A confession from a rebreather diver
I have always wanted to start using a rebreather. I wanted to become a true shark of the diving world. There’s nothing more calming than listening to nothing except the undersea life, without the sound of bubbles puffing up to the surface.
After training on the unit, I was up and ready to go diving every weekend just to try out my new toy. Diving in Monterrey Bay [California, USA], became completely different as fishes would bump into me; octopi would look and study the strange human I was; and sharks no longer ran away. Indeed, I became a true shark.
However, mistakes occurred and bad ideas were used during my rebreather diving time. Some were down right stupid, like trying to position the D-ring, as well as other ideas generally frowned upon by the rebreather community.
What follows is the story of one stupid idea that could have been life-threatening, leading to a situation that was easily prevented; it is an experience I am willing to share and learn from.
One day early in the morning, I poured scrubber into a tupperware container so that I could transfer it into the cartridge of my rebreather unit. Each dive day, I noticed a pattern and had a brilliant idea: I would take a marker and make a line on the tupperware container right at the spot where the scrubber will fill the cartridge for my unit.
On the day I made the mark, I filled the scrubber into the tupperware container just to the line, poured everything into the cartridge and set up the rebreather in my car. Simple enough, I didn’t think about it, and it was the first time I was trying out a new rebreather system and thought, “What a wonderful idea!”
At pre-breathing time on the boat, the unit worked fine, as new cells had been installed four month ago and the batteries were brand new. During the dive, whenever I turned around, I could hear rattling, like Mexican beans in a can. I thought, “What is going on?”
But I decided to just ignore it.
When I got to the surface after a 40-minute dive, I was so tired that I could not climb up the boat ladder. Two divers carried me up, and when I took the rebreather loop off my mouth, I was gasping and starving for air. I decided to call it a day and retired to the boat galley to rest while the charter went on.
After regaining my strength, I drove home thinking I should have eaten a well-balanced breakfast. Upon cleaning the rebreather, I openned up the scrubber chamber to dump the scrubber, and I noticed that the scrubber wasn’t filled up and packed correctly. The scrubber material was about one to two inches below the required fill. I swore I filled it up to the black line on the tupperware container, so it should have been enough.
This is what happened:
There were some air pockets in the scrubber cartridge, and I did not shake and pat the cartridge down. Because the scrubber was loosely packed, all the scrubber shifted from one side to the other while I was underwater, enabling carbon dioxide to flow through and mix with 100% oxygen.
Toward the end of the dive, I was breathing a fair amount of carbon dioxide, which could have been lethal. Had I continued doing the second dive that day, it could have been my last dive on Earth.
Sometimes good ideas that work well on paper don’t work well in real life. Throughout the night, I thought to myself that it was probably the dumbest thing I have ever done on a rebreather.
The next dive day, I ignored the black line on the tupperware containe, and I filled the scrubber fully, patting the chamber down, and filled some more until the scrubber reached the proper fill line. After a full day of diving, I felt fine.
To this day, I still remember that day when I thought I could just do a fast fill on the scrubber and shave off 10 minutes of packing the scrubber. For just spending 10 minutes more of packing and patting down, I would have enjoyed that beautiful day, but instead was treated to a headache and drowsiness, which could have been fatal.
These days, I now take my time in packing the scrubber and making sure the cartridge chamber is packed properly. The rebreather, afterall, is a life support machine, and being cheap and fast certainly isn’t a good idea. ■
The rebreather, afterall, is a life support machine, and being cheap and fast certainly isn’t a good idea.