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

[Storker]

Isnt this entire thread?

[-]ever so slightly[/-] over-the-top hyperbole, yes, I agree

 

[DevonDiver]

One tiny correction here. I'm the OP, and that's very much not what I meant

My apologies... that was a misquote. I meant someone else

(note to self, next time check, don't assume)

 

[tracydr]

This is one thread that I have watched because of the topic of how the need for unexpected deco recovery, OW diving, agencies and human nature all come into play. I particularly like TSM's post 173. The idea of CMAS covering deco in basic is a good idea. It either instills the reasons to be aware of your times or provides an excuse to ignore them. I would think that ow should cover some limited deco information to the extent of getting yourself out of a potentially threatening unexpected obligation. Sort of like emergency deco recovery to the level of CESA understanding.

What would be a rule of thumb for such a situation considering the worst of all factors? Such as:
--A new OW that believes his training covers them through out the recreational range of 130ft.
--He possesses a log book with 10 dives in it.
--This diver has a buddy with 9 dives in his book.
--They have computers that they use with minimal understanding. IE depth gage and clock and tank pressure if integrated.
--Some period of time they discover that the beeping is their computer telling them they have entered deco/exceeded NDL and from that point they don’t understand the displays as deco displays are foreign to them.

I realize that any resulting rule of thumb will mostly be overkill for most dives but that is ok, because that is what a rules of thumb are. It is what is used when a lack of specific actions for a situation are not available.

Could we say something along the line of divide your depth by 3 and go to that depth (if greater than 20 ft) or 20 ft and stay for 3 times the time you think you were past ndl then proceed to safety stop for normal time plus an additional 3minutes and then spend 3 min going to surface. Then boldly call this a rule of 3’s.

So if a diver is doing a repeditive dive and finds he is past ndl by maybe 2 minutes at 80 ft he would go to 1/3 of 80 or say 30 ft for 6 min and then go to safety stop for 6 min instead of 3 and then to the surface slowly and end diving for the day.

Something like this would cover . What to do if you find yourself suddenly past NDL. A less than optimal solution for a prior failure but a process that is concequence limiting.

Sounds like you're asking about "deco on the fly" which is taught by an agency. Or,ratio deco. It's a system similar to what you're suggesting.

 

[victorzamora]

My apologies... that was a misquote. I meant someone else

(note to self, next time check, don't assume)

I knew who you meant, I just didn't want someone associating me with that particular line of thought

 

[boulderjohn]

What would be a rule of thumb for such a situation considering the worst of all factors? Such as:
--A new OW that believes his training covers them through out the recreational range of 130ft.
--He possesses a log book with 10 dives in it.
--This diver has a buddy with 9 dives in his book.
--They have computers that they use with minimal understanding. IE depth gage and clock and tank pressure if integrated.
--Some period of time they discover that the beeping is their computer telling them they have entered deco/exceeded NDL and from that point they don’t understand the displays as deco displays are foreign to them.

I realize that any resulting rule of thumb will mostly be overkill for most dives but that is ok, because that is what a rules of thumb are. It is what is used when a lack of specific actions for a situation are not available.

Could we say something along the line of divide your depth by 3 and go to that depth (if greater than 20 ft) or 20 ft and stay for 3 times the time you think you were past ndl then proceed to safety stop for normal time plus an additional 3minutes and then spend 3 min going to surface. Then boldly call this a rule of 3’s.

So if a diver is doing a repeditive dive and finds he is past ndl by maybe 2 minutes at 80 ft he would go to 1/3 of 80 or say 30 ft for 6 min and then go to safety stop for 6 min instead of 3 and then to the surface slowly and end diving for the day.

Something like this would cover . What to do if you find yourself suddenly past NDL. A less than optimal solution for a prior failure but a process that is concequence limiting.

Wouldn't it be simpler to provide training in this sort of thing in the OW course so that divers know what to do when they unintentionally stray into deco while diving with computers--that is, so what the computer tells them to do?

 

[DevonDiver]

Wouldn't it be simpler to provide training in this sort of thing in the OW course so that divers know what to do when they unintentionally stray into deco while diving with computers--that is, so what the computer tells them to do?

They do, don't they?

PADI RDP teaches simple rules for emergency decompression.

I believe that you, yourself, said in other threads that the computer version of the course doesn't dispense with anything that was in the RDP course... that is was just as robust and comprehensive.

Does the PADI computer-based course teach emergency decompression or not?

 

[pdhenry]

Does the PADI computer-based course teach emergency decompression or not?

There's a significant difference between diving with tables and diving with a computer. With the tables, once you breach the NDL you're outside of the realm of the tables - terra incognita - so the emergency decompression rules have to be conservative to provide an adequate margin of safety for recreational NDL breaches (less than 5 minutes. more than 5 minutes). The rec computers tell a diver not to plan a decompression dive, but the algorithms still work when the diver has breached NDL, tracking depth and time despite being in breach . So the decompression procedures with a computer are less "emergency" and don't need to be as conservative to provide adequate margin of safety.

My PADI course is still table-based but I've been researching inexpensive computers especially in regard to what they do that the tables don't.

 

[dumpsterDiver]

There's a significant difference between diving with tables and diving with a computer. With the tables, once you breach the NDL you're outside of the realm of the tables - terra incognita - so the emergency decompression rules have to be conservative to provide an adequate margin of safety for recreational NDL breaches (less than 5 minutes. more than 5 minutes). The rec computers tell a diver not to plan a decompression dive, but the algorithms still work when the diver has breached NDL, tracking depth and time despite being in breach . So the decompression procedures with a computer are less "emergency" and don't need to be as conservative to provide adequate margin of safety.

My PADI course is still table-based but I've been researching inexpensive computers especially in regard to what they do that the tables don't.

Your profile says you are not certified. Your comments seem to back that up.

 

[boulderjohn]

They do, don't they?

PADI RDP teaches simple rules for emergency decompression.

I believe that you, yourself, said in other threads that the computer version of the course doesn't dispense with anything that was in the RDP course... that is was just as robust and comprehensive.

Does the PADI computer-based course teach emergency decompression or not?

Yes, they do, and yes, I have said it before. I was setting up for that response--the solution to the problem already exists.

Students who are taught using the tables are not taught anything about how computers work. Students taking the new computer version of the OW course learn how to use their computer to guide their ascent in case they accidentally stray into deco.

 

[DevonDiver]

The rec computers tell a diver not to plan a decompression dive, but the algorithms still work when the diver has breached NDL, tracking depth and time despite being in breach . So the decompression procedures with a computer are less "emergency" and don't need to be as conservative to provide adequate margin of safety.

You are very much mistaken. Plenty of discussion on this, and some other current, threads that explain what rec computers do and do not provide.

Being in deco isn't an 'emergency'. Being unable to complete that deco is an emergency. There is a lot of training, knowledge and equipment required to provide an assurance that you can, without fail, complete that deco. Such an assurance is simply not possible through recreational-level diving training for most agencies.

Recreational computers are far from ideal platforms from which to complete decompression. Most manufacturers stage catagorically that they provide 'emergency' decompression. They'll get you to the surface and try not to bend you. This is a huge gulf from technical computers, which look at much more optimal ascent profiles and require much more informed user direction/configuration.

The PADI RDP... well, that has it's <5min/>5min rule. It's simple and straightforward. Just as it should be for novice divers, who have to remember the protocols.... and probably shouldn't even be doing dive profiles that'd get them anywhere near a no-stop limit anyway...