Diving Without a BCD

by Sean Harrison, VP of Training

As article topics were being discussed, diving without a BCD (buoyancy control device) caught my attention and I jumped right on it. I did this for a few reasons. Over the years I have dived with many different BCDs, and in some cases without a BCD. I have also seen and heard of divers diving without a BCD (for the wrong reasons) and using the wrong BCD for the dive they had planned.

Let’s look at what not to do or use for a BCD. Often divers will get very comfortable with a BCD, and rightfully so. A good BCD should fit perfect, feel comfortable and the diver should know where every pocket and clip is, but one BCD may not be right for all types of dives.

Divers buying their first set of gear will choose equipment that is suited for the dives they have always wanted to do or for the trip they have planned, and often times this means warm tropical dives. For these types of dives, focusing on the BCD of course, the best BCD is one that provides appropriate lift for minimal thermal protect and features a single cylinder attachment. The BCD may also be very streamlined and have D-Rings made of plastic that are located in areas where lights and slates or even a camera may be attached. While this type of BCD is well suited for these dives, it will not work for colder dives, which require a lot more weight for the diver to submerge, or for technical dives, where the diver will be carrying additional cylinders. Technical BCD’s typically have metal D-Rings that are adjustable and are located differently so that stage bottles can be clipped in the correct location. Technical BCD’s also will have interchangeable air cells so the lift capacity can be increased or decreased based on what the diver is carrying. Finally, these BCDs also have the capability of attaching to a rebreather, if the rebreather is designed to be used with the diver’s BCD.

The final item on the ‘what not to do’ list is use other forms of trapped air as a buoyancy device. Divers have been known to use their drysuits as a primary buoyancy device. This is not only an unsafe practice, it also goes against most manufacturers’ recommendations (check owner’s manual for specific recommendations on how to use drysuit). In theory, this sounds like it would work, the diver is controlling one air space, the drysuit, rather than two, the drysuit and BCD, but it just does not work out that way. The unsafe aspect of using a drysuit as a ‘BCD’ is that the suit has seals to keep the air in, should a diver change his attitude to be vertical to make an ascent, the neck seal would vent excess air, decreasing the lift capacity and causing the diver to descend or swim harder to continue to ascend. This cycle would keep repeating itself, as the air expands during ascent.

Now for the slightly more sensitive subject of no BCD, this is really only practiced in commercial diving application where divers are tethered (connected by a line to a tender on the surface) to the surface and the surface support staff control their descent and ascent, sometimes by pulling on the diver or by raising and lowering a platform. These divers have no need to achieve neutral buoyancy and the additional air cell would only get in the way and may be punctured by sharp objects. Sport and technical divers should never consider diving without a BCD that has an air cell.

A BCD is just like any other ‘tool for the job’ in that you should pick the right BCD for the dive you are planning. There are simple solutions and BCDs that will work for multiple types of dives by simply changing out the air cell (adjusting lift capacity). This option allows the diver to get comfortable with one harness system and build the muscle memory of where his inflator, cutting device, lights and safety equipment are attached. The best thing to remember is to use the right BCD and don’t just use what you have, or you may find yourself in a sticky situation.

Contact SDI TDI and ERDI

If you would like more information, please contact our World Headquarters or your Regional Office.

Tel: 888.778.9073 | 207.729.4201
Email: Worldhq@tdisdi.com
Web: https://www.tdisdi.com
Facebook: www.facebook.com/SDITDI