of BCD’s specifically designed for the female physique. Ladies BCD’s tend to be shorter in the body so they sit up over the hips and the shoulder straps tend to attach further back under the arms to reduce pressure on the chest. This makes the BCD’s far more comfortable for the female physique and an absolute must for the regular female diver.
No matter which system you choose make sure you pick the system you feel most comfortable in. At the end of the day your the one wearing it, not your instructor or dive buddy so make sure you pick the system than meets all your needs and comfort, not someone else’s.
As well as the style there are several other features available on various BCD’s:
Integrated weight systems - Most BCD systems nowadays come complete with integrated weight systems. Unlike the conventional weight belt which puts pressure on your lower back and hips. The integrated weight system is built into your BCD meaning the pressure created by the extra lead weight is distributed throughout your whole back and shoulders. This system is a lot more comfortable than the classic weight belt system and a must for divers with back issues. Integrated weight systems tend to be some sort of simple pouch system to hold the actual weights, with some sort of quick release system so the lead can be dumped quickly and easily in an emergency. Make sure you familiarize yourself with the weight system on your BCD so you can easily install and release the pockets while wearing the BCD. If you trained with a conventional weight belt, ensure you practice first in a pool to get used to your new system before taking your new BCD out into the open ocean.
Dump Valves - Most BCD’s will have 2 over pressure valves installed. These simple one way valves allow the BCD to vent air once full to avoid damages to the bladder. These also double up as manual dumps allowing the diver to dump air quickly and easily from their BCD. These are generally located on the right shoulder, with a pull chord positioned on your chest and on your lower back with an easy to grab pull chord just above your bottom. The lower dump is generally positioned on your right but some systems will have it on the left so just make sure you are familiar with your particular system. Most BCD’s will also have a pull dump built into the inflator hose so as you pull down on the corrugated inflator hose this will open the top dump on your left shoulder.
Inflator System - All BCD’s will have some sort of inflator system, which allows you to simply add or release air to your BCD. The simplest and most common form is the basic inflator system. This consists of 2 buttons, one to add air and one to release air. These vary from manufacturer to manufacturer but they all basically do the same thing and are all very simple and reliable systems.
Another option available on most BCD’s is the air integrated inflator system which combines a secondary air source built into your inflator. This allows you to donate your primary air source in an out of air emergency while you switch to your integrated secondary air source. They are set up in such a way so you can continue to inflate/deflate your BCD while breathing from the secondary air source. This is a great system for the travelling diver as it means you can remove the standard octopus from your regulator system and reduce the overall weight of your system. Just make sure if you decide to go down this route you first practice in the pool with your buddy so you are both familiar with your new system in case of an emergency.
Trim Pockets - Most modern BCD’s now come fitted with trim weight pockets located somewhere on your back. These are non dump-able weights so will only tend to accept 1kg max per pocket. The use of these pockets allow you to experiment with the positioning of your weight around your body to maintain the perfect body position in the water. They also allow for additional weight to be worn when using thicker wetsuits or drysuits. Just ensure any weight added to these pockets still allows you to become positively buoyant when you dump your main weight system in an emergency.
Lift Capacity - A common question we get asked is what is the lift capacity of this BCD. The overall lift capacity of a BCD will increase with the size of the BCD and again will vary from model to model. For example an XS Aqualung Pro HD has 24lb of lift compared to an XL which has 55lb of lift. The average recreational BCD system will comfortably handle a 12L or 15L cylinder on a correctly weighted diver and handle the addition of a 3L pony bottle or 7L side tank. Generally speaking for the average recreational diver if you’re struggling to maintain positive buoyancy on the surface with a fully inflated BCD then you are more than likely over weighted.
As your diving expands into deeper longer dives you will find yourself needing to carry multiple cylinders. At this stage you are much better off looking at the Technical diving systems which consist of separate harness system, backplate’s and wings. These systems are designed to handle the weight associated with diving multiple cylinders (2, 3, 4 or more) and allow you to switch out wings easily and quickly to give you more lift capacity as you add more cylinders. This sort of diving generally involves additional training where you will learn the benefits of these more Technical systems
