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

[Bob DBF]

Yes, I know it's a sharp, black line drawn through a fuzzy gray area, but since I'm not a deco scientist I have to trust those - hopefully reasonably competent - guys and gals who wrote my computer's algorithm. And by choosing a DC I've made a choice about where my personal sharp black line is drawn, and if I deviate from that choice I'm probably normalizing deviance.

My point is similar, why would anyone buy and use a dive computer they were just going to ignore. It seems to me foolish to buy a conservative computer so that one can put it into deco so they can ignore the warning. Maybe they want to impress their friends later about how they cheated death, and deco is no big deal.

Maybe most of the agencies should stop teaching us to fear deco so much, that is where the reliance stems from. I took OW from both NAUI and PADI, definitely different flavors of the same thing. But deco was treated the same in both.

Now for deco: "Don't do that s**t."

My experience with a NAUI/PADI OW class in '80 spent a lot of time discussing the distinction between NDL and Deco diving. We were trained for emergency deco and the NDL tables included some deco stops. It helps when you have a long class and a good instructor. The training by catch phrases is newer style training, and gives little information for the student to decide if it is BS or not.


I'm not against rec divers doing deco, however not believing your DC, not adhering to deco procedures because your computer's deco "is not really deco", and making up your own rules for deco is not making good habits for future diving. The problems I have with self taught deco is that there is now very good formal instruction available, and the society as a whole is focused on immediate personal gratification but deco diving is more about training, practice, skill, and patience.



Bob
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was deco diving before certified OW, but that was 50 years ago... it was different then.

 

[stuartv]

If you have chosen GFs, why not just dive to them? Choose the amount of deco time you're willing to do (15 minutes in your example) and dive to that plan.

Why have a computer tell you that you're within NDL if you don't believe it? I know you're going to say that it means you can head straight to the surface anyway if you need to; but given that heading straight to the surface should be your LAST resort regardless, if you NEED to head to the surface, you need to head to the surface - regardless of the numbers on your wrist.

Why do you say I don't believe the NDL? The whole point is that I DO believe it.

Because, to the best of my knowledge, pretty much all recreational computers on the market these days are "statistically" safe. In other words, if you follow the NDL on any of them, you are pretty darn likely to be able to do a direct ascent to the surface and not be bent.

So, having a recreational computer that tells me that NDL (which I believe to be very unlikely to get me bent on a direct ascent) gives me confidence that I can stay down that long with very little chance of a problem if I need to do a direct ascent. It's an aggressive computer, so it does that while maximizing my bottom time.

Then I can use the other computer to execute a more conservative ascent - thus making it even more likely (though by an unknown degree) that I will not get bent. Without the Rec computer to tell me an NDL, all I would know from my tech computer is that I have some virtual overhead. But, I wouldn't have the same ability to evaluate my risks of going directly to the surface. (Even the Almighty Shearwater does not have a display to tell you what your GF99 would be if you went directly to the surface from your current depth.) Which would mean that I would need to plan the dive in a much more formal way than is necessary for a single tank recreational dive. I also would not dive a single tank, unless I also carried redundant gas (i.e. a pony bottle). But if I'm diving within the NDL of my recreational computer (thus feeling safe to make a direct ascent at any time), I do feel comfortable to dive a single tank with no redundant gas - even if I choose to do a staged ascent with one or more stops.

What I COULD do is set my tech computer to GF95/95, so I get the max NDL, and then ride the GF99 display to self-limit to, for example, a max of GF70. Or I could just change the GF to 3070 (or whatever) once I ran out of NDL. Either way is just not as easy as what I'm doing. Follow my Rec computer for NDL. Follow my tech computer for my ascent. Easy. Assures I get max bottom time, get out without getting bent (to the extent that CAN be assured), and can always go directly to the surface without violating at least the Rec computer.

What is wrong with using a Recreational computer for NDL diving but then choosing to follow a more conservative ascent than it recommends?? What is wrong with using a second computer just to tell me that ascent (instead of "making it up" in my head)??

 

[Storker]

to the best of my knowledge, pretty much all recreational computers on the market these days are "statistically" safe. In other words, if you follow the NDL on any of them, you are pretty darn likely to be able to do a direct ascent to the surface and not be bent.

So, having a recreational computer that tells me that NDL (which I believe to be very unlikely to get me bent on a direct ascent) gives me confidence that I can stay down that long with very little chance of a problem if I need to do a direct ascent.

This.

