DCS due to reading computer wrong (I think)

[Lorenzoid]

Having done this dive, I think some of the criticisms are a bit extreme. There are certain risks in everything we do in life. The acceptable risk for a given activity differs for everyone. There are some who post here who I wonder if they ever get in the water based on their posting personality, others who post who I am surprised are alive. These perceptions however are passed though my acceptable risk filter. The filter just isn’t the same for everyone.

Isn't it a goal of the various certification agencies to establish some nominal "risk filter"? All of them define "recreational" diving in pretty much the same way and teach that it is (unacceptably) risky to dive beyond the defined parameters. This theoretically gives divers some baseline by which they can filter out what is acceptable risk and what is not, since the vast majority of us don't have the kind of deep understanding of the risks that you do. Sure, anyone is free to disregard this established filter and substitute their own, but isn't the idea of establishing parameters for recreational diving to provide a filter for the masses?

 

[Boiler_81]

They add a small bit of extra margin. Since you put the experienced DMs in quotes, I will address that. All of the DMs (most I believe are actually instructor rated) on the Odyssey have been diving that wreck and the rest in the lagoon for many years. Sam was a very experienced DM when I was there in 2009. The OP indicated he was still a DM. In addition JJ's wife was a DM in 2009 and was on the OP's dive.

I was comfortable in the situation. As stated before everyone has a different level of comfort. What is risky for one person is acceptable risk for another. I made the dive with my eyes wide open. As I said before, I would do it again under the same conditions. If you search this forum, you will find the discussion of the SFM dive has played out many times. There are those who advise almost religiously that it should not be done in the manner it is commonly done in Chuuk. There are those of us who have done it under those conditions who were comfortable with it and would do it again. I certainly accept there are those who would disagree with me and I am OK with that. I would also never advise someone to make the dive or not make the dive. I would provide them with the information I have from making the dive and let them make up their own mind.

I have given my opinion on the dive itself and won't address it again. I am still curious to see the OP computer download shows.

---------- Post added February 22nd, 2013 at 01:50 PM ----------

A bit of sarcasim in the "the vast majority of us don't have the kind of deep understanding of the risks that you do" comment?

The bottom line is every diver who makes the dive on the SFM without deco training is violating content of their training. I was also training not to drive past the speed limit. However, I have done so on a few occasions given the right conditions.

Isn't it a goal of the various certification agencies to establish some nominal "risk filter"? All of them define "recreational" diving in pretty much the same way and teach that it is (unacceptably) risky to dive beyond the defined parameters. This theoretically gives divers some baseline by which they can filter out what is acceptable risk and what is not, since the vast majority of us don't have the kind of deep understanding of the risks that you do. Sure, anyone is free to disregard this established filter and substitute their own, but isn't the idea of establishing parameters for recreational diving to provide a filter for the masses?

 

[Lorenzoid]

. . .
I was comfortable in the situation. As stated before everyone has a different level of comfort. What is risky for one person is acceptable risk for another. . . .

But do most divers have enough knowledge to know what is risky or uncomfortable? A tec diver, yes. A rec diver, perhaps not. If the dive op explains to the rec diver all the precautions they take for a dive, and the rec diver gets some (perhaps false) sense of comfort from that, should the diver really rely on his feeling of comfort? I believe this is why there is a separation of tec and rec--people who have gotten the proper tec education are deemed capable of understanding the risks and trusting their feeling of comfort, and people who have only rec training should know not to trust their understanding of the risks and (perhaps false) feeling of comfort.

 

[TSandM]

I'm quite willing to accept that the pros were experienced. I'm still wondering what you thought they would be able to do for you, if you got into any kind of significant trouble at that depth? I trust my buddies on staged decompression dives, but we have all planned gas (and take a lot more of it than you guys had) and reserves and deco together, and we stay very close together. Expecting that someone hovering over the wreck at that depth is going to be useful just baffles me.

 

[Boiler_81]

I think you are twisting my statements, I said they could be a potential source of some small help. I did not count on it or plan to use it. We had a very conservative plan for the dive. Our bottom time was extremely short and we had almost no deco when we got back to the stop.

I fully agree the dive is not done in the safest manner possible. Given the potential failure modes and the extra gas on the deck plus the hang tank I found the risk acceptable. If this dive was in the North Atlantic in cold water and current within "recreational" depths. I may have come to a different conclusion.

