DCS due to reading computer wrong (I think)

[RJP]

Still, I believe they have an obligation to take reasonable measures to ensure that the divers on their boat are following generally accepted safe diving practices. They are leading dives, sending DMs into the water, essentially sanctioning the divers' behavior on their charter. This is de-facto dive 'planning', or at least dive 'supervision.'

We'll have to disagree as to whether they are leading dives (they are not, they are providing dive site briefings and offering tours). None of the guides local are DMs, as far as I know. (They weren't on either of the trips I spent on the Odyssey. Hell, I'd be surprised if they were certified.) Any discussion of a dive that that does not include depth/time/gas planning, is NOT a "dive plan" de facto or other wise. They are very clear up-front that they are not supervising your dives. They are PRESENT, yes. But they are not supervising. The moment the crew becomes part of a passenger's dive plan, they become liable if that plan goes sideways.

Assuming that a diver with AOW and 100 dives shows up on a charter and wants to dive the SFM, what reasonable measures would you like the crew to take to "ensure that the divers on their boat are following generally accepted safe diving practices"? Would you like them to tech train divers before allowing them below 130fsw? Should they make them dive doubles even if they never have before? Should they task load someone who's never slung a bail out bottle before? Should they provide a DM to hold each diver's hand while carrying an extra 80cf of gas for them?

I'm not sure what it means to "sanction" someone's behavior.

 

[flots am]

Assuming that a diver with AOW and 100 dives shows up on a charter and wants to dive the SFM, what reasonable measures would you like the crew to take to "ensure that the divers on their boat are following generally accepted safe diving practices"?

While I'm sure you already know this, there's no "safe" way for a diver with no decompression training to safely do that dive, any more than a diver without cave training can safely dive in a cave.

The way the boat crew could help is to explain to the divers that the profile required for a 15 minute dive on the shallow portion of the wreck requires close to an hour of decompression stops and around 140 CuFt of gas, and that if anything bad happens on the dive and the diver surfaces without the required stops, serious injury or death is likely.

They could also explain that Open Water training is insufficient for this dive, regardless of equipment.

However I believe this is unlikely to happen.

flots.

 

[RJP]

While I'm sure you already know this, there's no "safe" way for a diver with no decompression training to safely do that dive, any more than a diver without cave training can safely dive in a cave.

The way the boat crew could help is to explain to the divers that the profile required for a 15 minute dive on the shallow portion of the wreck requires close to an hour of decompression stops and around 140 CuFt of gas, and that if anything bad happens on the dive and the diver surfaces without the required stops, serious injury or death is likely.

And what happens when a diver follows such a "plan" that the crew might lay out... and still gets bent or killed? They, or their estate, will say "But I/he followed the plan the boat laid out as being safe." Sadly, from a legal perspective, the most reasonable thing for the boat/crew to do is to stay completely out of dive planning.

That said, I agree with your point that this dive shouldn't be done without proper training, equipment, and planning. Notwithstanding the fact that people do it without incident all the time. Sort of like the fact that people drive drunk without incident doesn't mean that it's safe to drive drunk.

 

[flots am]

And what happens when a diver follows such a "plan" that the crew might lay out... and still gets bent or killed? They, or their estate, will say "But I/he followed the plan the boat laid out as being safe." Sadly, from a legal perspective, the most reasonable thing for the boat/crew to do is to stay completely out of dive planning.

Maybe I wasn't clear enough. I wasn't looking for the crew to hand out a plan, I was looking for the crew to explain to the OW divers that this is not an OW dive, they have neither the training or the equipment and that they shouldn't do it.

Too many dive ops are afraid of saying "no, you're not qualified".

flots.

 

[halocline]

Assuming that a diver with AOW and 100 dives shows up on a charter and wants to dive the SFM, what reasonable measures would you like the crew to take to "ensure that the divers on their boat are following generally accepted safe diving practices"? Would you like them to tech train divers before allowing them below 130fsw?

They should require evidence of technical training before allowing divers to do technical dives off their boat. Every charter and dive op I'e ever encountered has some basic rules defining acceptable dive behavior. Like, for example, being certified to dive, or carrying an alternate 2nd stage. Why is this boat different? Do they require C cards? Regardless of whatever disclaimers they want to claim, they're knowingly sending recreational divers on technical dives, and sending guides with them. That's what I mean by 'sanctioning' this dive behavior. And I assume there's one reason for this; there is a much bigger market of recreational divers than there is technical divers.

A dive charter is NOT a water taxi.

