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Public Safety Buoyancy

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Photo Credit Keith Cormican

Public Safety divers spend a lot of time practicing search patterns, signals, evidence collection and team safety.  Each one of these skills and techniques are very important part of a safe and successful mission. Have you ever thought about what each of these things have in common?  What is required to perform these skill successfully? Buoyancy.  A search pattern cannot be successful if divers are floating away.   Signals cannot be transferred if they are not felt.   Evidence is impossible to collect if it cannot be found due to silting.  The team is not safe if they cannot control ascents and descents in the marine environment.  When is the last time your team practiced buoyancy skills?

The search patterns, such as the Sweeping Arc, Jack Stay or Expanding Circle, all require refined buoyancy to make them effective.  Consider a new public safety diver being deployed in any of those patterns and not taking a few seconds to establish proper buoyancy.  During these patterns they are trying to use their hand to feel for an object in near zero visibility.  Because of the lack of buoyancy their face is planting into the ground, their hand is being used to push off the bottom or they are floating away, out of reach of any potential object.  Each time their body disturbs the sediment it makes it that much harder to locate the target.

Recreational divers are trained to stay off the bottom with visual references.  They swim along looking for the fish and staying off the delicate plant life or structures.  If they get too far off or start to float away, they check their computers and have ample time to adjust their equipment or techniques.  Public Safety divers do not have those options.  They know their target object is on the bottom, but they cannot see the target, let alone the bottom.  They don’t know how far they are from the bottom unless they touch something.  If they float above the bottom, they are lucky if they can clearly see their computer in time to realize their actual depth.  The one thing they do not have is ample time to adjust for misjudgments. Their line is being pulled, the current is moving them or they are struggling their way through some aquatic obstruction.

The diver feels rushed to get into the water and complete their task.  They have a lot of things on their mind and they may have some hesitation going into an unknown environment.  If the diver is not trained to stop and obtain good buoyancy the mission could become more difficult or fail.  Proper buoyancy requires controlled breathing, an understanding of their equipment and the ability to make adjustments using their senses since they may not have a visual reference.

The Public Safety diver never has a choice of where they want to dive.  As much as the diver would like the mission to be in warm, clear, flat contour environments, we all know that is never the case. Buoyancy is a very important factor when the search pattern involves changing bottom topography.  If the team decides on a circle search pattern and the pattern runs on a slope, the diver will continually change their depth and buoyancy characteristics.  Just imagine a slight slope where the diver is at 10 feet during part of their pattern and 35 feet at the opposite end.  If the diver does not have good buoyancy control there is an increased hazard for runaway ascents or dragging the bottom and possibly destroying evidence.  Proper buoyancy will allow a diver to maintain neutrality no matter what depth during the pattern.

A buoyancy training technique you can try during your next drill involves a team of two divers. Have one primary diver place an obstruction in their mask which will limit their vision.  Have the second diver act as the safety and lead diver.  As the lead diver moves along in the training environment the primary diver follows by a slight touch to the lead diver as well as staying as close to the bottom as possible.  The lead diver can intentionally rise above the bottom to the point the primary diver cannot touch.  The primary diver will then need to adjust so they are touching the bottom again using only their fingertips. The lead diver can then re-establish contact and continue with the pattern.  The lead diver intentionally moves up and down, away from the bottom, making the primary diver feel and adjust using their senses. The primary diver will need to know where the adjustment points are located on their equipment.  They need to remain calm if they lose contact with the lead diver and maintain control of their breathing.  The exercise will give the primary diver confidence in their buoyancy while being trained in a controlled environment.

A second training suggestion involves team members and extra weights, for an underwater game of hot potato.  The divers all descend and establish neutral buoyancy with controlled breathing.  The team brings down a bag of varied weights, from a few ounces to multiple pounds.  When a diver gains good buoyancy, someone hands him a weight.  The diver must re-establish their buoyancy with breathing techniques, BC adjustments or drysuit adjustments.  Once they are neutral they hand the weight off to a nearby team member.  As they hand over the weight, their buoyancy changes and they must re-adjust, only to be given a different weight.  The exercise continues with the goal being the diver can quickly and properly adjust to changes in weight without overcompensating, or handing a weight off and not floating to the surface.

Dive teams need to become proficient with basic diver skills, such as buoyancy.  All too often the team training focuses on the exciting parts of the mission and high end equipment and ignores refreshing on the basic skills.  If the team works harder to become proficient at buoyancy, it will translate in to more efficient missions, safer divers and a greater likelihood of a successful mission.


