Shark Diving

I have not yet had the opportunity to dive with sharks, so photos of shark divers always struck me as odd. Scuba divers learn to be neutrally buoyant, and yet I would see photos/videos of shark divers resting on the ocean floor. Why?

So, I finally asked the question in reply to a tweet by @ScubaLuisCzm. Their reply was very informative.

First, it’s a buoyancy issue. Too many divers simply don’t have enough control to not flail their limbs and bodies about as the sharks swim nearby. Resting on the seafloor allows these divers to remain relatively motionless compared to the alternative.

Second, it’s an intimidation issue. Besides not drawing undue attention to themselves, this practice helps prevent scaring the sharks away.

The nearest place to me to dive with sharks involves observing threshers from above, so I don’t think this technique is used there. However, I hope to try it out someday, perhaps with my Twitter friends in Cozumel….

Advanced Open Water Diver

Upon completion of my SSI Diver Stress & Rescue course, I was immediately qualified for Advanced Open Water Diver recognition.

The qualifications for SSI Advanced Open Water Diver recognition are 24 logged dives plus completion of 4 diving specialties.

This differs from the PADI equivalent, which only requires sampling specialties. SSI requires completed specialties.

My 4 diving specialties are, in the order I earned them:

1. Enriched Air Nitrox

2. Perfect Buoyancy

3. Science of Diving

4. Diver Stress & Rescue

I also completed the React Right specialty course, but it is not considered a diving specialty. It is a prequisite for the Diver Stress & Rescue course, however.

Next up: Master Diver recognition. The SSI requirements are 50 logged dives with 5 completed specialties, one of which has to be the Diver Stress & Rescue specialty. My 5th diving specialty will be the Deep Diver specialty.

Stress & Rescue (Buoyancy)

I am one dive away from completing my Stress & Rescue specialty. The other day, as my instructor and “victim” threw scenarios at me, something interesting happened: my dive buddy became positively buoyant during our 5-meter safety stop and almost surfaced.

I saw him ascending, raced over to him, grabbed his Buoyancy Compensator Device (BCD), and then dumped air from my BCD while fully exhaling. This created enough negative buoyancy, along with my dive buddy dumping air from his BCD, for both of us to become negatively buoyant enough to descend back down to 5 meters.

I immediately began thinking that this was the second dive day in a row that I had to do this. I also thought about how I used to struggle at my safety stops before I was properly weighted and understood how to control my buoyancy using my lungs.

So, even though the digital textbooks say that decompression sickness is the most common issue to worry about, I disagree. In my admittedly-limited experience, I would say that buoyancy issues are the biggest concern.

Yes, the problem with positive buoyancy is the risk of decompression illness. However, I have observed issues with negative buoyancy, as well. Negatively-buoyant divers who drift along a coral-covered wall do not necessarily notice that they are at 20 meters… then 25… then 30… then, in one case, 45 meters. This happened to a young, inexperienced diver who had not trained for diving to that depth. He also did not have a dive computer.

Plus, let’s not gloss over the damage divers can do to corals when they lack the skill to maintain neutral buoyancy.

Therefore, I rank buoyancy issues — positive, negative, and neutral (or lack thereof) — as the most common issues to be concerned about.

2nd Specialty

After becoming certified as an Open Water Diver, I first completed the Enriched Air Nitrox (EAN) specialty. For simplicity’s sake, nitrox gas is safer to breathe at shallower depths than the air we breathe up here on the surface. I have now completed my second specialty, which was the Perfect Buoyancy course.

Buoyancy is important for several reasons. First, you consume air more efficiently, which means you can stay underwater longer. Second, you control your depth so you do not damage delicate corals on the sea floor. And, third, you move more efficiently, minimizing resistance against the water.

In every way, it is a great course to take. It is also a fun course to take, because the exercises are challenging. It is very rewarding once you can master your depth and body position.