---------- Post added February 24th, 2013 at 08:34 PM ----------

Any discussion of a dive that that does not include depth/time/gas planning, is NOT a "dive plan" de facto or other wise.

But I believe that they did discuss depth and time....they informed divers what the depth of the dive was and gave them a bottom time window, I think 15 minutes.

---------- Post added February 24th, 2013 at 08:36 PM ----------

the dive plan was very carefully discussed. For a start, we were required to miss the night dive the previous evening to increase the surface interval. The divers would go down in 2 groups of 8 divers each and each group was supervised by 2 divemasters who hovered just above the top deck where they could keep all their charges in sight....Bottom time was strictly limited to 15 minutes

That's the opening post in this thread. Sounds like a guided dive with prescribed dive plan to me.

 

[boulderjohn]

You can't draw any meaningful conclusions from overall DCS rates.

If we knew the numbers, simple arithmetic would give us the number of times the average American homeowner will shovel the driveway each year. Does that mean the average south Florida homeowner is just as likely to have to shovel the driveway as the average Minnesotan?

Divers in south Florida can dive the very shallow Molasses Reef every day and never come close to accepted NDLs, let alone DCS. On the other hand, they could take the boat a little farther and do their dives on the Duane and the Spiegel Grove and be on the edge of NDLs on every dive. Of course some dives have a greater probability of DCS than others.

 

[halocline]

You can't draw any meaningful conclusions from overall DCS rates.

With all due respect, that's not true. If the overall DCS rate is, for example, 3 in 10,000 dives for recreational diving, and on a particular dive it was found to have far higher incidence, you can conclude that that particular dive carries a greater risk. Of course the numbers are so low that you need a huge pool (no pun intended) of dives to draw conclusions, but they can be drawn with sufficient numbers. We apparently don't have those numbers for this particular dive.

However, I'm sure you'd agree that it's common sense that greatly exceeding recreational depth limits, and doing intentional deco dives without the proper training and gear, is risky dive behavior. We don't really need the statistics to reach that conclusion.

There are lots of popular dives that 'push the limits' of recreational diving. But this one obliterates those limits.

 

[boulderjohn]

With all due respect, you don't need an analysis of diving statistics to know that diving to or beyond recreational depths and time limits will be inherently more risky than a typical 60 minute dive to 25 feet on Molasses Reef. The fact that more people get bent on such dives than on Molasses Reef dives is as shocking as the discovery that homeowners shovel their walks more in Minnesota than in south Florida. I don't have any statistics to support that last statement, but I am pretty sure I am right.

---------- Post added February 25th, 2013 at 08:09 AM ----------

Just to add to this point about statistics....

We know that this dive is more risky than a typical recreational dive, and we don't need statistics to tell us this. What matters is not overall recreational statistics but rather the risk of this particular dive. Do we have any real statistics for the rate of DCS on this dive plan? I don't believe we do. Apparently the dive operator thinks the risk is low enough to make the dive worth while, but we have no evidence on which to evaluate that decision.

We also know less than I would have expected by now about this specific dive. We know the OP said (as I interpret it it) that he thought his computer told him he needed 14 minutes of "safety stop" when he began the ascent. We know that he did 15 minutes divided among 15, 10, and 5 meters. Despite repeated requests to supply more information, we still do not know

• what the computer told him during the ascent,
• why he selected those stop depths,
• how long he stayed at each stop depth,
• what his computer was saying when he finally went to the surface, and
• what his computer did after he was on the surface.

It is very possible that the OP actually did everything right in terms of the computer's algorithm, which would make him one of the approximately 50% of DCS cases that are unexplained, meaning there is nothing in the dive profile to indicate a reason for the DCS.

It is very possible that the OP paid no attention to the computer whatsoever after beginning the ascent and surfaced while the computer was fairly screaming at him to stay down.

Pretty much everything in between is possible as well.

 

[tekdvr2]

Hey let's not forget that the extra hang bottles along the line had 32% nitrox in them. Also after a week of diving like that I always add significant time hanging. .......it doesn't hurt....JIC

tb

 

[Peter69_56]

This occurred to me. I've been considering starting a thread where people can list "million dollar dives" that the dive ops promoting them know or should know the average rec diver shouldn't be doing. To the SFM and Belize Blue Hole, I might add the Turtle Cave in Sipadan.

I have done the Turtle cave in Sipidan, how deep is that cave, from my recollection I don't remember it being below max recreational depth? Just looked at all my dives there and cant see any below about 32 m ???? Its the cave near the pier on the island ???

