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Choosing Your Buoyancy Control Device (BCD)

by Andy Davis


Shopping for a scuba buoyancy control device (BCD) is like completing a jigsaw.  There is a huge variety of products and options available for the diver to chose from.

The diver needs certain functions, but may also want certain additional functionality.  Manufacturers/retailers will always try and make divers want more functionality because that is where profits are made.

Making the best purchase decision can be difficult if the diver is not sufficiently experienced to know what their needs are or can understand both the ‘pros’ and the ‘cons’ to the various designs, features and functions that they will be presented with.

technical diving subic bay philipines bcd

BCD manufacturers complicate this further, by marketing their products in a way that confuses the diver about what their needs actually are. They often attempt to sell higher priced BCD options by adding superfluous functionality and complexity to their basic designs.

The difference between a $200 BCD and a $600 BCD is often nothing more than the addition of numerous unnecessary gimmick features that the diver will never use.

Quite often, those gimmick features can actually detract from the performance of the buoyancy control device, impacting on its inherent buoyancy/weight, streamlining and ease of operation.   Also, the more components that a device has, the more chance that a component will fail. Thus, the more complex a BCD design is, the more likelihood exists that it will let you down at some point.

Be wary of scuba advertising.

Gimmicky advertising stresses how many features a buoyancy control device has.  The quantity and complexity of features are quite often more of a drawback than a benefit.

You’ll certainly be paying for every one of those features – every inch of fabric, every strap, every buckle, every quick-release, every screw, every bolt, every strip of Velcro, every single superfluous stitch.

Learn to look critically at a BCD design.

Decipher what design features/functions are there for your benefit as a diver and what features/functions are included just so that the manufacturer can charge you a premium cost.

A sceptical and questioning mindset is needed to separate the wheat from the chaff when it comes to buoyancy control device advertising!

Make your own comparison and evaluation of the options.

Be aware that many dive shops/schools will have financial incentives to sell you specific equipment.  Where possible, compare as many models and brands as you can.

Be prepared to shop around at different retailers.

Few retailers stock from a range of different manufacturers. Many are locked into contracts to represent a single brand.

Use the internet to aid your research.

But be wary of non-consumer based reviews.  Some diving magazines and online equipment review sites receive financial incentives from manufacturers for their reviews Consequently, what is often announced as an impartial review can be nothing more than a manufacturer-sponsored advert!   Again, remain sceptical.

Online scuba community forums are a good place to seek opinions, reviews and advice.  You can be more certain that the information here will be less influenced by financially induced bias, but remain aware that many experienced divers hold strong ego-invested opinions about their scuba equipment choices. Those opinions may not suit your individual requirements.

Step-By-Step Guide To BCD Selection

So, here’s my step-by-step guide on how to critically consider a buoyancy control device for purchase.  I’ve tried to make it as unbiased as possible, but please forgive me if my own preferences, likes and dislikes are evident in the advice given.

Core Buoyancy Control Device Functions (what a diver needs):

1)  Surface Floatation: The BCD should offer sufficient buoyancy to float you on the surface with all of your gear in place.  The exact amount of buoyancy needed to do that is specific to the diver and the equipment they use.  This can be calculated accurately (see here).  Excess buoyancy beyond that requirement is absolutely superfluous and only likely to cause you problems.

2)   Variable Buoyancy Underwater: The buoyancy control device should provide variable buoyancy underwater, based on greater/lesser water displacement through adding or removing air from the BCD bladder.  A properly weighted diver does not require a large amount of buoyancy compensation.

The main reason for adding air at depth is to compensate for the reduced buoyancy of exposure suits as you descend (water pressure compresses the suit material and reduces its buoyancy).

Cold water divers, in thick neoprene, suffer that largest loss of buoyancy from exposure suit compression on the descent.

Warm water divers in thin wetsuits (or no wetsuits) require only a negligible amount of buoyancy compensation underwater.

You should understand your variable buoyancy compensation requirements when investigating BCD bladder capacity. This is essentially an understanding of how much buoyancy your exposure suit will lose at maximum recreational diving depths.

