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Equipment SCUBA Diving

Balanced Rig and Neutral buoyancy

Exploratory view of balanced rig and neutral buoyancy.

Review of a real scuba diving accident.

A balanced rig is achieved by testing, it is no difficult but there is no magical solution. Just get into the water and test your equipment.

A few decades ago, divers in tropical water used less equipment, a plastic plate a regulator with an SPG and weight.

Those divers who weren’t using BCD, worn a weight belt with enough weight to maintain negative buoyancy at 3 meters with a near empty cylinder, but the diver was capable to swim at the surface at any time with the belt on and, they were capable of swim for a least 15 minutes without taking out the weight belt at the surface. The weight belt was quick releases for surface emergency only.

In those days, many divers attached the weight to the cylinder as well. Watch the photographs. Others attached the weight to the harness. The lesson to be learn here is that they took the time to test their equipment and not be overweight as tends to be now a days.

LLoyd Briges using a weight belt under the harness.

Remember that equipment and configuration evolve, real life lesson had been learned. Now we use a BCD that help us to manage buoyancy, but this is no reason for overweight ourselves.

Everything you carry, every part of your rig affects buoyancy.

With a balanced rig you should be able of:

  • Perform your safety stop been neutral at 4.5 meters with a near empty cylinder (30 bars) and BCD (wing).
  • Swim from the bottom to the surface at any time during your dive without detaching weight and with a failure BCD (wing).
  • Maintaining positive buoyancy and swim at least for 15 minutes on the surface wearing all your gear.
  • Handle your gear without difficulty, naturally.
  • Be horizontal underwater.

Old style front mounted BCD- Luis Recatero
Old style front mounted BCD- Luis Recatero

When a diver is overweighted, you will use your BCD to offset the excess, this shifts your center of gravity, so you swim with your feet low and your chest high.

On the contrary, if you are underweighted, you’ll swim with your leg high to hold yourself underwater.

Although is possible that your weight distribution may you sink too much in one of this position.

Detachable weight?

Balanced Rig

This old video owns by GUE, George and Jarrod explain what a balanced Rig is and options for weighting.

After all you had read, visualize that all your equipment components affect your buoyancy and streamlining (fins, mask, exposure suit, cylinders, boots, regulators, backplate, BCD- wing and so on…)

If you are using detachable weights, remember that should be only a portion and not all.

Do whatever you feel safe and comfortable. Me? I don’t use detachable weight; I use a v-weight for doubles or weight pockets for single cylinders.

Jeffrey Bozanic wrote this post for SDI in which he explores how we should, as instructor or recreational divers who likes to do just a few dives a year, take a practical approach “toward neutral buoyancy”.

NEUTRAL BUOYANCY—LET’S GET REAL!

By Jeffrey Bozanic

“OMG! Look at that diver, kneeling on the bottom! They should be banned from diving!”

Instant evaluation. Instant judgment.

Whether it is a photograph, video, or seeing someone in the water: instant villains. This is, in my opinion, an example of the same kind of prejudice that plagues our nation, our world. The “I am right and you are wrong” syndrome. And you know what? YOU are wrong!

Don’t misunderstand me… the ability to achieve and maintain neutral buoyancy is an important skill. Often it is critical to preserving the environment, protecting fragile animals and communities, or contributing to dive team safety. As divers, we should all be attuned to our bodies and how our actions and movements can harm the environment around us. But it takes time, often lots of time, to get there.

What really is the best way to proceed?

Coral reefs are a classic example where poor buoyancy or trim by a careless or unskilled diver can destroy decades, maybe even centuries, or growth. Many times, I have watched a diver swimming above the coral, wanting to be close enough to see and observe, but struggling not to be so close that they kick or hit anything. “Don’t touch!” they are warned during the briefing. So, in attempting to follow these directions, they inadvertently create a wide swath of intermittent devastation behind themselves, as they bob up and down, occasionally kicking the reef in sincere efforts to avoid exactly what they are causing.

Wouldn’t it be better to teach them an easier skill, one which would allow them to sidestep the potential to cause damage, and allow them more time to build better in-water skills? In this case, perhaps a better option might be to swim them over to the sandy bottom next to the reef wall. Here, they could lightly settle down to the bottom, stabilizing themselves in a location relatively immune to damage, to observe the reef and its inhabitants. They can now comfortably enjoy the dive, enjoy themselves, and not worry about damaging the environment.

How dive professionals can help

We, as dive professionals, need to take a different approach in our instruction. Instead of a “zero-tolerance” policy regarding developing buoyancy, we should be educating our students (and each other) how to assess the environment, assess their skills, and then have them select a dive location that is compatible with both. In the example above, while transiting from the shore or the boat to the reef, the diver could be gaining time in the water, learning more about themselves, and consciously working to develop a better skill set, like improving buoyancy, in an area not prone to significant damage.

But divers need to know this is OK. Pictures of divers sitting on the bottom are not being published. Divers are being told that ANY time they hit, kick, or touch the bottom, regardless of where it is, is a mortal sin. We all have done it. And, I venture to say, if we are truthful to ourselves, for the most part, we all do it still. Perhaps only occasionally, but none of us are perfect. And none of us began where we are now, skill-wise. We need to allow others the time and opportunity to do the same for themselves, without a truckload of guilt being heaped upon them.

