vjongene
Contributor
The incident I want to describe happened 10 days ago at the Castle of Chillon, in the lake of Geneva. I was not there myself, but several of my buddies from the dive club were present and told me about it.
This requires a little introduction: The lake is very cold (6 C at 30 m all year), and deep (over 300 m at its deepest). Most divers here have been trained by CMAS, and therefore learned deco diving on air. This is not considered "tech" diving by local standards. While many dive doubles, the majority of divers here carry single 15l steel tanks. It is not unusual to dive beyond 50 m (170 ft) for relatively short times, and to do a basic deco schedule on the way up. This all means that proper air management is a real issue. Also, because of the cold water, most divers wear dry suits.
The site has claimed a number of lives, mostly because it is one of the few places in the lake where one can dive very deep close to shore. There is a place where fish ("ombles" in French, I don't know the English name) are fraying in November-December, at 40-60 m depth, which is a favorite goal for divers.
Now to the story: A buddy team was diving to 50-60 m to look at the fish. They were wearing dry suits and diving singles. One of the two suddenly realized that he was down to 50 bar and still at depth. He signaled his buddy and started ascending, too fast. The ascent rapidly became uncontrolled. His buddy tried to slow him down by dumping all of his own air and hanging on to him, to no avail. He finally let go. The diver became a surface-bound rocket, completely out of control, and a prime candidate for a serious case of DCS. The buddy, not wanting to become a casualty himself, made a normal ascent and did all of his deco stops.
Very fortunately, there was a small dive boat at the surface (not a common sight on the lake, where most diving is from shore). They spotted the surfacing diver and asked him if he needed assistance. He declined their offer of a tank to return below the surface and do his deco (CMAS procedure here is to extend deco times by 50% after an uncontrolled ascent). They then took him on the boat and provided O2. They also called emergency services on their cell phone. Within 10 min, an ambulance and a police patrol were on the spot. The diver was taken to the nearest hospital and took a ride in the chamber. He was released the next morning, free of any DCS symptoms.
When his buddy surfaced, the diver was already breathing O2 and an ambulance was on the way.
The accident analysis is obvious: poor air management, lack of experience with a dry suit, plus a panic response when he realized he was running out of air. He could have made it to the surface safely by breathing off his buddy's secondary during the deco stops.
To me, there are a few lessons to be learned, though:
- do not dive a dry suit deep until you are completely comfortable with its operation
- always have a small tank of oxygen near your point of exit
- have a cell phone handy as close as possible to your point of exit, or even carry one in a dry container
This guy was lucky to surface near a boat that was properly equipped. I don't know if he had the O2 and phone in his car. Our club does, and this will certainly encourage us to always make sure that someone is carrying the emergency case.
This requires a little introduction: The lake is very cold (6 C at 30 m all year), and deep (over 300 m at its deepest). Most divers here have been trained by CMAS, and therefore learned deco diving on air. This is not considered "tech" diving by local standards. While many dive doubles, the majority of divers here carry single 15l steel tanks. It is not unusual to dive beyond 50 m (170 ft) for relatively short times, and to do a basic deco schedule on the way up. This all means that proper air management is a real issue. Also, because of the cold water, most divers wear dry suits.
The site has claimed a number of lives, mostly because it is one of the few places in the lake where one can dive very deep close to shore. There is a place where fish ("ombles" in French, I don't know the English name) are fraying in November-December, at 40-60 m depth, which is a favorite goal for divers.
Now to the story: A buddy team was diving to 50-60 m to look at the fish. They were wearing dry suits and diving singles. One of the two suddenly realized that he was down to 50 bar and still at depth. He signaled his buddy and started ascending, too fast. The ascent rapidly became uncontrolled. His buddy tried to slow him down by dumping all of his own air and hanging on to him, to no avail. He finally let go. The diver became a surface-bound rocket, completely out of control, and a prime candidate for a serious case of DCS. The buddy, not wanting to become a casualty himself, made a normal ascent and did all of his deco stops.
Very fortunately, there was a small dive boat at the surface (not a common sight on the lake, where most diving is from shore). They spotted the surfacing diver and asked him if he needed assistance. He declined their offer of a tank to return below the surface and do his deco (CMAS procedure here is to extend deco times by 50% after an uncontrolled ascent). They then took him on the boat and provided O2. They also called emergency services on their cell phone. Within 10 min, an ambulance and a police patrol were on the spot. The diver was taken to the nearest hospital and took a ride in the chamber. He was released the next morning, free of any DCS symptoms.
When his buddy surfaced, the diver was already breathing O2 and an ambulance was on the way.
The accident analysis is obvious: poor air management, lack of experience with a dry suit, plus a panic response when he realized he was running out of air. He could have made it to the surface safely by breathing off his buddy's secondary during the deco stops.
To me, there are a few lessons to be learned, though:
- do not dive a dry suit deep until you are completely comfortable with its operation
- always have a small tank of oxygen near your point of exit
- have a cell phone handy as close as possible to your point of exit, or even carry one in a dry container
This guy was lucky to surface near a boat that was properly equipped. I don't know if he had the O2 and phone in his car. Our club does, and this will certainly encourage us to always make sure that someone is carrying the emergency case.
