Quick Guide to Scuba Buoyancy Control Devices (BCD's)

To help you select the correct size BCD many dive shops have drawn up approximate size charts - some BCDs have their own size chart as supplied by the manufacturers which supercedes this chart. These are 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.

Denier refers to the thread thickness used in the weave of the material covering your BCD. A high denier such 1200 offers excellent scratch resistance (e.g. inadvertently scraping against a sharp edge on a wreck) but low puncture resistance (e.g. accidentally pressing a pointed object against the BCD). A low denier such as 420 offers low scratch resistance but high puncture resistance. A low denier jacket will have a lighter physical weight making it more popular in travelling BCDs designs whilst a high denier makes the BCD heavy but harder wearing. Many BCDs now incorporate different denier panels in different areas of the BCD to offer the best of all thicknesses.

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.

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 styles BCD 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.

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 regulator means that you do not have to have an octopus (secondary second stage) and in an 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. These should only be fitted by a trained technician and only to a BCD made by the same manufacturer.