"Riding your Computer Up" vs. "Lite Deco"

[Bob DBF]

The U.S. Navy tables were quite unsatisfactory for recreational diving because they used the 120 minute compartment to guide surface intervals, which meant that divers had to spend a very long time out of the water between dives. The Navy's decision to do that was made without any real testing, and it did not matter to the Navy since their divers rarely did more than one dive in a day.

The US Navy has been conducting ongoing dive research since 1912 using the decompression research of Haldane as a starting point. One of the reasons all Navy dives are logged is to collect data for for revisions of their dive manual.

In 1924 the Navy and bureau of mines started testing of helium-oxygen mixtures, around then the Navy Expermintal Diving Unit was started, and is continuing cutting edge diving research to this day.

They used the 120 minute compartment because they needed a diver on a job as long as possible and had others to switch out as necessary.

The Navy tables were unsatisfactory for recreational divers when rec divers started doing multi-dive and multi-day dive trips. It might be a reason I heard about more divers being bent and about the same number of diver deaths, even though there were less divers back then, without an Internet.

This was information, about the limitations of the Navy tables, I had given to me when I started deco diving in the mid '60's. This was probably why the PADI manual discussed decompression safety stop, later shortened to safety stop, when I finally got certified in '80.


Bob

 

[lowviz]

The current PADI program uses a computer simulation that shows all the features of a computer as it goes through various kinds of dives. Students can play with all kinds of situations on the simulator and see how the generic computer works.

That is just too funny. I lied, give me one more post. So after all that research, PADI offers an undiveable internet solution to IRL?

No, real people learn by doing in real life. First by someone's core principles under expert supervision, then by branching out if the student chooses that path.

All of the algorithms for recreational diving work plenty well enough. There is no need to pick one out.

Normalization of what was that???

No standard. Defend that.

 

[DevonDiver]

The initial premise of this thread was to explore an extended dive that was accomplished by either riding ones NDL computer up to the surface while constantly at the NDL (in order to maximize bottom time) or doing a direct ascent under deco conditions (with the same lengthened dive time) whose deco stops are imposed by an overly conservative algorithm.

And the counter-point raised has been that no agency would advocate an approach to diving that was hyper-aggressive in maximising bottom-time.

Agencies, without exception, advocate diving conservatively; which includes not pushing no-stop limits or entering staged decompression whereby immediate and predictably safe access to the surface is removed.

Evolving computer technology can empower divers, of unknown and varied ability, to second guess prudent agency recommendations.

Add to that a situation whereby a diver only needs to browse a few internet articles, or buy a copy of 'Deco for Divers' before considering themselves of sufficient individual 'authority' and 'expertise' to disregard the safety and operating recommendations refined by agencies through decades of real world diving and teaching experience.

Riding NDLs to the surface is the epitome of imprudent diving...nobody recommends that.

Using a staged decompression schedule to offset that imprudent diving approach is one method to redress the initial bad decisions made.

However, if that diver isn't trained and qualified to completed staged decompression, then it's probably a bad decision taken to resolve a bad decision.

Dismissing unspecified 'shorter' decompression limits as 'lite' merely constitutes a third bad decision, to compensate for the initial two errors.

Digging the hole deeper, based on an initial flawed premise that some internet education makes the diver sufficiently expert to dive imprudently in objection to a universal safety recommendation agreed globally by every scuba training agency.

 

[DevonDiver]

... real people learn by doing in real life.

I don't see the use of dive computer simulators as anything different to the plethora of skills and protocols first introduced and practiced 'dry', before being practiced 'wet'.

Plenty of fields use simulators in preparation for practical training.

The important factor is that simulations and dry practice are an initial stage of training and, in no way, should replace subsequent en-situ 'real' application practice.

 

[stuartv]

And the counter-point raised has been that no agency would advocate an approach to diving that was hyper-aggressive in maximising bottom-time.

Agencies, without exception, advocate diving conservatively; which includes not pushing no-stop limits or entering staged decompression whereby immediate and predictably safe access to the surface is removed.

Evolving computer technology can empower divers, of unknown and varied ability, to second guess prudent agency recommendations.

I think this is somewhat of a red herring. They may all say that, but do any of them actually give a definition for "diving conservatively"? It's hard to accuse someone of second guessing if you haven't actually given them anything to be measured against.

 

[lowviz]

... They may all say that, but do any of them actually give a definition for "diving conservatively"? It's hard to accuse someone of second guessing if you haven't actually given them anything to be measured against.

Thank you, stuartv.

My point exactly.

 

[DevonDiver]

I think this is somewhat of a red herring. They may all say that, but do any of them actually give a definition for "diving conservatively"? It's hard to accuse someone of second guessing if you haven't actually given them anything to be measured against.

Read: Alert Diver | Conservative Diving

See:

"Make all dives no decompression dives and allow a margin of safety"
PADI Statement of Understanding - Safe Diving Practices
​

Seriously...who couldn't understand the general premise of diving conservatively within the limits specified by their agency?

In what reasonably context would doing 'lite deco' beyond no-stop limits, that you'd be content to blow off if necessary, constitute diving conservatively as a no stop dive with a margin of safety and within the limits of your training?

 

[stuartv]

Read: Alert Diver | Conservative Diving

See:

"Make all dives no decompression dives and allow a margin of safety"
PADI Statement of Understanding - Safe Diving Practices
​

Seriously...what gibbering moron wouldn't understand the general premise of diving conservatively within the limits specified by their agency?

In what dimension of lunacy would doing 'lite deco' beyond no-stop limits, that you'd be content to blow off if necessary, constitute diving conservatively as a no stop dive with a margin of safety and within the limits of your training?

So does PADI define it as no less than 2 minutes of NDL left? 5? 10?

As I said, I don't think any agency defines "diving conservatively".

I dive a DSAT computer and never let it go below 1 minute of NDL remaining. Does that meet the PADI definition of diving conservatively?

 

[Scuba J7]

Technically, any number greater 0 would be conservative.

So does PADI define it as no less than 2 minutes of NDL left? 5? 10?

As I said, I don't think any agency defines "diving conservatively".

I dive a DSAT computer and never let it go below 1 minute of NDL remaining. Does that meet the PADI definition of diving conservatively?

 

[DevonDiver]

Technically, any number greater 0 would be conservative.

.... and the greater the number, the greater the conservatism.

However, set numbers (i.e. "5 minutes) becomes irrelevant because there has to be a relevance to the actual NDL itself.

Obviously, the deeper and more repetitively we dive, the shorter the bottom time. 5 minutes conservatism on a 55 minute NDL isnt the same as 5 minutes conservatism on an 8 minute NDL.

Trying to attribute a set number for conservatism would become ridiculously complicated.

It's a common-sense principle, not a mathematical rule.