How Do Scuba Divers Control Their Buoyancy?

Peter Letts   Feb 21, 2022

How do scuba divers control their buoyancy?

When scuba diving, it is important to control your buoyancy. This keeps you safe underwater and helps you maximize your diving enjoyment. There are three the ways to control your buoyancy:

• Use your weights for the course adjustment of your buoyancy
• Use your BCD (buoyancy control device) for the fine adjustment of your buoyancy
• Use your breath for the fine tuning of your buoyancy

 

Use your weights for the course adjustment of your buoyancy

The more weight you lug around than necessary, the more difficult your buoyancy control becomes. Every extra pound needs to be countered with about half a litre of BCD air. Since this volume expands and contracts with depth changes, you must constantly adjust to keep the volume at half a litre. Three extra pounds, which can easily happen without a pre-dive buoyancy check, means one and a half unneeded litres of volume that grow and shrink with every change in depth.

Even if there are reasonable intervals between dives or if there have been changes to things such as your wetsuit, or if you've recently changed your body weight, it's important to conduct a buoyancy check at the beginning of your dive. For properly weighted, you should float at eye level when holding a normal lungful of air with an empty BCD. Take care not to kick or scull while you do a buoyancy check. Let yourself hang vertically in the water column with minimal movement, and then exhale fully and you should then sink slowly.

Use your BCD (buoyancy control device) for the fine adjustment of your buoyancy

The suit compresses and loses buoyancy as you descend, which is why you use your BCD throughout a dive. Buoyancy changes in your wetsuit most occur quickly in the first few meters below the surface, which is why it can often be hard to get submerged, but once you're down a bit, you sink easily. Based on Boyle's Law, your suit has half its surface buoyancy at 10 meters, a third at 20 meters, a quarter at 30 and so on.

Naturally, this buoyancy change goes both ways, which is why you put air into your BCD when going down and release it when coming up. Mastering this buoyancy skill requires you to be aware of changes in buoyancy as you move throughout the water column and adjust your BCD accordingly.
The best way to improve your use of a BCD is to take a Peak Performance Buoyancy Course soon after purchasing your own BCD.

Use your breath for the fine tuning of your buoyancy

Your lungs can be used for delicate control, and it is this that gives a diver the sensation of flying. If you need to ascend a meter to swim over a rock, take a slightly deeper breath than normal. If you need to descend a half a meter or so, exhale extra deeply. Always remember to consistently breathe slowly and steadily and never hold your breath. When divers have mastered this part of the art of diving, breath control becomes a subconscious process.

 

Once you have all three buoyancy controls mastered, you'll be able to soar like a bird in the water column, around the reefs or through a hole in a sunken ship. Practice your buoyancy skills on every dive even for just a few minutes as this will undoubtedly make a difference in the enjoyment of your diving.