As a rec diver, what to do if I breach my computer's NDL???

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What is the hand signal for letting a DM or dive buddy know you inadvertently entered deco according to your computer? My dive buddy (wife) and I have our signals for such things, but I don't think I have been taught any particular signal. DMs have often signaled me to signal back how much gas I have remaining, but I have yet to have one signal me to ask about remaining no-deco time. With my Suunto, no-deco time is usually the limiting factor in my dive times, not gas.
 
Thanks for the response -- I'll fire it up on my tablet, would be nice to have something to work with, to provide examples for students.
 
DecoCeiling.jpg

What is the hand signal for letting a DM or dive buddy know you inadvertently entered deco according to your computer? ...//...

Either of these work...
 
I just read the original post, and have not read the thread; so if this has already been suggested, I apologize.

I would recommend looking at a dive table as part of your pre-dive plan:
Here's a link to the PADI dive planner, in case you don't have one. I'm not sure if PADI offers printed versions anymore.

http://www.google.com/url?sa=t&rct=...=cP4D9Z9TRGeP6Yg9k0xGvQ&bvm=bv.58187178,d.b2I

On the back of the table, or page #2 in the PDF there is a section for Emergency Decompression.

It might be good to review that as a basic guideline of what to do for a recreational diver.
Perhaps review that in your pre-dive planning, even if diving a computer.

Of course, this is not taking into account your gas supply; so you may or may not have enough gas to complete the emergency decompression stop.

It would be worthwhile to calculate your gas supply duration for your dive, which will then reinforce the need to be disciplined in following your planned depth and run time.

There's no free ride. If you exceed your NDL...you need enough gas to do the stops.

Know how much money is in your account, before you write the check. :cool2:

---------- Post added January 7th, 2014 at 02:59 PM ----------

The old YMCA dive tables also had some emergency decompression information, for planning purposes. But I can't find a PDF of that table.

Perhaps the NAUI tables, along with some other, have similar information.
 
The point is that on these dives, I was wearing a Suunto Stinger as my primary computer, with an Aeris XR1NX as backup. And 36 minutes into the second dive, at 59FSW, the Suunto had me in deco while the Aeris was happy as a clam. I knew the Suunto was ultra conservative, and I knew this was likely to happen. I had about 2200PSI left. I have no deco certifications, but I am also not an idiot. I could have just chosen to dive the Aeris. I let the DM know I was in deco, spent the next 3 minutes ascending to 40 feet (which did not clear the deco), stayed at 40 feet for 5 minutes, then ascended to 15 feet, where I shot a DSMB and hung around for the 10 minutes of deco the Suunto said I stilled owed, plus couple minutes more.

I am not familiar Stinger, but if it has the same algorithm as the Cobra and others that are not designated DS (deep Stop), then you piled up more required deco time during the 5 minutes you were at 40 feet.
 
This is an excellent point.
We were on Cozumel and the port had been closed by an El Norte. Around noon on the second day, they opened it. The good folks at Aldora called to see if we wanted to head out (duh!). So off we went.
We had a great first dive. During the SI, it was obvious that daylight was going to become an issue, since we'd started diving late and were doing longish dives. Twilight wasn't a real problem, since everybody had a light, but the group didn't really want to do a night dive (I'm kind of a fanatic about lighting, and always carry at least two on a night dive).
Profiles:
1st Dive: Santa Rosa Wall, 1:02 run time, max depth 84FSW
SI: 60 min exactly.
2nd Dive: Tunich, 57:20 run time, max depth 74FSW
We had been diving the day before, but in cenotes with a max depth of less than 30 feet.
I can provide the details of the profiles if needed.
The point is that on these dives, I was wearing a Suunto Stinger as my primary computer, with an Aeris XR1NX as backup. And 36 minutes into the second dive, at 59FSW, the Suunto had me in deco while the Aeris was happy as a clam. I knew the Suunto was ultra conservative, and I knew this was likely to happen. I had about 2200PSI left. I have no deco certifications, but I am also not an idiot. I could have just chosen to dive the Aeris. I let the DM know I was in deco, spent the next 3 minutes ascending to 40 feet (which did not clear the deco), stayed at 40 feet for 5 minutes, then ascended to 15 feet, where I shot a DSMB and hung around for the 10 minutes of deco the Suunto said I stilled owed, plus couple minutes more.
Again, the Aeris was happy as a clam throughout. But it's a console, and I prefer a wrist mount, so I didn't want to lockout the Suunto.
I've since replaced the Suunto with an Aeris Manta.

