PADI Deep Diver course- gas management

[crofrog]

I am becoming thoroughly baffled. We are still talking about a NDL class, aren't we? If so, what does minimum decompression time have to do with things?

Do you materialize at the surface at the end of your bottom time?

If the answer is no, then the time spent ascending, and the time spent at the safety stop represent your decompression time. It has to do with the controlling the pDCS for a given exposure.

It would look something like this:

For the purposes of the PADI deep diver class

Max Depth	130ft (40m)
Maximum Bottom Time	10 min
Ascent speed (non-emergency)	30ft/min (10m/min)
Minimum safety stop time (non-emergency)	5 min

If you define those parameters you're basically ensuring that leading compartments M-value upon surfacing is ~75%, any use of nitrox would lower that number, as would any additional time at the safety stop. The ascent speed should be a target value because slower deeper would raise the M-value of the leading compartment and faster shallower would do the same.

 

[tursiops]

Without some sort of maximum exposure defined for the class you're allowing individual instructors to define what the maximum risk is for the class. PADI defined half of it. Max Depth 140ft (40m), but not the other pieces which are time at depth, and minimum decompression time.

You keep saying stuff like this, but it is not true.
The maximums are 130 ft for depth, and NDL according to the RDP or one's computer.
There is no decompression time allowed. It is an NDL class.

 

[Josh the diver]

deleted*

 

[crofrog]

if a safety stop is required to make the dive safe its not a NDL dive. its there to add more safety

Define safe as it relates to decompression.

 

[crofrog]

You keep saying stuff like this, but it is not true.
The maximums are 130 ft for depth, and NDL according to the RDP or one's computer.
There is no decompression time allowed. It is an NDL class.

Sorry my brain works in meters these days.

 

[tursiops]

If the answer is no, then the time spent ascending, and the time spent at the safety stop represent your decompression time. It has to do with the controlling the pDCS for a given exposure.

The time spent ascending is determined by the ascent rate and the depth; the ascent rate is a maximum of 18 m/min or what your computer says, whichever is slower; since nearly everybody is using computers, and the class ascends together, the ascent rate is in the vicinity of 10 m/min. The SS is 3-5 minutes, depending on the computer.

What about this don't you understand? What don't you like?

 

[boulderjohn]

if a safety stop is required to make the dive safe its not a NDL dive. its there to add more safety

Sorry, not the way it is defined. In fact, with more than a quarter century of diving behind me and two decades as a professional and two decades on ScubaBoard, I believe this si the first time I have ever seen anyone claim this to be true.

 

[boulderjohn]

Do you materialize at the surface at the end of your bottom time?

If the answer is no, then the time spent ascending, and the time spent at the safety stop represent your decompression time. It has to do with the controlling the pDCS for a given exposure.

It would look something like this:

For the purposes of the PADI deep diver class

Max Depth	130ft (40m)
Maximum Bottom Time	10 min
Ascent speed (non-emergency)	30ft/min (10m/min)
Minimum safety stop time (non-emergency)	5 min

If you define those parameters you're basically ensuring that leading compartments M-value upon surfacing is ~75%, any use of nitrox would lower that number, as would any additional time at the safety stop. The ascent speed should be a target value because slower deeper would raise the M-value of the leading compartment and faster shallower would do the same.

So you created a term that is not used by the general diving community. Wonderful.

 

[crofrog]

So you created a term that is not used by the general diving community. Wonderful.

Do you want to call it total ascent time instead?

You're doing a lot to dodge and weave vs just addressing why you think it's reasonable to not define a maximum exposure.

 

[tursiops]

Do you want to call it total ascent time instead?

You're doing a lot to dodge and weave vs just addressing why you think it's reasonable to not define a maximum exposure.

The maximum exposure IS defined. Why do you think it is not?