Exceeding the NDL during recreation diving

[johndiver999]

No you are mistaken, you are doing deco with some knowledge, albeit poor knowledge.

'Good judgment comes from experience; experience comes from bad judgment' - Dr Kerr L White.

There is a great quote when diving in Chuuk in Truk Lagoon, "if your computer screen shows a view you have never seen, you are likely in deco." During the surface interval, one then sees said diver pouring over the computer manual.

LOL, a weird computer screen : today I started my third dive of the day and I take a quick peak a minute or two after reaching the bottom. For some reason, it is immediately showing like 1:57 (1 hour and 57 minute) ascent time (deco). This is the second time the computer has gone wacko, but it seemed to be reading depth perfectly.

I'm solo with an 85 tank with 32% and a pony . What to do?

I started the stopwatch on my G-shock and promise myself to start the ascent with at least 1000 psi and keep it less than 25 minutes of BT at around 100 + feet. Experience tells me this should be "about right" for a typical dive close to the blurry line.

I left the bottom showing 2:46 deco and got out with about 2:41 deco remaining. I did a very slow ascent above 50 feet, taking about 12-13 minutes for the entire ascent to the surface, with 5-6 minutes of that above 20 feet.

Experience - Bad judgement - Poor Knowledge ? Maybe?

 

[tursiops]

LOL, a weird computer screen : today I started my third dive of the day and I take a quick peak a minute or two after reaching the bottom. For some reason, it is immediately showing like 1:57 (1 hour and 57 minute) ascent time (deco). This is the second time the computer has gone wacko, but it seemed to be reading depth perfectly.

I'm solo with an 85 tank with 32% and a pony . What to do?

I started the stopwatch on my G-shock and promise myself to start the ascent with at least 1000 psi and keep it less than 25 minutes of BT at around 100 + feet. Experience tells me this should be "about right" for a typical dive close to the blurry line.

I left the bottom showing 2:46 deco and got out with about 2:41 deco remaining. I did a very slow ascent above 50 feet, taking about 12-13 minutes for the entire ascent to the surface, with 5-6 minutes of that above 20 feet.

Experience - Bad judgement - Poor Knowledge ? Maybe?

What computer are you using?

 

[johndiver999]

Some old one button, nitrox Oceanic?

 

[tursiops]

Some old one button, nitrox Oceanic?

The old Oceanics gave very long deco times, especially on repetitive dives. One of the problems of sliding into deco with recreational gear and procedures.

 

[LI-er]

You do "to effectively manage the risk of decompression diving"

No, you don't (need all that gear) to effectively manage the risks of (light) DECO diving.

A pony bottle with sufficient gas plus the reserve in the main tank in the event of a failure is sufficient.

Now it's your turn to say yes I do.

 

[johndiver999]

The old Oceanics gave very long deco times, especially on tepetitive dives. One of the problems of sliding into deco with recreational gear and procedures.

LOL not 2.5 hours after 2 min of BT after an hour SI... It is an error, if that is not obvious.

 

[lowwall]

Some old one button, nitrox Oceanic?

I had one of those fail the same way. Mine was an Oceanic Veo 100NX and it displayed a deco obligation a few minutes into my second dive of the last day of a dive trip.

Luckily I was able to continue the dive because during the surface interval the computer display cycled through the max NDL time at different depths and I had noted what it was for the depth of the site we were diving. Since the elapsed time and depth displayed correctly, I was able to treat it like it was in gauge mode.

 

[LI-er]

Not understanding why experienced tech divers carry only one computer.

As a recreational diver who often goes into light DECO I carry 3 computers.

The old Oceanics gave very long deco times, especially on repetitive dives.

I dive an Oceanic VT Pro. Same algorithm as newer PCs. If anything it's known to be rather generous when it comes to NDL limits, but rather restrictive when it comes to 02 levels when diving Nitrox. I've never experienced a tepetitive dive and I'm not sure I even want to.

 

[Angelo Farina]

I agree completely. It is the casual entry into "light deco" on an NDL dive without preplanning for gas needs that I strongly object to.

No pdf to see.

Sorry for the badly formatted link.
Here the PDF describing Self Rescue Diver program on CMAS web site: Self-Rescue Diver Training Programme
As a CMAS instructor, I must say that for CMAS solo diving is generally a deprecated practice.
This course is not for solo diving, it is for diving safely when, by error, mistake, accident, etc, you loose your buddy and become forcedly "solo".
Hence the focus on "self rescue"...
However, for CMAS it is entirely normal being under deco obligation during rec diving (our mantra is "every dive is a deco dive, so better to train, equip and plan as such").
We discourage the whole concept of ascending when there is a problem, CESA also is a strongly discouraged practice, as we assume that, in general, a direct ascent to surface is way more dangerous than being trained and equipped for solving any problem remaining down.
So, if you loose your buddy during a deco dive, then of course you are a solo diver with deco.

 

[tursiops]

Sorry for the badly formatted link.
Here the PDF describing Self Rescue Diver program on CMAS web site: Self-Rescue Diver Training Programme
As a CMAS instructor, I must say that for CMAS solo diving is generally a deprecated practice.
This course is not for solo diving, it is for diving safely when, by error, mistake, accident, etc, you loose your buddy and become forcedly "solo".
Hence the focus on "self rescue"...
However, for CMAS it is entirely normal being under deco obligation during rec diving (our mantra is "every dive is a deco dive, so better to train, equip and plan as such").
We discourage the whole concept of ascending when there is a problem, CESA also is a strongly discouraged practice, as we assume that, in general, a direct ascent to surface is way more dangerous than being trained and equipped for solving any problem remaining down.
So, if you loose your buddy during a deco dive, then of course you are a solo diver with deco.

I suppose it is unlikely that CMAS will modernize its policies and training and harmonize with the rest of the world.