Quiz - Recreational Dive Planner - Exceeds NDL By 6 Minutes

[Pedro Burrito]

Sorry this question is too wordy for the poll.

From the PADI Dive Theory Exam:

If a diver exceeds the no decompression limit by six minutes, and does not realize this oversight until after surfacing, what is the recommended procedure?

a. Remain on the surface, rest and be monitored for signs/symptoms of decompression sickness; wait at least three hours before diving again.

b. Reenter the water and make an emergency decompression stop at 5 metres/15 feet for 15 minutes or longer.

c. Reenter the water and make an emergency decompression stop at 5 metres/15 feet for 8 minutes.

d. Remain on the surface, rest and be monitored for signs/symptoms of decompression sickness; wait at least 24 hours before diving again.​

I will post a daily question from my exams to help newer divers and to encourage more experienced divers to interact gracefully and helpfully with the newer divers.

Reminder - this is a post in the Basic Forum and it is a green zone. Please be nice and on topic.

Thank you for your patience while we try to give people something to discuss other than Covid-19 and/or Politics. I will post the answer covered by the spoiler tag later today.

 

[tursiops]

Your question is about what happens if you surface after exceeding NDL by 6 minutes. The other case is if you discover you have exceeded NDL by more or less than 5 minutes but have not yet surfaced. In this case, I like the rule of "3 and 5". Normally it is a 3 to 5 minute safety stop at 15'. If you exceed NDL by less than 5 minutes then you add 3 to 5 so it is 8 minutes at the safety stop. If you exceed NDL by more than 5 minutes then you multiply 3 by 5 so it is 15 minutes at the safety stop. In both cases after you surface you have a wait time before reentering the water: 6h and 24h respectively. Those times are chosen to monitor for DCS and to wash out the excess nitrogen.

 

[Steve_C]

Your question is about what happens if you surface after exceeding NDL by 6 minutes. The other case is if you discover you have exceeded NDL by more or less than 5 minutes but have not yet surfaced. In this case, I like the rule of "3 and 5". Normally it is a 3 to 5 minute safety stop at 15'. If you exceed NDL by less than 5 minutes then you add 3 to 5 so it is 8 minutes at the safety stop. If you exceed NDL by more than 5 minutes then you multiply 3 by 5 so it is 15 minutes at the safety stop. In both cases after you surface you have a wait time before reentering the water: 6h and 24h respectively. Those times are chosen to monitor for DCS and to wash out the excess nitrogen.

Had not heard this before. Interesting. Of course for NC diving where often the boat allows a SI of 1 hour (2 if doing deeper dives), essentially it says you are done diving for the day.

With a dive computer if you were over NDL by a few minutes during the dive and you can clear the obligation on the way up and on the safety stop. So you are saying if the diver goes over NDL at any point in the dive then they should sit out for 6 hours?

 

[tursiops]

So you are saying if the diver goes over NDL at any point in the dive then they should sit out for 6 hours

That's what the RDP says. That's why people buy computers....and the problems begin to occur when they don't know how to use the computer. But, hey, they probably didn't know how to use the RDP, either.

 

[Steve_C]

Bad air consumption for many new divers is a safety bonus. They never hit NDL.

Of course if there is a new diver who is naturally good at air and dives with typical new divers they can find them selves in NDL on air when having better instabuddies on Nitrox on a deep dive (100ft). She followed our lead going up and we were able to get her cleared and she got a lesson in NDL and reading her computer during the safety stop.

 

[Khrissi]

@Steve_C rather it's excessive air consumption ....' bad air ' consumption , yr probly not coming up at all k

 

[scubadada]

How do you exceed NDL by six minutes and not discover it until after you surface?

 

[tursiops]

How do you exceed NDL by six minutes and not discover it until after you surface?

Diving on tables with air and no computer, ignoring or misreading watch, buddies on computers and nitrox. Easy!

 

[scubadada]

Diving on tables with air and no computer, ignoring or misreadind watch, buddies on computers and nitrox. Easy!

Sorry, easy? Careless. Is that how one runs out of gas too?

Many of us dived for years with a watch, depth gauge, and SPG without exceeding table NDLs or running out of gas. It was actually a couple of years before I had a SPG

 

[Edward3c]

Sorry, easy? Careless. Is that how one runs out of gas too?

Many of us dived for years with a watch, depth gauge, and SPG without exceeding table NDLs or running out of gas. It was actually a couple of years before I had a SPG

Was that before the new high presure cylinders at 207bar (3,000psi).