(For a greater understanding of buoyancy and weighting; please see here: Buoyancy Masterclass)

3)  Securing Cylinder/s to the Diver: The buoyancy control device must offer a secure and stable method of attaching scuba cylinder to the diver;

  • Secure Cylinder Attachment: The cylinder should not slip or move within the attachment. BCDs have cam-bands to secure cylinders.  Cylinders ‘dropping’ from cam-bands can happen.  A BCD with 2 cam-bands offers more secure cylinder attachment.  Cam-bands vary in quality of construction.  Investigate those factors.
  • BCD Attachment to the Diver: The buoyancy control device is worn by the diver.  At a minimum, this includes shoulder straps and a waistband.  Crotch straps are included with some BCDs to enable further security and fit adjustment.  The straps and harness may have adjustable buckles to enable a varied fit.  There may also be quick-release buckles for convenient removal and to aid rescues.  Wide velcro waist-bands are often included to compensate for a less precise fit, especially with ‘jacket-style’ BCDs (see below).
  • ‘Jacket style’ BCDs: These are BCDs in which the air bladder runs up that back and also surrounds the divers’ torso.  They are typically used in open-water classes, which makes them a familiar option for the novice diver. They adjust in fit as the air volume of the bladder is adjusted.  When inflated, they are tight.  When deflated, they are loose.

As the diver varies their buoyancy during the course of a dive, they need to re-adjust the fit of the BCD using adjustments on the shoulder and waist straps.  If they fail to tighten the straps when they empty the buoyancy control device to descend, the BCD will become too loose and will roll and wallow around their torso.  This causes them to feel less control during the dive.

Also be aware that all of those adjustable straps will float around the diver once underwater.  Many divers find an excess of long floating adjustment straps to be a considerable distraction and annoyance.

  • ‘Rear-Inflate’ BCDs: These are BCDs that have the air bladder behind the diver.  Adjusting the buoyancy of the BCD does not interfere with the fit of the buoyancy control device to the diver.  No adjustments to fit are required as the relative displacement of the BCD is varied.  They typically have a similar design of adjustable harness to jacket BCDs, which brings some familiarity to divers who previously trained in a jacket BCD.
  • BP&W BCDs: Backplate and Wing (BP&W) BCDs are a sub-class of ‘Rear Inflate’ BCD, which has a modular construction.  This modular function is based around a rugged backplate, to which attach cam-band/s, harness and the buoyancy bladder (‘wing’).

The diver can choose between different styles/materials of the backplate, different cam-band options, different designs of harness and different designs and volumes of ‘wing’ bladder.  A crotch-strap is typically seen as an essential add-on, as this ensures security and fit of the harness.  The use of a plain webbing-style harness enables the user to add ancillary and storage options as they desire, including pockets, knife sheaths etc.

Divers can purchase typical ‘adjustable’ harnesses, or they can opt for a ‘single-piece’ webbing harness which is initially trimmed to fit them perfectly and requires no further adjustment before, during or after diving.

These BCDs are very popular with divers who seek a ‘minimalist’ (less is more) approach to their configuration, as they can pick and choose exactly which features they wish to include.

The use of metal (steel or aluminium) backplates reduces the need to carry weights on a weight-belt and helps encourage instinctive horizontal trim by spreading the weight across the length of the divers’ torso.

BP&W also tend to be more streamlined and less bulky – offering considerable advantages in reducing exertion underwater and when operating in confined spaces (wrecks/caves).  The drawback to the modular design is that the diver must pay more attention to the initial set-up and fitting of the configuration.  As such, they are less convenient when first purchased/used.