---------- Post added March 15th, 2013 at 12:54 AM ----------

Hintermann, thanks for the posting. We all need to see others mistakes which at their expense help us all learn valuable lessons. I too have dived the San Francisco Maru and in similar circumstances which I will relate for the benefit of others here.
Prior to going to Truk my cert was DM and had a number of dives to 40m. Always wanted to go to Truk, the mecca for the diving world and so when the opportunity arose with a local dive company we took it but knew litle about it other than shipwreck paradise. We went on an extended holiday in Australia and met the dive group at Cairns airport. We were supposed to have a pre brief prior to leaving Melbourne, about what to expect but due to our leaving earlier than the rest (and other things which I will not go into here) we did not get this essential brief.
I did some reading up on Truk whilst we travelled and this was my first alarm bell. Depths exceeding 40m, simply put decompression diving, not certified, and understand I don't know what I don't know. I attempted to contact the dive company with no success, so I contacted the Truk dive company and told them we had no experience in deco or twin tanks and was told all is well there are many dives not deco or needing twin systems. Then I got an email from local dive company asking if we were going to dive twins or singles, replying "we have no experience in twins". This got a non reply from them.
Met the group at the airport and flew into Truk. By this time I had done some calcs on some of the deeper dives and worked out what air I thought we should carry (I was using Baltic by then thank goodness). Worked on carrying 15 litre single and a 11 litre sling with spare computer and with 50% 11 litre deco at 6m under the boat. Everyone else had twin 11 litre independents (most with little or no formal training on them either). We did 2 dives daily with all of the dives prior to SFM being non deco dives.
On the day of the SFM dive we spoke with the other 4 divers on the boat and said we as a couple would follow them down the line and may stop at 40m or may continue to the deck 45-48m depending on how we felt as the dive progressed but they were not to worry as we would either dive independently and abort early or dive immediately behind them being tail end charlie. If they saw us ascending then not to worry as we were coming up early. I believe their concern was more of perhaps us causing them to have to abort their dive early due to us having issues rather than a great concern for our welfare. Hence my offer to dive with them but independently if needed.
We descended behind the others and went down to the deck 45-52m and stayed the agreed max time of 14 min RT before ascending to 25m for an agreed 1 min stop, then following our computers 6m 14 min which cleared early and then 3 m for 10 min and then stayed at 3 m for an additional 9 min before using 50% for an additional 3 min each. Total run time of 45 min.
The guide used a single 11 litre and had a second sling tank in his arm. We never encroached into our sling supplies other than to check that they were working (in hindsight wrong). What I got out of this was; we don't know what we don't know, so go get tech certified.
On getting home and getting tech certified it certainly opened our eyes to many of the risks we had exposed ourselves to unknowingly. No thirds rule, no real sharing of gases in cylinders to prevent total gas loss, yes I did a dive plan, yes we stuck to it, yes I knew our gas consumption and calculated reserves (but not enough), yes we had backup computers, all with the same algorithms, whilst I was aware of O2 exposure and had worked out 55m was a good depth to stop at, I know now I didn't really appreciate all the risks involved in these deco dives.
Now at this point in time I could relate to another incident on the trip about the dive leader organising 2 groups to penetrate the same ship from opposite sides to pass each other when in the middle of the ship (yes a disaster waiting to happen), (alarm bells again) which we aborted when we started in one side only to be met by others who penetrated from the other side streaming out as they left the ship. All I could see was a dark hold with several possible entry points that the others in our group might have taken ahead of us (as we had lost sight of them by then), so rather than take one hole and hope for the best I immediately aborted, came back out and went over the ship and waited on the other side for our group to reappear. Meanwhile members in our group were all having kittens thinking we had got lost inside. This was not the fault of the dive guides, rather the tour leader with poor planning and dominating the locals with his requirements (this happened on the second day of diving). After this incident we stuck to our own boat with 6 divers and didn't get involved in other groups again or the tour leader.
The twin tank divers were all told by the dive leader to suck only one tank down as you will only then have to pay for one tank daily (stupidity at best) so all these twin divers didn't really have good redundancy but I bet all thought they did (you don’t know what you don’t know). So many different things could have gone wrong but didn't. I know that one outcome from this experience is that we are both better divers, with more education and knowledge now, however how many others in the group even understand the risks let alone have tried to get further training? Another outcome is that we are going to Santos in a few months to dive Coolidge, and a work buddy is coming too. I convinced him to go get tech certified and the penny has just dropped for him too. He wasn't even deep certified when we first spoke of going.