Dive safe! A short story from a chamber operator

[DBPacific]

Not knowing how your computer works is a real problem. I dive off SE FL very frequently. Several times each year I am asked by an individual on the boat why their computer seems to not be working normally. The answer is often, your computer is in violation gauge mode because you neglected to satisfy a deco obligation. They often look back at me like I am an alien, speaking in an unknown language.

When I had just finished my OW (only a year ago, so I can't really talk much about diving experience), I violated my NDL by about two minutes because I had been too concerned with watching the marine life than checking my computer. I also had been an idiot and hadn't checked what my decompression menu looked like so all of a sudden my computer screen changed, started beeping, and terrified me. I followed all the directions for stops because I pretty much figured out what had happened, but I was definitely more paranoid that afternoon about DCS. Now every few months I reread my computer manual but I run into people I dive with for work or in classes who don't even know what an NDL is and it terrifies me that they aren't even interested in learning how to read their computer for their own safety.

 

[melanie.]

I really enjoyed reading what an accurate picture of what a chamber ride is really like. Thank you for sharing

 

[scubadada]

When I had just finished my OW (only a year ago, so I can't really talk much about diving experience), I violated my NDL by about two minutes because I had been too concerned with watching the marine life than checking my computer. I also had been an idiot and hadn't checked what my decompression menu looked like so all of a sudden my computer screen changed, started beeping, and terrified me. I followed all the directions for stops because I pretty much figured out what had happened, but I was definitely more paranoid that afternoon about DCS. Now every few months I reread my computer manual but I run into people I dive with for work or in classes who don't even know what an NDL is and it terrifies me that they aren't even interested in learning how to read their computer for their own safety.

So, you didn't end up in violation gauge mode, good for you. And, you learned some things, good for you.

 

[Bubblesong]

Deleted, I was going to tell a "clueless diver that I once met" story but that is not the purpose of this thread.

Please do tell, or even start a thread with that heading. I might “get a clue” from hearing other people’s stories, as that is part of “NOT learning the hard way.”

 

[Joneill]

I really enjoyed reading what an accurate picture of what a chamber ride is really like. Thank you for sharing

Agreed - really sends a message to be very aware of limits when we dive. I don’t want to have that dive vacation “experience” if I can avoid it!

 

[Divetech Cayman]

Obviously the gentleman hadn't checked his own tanks but any idea why he would have thought that he was diving nitrox but instead air, for 4 dives?

The most likely scenario is that I mis-understood him, or he misunderstood what I had asked him.

 

[Divetech Cayman]

I really enjoyed reading what an accurate picture of what a chamber ride is really like. Thank you for sharing

I'd love to be able to video record the experience, especially from an attendant point of view. When transferring in or out, you sit in a very tiny lockout chamber, and the first time I did that, I felt a tinge of claustrophobia. Also one thing that surprised me, is how much different equalizing your ears is in the chamber. I have very good ears for diving, but during decent in the chamber, I find that I have to equalize almost every foot, which is way more often than when I'm diving.

 

[NorCalDM]

I don’t do the long, packed with dives, trips that many do. I dive regionally and at most have done 6 dives over 3 days. People have reported doing some really stupid stuff to me with regards to diving - not paying attention to their computers, getting locked out for missed deco (borrowing another computer to keep diving), never analyzing tanks, etc., so excuuuusssee me for asking a question. My diving on the Great Lakes is very different from the tropics. We tend to do long weekends. Week long (or more) trips are rare here.

I thought scoobydrew answered your question quite nicely and I tend to agree. What you have described is idiot diving and they may want to rethink their choices and if they did get bent it would definitely not be an undeserved hit. I have ran my computer both ways on long recreational dive trips and I have never got close to my O2 limit. I now tend to run my computer with an air profile but always analyze my cylinders so I know what my MOD is and stay within it. Also in my experience many of the guides I have had in other parts of the world use Nitrox on an air profile and they are in the water everyday.

 

[Jayfarmlaw]

@The Chairman, I nominate this post for Post Of The Year 2019... and make it a sticky....and some Scubaboard swag....and a beer. And change Nassau Grouper to "Chamber Hero" or something cool.

Seriously though, this is probably one of the best posts I've read in 5 years of daily feeding my SB addiction. Great information about how to avoid peeing on a strangers leg at simulated depth. Thank you Divetech and although the Caymans are not my happy place, I'll happily buy you a beer, or 10, in Cozumel. Thank you for what you do!

Great post!
Jay

 

[rsingler]

Acute oxygen exposure has a 4hr half-life, if I remember the NOAA manual correctly. Getting close to 100% oxygen exposure would require Nitrox 36 dived to MOD for close to NDL on multiple dives on the fourth day of a trip. Remember that however close you get to 100% at the end of the dive day, 12 hours for dinner, sleep and setup that next day is three half lives, which will drop your starting O2 exposure on the next day to 12.5% max.
So folks that dive with their computer set to air are not likely courting disaster, as long as they adhere to their MOD for the mix they're diving.

The bigger issue would really be some 14-day liveaboard with the same practice, where OTU's are not being tracked and no breaks in diving are taken. There, the pulmonary effects of high OTU's might theoretically be seen unexpectedly. But if you're diving Nitrox on a 14-day liveaboard, it's not likely to be EAN36, so much of this is really moot.

Me, I think it's stupid to not tell your computer what you are really diving and adjust your dive profile instead. But dangerous from an ox tox standpoint? Not unless you ignore your MOD and repeatedly dive the limits.