As a dislaimer, I’m not sure anyone has “perfect” buoyancy after taking this course. However, you should definitely have greatly improved buoyancy after this course, as well as greater and greater buoyancy control over time.

Perfect Buoyancy

Caption: this is a bad photo of the “boxing ring.” It is a series of ropes for practicing buoyancy by swimming under, over, and around different ropes with proper trim and technique.

This past Saturday I took the SSI Perfect Buoyancy course. I still need to take the written test and practice, practice, practice.

We started off in the swimming pool and did some exercises. Then we did two open water dives at the house reef.

This is a really fun course, if anyone reading this has not taken it yet. My favorite part is the 10-second hovering challenge. 

In the swimming pool it was a little challenging, but not too much. In open water it was much more challenging. I was concerned about surfacing prematurely, but I was able to to successfully control my depth.

The way it works I was given 3 markers. I started at the bottom and hovered 10 seconds, ascended to the middle and hovered 10 seconds, ascended to the top and hovered 10 seconds, descended to the middle and hovered 10 seconds, and then descended to the bottom and hovered 10 seconds.

The depth change in open water was significant. But, I ascended slowly and stopped at the proscribed depth. Descending back down was comforting.

We then did some real exercises. By this I mean picking up trash from the seafloor and taking photos while practicing proper buoyancy.

I was able to do everything I wanted to do while maintaining air consumption at the same rate as my instructor.

I’m now looking forward to doing a few fun dives while trying to turn my new buoyancy techniques into habits.

Recycling Air

Before taking the SSI Perfect Buoyancy course, I had one dive with absolutely terrible air efficiency. I used 180 BAR in only 35 minutes, and even borrowed some of my dive buddy’s air. 

I did many things wrong. I was swimming instead of diving, and that uses more energy. I was focused on picking up trash and taking blurry photos instead of thinking about my buoyancy at all. And I inflated and deflated my buoyancy compensator device (BCD) a few times.

After taking the buoyancy course, which I will blog about as soon as I can process the photos and videos, we have determined that my BCD usage probably wasted an awful lot of air.

So, he gave me an amazing tip. First of all, I shouldn’t need to use my BCD. After completing the buoyancy course *** SPOILER ALERT *** I agree! However, if I should really, really need to inflate my BCD at depth, for some reason, I should recycle my air.

Instead of auto-inflating a BCD at depth, technical divers apparently exhale into their BCDs. They need to breathe anyway, so they use exhaled air instead of air directly from their cylinders. I have seen that done with surface marker buoys (SMBs), instead of using an octopus (backup regulator), so now I understand what an efficient idea this is.

Human Catfish

You do not need to know how to swim to go scuba diving. You bring air with you, so you can’t drown. Your buoyancy compensator device (BCD) functions like a life jacket. And you propel yourself, admittedly simplified, by kicking your legs. Too easy.

That said, I believe that my initial scuba lessons went relatively quickly because of my swimming ability. I had no problem resting at the bottom of the swimming pool, nor swimming around the deep end.

I told my dive instructor that I have always swam like a catfish. I hold my breath, open my eyes, and skim the bottom of the pool. Sometimes, I even just rest at the bottom. It seems that this translates to scuba diving quite nicely.

However, there is one big positive and one big negative to swimming ability. 

The positive is maneuverability. If I see a piece of trash on the seafloor, I can maneuver to pick it up and put it in my mesh bag. I can quickly change my depth and direction.

The negative is cheating. I should rely more on buoyancy, but it is often easier to swim over or around obstacles. This uses more energy and, thus, consumes more air. I still manage to squeeze an hour out of an 11-liter tank, but I could probably be quite a bit more efficient if I stopped cheating.

I still think that swimming ability is good to know, and makes scuba diving easier to start. It is probably easier to learn good scuba habits after knowing how to swim, than to build up the courage to start scuba diving without knowing how to swim. In fact, an inability to swim seems to be the number one reason that I have heard why people do not try scuba diving.

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