What are some other examples?

A cave diver: It is sometimes better for a cave diver to settle slowly and calmly into the silt when control is lost, pivoting on still and stationary fin tips while reestablishing proper trim and buoyancy, rather than flailing and kicking to stay off the bottom. Cleaner, calmer, safer.

An underwater photographer: It may be better for a photographer to lightly rest a finger on a dead rock, stabilizing themselves for a picture, rather than kicking to stay off the bottom or crashing their camera into a gorgonian.

Location considerations: I grew up diving in California, often in heavy surge and poor visibility. Holding the bottom was the most realistic and effective dive technique available to stay in contact with my buddy and an awareness of where was.

The alternative

I would rather maintain control of a group of entry-level divers by firmly settling them on a durable surface (like sand), rather than risk losing control of one or more class members trying to achieve and sustain neutral buoyancy during all phases of skill instruction. Safer for them, for me, and ultimately for the organisms near us.

Newer divers are being shamed, being told they are idiots or morons. It makes diving not fun. We are losing divers because of that. Why continue with a sport where you are constantly being told you are a failure?

Let’s get real

Yes, we need to teach neutral buoyancy. Yes, it is an important skill. But it is not the only dive skill, nor is it “Rule #1” in importance. Collectively we need to discard our “Holier than thou” mentality and return to a more holistic instructional paradigm… using weighting and buoyancy (heavy, neutral, or light) as a tool, coupled with the knowledge to evaluate when and where to use them properly, and in a manner consistent with our personal skill limitations.

The Expedient gear technician, a real accident.

Extract of the text below.

Ray and his friends ate an early breakfast before stopping by the gear lockers and grabbing their dive gear to board the boat for the day’s excursion. His companions would later recall that Ray had spent a few extra minutes getting his gear together because of some part he thought was broken. But in fairly short order he had it all sorted out and was climbing aboard the boat with everyone else…

… Arriving at the site, the captain tied to a preset mooring at the top of a nearly vertical wall that started at between 50 and 80 feet and dropped into a great abyss. The divers were warned that the bottom was at well over 1,000 feet and that the deep water could sometimes create tricky currents…

…Then the divemaster went into the procedural part of the dive briefing. There were six divers in three two-person buddy teams, and the dive was to be guided by one of the resort’s most experienced dive masters. His instructions were clear and concise. Each buddy pair was to enter the water together, swim to the bow of the boat, and hang on the mooring line at 15 to 20 feet of depth. Once the entire group was in the water and gathered at the mooring line, the divemaster would lead the group over the wall and drop to a maximum depth of about 110 feet. The group was to always remain directly above the divemaster. All the divers were to stay within arm’s reach of the wall. They would swim along the deep part of the wall for approximately 10 minutes, then move up to the top of the ledge and swim back toward the boat, viewing the shallower-water coral reef along the way. The plan was simple, straightforward, and easy to follow—until the divers entered the water.

…Ray and his dive buddy were the first to enter. His buddy stepped into the water slightly ahead of Ray. Neither of the divers signaled back to the boat as they had been directed, but a bubble stream immediately began moving to the bow of the vessel. The remainder of the group entered the water without incident and gathered at the bow. However, when the divemaster arrived, his group of six advanced divers had been reduced to five. Giving the divers the hand signal for buddying up, he quickly determined that Ray was the missing diver.

Asking Ray’s buddy where Ray was, he received the universal shoulder shrug meaning “I have no idea.” The divemaster directed the group to wait while he made a quick circuit around the mooring position looking for Ray or signs of his bubbles. What he found was quite alarming. Ray’s bubble stream was visible, but it was coming from deep water below the ledge and Ray was too deep for the divemaster, now at 80 feet, to see, even in the clear visibility. Quickly, the divemaster swam back to the group and signaled for them all to exit the water. He then popped to the surface and told the captain that there was a possible problem, directing him to get everyone back on board. The divemaster then located Ray’s bubble trail just off the stern of the boat and descended, following the stream. But shortly after he began his descent, the stream of bubbles stopped.

Since there was no current, the divemaster reasoned that if he dropped straight down as deep as he could go, he might be able to find Ray. The strategy worked. He located Ray in 150 feet of water with his arm looped over a coral outcropping. Although the regulator was still held loosely in his mouth, Ray was unresponsive and not breathing. Ray’s cylinder was empty and his computer indicated that he had reached a maximum depth of 169 feet—far too deep for his experience and skill level. Ray’s BCD was completely deflated and his weights were still in place, though one weight pocket was partially dislodged. The divemaster grabbed Ray but found that he could not inflate Ray’s BCD, even when he tried to do it orally. He decided to drop the diver’s weights and bring him directly to the surface. Grabbing Ray and keeping the regulator in his mouth with his head tilted back to maintain an open airway, they ascended rapidly to the surface. An open airway is vitally important because as a diver ascends, any air trapped in the lungs will expand with the reducing water pressure, potentially causing an air embolism or other catastrophic lung injury. The divemaster made what he would later relate was a textbook rescue ascent. Breaking the surface with the injured diver in tow right off the stern of the boat, he immediately began resuscitation efforts. Two members of the dive group jumped into the water, removed Ray’s BCD, and assisted in getting him aboard the boat. As soon as Ray hit the deck, the captain put him on pure oxygen and directed the dive group to release the mooring so that they could quickly get back to the dock.

