What is Buoyancy?  

In scuba diving, neutral buoyancy is the ability (or inability) of an object to float in water and we focus on the positive and negative buoyancy forces acting upon a diver that causes them to sink, float or remain at a fixed depth.  The ability to “remain at a fixed depth” is what we refer to as neutral buoyancy and is a function of our ability to balance those positive and negative forces at any given depth while on our dive.

Why Buoyancy?

Being proficient with your buoyancy makes all other aspects of diving safer and easier.  Safety is certainly at the top of the list.  It is commonly sited that poor buoyancy is a contributing factor in many diving incidents and can result in serious injury or even death. Additionally, good buoyancy control is also critical for many situations including diving in sensitive or silty environments, wreck diving and overhead environments and for any type of underwater video or photography.

My Teacher the Sea Turtle: 

One of the best examples that I use with my students is the sea turtle.  Sea turtles have amazing buoyancy control and maintain a sense of ease in everything they do in the marine environment.  They eat, sleep and effortlessly move around in a three dimensional environment while always maintaining neutrally buoyancy.  As we attempt to model the turtle’s natural skills, we focus on our own ability to remain stationary at a particular depth and also maintain that buoyancy during descents, ascents and while performing other activities.  

Buoyancy Control: 

So how do we become the sea turtle?  Remember, as we descend and ascend in the water column, the pressure surrounding us increases and decreases respectively.  Assuming we are properly weighted, our buoyancy becomes a function of the amount of gas/air in 2 to 3 flexible containers (our BCD, lungs and *optionally* dry suit).  

• Our BCD is used to counteract the weight we are carrying and achieve neutral buoyancy for a given depth with a normal breath and once set, we should not need to inflate or deflate our BCD until we want to significantly change our depth.  

• Our lungs become the primary mechanism to perform fine adjustments within a given depth range and only when we go deeper or shallower should we need to add or remove air from our BCD.  The key is to remember that taking a full breath will cause us to rise slightly in the water and fully exhaling will cause us to sink.  With simple breath control, we can make fine-tuned adjustments and maneuver over varying underwater terrain.  

• Our dry suit (if you wear one) is another flexible container to manage.  Just like the BCD, you will need to add or remove gas from within the dry suit as you descend or ascend in the water column.  Now there is some debate over how much gas to add and we follow the practice that you only add enough gas to the dry suit to maintain the thermal comfort while continuing to utilize the BCD as your primary buoyancy compensation device.  

Safety and Practice: 

A final note on safety:  Remember, we NEVER hold our breath underwater.  Taking a full breath to rise slightly does not imply holding one’s breath and is something we should never do while scuba diving.  Beyond that, practice, practice, practice.  Every single dive is an opportunity to practice buoyancy and improve it.  In many cases, practice in shallow waters can net the best results since the percent of pressure change near the surface is much greater than at depth so if you are able to hold buoyancy in shallower waters, it will be much easier as you descend deeper.  Finally, a great place to practice is while you are holding your safety stop at the end of every dive.  Using a mooring line or the line from your dive flag as a reference, try to maintain a fixed depth in the water while only using breath control and you’ll start noticing immediate improvements.

Hopefully you enjoyed this discussion and we’ll continue to talk about this and other topics as we explore Adventures in Neutral Buoyancy.

Thanks and Safe Diving