DCS due to reading computer wrong (I think)

[xyrandomyx]

Of course it would everything to do with diving! What do you think, someone's politics affects safe diving practices? How is that possible?

To me this is really very simple; all professional dive operators, meaning companies or individuals that are taking money for organizing and leading dives, providing tanks, sending guides into the water with divers, etc...have a responsibility to adhere to generally accepted safe diving practices. If what has been posted on this thread is accurate, I believe that any reasonable, informed 3rd party would easily come to the conclusion that this dive does not adhere-not by a long shot-to safe standards for recreational diving.

Legally, that's a different story, but you can bet that no dive op in U.S. jurisdiction would dare do this. They'd get creamed if someone got hurt and sued. They're apparently violating the most basic standards of safe recreational diving set by any of the recognized agencies.

And of course, I think everyone agrees that the ultimate responsibility for diving safely lies with the diver. I believe that, and I try to dive accordingly. But that doesn't release the operator from responsibility IMO. And the idea about the captain being a "bus driver"? No way...this boat is leading dives, not simply picking up passengers on a route.

If you want to start a new thread, I'll be happy to reply there -- think it's a little off topic here.

 

[RJP]

...while just out of recreational dive depths...

You make it sound like you dropped 10ft below everyone else to take a peek at an eel on a reef dive in the Caribbean. The deck of the SFM is 40ft deeper than the LIMITS of recreational diving.

[EDIT] In fact, the more I think about it...

If, in arguendo, we suppose that the typical recreational dive is somewhere in the 50ft/15m range... then THE TOP of the SFM is MORE THAN THREE TIMES DEEPER than the typical recreational dive.

People who lack proper training/gear/gas/planning would do well to think of diving the San Francisco Maru in those terms, rather than approaching the dive as being "just outside the limits of recreational diving."

 

[The Diving Badger]

Nitrogen, oxygen and CO2 all have narcotic properties Roles of nitrogen, oxygen, and carbon dioxide in compressed-air narcosis

Excellent, just the paper I was thinking of!

---------- Post added February 21st, 2013 at 05:08 AM ----------

I would appreciate your expert enlightenment on the effects of these gasses for the dive under discussion; 54m on a 24% mix v Air?

Kind regards

No problem, I run a 4 day class that covers a lot of this sort of thing....Aquanauts Course Dates

 

[Edward3c]

No problem, I run a 4 day class that covers a lot of this sort of thing....Aquanauts Course Dates

Which just confirms to me your here to promote your own business not help those less knowledgeable/experienced.

 

[openmindOW]

They are doing what they can to make it as safe as possible,

Balogna. They're not trying to make it as safe as possible. If they were, they're wouldn't be solo divers diving without redundancy to 50 metres.

Both the operation and the divers have responsibilities regarding safety.

Notice that even the Dms weren't wearing twins.

 

[The Diving Badger]

Which just confirms to me your here to promote your own business not help those less knowledgeable/experienced.

You are BSAC council member and an instructor so it would be somewhat discourteous of me to call you less knowledgeable or experienced, plus it was supposed to be slightly tongue in cheek.

So, for the record...

There is no application where we would consider N2 or O2 any different from a narcotic perspective, they are essentially the same size and if anything we thing know about narcosis is true then molecule size probably plays a role, so it is incorrect to say that a Nitrox mix is less or more narcotic. In fact all gasses are narcotic at some point. I am surprised that anything other than this still taught.

It's CO2 narcosis that is the elephant in the room for open circuit divers, and as a concept is not fully discussed in many 'tec' courses and certainly not in any recreational course that I have either taught or seen taught. CO2 is a highly toxic by product that a glance a the Meyer-Overton scale will tell you that it's many more times narcotic that N2/O2, again it's atomic weight may give us an indication as to why. The problem with it is three fold. Firstly is as our depth increases our CO2 retention increases due to the increase in gas density (as a function of the reduction in ventilation) this dramatically increases the arterial PP of CO2, causing an increase in breathing (hypercapnia symptom) and the cycle continues. As the arterial pressure increases the narcotic effect of CO2 increases typically reducing motor skills rather cognitive ability that is most closely linked to N2 impairment. For reasons unknown the narcotic effect of the two gasses is additive and causes a spiral of impairment and gas consumption. This is as likely to happen on a single tank recreational dive as a deep technical one.

