DCS due to reading computer wrong (I think)
- Thread starter Hintermann
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The OP may well have been narc'd. And, he now appreciates that possibility. And, that may one of the reasons he started this thread.
But, let's not be unrealistic. More than a few people dive to 50 meters, in warm water with good visibility on air, and the OP was on 24%. Yes, it would have been proper to plan the dive as a deco dive, with a dive schedule written on a slate, to head off the kind of problem the OP encountered. But, I am not sure that doing a dive to 52 more without helium was a 'predictable' prescription for the level of narcosis that rendered the OP incapable of reading his computer correctly.
I dive to depths of 160-200 feet on air, in warm high viz waters, with some regularity, and retain the ability to read my computer. So, I will claim that I can dive to 50 meters, without conspicuous narcosis (and without helium) - perhaps because I have learned to manage its consequences. But, maybe that is because I have a runtime schedule written out before the dive, and whatever displays on my computer is usually not unexpected. That isn't a slam at the OP at all. I think the oversight, in hindsight, was failure to plan for a deco dive. But, most of us learn the more important lessons from events like this, and I think the OP did just that.
I understand that you are writing in response to my comments. Let me say yet again that I intend no insult, but I also don't believe that this serious incident merits coddling your sensibilities. Here is a definition of complacent:
You are a very experienced diver who has had the means and opportunity to dive in the world's premier dive destinations. I would expect anyone who has done as much diving in varied locales as you have to be a confident diver. I believe that any of us, in your situation, would be 'pleased' with ourselves, our accomplishments, and our good fortune (in the terms of the definition above)! However, when it comes to technical diving conditions like your 52 meter dive to the SFM, you simply didn't have the first clue what you were getting yourself into. In other words (and again in terms of the definition) you were 'without awareness of some potential danger or deficit'. In reality, my post only offered an analysis of events based on the facts you yourself have provided. There is simply no way to sugar coat reality: you attempted a technical dive (danger) that you were unprepared to do (deficit) in spite of of your extensive experience with other sorts of dives.
The objective of this forum is to provide 'case studies' that might help other divers avoid making the same mistakes as those who have experienced incidents in which they were in mortal danger. You, Hintermann, were in mortal danger, and not because you were suffering from narcosis, or because you weren't 'careful', but because you quite simply did not know how to plan and execute a dive of this type. 'You don't know what you don't know' is a common theme running through the Accdidents and Incidents forums. Fortunately, ignorance is easily remedied by getting training, particularly for someone with the resources and intelligence you appear to possess. Here is my 'constructive criticism' exactly as I phrased it in the first post I made to this thread. I still don't see how this can be construed as an insult--your belief that it is lends credence to my belief that you're in denial. In other words, merely being 'more careful in the future' isn't enough. You need additional training before you can attempt another dive like the one you injured yourself on.
I'm sorry that your feelings are hurt, I'm glad you've learned something from the event, and I hope that others can learn through it to avoid the same mistakes, but most of all, I'm glad that you have lived to recount your experience.
clownfishsydney
Contributor
A few more comments:
* until recent years, more people would dive the San Francisco Maru on singles than doubles/single and pony
* you do not need "technical training" to dive deeper than 50 m - I have been doing this before there was a single agency offering such training and probably have more dives over 40 m than anyone who would attempt to train me
* dives to deeper than 50 m are perfectly safe on air or even a light nitrox mix so long as you are used to doing similar depths - I know I am narced at that depth, but it is controllable
* I ran OP's profile for the dive through my computer, when he left 5 m to surface I still had 3 mins of deco
* I prefer to dive Chuuk with Blue Lagoon and limit my diving to 2 a day but stay for almost 3 weeks (same cost, much safer and you get to see more deep wrecks)
* the Amagisan Maru is nowhere near as deep as the San Fran. The San Fran is 50 m to the deck and 55 in holds, just over 60 to the sand - Amagisan is 41 to sand under the bow and 58 m to sand at stern. The Amagisan is a brilliant wreck, almost as good as San Fran
Main thing about any diving, dive to your ability, which may be more or less than your training!
* until recent years, more people would dive the San Francisco Maru on singles than doubles/single and pony
* you do not need "technical training" to dive deeper than 50 m - I have been doing this before there was a single agency offering such training and probably have more dives over 40 m than anyone who would attempt to train me
* dives to deeper than 50 m are perfectly safe on air or even a light nitrox mix so long as you are used to doing similar depths - I know I am narced at that depth, but it is controllable
* I ran OP's profile for the dive through my computer, when he left 5 m to surface I still had 3 mins of deco
* I prefer to dive Chuuk with Blue Lagoon and limit my diving to 2 a day but stay for almost 3 weeks (same cost, much safer and you get to see more deep wrecks)
* the Amagisan Maru is nowhere near as deep as the San Fran. The San Fran is 50 m to the deck and 55 in holds, just over 60 to the sand - Amagisan is 41 to sand under the bow and 58 m to sand at stern. The Amagisan is a brilliant wreck, almost as good as San Fran
Main thing about any diving, dive to your ability, which may be more or less than your training!
vladimir
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In your estimation, is it "perfectly safe" to dive to 50 meters and spend 15 minutes there using just a single AL80?
For any dive (especially one that's 'technical' in nature) the diver can't just follow the tables or their computer. Any decompression algorithm must consider modification in-light of the user making the dive. Decompression tables are based on results of the divers that test them. Traditionally this is a Navy Diver, who tends to be a fit physical specimen. In any regard, not everyone falls into this category of fitness and fat content. Even though 'recreational tables' and subsequent computer algorithms are modified slightly, they don't meet the needs of all possible users. Many of the best computers available (that are often designed specifically for technical diving) have a 'User Conservatism Factor' that modifies what is needed by way of decompression.
Even Navy Divers get bent by not breaking the rules. A lesson some recreational divers seem to overlook when planning a deeper dive.
Even Navy Divers get bent by not breaking the rules. A lesson some recreational divers seem to overlook when planning a deeper dive.
halocline
Contributor
Maybe for you personally, but for the vast majority of divers in the world, diving deeper than 50 meters with no redundancy or decompression training is considered dangerous dive behavior, with excellent reason. I can't believe anyone is even arguing that point.
That of course would depend upon the diver's training/experience and that of his Buddy. We each have a 'safe diving envelope;' certainly the dive you describe falls within mine (as well as most of the experienced divers I dive with).
I don't advocate any diver exceeding his personal safety envelope regardless of training or experience. The fact remains that what is safe for one diver may not be safe for another. Personal fitness, good judgment, proper planning and prudence are some of the best ways to ensure safety.
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