The Sea Turtle - My Buoyancy Teacher

Bill Mitlehner   Oct 07, 2024

What is Neutral Buoyancy?  

In scuba diving, neutral buoyancy is the ability of an object to remain stationary at a given depth in water.  As a diver, we focus on the upward forces (buoyancy) and downward forces (gravity) acting upon us underwater that causes us to float, sink or (when in balance) 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 keep these positive and negative forces at any given depth during our dive.

 

Why The Focus On Buoyancy?

Being proficient with your buoyancy makes all other aspects of diving safer and easier.  Safety is always our number one concern when diving and 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, diving in overhead environments like caves or for any type of underwater video or photography.  Mastering neutral buoyancy provides the foundation for nearly every aspect of scuba diving and will have a positive impact on your enjoyment, air consumption and safety on every dive. 

 

My Teacher the Sea Turtle

One of the best examples we use with our 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 neutral buoyancy.  As we attempt to model the turtle’s natural skills, we initially focus on our own ability to remain stationary at a particular depth.  As we improve our buoyancy skills, we start being able to perform other activities with ease, such as easily maneuvering over or under obstacles using only our breath control, holding our safety stop without holding onto a line, or rigging and shooting a SMB at depth.  Mastering neutral buoyancy also becomes a critical skill if you want to progress to using dry suits or venture into the technical diving realm.   

 

Buoyancy Control

So how do we become like 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 for the conditions and thermal protection, 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 downward pull from gravity on our own mass, the mass of the weights and gear we are carrying and the increase pressure exerted on us as we descend into the marine environment.  It does this by providing a flexible container that we can add and remove gas from to increase or reduce our buoyancy, allowing us  to achieve neutral buoyancy for a given depth.  Once we have our BCD filled with enough gas to remain at a given depth, we should not need to inflate or deflate our BCD until we want to significantly change our depth.  

• With our BCD balancing the forces of gravity and bouyancy, our lungs now become the primary mechanism to perform fine adjustments within a given depth range. It's only when we descend significantly deeper or ascend to a shallower depth should we need to add or remove air from our BCD.  In most cases, you should be able to adjust your depth by about 5 feet up or down in the water column simply through breath control.  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 third flexible container that can significantly effect our buoyancy is the dry suit.  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 whether the drysuit becomes your primary buoyancy device when in use.  Since the gas in your drysuit is much more difficult to manage than a BCD, having an excess amount of gas in your drysuit can increase the safety risk so we follow the practice that you only add enough gas to the dry suit to maintain thermal comfort while continuing to utilize the BCD as the primary buoyancy compensation device.  This method helps reduce the risks uncontrolled ascents and will aid in proper buoyancy and trim in the water.

 

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.  Its important to emphasize that holding our breath underwater is something we should never do while scuba diving.  One way to think of proper Scuba breathing to equate it to yoga breathing: A relaxed 3 seconds in...slight pause..3 seconds out...slight pause and repeat.  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, the line from your dive flag or your dive computer as a reference, try to maintain a fixed depth in the water while only using breath control and you’ll start noticing immediate improvements.

In addition to practice, Scuba Shack has created a workshop focused on improving not only your buoyancy, but all the key aspects and skills related to being a diver.  The course, Foundations and Principles of diving is a combination of classroom sessions, filmed, in-pool sessions and video review focused on improving your personal diving skills and setting the foundation for nearly any other interests you may have while diving.  The course is open to any certified open water diver and now is a PADI certified speciality.  

 

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