 

[halocline]

You could be right. The problem with SFM seems to be that while just out of recreational dive depths, it is loaded with a lot of war material - the so called "million dollar wreck" reputation. I guess that makes it stand out as a special dive to all comers - I admit that I was keen to dive it as were most divers on board.

Sure, 170 ft is 'just out of recreational dive depths.' And the fact that it's an attractive dive certainly means it's okay to dive it without widely established training prerequisites....

Sorry, I just have less sympathy with each new post of yours. Nothing personal.

 

[Duke Dive Medicine]

For reasons unknown the narcotic effect of the two gasses is additive and causes a spiral of impairment and gas consumption. This is as likely to happen on a single tank recreational dive as a deep technical one.

We do know that CO2 is a vasodilator, and that CO2 retention increases cerebral blood flow. We also know that CO2 retention is directly related to gas density, so depth definitely has an influence. One of our attendings, Dr. Jake Freiberger, is designing a study to examine the effects of CO2 narcosis; he'll be kicking it off soon.

 

[Edward3c]

You are BSAC council member and an instructor so it would be somewhat discourteous of me to call you less knowledgeable or experienced, plus it was supposed to be slightly tongue in cheek.

So, for the record...

There is no application where we would consider N2 or O2 any different from a narcotic perspective, they are essentially the same size and if anything we thing know about narcosis is true then molecule size probably plays a role, so it is incorrect to say that a Nitrox mix is less or more narcotic. In fact all gasses are narcotic at some point. I am surprised that anything other than this still taught.

It's CO2 narcosis that is the elephant in the room for open circuit divers, and as a concept is not fully discussed in many 'tec' courses and certainly not in any recreational course that I have either taught or seen taught. CO2 is a highly toxic by product that a glance a the Meyer-Overton scale will tell you that it's many more times narcotic that N2/O2, again it's atomic weight may give us an indication as to why. The problem with it is three fold. Firstly is as our depth increases our CO2 retention increases due to the increase in gas density (as a function of the reduction in ventilation) this dramatically increases the arterial PP of CO2, causing an increase in breathing (hypercapnia symptom) and the cycle continues. As the arterial pressure increases the narcotic effect of CO2 increases typically reducing motor skills rather cognitive ability that is most closely linked to N2 impairment. For reasons unknown the narcotic effect of the two gasses is additive and causes a spiral of impairment and gas consumption. This is as likely to happen on a single tank recreational dive as a deep technical one.

Thanks for the info. I'm only an Advanced Diver and then only on air and occasionally Nitrox. I leave the challenging stuff to those that want to do that sort of thing and would direct individuals to someone more qualified than myself.

For the record we do cover CO2 in our core training programme, not to the extent of your description I agree.

CARBON DIOXIDE TOXICITY
Carton Dioxide is a waste gas produced by body metabolism.
● It is normally exhaled and is the trigger mechanism to breathe

Any retention is dangerous
● At levels as little as 0.05 bar above normal, Carbon Dioxide becomes toxic
● At levels more than 0.1 bar above normal, it can be lethal
● Can predispose to DCI

Kind regards

 

[wench]

I commend you for starting this thread knowing the reactions you'd get beforehand. In fact, making this post was quite brave on your part. It helps the rest of us who are not as expereinced as most divers who post on here.

Having said that, I have learned a lot from this thread and it's created much awareness. Thanks to everyone who chimed in with their expertise.

I bet this thread alone will save a life or three.

Thanks for sharing your experience so others may benefit from yours.