Exceeding the NDL during recreation diving

[inquis]

What’s their plan for getting to the depth they can use the deco cylinder?

In the case of regulator or hose malfunction, shutdown the problem valve and switch to the other reg. They also teach team mentality, so that's the plan in the case of multiple failures, including Rock Bottom for reserve gas.

 

[crofrog]

In the case of regulator or hose malfunction, shutdown the problem valve and switch to the other reg. They also teach team mentality, so that's the plan in the case of multiple failures, including Rock Bottom for reserve gas.

You made it sound like they could have a single cylinder without redundancy if they had a deco stage or did I miss understand you?

 

[chrisjur]

No, it does not. PADI 40 is 10mins deco with a single deco gas up to 50%, non-accelerated deco. But in no way it certifies to use a single cylinder...

Not true. That's the old Tec 40 certification standards. The PADI TecRec program was updated in Q3 2023. Tec 40 now allows you to:

• Plan and make decompression dives with not more than 10 minutes of decompression using a decompression gas, or not more than 15 minutes of decompression using bottom gas, and not deeper than 40 metres/130 feet.
  
  
• Dive with a redundant gas source, either single cylinder plus bailout cylinder, sidemount or back mount doubles.
  
  
• Use a single cylinder of decompression gas with up to 50 percent oxygen (EANx50) for decompression.

(Source: PADI Tec 40 Course Introduction - Further details in the course guidelines go into specific equipment configurations, etc.)

 

[chrisjur]

In the case of regulator or hose malfunction, shutdown the problem valve and switch to the other reg. They also teach team mentality, so that's the plan in the case of multiple failures, including Rock Bottom for reserve gas.

You made it sound like they could have a single cylinder without redundancy if they had a deco stage or did I miss understand you?

Yeah, seems to be some confusion here. Tec 40 does allow for a single cylinder but requires valve redundancy OR a bailout. Per the new PADI Tec 40 equipment requirements, you can have a:

1. Single cylinder with a dual outlet valve, such as an H or Y valve.

1. Single cylinder with single outlet valve and a bailout cylinder. The bailout cylinder:

• May have the same gas as the main cylinder or have a higher oxygen mix, but it must be breathable at the deepest planned dive depth.
  
  
• Must contain at least 850 litres/30 cubic feet of gas.
  
  
• Should have sufficient gas to ascend from 40 metres /130 feet and complete any required decompression. You'll learn more about gas planning later, but if, during your gas planning, you calculate that you'll need more than your cylinder capacity you'll need to either adjust your plan or use a large cylinder.

(Above bullets copy/pasted from PADI)

In reality, I don't know who takes the class with a single cylinder.

 

[Searcaigh]

Not understanding why experienced tech divers carry only one computer.

Where do you get that information from?

Every tech diver I know uses two computers even while rec diving.

 

[Angelo Farina]

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

I agree. We are old, and use old school techniques.
I started using a dive computer in 2019! And still i prefer my trusted Seiko watch, analog depth meter and US Navy dive table, the computer is there just because in some places they find it to be mandatory, and giving me some additional info and reference.
But my deco stops will never be managed by a crappy electronic device...
The point is that I work building and programming electronic devices (20 years ago I founded a spinoff company of the University of Parma, building noise and vibration meters, and just this year I founded another, building complex monitoring systems for machineries and buildings), and I know first hand how many shortcuts and errors are made even in professional scientific instruments costing 20 times more than a dive computer.
My life and health cannot be in the hands of an obscure programmer who probably did never make a deco dive.
Regarding solo diving, this is a common accepted practice here for COMMERCIAL DIVING, not for recreational diving. It is also quite standard for rescue divers (firefighters, civil protection, etc.), but in these cases the solo diver is always in communication with the surface support, employing some sort of intercom system, either wired or wireless.
This is particularly true when doing search of dead bodies in zero visibility (in such conditions a buddy is a nonsense), which is an activity I practiced as a Civil Protection volunteer for 20 years.
I did build my own intercom system, which requires a full face mask, of course.
Special training is required for such activity, well beyond any recreational or "tech" training, and based on the training system developed in the eighties at the top commercial diver school in Italy, the Istituto Rossi in Vicenza, which now has unfortunately terminated these training programs.