About the author
donkinneyDon Kinney – ERDI Instructor Trainer
Don Kinney has been a Public Safety Diver since 1991.  He continues to lead his public safety team as well specialize in training other dive teams around the world.  He has extensive experience in lakes, rivers, ponds, oceans and water holding tanks.  He prides himself on developing training around the needs of each team and their unique environments.  For further information please go to www.etds.org.

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/PublicSafetyDiving

The Art of Buoyancy – Controlling Your Ascent and Descent

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Photo by Harry Averill

In a way, diving can be compared to flying an airplane; the hardest part is taking off and landing.  This is true for diving as well; the ascents and descents are often what cause people the most trouble.  Once you’re at depth and neutrally buoyant, it’s “easy peasy.”  It’s getting to that point and making a nice controlled ascent to your safety stop and the surface that can be a bit tricky…

Making a controlled ascent and descent can add to your overall enjoyment of the dive as well as help prevent barotraumas (pressure related injury).  After a controlled descent you arrive at depth already neutral, calm, relaxed, and ready to enjoy the dive.  This a vastly different than the over weighted negative free fall many divers make; struggling to equalize and landing on the bottom causing damage to the reef or wreck and ruining the visibility.  This is a bad way to start a dive, and it takes time to regain control and enjoy the remaining portion of the dive.  Also, this is often the cause of many pressure related injuries to the ears and sinuses because the diver is descending faster than they can equalize those air spaces.

Making a controlled ascent is important for similar reasons.  Making a nice controlled ascent to your safety stop, you arrive neutrally buoyant and can hover effortlessly while continuing to enjoy the marine environment around you.  You also avoid injury by allowing time for the expanding gas in your air spaces to escape safely.   All too often we see divers “float” up and blow right past their safety stop ending up at the surface wondering what the heck happened.  We are going to take a look at how to control your ascent and descent by using the art of buoyancy control.

In order to control your descent, you should remain neutrally buoyant.  This seems counterintuitive at first.  “If I’m neutral, how am I going to go down?”  Well, if you are properly weighted you should really only be descending when you exhale all the gas out of your lungs, and you should only be descending a couple of feet at a time.  We were all taught in our open water course, that to be properly weighted and an empty BCD you should float at eye level while holding a full breath.  When you exhale, you should become slightly negative and descend, when you take another breath, you should become neutral again.  As you descend in this controlled manner, you will need to add small amounts of air to your BCD every few feet to counter the compression of your wetsuit/dry-suit and BCD to remain neutral. This allows you to easily stop your descent to equalize, acclimate to a thermo-cline, make contact with your buddy, watch that dolphin swimming by, or avoid landing on the bottom.  Now you will arrive at your target depth already neutrally buoyant, air spaces comfortably equalized, and ready to look for that dolphin you spotted on your way down!

Ascending should be pretty much the same process, just in reverse.  You should already be neutrally buoyant, so to ascend you should only need to swim lightly towards the surface.  Now it’s extremely important to monitor your dive computer’s ascent rate indicator to make sure you are going up at a safe rate and vent the expanding gas out of your BCD so you do not become positively buoyant.  If you become positive, you can find yourself on an uncontrolled ascent to the surface.  Floating up, the air in your BCD can begin to expand faster than you can dump it, which makes you even more buoyant and you float up faster while the air in your BCD expands even faster.  This is a dangerous situation which can result in a barotraumas or even decompression sickness.  To avoid this potentially hazardous situation, pause every few feet on your way up to make sure you are not starting to float towards the surface.  This way, once you reach your safety stop, you can easily just hold your position hovering weightlessly showing off your excellent buoyancy skills to that dolphin that decided to come back to play.

Your safety stop is an excellent place to make a final weight check.  If you are weighted properly, you should have almost NO air in your BCD at the end of the dive and be perfectly neutral.  If you are struggling to stay down, you may need another pound or 2, if you have to add air to your BCD to remain neutral, you can probably take a little weight off for the next dive.

Like everything else, practice makes better.  Luckily, on every dive, you have to make at least one descent and ascent, so you may as well use this time to practice.  We’ve found that using a line or sloping bottom as a visual reference is a great way to get your ascents and descents dialed in, and suggest using them to hone your skills whenever available.  Even better than practicing on your own, is having an instructor help you through it with an SDI Advanced Buoyancy course.  Find an instructor near you here!

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: https://www.facebook.com/SDITDI