4)      BCD Bladder Inflation:  The buoyancy control device utilises a Low-Pressure Inflator (LPI) to add air to the BCD.  This is typically on the end of a corrugated hose attached to the left shoulder of the BCD, although some BCDs use more complicated methods with ‘remote’ inflators incorporated into the body of the BCD (these are often more failure prone and less intuitive to control).
LPIs can vary in performance; offering different speeds of inflation (i.e. high ‘power’ inflators). Whilst a quicker, more ‘powerful’, low-pressure inflator may seem attractive (and is often marketed by BCD manufacturers as such).
It is worth bearing in mind that most novice-intermediate divers find that precise inflator control is a difficult skill to master.  In many cases, a slower, less ‘powerful’ inflator is preferable as it offers more fine control when adding air to the buoyancy control device.
There are few occasions where a ‘high power’ inflator offers any tangible benefits to the recreational scuba diver.  The length of the corrugated hose should also be considered, as some divers find the standard length hose is too long and, consequently, always dangles below them.  Some BCDs offer shorter length corrugated hoses.

5)    BCD Bladder Deflation: The BCD must have methods to vent air from the bladder.  Firstly, the LPI module will normally have a dump button for releasing air.   In order for this to be used, the LPI corrugated hose must be raised above the level of the BCD bladder, typically with the diver in a vertical orientation in the water.  Check that the buoyancy control device design does not limit your ability to raise the LPI hose to access this feature.

Secondly, the BCD will have one, or more, dump-valves that offer alternative methods of deflation.  The location of these is important for dumping air if the diver is not in a vertical orientation.

As a minimum, the BCD should have a dump valve at the lower/bottom area of the BCD for deflation when in a horizontal or head-down orientation. Dump-valves also allow a more rapid deflation, should circumstances require it (i.e. uncontrolled ascent).

The effectiveness of any venting method is also determined by the ability/design of the bladder to permit air to migrate around it.  Overly complicated designs, particularly some jacket BCD types, may not permit easy air migration inside the buoyancy control device.

Additional BCD Functions:

1)     Storage/Stowage: The buoyancy control device may offer some options to store/stow ancillary items required by the scuba diver.  These may be via pockets, d-rings and other styles of attachment point.  The diver should consider what ancillary items they will be using when deciding upon the storage/stowage features offered by the BCD.

  • Pockets: Pockets are an ideal way of storing items in a streamlined manner.  Streamlining your kit reduces exertion in the water and helps prevent entanglements.  Most BCDs offer some form of pockets, but many of these are not of suitable size for actually storing the equipment you may intend to carry.

This is especially true of some jacket BCDs, where inflation of the bladder will constrict the pockets and make access to them very difficult.  When trying out a BCD in a store, do look at the pockets and, if possible, see how they perform in storing common items; such as a DSMB, reel, compass, slate, pocket mask etc when the buoyancy control device is worn fully inflated.

Having a D-ring located inside, or next to, a pocket is also a very useful feature as you can securely attach items to prevent their loss.

Pockets may be secured with either Velcro or zips.  Velcro offers easy access, but its function tends to decrease with age.  Velcro is the least secure method of closure, especially if it doesn’t cover the entire opening of the pocket.  Zips are the most secure method but sometimes can get jammed with silt/sand.

  • D-Rings: D-Rings offer the diver the ability to conveniently clip items to the BCD.  Consider the quality of manufacture and material of these; as they are essentially load-bearing points to which you may clip valuable items.  Also, consider the number and location of these D-rings.

As a minimum, the buoyancy control device should offer 4 D-rings; one on each shoulder strap and one at each hip.  This permits the attachment of slung ‘pony’ or ‘stage’ cylinders, should you ever require them.

Consider that technical and cave divers typically only use harnesses with 6 D-rings (2x shoulders, 2x hips & 2 front/back on the crotch strap) to carry all of the cylinders and kit needed for highly advanced diving, and you might wonder why some recreational BCDs will boast of having 12, 18 or more D-rings.

This is normally because the D-rings are not adjustable on the harness, so multiple D-rings are fitted to allow more fit options.  Logic says that one adjustable position D-ring is far more efficient than multiple fixed ones (of which only one will be used and the rest will be superfluous).

  • Other Attachment Methods: Some BCDs offer specific attachments for BCD knives, lights, strobes etc.  These can be useful, depending on whether they fit your chosen kit configuration or not.  If they don’t, then you’re just paying for something you won’t use…and adding unnecessary clutter.

