It’s been a perfect day of diving in the islands of the Dutch Caribbean. Glass seas, fantastic visibility and aquatic life that most people would only see in movies made by National Geographic. 100′ below the surface the shadows cast by the sunken vessel danced across the ocean floor. For a moment my mind returned home to the crystal hanging in the window above my kitchen sink, that cast rainbows of light around the room. It had been weeks since I had been home and my vacation was drawing to a close, and although it had been a great visit I was starting to miss the small quarks of my own house.
I was jarred back to the present by the beeping of an alarm on my dive computer. The time to turn the dive had arrived, air pressure in my tank had dropped below half. At that moment the light from the surface was blocked from somewhere overhead. Looking to the surface my eyes caught sight of what I had been hoping for through out the 25 dives of my vacation. A huge manta, I quickly started snapping pictures as the giant creature was back dropped by the sun like a halo.
Again my dive computer disrupted my peaceful world as the alarm triggered yet again. Pressure on my tank had dropped down to 1/3. I silenced the alarm knowing that 1,000 psi was still more then enough to allow me plenty of time to reach the surface even if I spent another five minutes collecting photos.
A few more pictures and I turned to head back to the boat. Checking my pressure 900psi remained for the journey back to the surface. Then it happened, like a gun firing my ears where ringing and my world was filled with bubbles. I took a breath from my regulator and tried to comprehend what had occurred. I took another breath but instead of having my lungs fill with air, all that greated me was the resistance of a regulator attached to an empty cylinder.
My lungs burned for air and I struggled with the urge to bolt for the surface. Suddenly I remembered the SpareAir unit that was attached to my BCD, quickly I deployed the unit and drew a deep breath of life giving air. It seemed like only a second had passed but my lungs burned again for air. Drawing another breath I began my ascent to the surface. As I passed 70′ I drew another breath, but instead of the feeling of air rushing to my lungs only a small amount passed through the regulator and then nothing.
My lungs screamed for air, suddenly I found myself bolting uncontrollably to the surface. I was sure to end up in a chamber being treated for decompression sickness, but I would be alive. As I passed 30′ the sun directed me to the surface but no matter how hard I kicked it seemed out of reach. The sun blurred and my body stopped responding to my requests. The ocean world that seemed so peaceful only moments before was now my prison.
The above story is fictional but very much a possible occurrence. SpareAir units are a common purchase for divers as they provide an escape when all else fails. They provide a second chance to recover from a bad situation, or do they?
Like many, as a recreational diver I purchased a SpareAir unit as a emergency bailout device. I got it just after finishing my rescue course where I learned just how likely it was for a problem to occur. Excited by my purchase I took it to a pool and sat peacefully at the bottom breathing off my new life saving device. 10 minutes, more then enough time to make it home from any recreational dive.
At least that’s the thought process we just to justify carrying this device around but does that line of thinking actually convert to reality? The average diver has a resting SAC (surface air consumption) rate of between 0.5 – 0.75, meaning at the surface the 3 cu ft spare air unit will last just under six minutes. Thinking back to our entry level diver training that means 3 minutes at 30′, 2 minutes at 60′ and around 1.5 minutes at 90′. All of which means that the average diver will be able to return to the surface from a depth of 100′ on a SpareAir unit alone. Assuming of course you are at rest, which clearly in a emergency situation you would not be, in fact even a working SAC rate of 1.5 your resting SAC rate would not provide the right math for the situation at hand.
In an emergency situation the SAC rate of even the most seasoned diver is often between 1.5 – 3.0 cu ft per minute. Reworking the above numbers with a more realistic air consumption rate we quickly discover that at any depth greater then 30′ a 3cu ft SpareAir unit is nothing more the placebo to provide us with a sense of security while providing almost no security at all.
I know what your saying to yourself. I am a good diver, maybe you even dive for a living like I do, you would never find yourself in a out of air situation. The fact is sometimes that is completely outside of your control. Most of use elect to ignore the fact that a blown o-ring on your regulator or a blown hose can drain a full 80 cu ft scuba cylinder in only 28 seconds at a depth of 100′, and when was the last time you where at 100′ with a completely full cylinder?
Don’t get me wrong the concept of the SpareAir unit is a great one, in fact a very similar device is provided to helicopter pilots in the event of emergency water lands, but simply put the situations are no where near the same. In these situations the likelihood of a water landing is extremely rare. While in diving the most common types of emergency all involve water.
So what about the practicality of a SpareAir unit. It’s small which makes it much easier to travel with then a traditional pony bottle except there is one major problem. You can not fly with it. All cylinders must have there valves removed to be transported on a commercial airline and only a very limited number of dive shops have the ability to do valve replacements on a SpareAir unit due to the proprietary nature of the tools required for it. Which means the only time you can travel with it is when space is not at a premium, meaning you could just as easily transport a larger more effective backup cylinder.
Ok so what about the price tag. I mean it’s a steal at the suggested retail price of only $299.99. You could never get a pony bottle configuration at that price! It’s true there is little argument here but in reality we are talking a difference of between $50 – $200 dollars for a proper and more effective configuration. Is your life really worth the cost of a single trip on a dive boat.
If your like me and are already the proud owner of one of these wonderful devices what do you do with it now? Well for starters it’s still a very useful option for shallow water diving. Not a huge fan of needing one device for shallow water and another for deeper water? There are still slot of great uses. It’s great for lobstering, kayaking, white water rafting and snorkeling. Mine even spent some time as a pool toy.
So what is the proper solution. The answer is simple and it’s the same answer your have likely heard from the day you started you dive training. Proper training and proper equipment for your planned dive is what will bring you home safe from you adventure to a world below the waters surface.