In order to achieve what’s known as neutral buoyancy while diving, a jacket called a buoyancy compensator (BC) or buoyancy-compensating device (BCD) is used.
Positive buoyancy is when an object in the water rises. If the object sinks, instead of rises when in the water, it’s said to have negative buoyancy. If, on the other hand, an object in the water does not rise or fall, it’s said to have neutral buoyancy. Neutral buoyancy is what divers want and need.
The real fun of scuba diving is discovering and investigating wonderful undersea worlds. If, while doing so, you are constantly being pulled up or down, i.e. rising or falling, it kind of ruins the mood. If a diver has neutral buoyancy, he can enjoy the sites without being dragged up or down by the ocean. Fortunately, divers are taught several techniques to achieve neutral buoyancy during scuba school.
Buoyancy compensators are basically pretty simple.
Buoyancy compensators fill bladders within the device with air. That’s how they work. Air is positively buoyant because it's not as dense as water. The buoyancy compensator jacket, filled with air causes the diver to rise in the water. For the most part, the more air in the jacket the faster the diver will rise.
As often happens in life, things aren’t always equal. As a result, Boyle’s law comes into play. Boyle’s law says the Pressure x Volume = a constant, at a given temperature.
Also, when the diver sinks lower in the water, pressure on the jacket goes up and that lowers the volume of air it contains. The reduced volume results in the upward buoyant force to lessen and this results in an even faster descent.
A scuba diver can control ascent and descent by using the buoyancy compensator. Control is achieved by inflating and or deflating the buoyancy compensator jacket air pockets. Some of the better buoyancy compensator jackets also have weights built in to them to help with buoyancy.
Divers often place weights on their ankles and around their waists to help them get to the desired level of buoyancy. The ankle weights are to counteract the buoyant effect of swim fins. As mentioned above, some buoyancy jackets have weights built in. It should be noted that these jackets are design to eject the weights quickly and easily in case of an emergency.
Dealing with all the various forces that impact buoyancy is an ongoing process for divers, aided by the jacket. Fortunately, scuba diving certification courses cover how to deal with buoyancy issues in detail.
Buoyancy compensators have a great safety function built in. So, not only do they make diving much more pleasant, turns out they could also save a life. Here’s how it works. If a diver becomes disabled while on a dive, another diver can operate the disabled diver’s buoyancy compensator jacket and use it to float the disabled diver to the surface.
In order to make use of the safety feature (of the buoyancy compensator) we just talked about, it’s essential to avoid two potential problems. The first problem is that you need to make sure the disabled diver does not come up to quickly. Doing so can cause decompression sickness. The second problem to avoid is that, depending on the design, some buoyancy compensators face divers down instead of up. This could be a huge problem because the disabled diver could drown even though they make it to the surface.
One of the most important safety rules in scuba diving is to not dive alone. It’s best to dive with at least one buddy underwater with you and an additional person topside in a recovery boat. The guy in the boat is the one who will find and help any diver who bobs up to the surface in an unconscious condition.
Well, there you have it. You now know all about buoyancy and why it’s such a key issue for scuba divers. You also know how divers deal with buoyancy. You also know what a buoyancy compensator is and how they work. You are now more prepared to have a safe and fun time scuba diving.