Other factors:

1)      Material: The quality of material and construction varies depending on the manufacturer.  Consider the material used, in addition to inspecting the quality of stitching/glueing/seam-welding etc of the BCDs considered.  Some BCDs have a single layer bladder.  Other BCDs have an inner (air-tight) bladder, with a protective outer cover.  The quality of inner-bladders can vary considerably – always check those.  The lifespan of the buoyancy control device will ultimately be decided by the quality of its materials and construction.

2)  Repair/Service/Warranty: Always investigate the warranty provided on a new BCD.  Do some investigation about how widespread (locally, nationally and internationally) the manufacturer’s repair/service/dealer network is.  If you move to a new area or have an issue when on holiday, the availability of that support will be critical.  Having to occasionally ship the buoyancy control device away for service or repair can substantially add to the overall ‘life cost’ of the equipment.   Also, confirm and compare the approximate service and component costs of different manufacturers; as this will play a large role in the overall, long-term, cost of the BCD.

3)  Travel BCDs: Some BCDs are deliberately made with lightweight material and are marketed as ‘travel BCDs’.  Those efforts can be undermined if the ‘travel BCD’ is still covered with superfluous d-rings, attachments and are otherwise badly designed without minimizing unnecessary items and volume of material.  ‘Travel BCDs’ are a new trend in the market.  Some manufacturers have embraced this and applied clever design to the problem.  Others have just leapt onto a sales bandwagon and simply re-produced their standard buoyancy control device design using less robust materials.

4)  Weight Integration: This is a relatively popular additional function; that enables the diver to transfer some, or all, of their lead weights into purpose designed, quick release, pouches built into the BCD. There are both ‘pros’ and ‘cons’ to this feature, so avoid the assumption that it is automatically a good feature to have.  The decision should ultimately be decided based on a specific requirement.

If there is no requirement, then this feature is likely to be a drawback.Integrated weights can make the BCD more ungainly in the water (it will amplify any issues caused by bad fit), will make the BCD much heavier to lift and can complicate the process of ditching weight in an emergency.  It will also make the buoyancy control device much bulkier and reduce streamlining.

The benefit is that the diver can reduce the weight on their weight belt by transferring it to the buoyancy control device – which helps if the diver carries a lot of weight and/or has a problem with the weight belt slipping down from their waist.

If weight integration is considered, then the diver should have a clear idea about how they will spread their required weight amongst the integrated pouches and weight belt. They should also be prepared to re-learn the emergency weight ditching procedures so that their operation of the new system is ingrained and instinctive.

When considering different weight-integrated BCDs it is important to analyse how well designed the weight integration system is.  Integrated weights are normally kept in some form of a pouch. The diver must be able to dump these pouches quickly and efficiently in an emergency.

The typical design involves releasing the pouches via a ‘pinch buckle’, pulling the pouches out of a pocket and then dropping them.  Some, more complicated, designs have a quick release ‘handle’ that pulls on a wire that opens the bottom of the pocket/s and lets the weights fall out.  Some quick release mechanisms are not very secure and might allow the weights to drop out accidentally.  This is potentially very dangerous (rapid, uncontrolled ascent).  Critically examine and test the function of a weight integration system before purchase.

   SEE ALSO:  8 Factors When Purchasing Your Scuba Diving Regulator



About the Author andy davis technical diving philippines

Andy Davis is a RAID, PADI TecRec, ANDI, BSAC and SSI qualified independent technical diving instructor who specializes in teaching advanced sidemount, trimix and wreck exploration diving courses across South East Asia.  Currently residing in ‘wreck diving heaven’ at Subic Bay, Philippines, he has amassed more than 9000 open circuit and CCR dives over 27 years of diving across the globe. Andy has published many magazine articles on technical diving, has written course materials for dive training agency syllabus, tests and reviews diving gear for major manufacturers and consults with the Philippines Underwater Archaeology Society. He is currently writing a series of books to be published on advanced diving topics.  Prior to becoming a professional technical diving educator in 2006, Andy was a commissioned officer in the Royal Air Force and has served in Iraq, Afghanistan, Belize and Cyprus.


Andy Davis technical diving subic bay philippines

Originally posted 2018-11-05 06:10:17.

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