It was a perfect dive day, not too hot but with plenty of sun. My buddy, his wife and I were on a dive boat off Catalina Island, California. We were to dive Little Farnsworth Bank, a spectacular site with large reef outcroppings packed with life. It had been selected for its depth - 40 metres.
I consider myself a good, safe and fairly knowledgeable diver, training to be a PADI Dive Master and planning to go on to become an instructor. My buddy had the same NAUI Advance and Rescue training and goals in mind, which made us a good match.
We beach-dived almost every Sunday along the coast of southern California between Point Dume and Point Conception, and considered ourselves quite good in adverse conditions such as current, surge and low visibility.
Because we did most of our diving from shore through the waves at just 8 to 12m, a boat dive was a treat - a chance for some relaxing dives with good bottom times. Today, however, would prove to be the scariest of my life.
After checking each other's equipment we entered the water, swam to the bow anchor line and agreed to meet at the bottom. The plan was that my buddy would lead with his wife while I tagged along.
The conditions at the bottom were very good - no current, no surge and 15m-plus visibility. We met at the anchor at 37m, and again checked our gear and each other's pressure gauges. It was determined that I had the least air at 190 bar.
My buddy signalled, and we were off on his tour of a site he had done three times before.
I have always been one to worry about my air supply, to the point that on some dives I check it every couple of minutes. This dive was no exception, because it was a deep one for me.
One of the first items I had bought on top of the basic dive gear was a Spare Air cylinder. Being something of a mechanical engineer I know that regardless of all the best maintenance sometimes things just stop working. I would never dive without what I considered a cost-effective independent air source.
It was just after encountering two very large sea bass swimming inverted that, without warning, my air was reduced to less than a quarter of a breath at each inhalation.
My initial reaction was that my regulator had failed. I switched to my octopus, but found that it too was failing to deliver the needed air.
As I tried to draw that first breath out of my octopus I was looking at my pressure gauge. It was now obvious that the problem lay not with the regulators but with my first stage. When I inhaled, the needle would move from 130 to 0 before I had drawn half a breath.
I was closer to total panic than I had ever been. I thought of my wife, kids and my parents. I then realised that panic would definitely kill me - I needed to solve this problem now.
I knew three things - one, I needed to get air very soon; two, I needed to get to the surface properly; and three, I had my Spare Air if the air quit completely.
My buddy and his wife were about 5m in front of me and both looking the other way. I swam quickly up to them, breathing very shallowly but certain I could not keep it up for long.
I quickly attracted my buddy's attention and made him watch my contents gauge as I tried to breathe. Later I learned that he had thought I was having a problem with the gauge, which had been acting up a few weeks earlier. He was unaware that it had been repaired.
I was not planning to hang around at 30m trying to communicate with him. For some reason I was not ready to buddy-breathe. I wanted to solve this problem without endangering anyone else if I could.
I had practised several times with my Spare Air in similar conditions and reassured myself that I could rely on it if needed. By now about a minute had passed, and my need for a full breath was steadily increasing.
I decided to head for the surface as fast as I could. I started swimming straight for the anchor line, about 8m away. I could see that the other two were following, so help was right behind me if needed.
I started up the line as fast as my computer would let me go. When I reached about 15m my regulator started to deliver a little less air than before. At about 8m, it was still delivering the same amount, barely enough.
As I watched my gauge, the needle would plunge from 110 or so to zero. I concentrated on relaxing as much as possible to conserve the air I was getting.
I continued up the anchor line until I reached 5m, where I stopped. Forcing myself to remain calm, I did a three-minute decompression stop.
When I broke the surface I immediately spat the regulator out and took the best and longest breath of my life!
Back in the boat I told the crew what had happened and started inspecting my equipment.
On removing the first stage, the problem became evident - packed in the filter was what looked like flaky white powder.
We concluded that this was corrosion from the inside of the aluminium cylinder, and wondered whether the small tube that hung inside it to prevent debris entering was missing.
We drained some air out through a dark cloth and found that the powder was coming out of the tank when inverted. It was then that I noticed that none of the tanks on the boat had visual inspection stickers.
I consider myself lucky in having had such good instructors. But I will be very cautious of rental cylinders in the future unless I know their source and maintenance history.