Overshooting NDL and mandatory deco stops

[NAUI Wowie]

Caveat this has not happened to me and im not going to do it. But if someone else has in the dive what would be the time for a mandatory deco stop? And im only asking the question as im sure it does happen to divers I just want to know the process.

If a diver were at 100ft depth and for whatever reason lost track and overshot the NDL by say 2 minutes and started up then at what depth would the mandatory stop be and for how long? On air. I assume if you hit the NDL on 32 nitrox it would end up being the same thing you were just at 100ft longer to get there.

Also do all modern dive computers automatically warn you at NDL and then tell you when and how long to stop?

Obviously if theres not enough air left you are going to avoid a mandatory stop of course.

 

[Ryan Mcshane]

On 32% it’s pretty much 1min deco @6m for every 1 min over the NDL.

As far as I know most computers will have at least a “get you home” mode that will tell you where to stop if you go over your NDL.

Being aware of your NDL’s, keeping an eye on your time and depth is key. Don’t rely on a computer beeping or flashing to tell you when it’s time to come up.

If you’re really not sure, gas allowing, 10 mins at 6m will cure most evils provided you’ve not massively blown your NDL

Safe diving and don’t do deco without training!

 

[shurite7]

If a diver is using a dive table then he/she would follow the procedures printed on the dive table. Each table (NAUI, NOAA, PADI, etc) is slightly different.

I can't answer for every computer out there, but the ones I am familiar with will display the deco information if a diver exceeds the NDL. It is up to the diver to understand how to read the computer and understand the procedure. This is where many people drop the ball; they don't know how to read, or understand, the information displayed on the computer. There is a chapter in a book titled Diver Down that pertains to this situation. Each dive computer has its own algorithm that will calculate NDL and deco (if NDL is exceeded). Like dive tables there is no single procedure. Know your computer.

 

[Gareth J]

If you are using a dive computer, the vast majority will immediately give you a ceiling depth and a time to surface / decompression stop time. (You should know how your computer will behave!)

If you are using tables, then it depends on the tables. Buhlmann and BSAC88's to name two, will give you the required decompression stops. The PADI tables don't, from memory I believe there is a specified procedure, go to X depth for Y time, then surface and don't dive again (and be monitored for potential DCI).

Stop Depth, changes with the amount of decompression you have accrued.
Most dive computers work in 3m interval's, working progressively deeper, i.e. 3m, 6m, 9m, 12m 15m, etc.
The BSAC88's work from 6m down in 3m increments i.e. 6m, 9m, 12m etc.


Does that answer the question?

 

[divinh]

EDIT: IGNORE

-----

In my experience, when we were expected to go into 5 min of deco, due to short surface interval and 25m+ consecutive dives, the guide said to the three of us, to flag her when we reached 5 min deco on our dive computers. As soon as someone hit 5 min deco, we would end our dive and proceed to the safety stop.

For the dive computer, it can be set to have Deep Stops or not:

If Deep Stops are set, then the computer will indicate a depth and duration for the mandatory stop(s). Once you're within the depth plus a bit of tolerance, the dive computer will start counting down. You're clear when the computer gets to zero. After completing all the Deep Stops, you would proceed to the normal safety stop and do the typical 3 min at 5m.

If Deep Stops are not set, then you would likely proceed to the normal safety stop depth of 5m and wait out the mandatory stop. The computer would count down until the mandatory stop is complete... then it will start counting down from 3 min for the normal safety stop. Maybe some computers will combine the two counts.

If you're low on air, going progressively more shallow will gain you some time.

As the others have said, know your dive computer. It will tell you your obligations.

 

[dewdropsonrosa]

Standard notice that decompression diving should never be conducted without appropriate training, etc.

My personal experience is that very slight over-runs past NDL (1-2 minutes) might cause your dive computer to begin calculating decompression stops, but promptly beginning to ascend at a safe rate will often clear the need for stops before you reach the target depth.

Whether or not your computer has functions to assist you in managing decompression depends upon the make/model of computer. If you are diving a computer when this happens, you should follow its instructions.

If you've gone into decompression and you lack air to conduct required stops, something has gone terribly wrong in planning, execution, or both - this is an entirely avoidable emergency situation.

 

[PfcAJ]

Naui Dive tables have stop information on them for modest times past NDL.

 

[rhwestfall]

RTFM

This then also opens up a whole chapter in things like gas planning & reserves......

 

[JackD342]

When using PADI DSAT RDP:
Exceed NDL < 5 min, then 8 min deco at 15ft, no diving for next 6 hours.
Exceed NDL >= 5 min, then 15 min deco at 15ft, no diving for next 24 hours.

 

[Tribal]

If you exceed the ndl by 2 minutes and then slowly ascend, its most likely you have no deco time left once arriving at 3 meter.

Not saying you should do deco dives without proper knowledge but its not like something strange happens from the moment you get past the ndl.