The way this dive is discussed by many on this forum, you would expect they haul 10s of bodies from the SFM every year. This is simply not the case. The OP had a serious issue. However his issue was not related to gas management. I am still not sure what the root cause was. Did he violate his deco? Did he do the recommended deco and still get a hit? It sure would be helpful it we could see a download of the profile.

 

[halocline]

They way this dive is discussed by many on this forum, you would expect they haul 10s of bodies from the SFM every year. This is simply not the case.

I would be willing to wager that if this dive is done repeatedly as described on this thread with enough recreational divers, the incidence of DCS or other accident is substantially high than it is in 'normal' recreational diving, meaning dives that conform to the commonly accepted standards of the major training agencies. Remember, this entire thread started because a diver was bent on this exact dive.

What constitutes 'safe' diving practices is a little bit individual, but certainly there are relatively clear guidelines for dive behavior in every level of training and every type of diving.

---------- Post added February 22nd, 2013 at 04:07 PM ----------

and the key to deco is that you have to have enough gas to do it.

I think that certainly is a key to deco, but not the only one. There's also dealing with narcosis, planning based on understanding basic theory, being prepared for the unexpected, and having the mindset of overhead diving. These are all aspects of technical diving that are simply not addressed in recreational training.

 

[flots am]

. Expecting that someone hovering over the wreck at that depth is going to be useful just baffles me.

I'm surprised we don't hear of more cascading failures, considering that with a bunch of people on single tanks, an air share at depth is just as likely to cause two OOA divers as help one.

flots.

 

[DandyDon]

I'm surprised we don't hear of more cascading failures, considering that with a bunch of people on single tanks, an air share at depth is just as likely to cause two OOA divers as help one.

flots.

See Belize's Blue Hole - trips daily, similar approach.

 

[Quero]

and the key to deco is that you have to have enough gas to do it.

I think that certainly is a key to deco, but not the only one. There's also dealing with narcosis, planning based on understanding basic theory, being prepared for the unexpected, and having the mindset of overhead diving. These are all aspects of technical diving that are simply not addressed in recreational training.

Exactly. Because the operation allows and even encourages recreational divers to do this dive (remember that the OP believed that the dive plan had been discussed in depth during the briefing), a number of divers like the OP end up doing the dive with insufficient awareness of how to plan and execute a deep dive requiring staged decompression--the subtleties of nitrogen narcosis (the OP initially believed he had not been impaired), where and for how long stops should occur (the OP for whatever reason chose to do 5-minute stops at 15/10/5 meters), what the data displayed by the dive computer indicates (the OP not only misread his computer, but also failed to monitor the data on ascent, and perhaps didn't notice whether the comp locked up on the surface). Gas is a factor in planning for the dive and for potential emergencies, but it doesn't seem to have been a direct factor in the OP's bend though if he had done all the deco he needed to do, perhaps it would have been.

Let me add my thanks to Hintermann for posting. I truly believe this thread has been hugely educational for many readers. A perfect case study, particularly since he recovered well from the incident.

 

[Hintermann]

Hintermann, if you're still following this Thread, I have a question. If you should decide to not answer publicly, I undertand.

I can't remember how many dives you had done ON THAT TRIP before you dove the SFM. Did you dive the day before you dove the SFM?

I wonder if there might have been a healthful impact if you had taken a non-diving day on the day before. Would a day of hydration and plenty of sleep before the dive had any impact? I don't know.

So, did you dive the day before? If so, what kind of diving did you do that day?

Thank you again for posting, Hintermann. You have helped promote safety in the diving community by posting here.

Thanks, openmindOW. I am quite happy to answer your questions in public. The SFM dive was my 23rd and last dive of the trip. I had done 6 land based dives with BLR before boarding the Odyssey and 16 more dives off the boat before the SFM dive.

Yes, I dived the day before. We ALL did. Basically, we were following the plan that JJ and Kim had and that included missing only the night dive on Friday before the SFM dive Saturday morning. The last dive on Friday was around 4:30pm and was over the wreck of the Heian Maru. My max depth was 29.8m for that dive. The SFM dive at around 09:30 the following morning. JJ had even written the timetable on the whiteboard.

I realise that I'll get probably get more flak following this post but those are the facts and I cannot change things that have already happened. Basically, I did not do anything different from any other diver on board except the major error during the ascent and safety stop with the SFM dive. As I have said many times, I realise that it was a big mistake, the consequences could have been more serious and I was very lucky that they were not. I will be more careful in the future and plan dives properly. I will not even consider any dive which is beyond acceptable recreational depths. Beyond that, I cannot do anything now; I am certainly not going to cut my own throat to appease anyone.