Once Ray was on board, they were able to determine that he had no heartbeat, and the group continued doing CPR until they reached shore. The resort staff then assisted in transferring Ray to the back of a truck, where he continued to receive CPR and oxygen as they rushed the short distance to the only medical clinic in the area. Ray continued to be unresponsive, and within minutes of his arrival at the clinic doctors pronounced him dead.

It was later determined that Ray died from asphyxia, apparently caused because he consumed all of the gas in his cylinder. Devastated by Ray’s death and faced with many unanswered questions, the remainder of his group, the dive resort staff, and the local authorities turned their attention to Ray’s equipment. His regulator was attached to a full cylinder, where it was found to be leak free and properly functioning. His BCD was free of any holes or tears, and the inflator also seemed to be functioning properly. However, the BCD would not hold air. When the group’s divemaster was interviewed, he clearly recalled attempting to orally inflate Ray’s BCD at depth and being unable to do so. It was discovered that the air passing through Ray’s inflator mechanism was not reaching the air bladder of the BCD. One of the resort’s technicians quickly identified the problem. Ray’s BCD was equipped with a jet dump, and this mechanism was not holding any air pressure at all.

Ray’s dive buddy would recall after the accident that Ray had found parts of his BCD lying at the bottom of his wet locker that morning before the dive. Since Ray had used the BCD without incident on the preceding three days, we can assume that the jet dump had been functioning properly the day before and that the parts Ray found were parts from his jet dump. The back of the valve is a simple threaded cap that unscrews quite easily if it is not properly installed and torqued tight enough. If this cap is removed, the seal will easily come out of the tube; however, the rest of the parts are held together and in place by the stainless steel cable attached to the BCD’s inflator. Ray located the missing cap but failed to realize that there was also a rubber seal that needed to go under the cap. Instead of checking with one of the resort’s technicians or instructors, Ray apparently looked at the pieces, assumed he understood how they worked, and reassembled the valve without replacing the seal. This was Ray’s first error of the day.

Ray’s second error was using too much weight. Although his weights were discarded during the recovery effort and are too deep to ever be recovered, the divemaster remembers pulling weight pockets that were far too heavy for the thin 3-millimeter wetsuit that Ray was wearing in the warm tropical water. When diving in the cooler waters of the Pacific near his home, Ray would have worn a much heavier wetsuit and required much heavier weights to offset the suit’s buoyancy. None of the resort staff or his dive buddies could remember Ray checking his buoyancy and adjusting his weight after arrival at the resort. It seems apparent that Ray had overweighted himself for the conditions of the dive.

Ray’s third mistake was actually a joint mistake. When Ray and his dive buddy entered the water, they both failed to surface and signal the boat that they were OK• They also failed to link up immediately after entering the water. As a result, Ray’s buddy moved off alone to the bow of the boat to wait for the rest of the group as directed. Even though he knew that Ray did not arrive at the bow with him, he did not

know where his buddy had gone or that he was having problems. Additionally, the procedure adopted by Ray and his buddy resulted in a delay of several minutes before the divemaster learned of Ray’s situation, and because the buddy had lost track of Ray, the divemaster burned another couple of minutes searching around the mooring position. Apparently, their procedure of entering the water solo and linking up on the descent line was common for this buddy team, and they had used it on previous dives. Divers should remember that they are most likely to have major equipment problems immediately upon entering the water because certain types of equipment failures do not become evident until the equipment is submerged.

Apparently, when Ray entered the water he was unable to inflate his BCD. This, coupled with his overweighting, sent him plunging down along the wall. We can never know exactly what happened, but it is likely that Ray tried to swim upward and continued wasting air trying to inflate his BCD as he sank.

Ray had two fairly easy courses of action that would have saved his life, even after all the mistakes he made. His best move would have been to simply dump his weights. At some point Ray attempted to do just that, as the divemaster recalled that one of Ray’s integrated weight pockets was unfastened and the weight pouch inside was partially removed. Even in the thin wetsuit that Ray was wearing, he would have had sufficient buoyancy to immediately pop back to the surface if he had succeeded in this. Ray must have waited too long and run out of air before he could jettison the weights. Ray’s second course of action would have been to swim horizontally to the wall. Both the captain and the divemaster believe it was impossible that Ray was hanging completely over deep water when he stepped off the boat, based on the position of the mooring along the ledge. It is possible, however, that he was very close to the drop-off. In any event, Ray should have seen the wall very close by, and eventually he must have realized that he needed to reach it. Unfortunately, he descended to a depth of nearly 170 feet before recognizing this. Ray probably took too long trying to analyze the problem with his BCD while plummeting to the bottom when instead he should have been taking immediate action to stop his descent. This series of bad decisions and poor procedures cost Ray his life.

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