Those who reflexively decry anybody without formal deco training incurring even a light deco obligation will no doubt be bothered by my doing so. On the other hand, they wouldn't be at all upset if I'd simply ignored the Suunto and dove the Aeris.

This is a great thread, so many important topics. I dive an Oceanic VT3 primary and a Geo2/SPG backup. I'm obviously very fond of the relatively liberal DSAT decompression algorithm. I've been diving it since my 1st Pro Plus in 2001. My two computers are very closely matched, within minutes, but the Geo2 is slightly more conservative. Obviously, I obey the Geo2 so that I can continue to dive both my computers. This requires a minute or two of additional deco time prior to the added SS. I accept this and am happy to "do my time"


Good diving, Craig
 
I'm sorry but I still don't buy the blow off the remaining deco obligation to surface with "several hundred psi" in the tank plan. I take "several hundred" to mean at least 300 psi.

Now I was certified in the days of a J valve so surfacing from 15 feet with no air is no big deal, but even then.

That several hundred psi is your reserve - IMHO you have done something that requires that you use that reserve. So use it, don't save it for a rainy day - its raining now. You have gone into deco without enough gas to do the deco.

I get that guages are not particularly accurate, but you are at 15 feet, you have been sitting at your safety stop looking at your guage and computer and thinking about what to do when the air gets low or runs out before the deco obligation clears. If the air runs out before the guage you should be ready for that contingency and have a plan. If surface conditions are such that you still feel the need for a reserve then by all means keep one but personally I would breathe the tank down as low as I was comfortable with in the particular conditions I was in and then surface rather than blowing off 10 - 15 minutes of deco obligation to retain a reserve just in case my guage was wrong.
 
...//... This quick and dirty procedure implies a recreational diver hitting unexpected deco and responding to it in a timely fashion.

This is the scenario that we are discussing.

I'm sorry but I still don't buy the blow off the remaining deco obligation to surface with "several hundred psi" in the tank plan. I take "several hundred" to mean at least 300 psi. ...//...

So did I when I posted that. 300 psi is exactly what I meant as an absolute minimum under these conditions. Yes, blow the rest of your obligation off and get back on the damn boat.

I'm weighing the risks of blowing off light deco with being OOG at the surface for the average, overweighted, unpracticed, vacation diver. You are most welcome to your stance, I just don't give the average diver that much credit. My opinion, no more than that...
 
People do deco all the time and go have a beer afterwards. Knowing a little bit about that is a safety thing; to that degree, I think classes like Fundamentals and Peter's Techreational Diver class, classes that introduce technical level skills and technical attitudes toward gas planning and reserves, are a highly desirable education for people whose SAC rate, tank size, and diving environment make coming nose to nose with a deco obligation a foreseeable possibility.


I may be a relatively good example of one of Peter's techreational divers. Most of my dives are firmly in the recreational space but I do push the limits. I nearly always dive nitox and generlly push both the NDL and, often, the pO2 limits. I dive a single and generally have a 19 cu ft pony. I am a SDI solo diver and often dive by myself. I do mostly drift diving, and even when diving with a group, not infrequently, I end up shooting my own SMB and surfacing by myself. I am quite good at leading a group if I'm given the flag. I have done numerous DPV dives, and though I do not own one, seek out the experience when available. I dive whenever the boat goes out, day or night, and shore dive when I have the opporunity.

Most of my dives are within recreational limits but about 2% of my dives are below 130 feet, as deep as 153 feet on Ghost Mountain in Grand Cayman on air (I won't bring up deep air, and yes, I was narced and enjoyed it). About 5% of my dives are "light deco", less than 10 minutes on back gas. I am acutely aware of my relatively good SRMV of 0.37 +/- 0.04 cu ft/min and do careful gas planning.


I very much enjoy my diving on the cusp between recreational and technical diving and do not plan to move from that space in the near future. I'm quite certain many of you out there operate in the same space.

Good diving, Craig
 
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