More than "Advanced", but not really "Technical"

Just got an email from a really great dive bud. To her dismay, a potential TDI instructor required doubles for TDI's "Decompression Procedures" course.

I have a serious problem with this requirement.

A bit of background first:
I'm best described as a rec-tech (recreational / light technical) diver. I have no problem with going into light deco. In fact, I consider it far, far safer than using an aggressive dive profile (or dive computer) and jamming myself up against the NDL dive after dive. "Don't cross the line if you can't do the time." When done properly and conservatively, crossing the line is the better of two choices.

So let's add cold water, old (me), and sporty seas. That would be an additional 30 feet (10 meters). OMG! Nah, pass. That would be too restrictive, puts me into deco! -Think about that....

I remain convinced that the drive for "more aggressive" dive computers is mainly due to the unspoken fear of violating NDL. TDI really had (still has?) this totally under control with their Decompression Procedures course.

So read the background material first:



1) Does this make any sense to aggressive recreational divers?

2) Did TDI really abandon their highly enlightened position?

Not sure what you are really asking....most of the post is about you. The TDI material you show is from 2000...things have advanced a bit since then; you might want to look at more current materials...you can even purchase the textbook for the course. No, doubles are not required, but enough gas to do the dive IS required....and some redundancy is always a good idea; doubles, or sidemount, are the most common way to do this. More importantly, why would you want to take a class in staged decompression if you don't want to do a decompression dive as part of the course?

The biggest problem with incurring a deco obligation is not having enough gas to complete it. When you go into deco on a single tank, you are trusting a great deal to the idea that a system with no redundancy will not have any leak or malfunction that would leave you without enough gas to do the time. Most people who deliberately incur deco obligations ensure some redundancy -- and I suppose that could be a slung bottle or doubles.

Teaching a class to recreational divers on typical single tanks, which gives them the intellectual ammunition to incur a deco obligation, seems to me to be unwise. Perhaps Doppler could weigh in on this -- I'm sure he knows more about the evolution of the TDI classes than I do.

Yes, as far as "about me" -hard to make it otherwise. My experience with TDI was a good one. Nothing to do with staged decompression, I can easily hit deco and return (with a proper hang) all on a 120cuft cylinder.

See, that is really my point. I believe that the typical rec diver sees the NDL very differently than you do.


And yes, redundancy dictates a second source of gas. Me, a 19 cuft pony.

---------- Post added January 5th, 2014 at 11:08 PM ----------

TSandM:

...//... Teaching a class to recreational divers on typical single tanks, which gives them the intellectual ammunition to incur a deco obligation, seems to me to be unwise. ...//...

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Indeed. So they put enough "spin" onto their dive plan to just miss going into deco... I'm talking light, properly managed deco. No more than 10 min.

No, sorry, I'm also having a hard time understanding what you are asking as well.... what does the typical rec diver see regarding NDL?

But if you are asking if a course involving staged deco should allow for single tank divers, then I agree with TSandM - not a good idea to be in a virtual overhead environment without some type of redundancy. As they say in tech diving circles - "three is two, two is one, one is none".

I'm not sure what the relevance is of the fact that you can put yourself into deco with a 120 CUF cylinder (most people can).

doctormike:

...//... I'm not sure what the relevance is of the fact that you can put yourself into deco with a 120 CUF cylinder (most people can).

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Well, that is the point. If one can easily get into trouble, then one should have the knowledge to get back home safely. My point exactly.

I feel that this is a "USA think" thing where computers lock up when you need them most. That way, there is no liability on the manufacturer.

lowviz:

Well, that is the point. If one can easily get into trouble, then one should have the knowledge to get back home safely. My point exactly.

I feel that this is a "USA think" thing where computers lock up when you need them most. That way, there is no liability on the manufacturer.

Click to expand...

OK, still not quite sure of what you are saying... If a diver gets into trouble (incurs a deco obligation), but doesn't have enough gas to do that deco, how will training help? Are you saying that people should be trained not to violate NDLs? Or are you saying that if you incur a minor deco obligation that doesn't put you OOG, basic OW training should teach you to do that?

No computer that I have ever dived locks up when it goes into deco, they show you your deco obligation. They do lock up if you blow off deco and surface with an obligation, which makes sense. So I don't get your point about computers either...

doctormike:

OK, still not quite sure of what you are saying... If a diver gets into trouble (incurs a deco obligation), but doesn't have enough gas to do that deco, how will training help?

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All about gas management, not really taught/enforced in OW. -Deco Procedures stresses management.

doctormike:

Are you saying that people should be trained not to violate NDLs? Or are you saying that if you incur a minor deco obligation that doesn't put you OOG, basic OW training should teach you to do that?

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No, saying that an advanced recreational course should exist (Deco Procedures) that allows the diver to be manage light deco, because it way too often is a reality of recreational diving.

doctormike:

No computer that I have ever dived locks up when it goes into deco, they show you your deco obligation. ...//...

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Only so far into deco and they make quite a fuss about it.

lowviz:

No, saying that an advanced recreational course should exist (Deco Procedures) that allows the diver to be manage light deco, because it way too often is a reality of recreational diving.

Click to expand...

TDI Deco Procedures is not the course you are looking for (Not sure what is unfortunately) Last dive on my Deco Procedures course was 150 feet for 30 minutes with 2 deco gases. Not the sort of thing I would choose to do with a single tank.........

ianr33:

...//... Last dive on my Deco Procedures course was 150 feet for 30 minutes with 2 deco gases. ...//...

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That fits the other extreme end of the course description. I'm interested in what the minimum requirements are for someone who just wants to understand what happens when one crosses the line and has the gas to return, but not the knowledge...