Lesson for Life, what do new divers think about this?

[drrich2]

So the dive wasn’t really 123 feet for 68 minutes, it was 123 feet for less than a minute, followed by 60 feet for 42 minutes, followed by a slow ascent to 15 feet for 13 minutes, followed by a safety stop, all without ever violating an NDL. But it’s way quicker and meets convention (a liveaboard records depth and bottom time, not profile). And, why pay for 37 words where 3 suffice?

I think it depends on the article's audience. If this article goes in a print edition, words cost money. Is the intended audience likely to understand it without risky misperceptions? I wish the author'd commented on the EAN32 MOD violation issue. Those Spree boat captain school divers would know what risks they were taking; a newbie with a fresh nitrox card shore diving in Bonaire maybe not.

On a positive note, most 'green' enough to be dangerously misled may not have SAC rates good enough to come close to emulating such dives. And many are doing guide-led 'tourist' dives. Some live-aboards set depth issues.

Richard.

 

[Bob DBF]

Sure (see my response to Richard), but my point was about the way the article was written. If you have to assume all sorts of things that aren't in the text to have it make sense, then it's not written well. I know that the whole point of a dive computer is to give you deco credit for time above the bottom.

That was my take on the article, a lot of facts but not written in a manner that gave me information that could avoid me winding up in a chamber. He says the dive profiles are multilevel but only gives information for a square profile, giving bottom time rather than run time. It encourages one to take out the tables even though the dive is an unknown multilevel, and the results may be quite misleading.

Since the dive seems to be a multilevel dive on a computer, I would think the author would spend more time on explaining computers and how to minimize risk when using one.



Bob

 

[Ouvea]

The author does state that he is performing multi-level dives but doesn't specify the exposure of each level. The total bottom time must be the total run time of the dive. Even with a consumption rate of .5cft/minute you would exhaust your gas supply on all three mentioned profiles with the common AL80 cylinder.

People need to better differentiate between a bottom time at a specific depth and the dive's total run time. Perhaps for those that do not dive, it makes very little difference. However, such lack of precision creates ambiguity in interpretation. In Cozumel, where I vacation, the dive operator routinely performs these types of profile, where we have a very limited exposure near 80-100ft with the remainder of the run time at moderate to shallower depth. I believe most of us would have like to known the average depth with the total run time of the dive, in comparison to his surface interval time.

Sadly, I see this type of sensationalism/sloppy journalism/reporting through out all media outlets. It appears that writing a proper and accurate article has faded into history.

 

[doctormike]

The fact that we are discussing this means that the central point of the article wasn't clear. Sure, you can reverse engineer a profile within NDLs by assuming that what the author explicitly said actually meant something else. But that's a poor way of teaching a lesson, right?

The author wrote: "Dive two was to 123 feet for 68 minutes". Those exact words. Sorry, I'm not feeling charitable, especially for a published author who does this for a living. Because if you are gong to just assume that the diver did some random multi-level profile, then what did he do wrong? What's the lesson? Why did he get bent at all, if we are just going to guess that those were all quick bounce dives followed by a long safety stop on the reef?

Words mean something, and these words were poorly chosen.

I didn't even get to gas usage with these ridiculous numbers. Even if the diver was running 100/100, and blew off the 75 minutes of deco that I calculated and had an awesome SAC rate of 0.4, , he still would have used 4.7 ATA x 0.4 x 68 = 128 CUF of gas.

It would have been pretty easy for him to write something like "Dive two was a 68 minute dive to a maximum depth of 123 feet, with an average depth of 60 feet".

 

[rongoodman]

In another of these tales he has a AOW student staying on a wreck at 105' for 74 minutes before exiting and beginning his ascent.

 

[Nick Steele]

I’m about to hit my 1 year mark in diving (still new under 10 dives). I’ve been reading these stories since before I was certified. And while I like these stories I come to believe most of them are lacking info or simply he doesn’t know the info so he inserts what he believed happened. As with most dive accidents I don’t believe we will ever know the truth behind them but with articles like his it can make one think.

As for the profiles in that story he did say multi level dive so you have to take that into consideration. Now while most vacation divers won’t understand this I believe even newer more serious divers will or atleast should. Also if it’s was a wall dive like previously described it’s easy to lose focus and to drift down quickly and then bounce back up because you noticed.

One time I was snorkeling in about 8-10’ of water less than 100 yards off the beach with no plans to go any further. A big manta ray swam by and I followed him out to about 25-30’ of water and 500+ yards off shore. Didn’t freak cause I go that far out sometimes but didn’t plan to that day.

 

[icechip]

Newer-ish divers might readily assume that LOB vacation diving can really be like that.

 

[Kharon]

When I read the "stories" my first thought was "Total Bushwah. Unless they were diving rebreathers there's no way they had enough air for that depth for that long. Especially for the amount of deco they would have incurred." Even with the multi-leval caveat, it's still misleading. Particularly for divers with little real life experience.

 

[doctormike]

Exactly.

And the thing that makes it really silly is that these stories are just BASED on real events, but the author is under no obligation to accurately report any particular dive profiles. They are created specifically to make a teaching point.

So it would have been very easy to sit down with MultiDeco for a half an hour and come up with four realistic dives that would be pushing the limits without making the violations of deco, gas usage and MOD so obvious that they ruin the article.

 

[Eric Sedletzky]

Although poorly written with not many specifics, I read through the lines. Those bottom times are (probably) dive run times. The depths mentioned are (probably) average depths. He mentions multi level dives. On a LOB I’m guessing they use AL 80’s, so there would not be nearly enough gas to do those depths/ times in square profiles.
He said the diver rode the computer to the max but never violated it (does that mean he never went into light deco??).
He also never mentioned the brand of computer and what algorithm. If it was any generic grade consumer version then there was some sort of multi dive conservatism built in.

The lesson should be not to ride your computer to the max to get every last drop of bottom time out of it. I see this as a problem with what computers are capable of doing when combined with a divers general lack of overall gas loading and deco knowledge. Not saying this particular diver had a lack of knowledge, I’m just saying that there is generally too much thinking of “just follow your computer” in todays diving.

We cant always protect the new divers like tender eared children all the time and think they need to be insulated from anything that can cause harm in the sport of diving. This information should be taught extensively and thoroughly by their instructors in open water class. We were taught NOT TO PUSH IT back in my OW class and that was with tables.
The information was passed onto us and the instructor made sure we thoroughly understood it before we passed. Beyond that it was assumed we were adults and were smart enough to take full responsibility for our own actions.