I usually dive fairly conservatively. Particularly after standardizing on EAN32; now my dives are almost exclusively limited by exposure protection or min gas, while on air they used to be limited by min gas and nitrogen saturation together. If I have to abort a dive and blow my safety stop, or ascend quicker than I planned to, I don't have a huge problem sitting out the rest of the day or making my last dive a short one. The ocean will always be there, and there's a more than fair chance I'm going to live another day to do another dive.

 

[admikar]

I am not against training, in fact, I plan on taking AN&DP class, as soon as one is available in my vicinity.
IANTD Advanced EANx Diver (OC, SCR, CCR) is good for up to 15 min deco.
IANTD Decompression Specialist don't have any limits posted, so I guess it is no limit deco.
But, what I want to know, what exactly is taught in these classes ( beside skills part) that can't be self taught from resources, both on and offline? Please, I'm not being inflammatory, just genuinely curious.
I have no formal training in deco diving, but having somewhat "BSAC diving culture" club, did some informal training.
It has been posted in this thread that some people tend to consider NDL as a "don't cross or die" line.
There was an instance where riding up on my computer would put me dead ahead of a cruiser ship. Instead, we chose to stay on the bottom for 5 more minutes, which resulted in 10 min of deco. I must point that this was not an unplanned emergency, it was planned contingency. Since I was diving doubles, it could be said it was a tech dive, but I am a rec diver.
So, I might say it is OK for rec divers to go for lite deco, but I am not that stupid.

 

[lowviz]

I am not against training, in fact, I plan on taking AN&DP class, as soon as one is available in my vicinity. ...//... But, what I want to know, what exactly is taught in these classes ( beside skills part) that can't be self taught from resources, both on and offline? Please, I'm not being inflammatory, just genuinely curious..

It's the real deal.

Your bod is on the line. You can break yourself badly. You REALLY want someone capable, observant, and serious on your first few dives who will watch, instruct, and assess you.

 

[admikar]

It's the real deal.

Your bod is on the line. You can break yourself badly. You REALLY want someone capable, observant, and serious on your first few dives who will watch, instruct, and assess you.

I agree. Sorry, I wasn't clear enough. I was with instructor I had "training" with, and which will teach my AN&DP class.
Would I do something like that on my own? Like I said, I am not that stupid.

Edited to add: What you say I consider as a skills part of a class. I was asking about theory part.

 

[uncfnp]

I really should stay out of this thread since I am an outlier and will/have just thrown the discussion off.

To me the biggest difference between a liberal and conservative profile and "lite deco" is not that the deco is optional. Its that I have more back gas reserve to allow for safe lite deco.

Deco is deco, liberal or conservative the algorithm makes no difference. "Lite deco" is deco that can be done with the given back gas and or less then (insert your comfort level time limit) although I probably would not do it on a liberal computer without redundancy, And this would be more because the dive will likely be longer then a conservative algorithm and so less reserve in the back gas. I have never surfaced with an obligation and I not intend to.


And I am not sure who DevonDiver is referring to with "hacking the computer."

For the recond and to hopefully unconfuse readers that don't know me. I would love to just dive an aggressive computer, surface and repeat. But that is not an option, even with extended safety stops. So for me its very conservative dives and I guess you could not really call it lite deco since I use a small deco bottle. For me, the "faux deco" is a true ceiling. Yes its a rec boat and in an emergency I would adjust. I know the risk I take and its taken me years to find the compromise that will let me stay in the water.

 

[Storker]

It has been posted in this thread that some people tend to consider NDL as a "don't cross or die" line.

While others have stated that they don't think they'll die, but they prefer to stay within limits to avoid normalization of deviance (which is a serious issue)

 

[lowviz]

I really should stay out of this thread since I am an outlier and will/have just thrown the discussion off. ...//... For the recond and to hopefully unconfuse readers that don't know me. I would love to just dive an aggressive computer, surface and repeat. But that is not an option, even with extended safety stops. ...//... a rec boat and in an emergency I would adjust. I know the risk I take and its taken me years to find the compromise that will let me stay in the water.

No, you of all people should be foremost in this thread. This is situational, one has to "get it" for oneself.

We don't all blindly go with the norm and expect success. You have found that out, on your own, brilliantly.

...//... What you say I consider as a skills part of a class. I was asking about theory part.

I have two books from AN-DP, reviewed both. Brush up on EAD before the course. I have a much more intuitive way to calulate it but it won't make sense until you get it (memorize it) the usual way.

 

[KenGordon]

Not a great advert for Suunto as technical diving instruments mate...

So, how should they differ? Should the 'technical' computer be more aggressive on the same settings as the 'recreational' computer?

And if you plan a square dive but do not stay at the maximum depth do you do expect your computer to give you the planned stops are something shorter?